Telescope back focus calculator. Guider SX lodestar (any version) optical back focus = 12.

Telescope back focus calculator Mar 27, 2024 · By using gears, this type of focusing design is less likely to suffer from slippage as other focusers are prone to, and are one of the most commonly used in today’s most popular telescopes. Back focus is a little different on a Rowe-Ackerman Schmidt Astrograph (RASA) t Calculate the focal length of your telescope. No need for a separate field flattener It now uses the more aggressive calculation based on the Goldman/Megdal article, In Perfect Focus, in Sky & Telescope, August, 2010. Then turn knob counter-clockwise to push the primary mirror forward and push the focal point further out the back . Some telescopes use extra lenses and/or mirrors to create a long effective focal length in a short tube. 5mm back focus is without the tilt plate. 6. This is a critical parameter in astrophotography. BUT - the field flattener you want to use at 700mm requires 96mm of backfocus - your camera takes up only 12. The back focus is the distance between the back of the telescope and the focal plane, i. For large numbers, do not use commas. Sep 1, 2022 · Back focus has multiple meanings. Guider SX lodestar (any version) optical back focus = 12. You can also find the back focus of your ZWO camera in this document: link (Excel, easier to view) or link (PDF, three pages). Flange back focus distance = 44 mm T-ring adapter for EF/EF-S mount back focus = 8 mm. Telescope back focus, Minus ½ Apr 9, 2017 · Page 1 of 3 - Telescope Simulator & Eyepiece Set Calculator - posted in Eyepieces: Hi all ! As I am currently translating my Stelvision personnal website, I am glad to present you the English version of an online tool which is beginning to be well known in France: a telescope simulator & eyepiece set calculator. I am informed by others that, no, it is 66mm. Your eyepieces are the first accessories you should learn to use with your telescope. That would leave an adapter Mar 22, 2018 · Page 1 of 2 - Calculating back focus for Celestron 0. So as the title implies, how do i calculate whats the back focus that i need for a specific telescope and camera. Sep 21, 2022 · With tilt adjuster attached, the diagrams show the back focus distance is 17. In the later years, I have been more and What is telescope back focuswhy is it importantand how do you set it correctly?Having the proper back focus between your telescope and camera is critic Jul 6, 2017 · What is Backfocus? In the simplest of definitions, it is the ability or inability of the focuser to bring the image into sharp focus be it through your eyepiece or your CMOS camera. My camera has been a Canon 1300D. Aug 24, 2006 · Since the calculator page that CF linked doesn't show how this actually works, here's the math. 8x. Image Circle will vary with scope design. Oct 1, 2023 · Telescope focal lengths vary widely, depending on the type and design. I finally found on a forum that I might need to extend the back focus (distance between the camera and the scope) so I tried this kit. SkyPortal App. Apr 19, 2024 · With these types of telescopes, typically as long as you can reach focus, you will see optimal optical performance, regardless of what spacing you use to reach focus. This is a Bower/Samyang mirror lens with a 6. 3″ BIG Paracorr Type-2 The first and most important thing to know is that that the 3” BIG Paracorr (VIP-3010) is only really necessary for fast scopes when you’re imaging with chip/sensor sizes beyond 30mm diagonal. pdf [PDF] 2 Practical Focusing - The New CCD Astronomy Apr 28, 2020 · Getting the proper back-focus for your imaging camera is a vital step in getting the best data possible out of your telescope imaging/research rig. 2X, and ZWO2600MC Pro with Filter Drawer, and was having lots of issues with back focus. Cheaper filters tend to be thinner, and you will need to add less compensation. In this article, we’ll discuss why back focus distance is so important, all the factors you need to consider for back focus distance, and how to use adapters and spacers to get the perfect back focus distance. If the threads of your telescope is M42 or M48, then we recommend you DIY the relative adapters or choose the 2” EFW. Celestron’s FREE planetarium app is an astronomy suite that redefines how you experience the night sky. 4 mm of aperture and 2,794 mm focal length at f/10. If I use the Celestron f/6. Field of View Calculator Test different telescope, camera & eyepiece combinations. Additionally, the beam quality parameter can be specified if the beam deviates from an ideal Gaussian. 142857142857×158=22. The Problem: I am unable to find an image focused Apr 9, 2017 · As I am currently translating my Stelvision personnal website, I am glad to present you the English version of an online tool which is beginning to be well known in France: a telescope simulator & eyepiece set calculator. Presumably, if I place a 20mm spacer between the rear cell and the focal reducer the focal length of the telescope will be different than if I place the focal reducer between the rear cell of the telescope and the 20mm spacer. 4km All values are approximate and purely theoretical under ideal observation conditions. They are based on the FR being placed in its designed position at the back of the SCT: In this episode of back-focus 101, I show how to obtain proper back-focus on the Petzval, using the William Optics RedCat51 as an example. Aug 31, 2017 · In most telescopes the focal length is roughly equal to the length of the tube. Telescopes come equipped with various types of focusers, and the focusing technique can vary This extra back focus can be useful, for instance when connecting your camera to a Newtonian reflector. For example, in a 12. Considerations on EHD Back Focus Tolerance under Seeing Limited Conditions. Already, the variation of effective focal lenght is far more noticeable than many of us usually think. It’s equal to the telescope’s focal length divided by the eyepiece’s focal length. You can start by consulting your telescope and accessory manuals for the necessary back focus distances. I think this will be the first post Im making on this forum. A camera with 55mm of back focus means that the imaging chip is located 55mm from the front of the camera. Attaching the Askar field-flattener/reducer will turn this telescope into a wider and much faster instrument, more info on Sep 20, 2017 · recommended back focus - posted in Beginning Deep Sky Imaging: I made a post yesterday about getting a new zwo asi224mc. Determined by the telescope's focal ratio, the CFZ is narrower in faster (lower f-number) telescopes, demanding precise focusing to capture clear, detailed images of celestial objects. Formula: Aperture X Focal Ratio . In addition to focusing fairly frequently, I also used Focus Feb 3, 2017 · Near focus is usually set to the Practical distance of the design of the Telescope in question. 63 times, taking it from 2032 mm to 1280mm. I have all the required spacers and no problems. Back focus is important because some accessories require a specific back focus distance to work properly and correct optical aberrations such as coma or field curvature. An infinity focus on a camera lens means that light rays flowing into the camera sensor are parallel and arrive as points. /Ira Feb 10, 2023 · The Askar FRA500 is a compact beginner refractor telescope with an aperture of 90mm, a focal length of 500mm, and a focal ratio of f/5. Then, use a ruler or a digital caliper to measure the distances from the focuser to the camera sensor. I am happy to spend lots of time perfecting backfocus and tiltIm just a precision kind of guy. The specific focal length of a telescope can significantly impact its magnification and field of view for astronomical observations. Dec 26, 2021 · I do not like using my fingers to achieve fine focus on the manual focus knob, so that is why I use the Meade’s micro focuser, using the hand controller, that came with the LX200GPS. Achieving a crystal-clear image through your telescope’s eyepiece is crucial for a successful stargazing experience. If your telescope has 100mm of back focus and you space things out so your camera chip is exactly 100mm behind the telescope but you have some optical filters in the path, your focus will be off. The primary is a parabola, so we know how to Focusing a telescope may sound intimidating, but it’s actually a remarkably easy process. 7 cm² • Light gathering power: 319x • Angular resolution: 0. May 18, 2020 · Question about focal reducers and back focus. Equations to determine the conic constant of primary and secondary mirrors in Cassegrain telescopes. The CFZ is related to the telescope angular separation under diffraction limited conditions. Focal Ratio Calculator Mar 3, 2017 · How do you calculate the true focal length of an SCT with a focal reducer in two different positions. Sep 26, 2024 · Note: This solution only applies to telescopes with M68 interface threads. if the calculator shows that a certain eyepiece gives 100x in your telescope, and you add a 2x Barlow, the resulting magnification will be 200x (100 x 2). Adding extensions tubes before the diagonal can correct situations where you need more backward focus, but for Aug 27, 2021 · Procedurally, if the back focus distance isn't known but the reduction factor is, am I safe to test at two or more different distances, platesolve to establish the achieved focal length at each distance, and calculate the back focus distance that gives the required reduced focal length? (in my case, 2032mm x 0. 1, I need to adjust FLAT6III to 7. Contacted Meade, OPT, Lepus, and was informed by all that back focus should be between 105mm and 110mm with 110mm supposed to be optimum. Sep 10, 2023 · The back focus for your telescope imaging train is the measured distance from the last optical component at the back of the telescope, whether it’s a coma corrector or field flattner / focal reducer and the focal plane of the telescope where the camera detector is. Will the barlow affects the focus, and if so will the focusing tube be more inward or Feb 21, 2021 · William Optics GT81, FLAT6AIII, AIS533 back focus question - posted in Beginning Deep Sky Imaging: I have this setup and I have a question for back focus 1. By folding the light path and slowing down the convergence of the light cone, we shorten the tube to about the focal length of the primary mirror, while the telescope has a focal length of somewhere between 3 and 15 times the focal length of the primary! A telescope focuses a star as a round point of light. Jul 15, 2008 · Page 1 of 2 - Barlow : effect on focus - posted in Eyepieces: hey! another newbie question!How does a barlow affects the focus of a setup? I have a WO66SD, a TMB 6mm Planetary and an Antares 1. Aug 23, 2016 · That means the portion of the backfocus - the distance (basically) from the back of the telescope to where light is correctly focused - that this camera takes up is 12. A side effect of Barlow lenses is the increase in back focus (the distance between the telescope to the end of the optical setup). I expect that you would find in the eyepiece , swap over to camera, then wind the focus "inwards" to get the camera at the correct place. Jan 11, 2018 · Backfocus measurements specify the distance between the back of your telescope and the point at which light is focused. How Do I Measure Back Focus on My Telescope? Measuring back focus requires precision. Apr 26, 2011 · prime focus image circle - posted in Beginning Deep Sky Imaging: Is there a formula to determine the diameter of the image circle produced by a given telescope, and/or the angular dimension (TFOV?) of that circle (Im not sure I have the correct terminology. It seems it lacks about an extra inch of back focus to bring most of my eyepieces to focus. Barlow lenses can help you increase it. 5 Classical Cassegrain, K p = -1 for the primary and K s = -4. I have an APM/LZOS 152 triplet refractor and APM was kind enough to provide a spreadsheet (attached) that shows the focus distance from the back of It is primarily oriented to the Newtonian reflecting telescope, which is what most first time telescope makers build, although many sections of it are applicable to other types of telescopes. Mar 29, 2016 · Page 1 of 2 - Effective focal lenght in a Maksutov-Cassegrain - posted in Cats & Casses: Hi, We know the effective focal lenght (EFL) of moving mirrors Cassegrain type telescope systems depends of distance between mirrors. 5mm and when off it is 12. Since many telescope makers want to compare two designs in order to decide on the right telescope for them, this calculator computes parameters for two Nov 28, 2024 · Applicable to the following Flattener: Ultra Flat 132; Ultra Flat 156; For other flatteners, please refer to Flattener Back Focus Adjustment Aug 18, 2023 · This adds up to the standard 55mm. Refractor / Refracting Telescope. Worry not! Today, you will learn how to properly focus your telescope and make the experience of viewing the starry sky a better one. 8 x) with 55mm back focus, a ZWO ASI294MC pro cooled cmos imager with 6. Feb 16, 2019 · As you can see, the 1200mm telescope gives a higher magnification with these eyepieces – and the 10mm eyepiece gives a higher magnification with both telescopes. I have read post after post here where people say they are still working on getting proper back focus. Due to their design, some telescopes like Newtonians/reflectors, have very little back focus. I want to attach a flattener/reducer (Astro-Tech 0. The design of barlow lenses also results in an exit pupil which is further back from the eye lens (increased eye relief). First is a Meade Series 4000 f/6. 5x or 0. Which is it 61mm or 66 mm? There are two editions, that I know TripleSpec Slit Viewer Focus Calculator TripleSpec is a fixed configuration Near Infrared Spectrograph. Highlight the numbers already entered in the boxes and delete them and enter your own. So the telescope and eyepiece affect the magnification in different ways: Telescopes with longer focal lengths will give a higher magnification (for a given eyepiece) Assuming you use the telescope as the lens for the camera at prime focus the focal distance of the camera becomes that of the telescope. 5 mm of back focus with the ASI533MC Pro camera. 3mm (black), 0. 63 reducer and it should have back focus of 105mm, so if I use celestron SCT 2 diagonal how do I calculate correct spacing thank you!! Jun 20, 2018 · I also get a bit confused by this, I thought it related to the distance of travel on the telescope's focusing mount, but with my ES Refractor the spec stated 130mm backfocus, but there was only 45mm of travel on the focusing mount, I think they also added on the two 40 mm extension tubes supplied with the instrument, which I thought was misleading. Using Telescope Eyepieces. This process is easier when the telescope is pointed straight up near the Zenith, so try to use a bright star that is high overhead to focus on. How would a person go about figuring out what the recommended back focus is. The diameter is the same as their regular Astronomical telescope, but the tube is extended so near focus is a matter of feet instead of Yards or meters. I have always been careful to focus for each filter and would also re-focus every 30 minutes or so as the temperature up here falls pretty quickly in the early evening. Calculate the focal length of your telescope. 2mm when you are using Radian and Chroma filters (3mm thick). But the optical plane of an eye peice and a camera are in different relative places. thanks, Davidt Nov 9, 2020 · The Barlow lens will extend the position of the primary focus plane out of the back of the telescope, as compared to its original (non-Barlow) position. Please see the What is HyperStar? page for This site contains affiliate links to products. , how far back the telescope+flattener will focus the image. 5mm of that. So, now we know what 17. An example is Questars 90mm Close up lens. A formula to calculate how much extension rings you need to fill the gap to achieve the backfocus set by the optics is the following: ER = BFopt - BFcam - BFother. Im looking at Dec 21, 2020 · Backfocus calculation on a camera lens - posted in Experienced Deep Sky Imaging: Album: Misc 1 images 0 comments I am wondering how to calculate the required backfocus in this setup. 00 for the secondary. And much more. My Canon Rebel T7i camera has a back focus of 44mm. The telescope can be used with full-frame cameras, and the built-in reducer/flattener means you do not need to calculate the back focus. 5 for GT81. A refractor has a fixed focal length, the distance from objective to the focal planed, and no back focus requirement. Aug 3, 2023 · 2600MC Pro - Back Focus Question - posted in Experienced Deep Sky Imaging: Ok folks, so I am one of those pixel peepers that likes to have perfect stars to whatever extent possible. You might find you have closer to 101mm of back focus rather than the expected 100mm. Then, add up the spacing distances of all of your pieces in your optical train to your sensor. There are five connection solutions for ASI6200MM Pro. Most telescopes have an external focusing device that physically shifts the eyepiece or camera back and forth along the optical axis Nov 23, 2023 · Utterly confused about back focus - posted in Experienced Deep Sky Imaging: Hello all, I have grappled with this all my astro-imaging life, but I had kept my equipment simple up until now - so there was no need to worry too much about it. It came with a FLI Atlas focuser and a TOA-67 flattener (disregard the reference to Mar 28, 2018 · SkyWatcher Esprit 80mm - back focus - possible confusion - posted in Refractors : I have recently gone through a rather intense period of confusion over what the correct back focus is for my lovely SkyWatcher Esprit 80mm. I recently purchased a used TOA-150 to set up at my remote observatory. 2. 4mm which you can set with the built in scale, or more accurately with callipers. My field flattener is the 2“ from Skywatcher and has a back focus of 55mm and my T-Ring is 15mm. 6x 2in barlow (dont have it yet, want a 2in for photography, and plan to use it visually with 2in-1. Magnification (power): The amount that a telescope enlarges its subject. Optimum back focus distance (T-Ring shoulder to focal plane) is 56mm. You first need to know the metal back distance requirement of your telescope or corrective optic piece. Jan 24, 2022 · Achieving Optimum Back Focus Distance - posted in Beginning Deep Sky Imaging: Im working to better understand back focus and how to achieve the optimum back focus distance of a particular imaging train. 3 focal reducer/corrector on a 6SE OTA? Ive seen the number 105mm in a few places Mar 10, 2021 · Filters refract, so they actually add to the back focus. Enter any ONE of the following four parameters and click the corresponding "Calculate" button to calculate the other three parameters. No need to calculate back focus Small and round stars, with a central RMS radius of 2. Or setup with eyepiece at same Sep 30, 2023 · The back focus for your telescope imaging train is the measured distance from the last optical component at the back of the telescope, whether it’s a coma corrector or field flattner / focal reducer and the focal plane of the telescope where the camera detector is. 5mm back focus. See the image further down the page for more info. Its purpose is helping beginners to get an idea of what they can see in an amateur telescope, according to its diameter SC 3. This includes the depth from the front of your camera to the chip itself, the depth of a filter wheel or off-axis guider, and the depth of any Enter your GoldFocus mask, telescope, camera, and imaging data in the boxes below. Cassegra in Equations for description of terms in drawing: primary focus intercept point (p), secondary to Cassegrain focus (p ·), primary focal length (F), secondary magnification (X ), back focus (b), mirror separation (B), secondary clear aperture (c), final image size (I), primary diameter (D). 25 SCT and use a focal reducer, I Feb 1, 2022 · New fine-adjustment spacer rings from Baader in three sizes 0. The focal length of the objective usually goes hand in hand with the length of the telescope itself. Essentially my understand is that the back focus is the distance from the last optic element to the sensor. The Cassegrain telescope optical equations. In other words, you rack the focuser all the in or all the way back but can not acquire sharp focus. It worked perfectly. Jan 8, 2024 · Determining the correct back focus for your telescope can be a daunting task for both beginners and experienced astrophotographers. Where: ER: Width of extension rings Jun 5, 2022 · Image circle size calculation? - posted in Beginning Deep Sky Imaging: How do you calculate image circle size for a telescope? I am trying to determine the circle size on an Orion EON 115mm triplet. The focal length 805mm. 5" of back focus—sufficient for catadioptric telescopes (Schmidt-Cassegrain and Maksutov-Cassegrain), as well as a good number of refractor telescopes. One of the mistakes frequently made by beginners is starting with too high of a magnification. 5" F/12. 63 reducer/corrector - posted in Beginning Deep Sky Imaging: Apologies in advance, Im sure this would have been discussed before but Ive searched to no avail Could someone help explain how to calculate the optimal back focus/spacing for the Celestron f/6. Messier: Solar System: A telescope focuses a star as a round point of light. While a C11 scope at f/10 can deliver a 0. 3 focal reducer. Simply screwed the T rind right to the reducer. The camera kit takes up 63. I recently picked up an ASI1600 MM cooled camera, the ZWO Filter Wheel, and have the following scopes: ES 80mm f/6 refractor Meade ACF LX600 12 (305mm aperture, f/8) Do I need to add spacers if I have the 1600 at prime focus? I know that if I were to get a field flattener Jun 13, 2019 · The design reduction factor of a focal reducer is the relative amount by which the effective focal length of the telescope is reduced when the focal reducer is used at its specified working distance or back focus. Afocal photography is different and varies based on each optical element in the train. There is also many times a debate of what the proper back focus distance actually should May 31, 2024 · As you can see, the magnification of the telescope gets greater when the focal length of the objective increases or when the eyepiece's focal length decreases. So I use the Explore Scientific 80ED telescope which has a back focus of 165mm. Depending on the diameter and thread on the back of your telescope, you may need different adapters or extension rings. 93" • Limiting magnitude: 13. For prime focus scenarios . Focal Ratio Calculator Apr 14, 2023 · LXD75 Back Focus - posted in Meade Computerized Telescopes: The Equipment: I am trying to use a ZWO ASI2600 camera with my Meade LXD75 10 inch telescope with the factory focuser installed; Ive attached a photo. Before buying a telescope and a flattener, you need to verify how much backfocus is available for that combination. Assuming high quality optics, the diameter of the point of light is determined by the telescope’s focal length (longer focal lengths result in larger star diameters) and the sky's ‘seeing’ conditions (atmospheric dispersion spreads the point of light, making it larger). Feb 2, 2021 · Back focus calculation - posted in Beginning Deep Sky Imaging: Hello everyone, So i think decided on what telescope and camera i should get for AP but i dont know if theyre compatible right out of the box. 5mm back focus refers to the camera with the tilt plate and the 12. Telescope focal length increases 15%. 57142857142 So, if this is correct, the image circle at Sep 3, 2019 · Barlow and Back Focus - posted in Beginning Deep Sky Imaging: Hey folks, can someone help me understand how much a barlow impacts optimal backfocus in an imaging train? I assume this has been answered clearly some place that I simply cannot find My gear: OTA: Celestron EdgeHD 8 Barlow: Televue Powermate 4x + 2x Filter Wheel: Starlight Xpress USB Camera: Altair 1600M PRO My current Dec 15, 2018 · The 12" SCT has a huge back-focus range ! How much back-focus do you need? Begin by turning the knob fully clockwise - that pulls the primary mirror all the way back and focal point all the way in. Backfocus Formula. So 62. I use celestron 0. The back focus is 158mm. Generally speaking, if I'm adjusting my telescope optics, I let the scope equalize outside for about two hours. Im curious about trying some prime focus Oct 5, 2023 · There is an excellent blog post on the Takahashi America website (https://takahashiamehe-gordian-knot) that provides information and directions to calculate the right amount of spacers that will put the focal plane at prime focus roughly in the middle of the focuser range: "A. Just about all scopes will cover the field of a 1. Since the ESATTO has a depth of 67mm and the 3. Using adapters only *This solution needs the M48-M48 16. These conditions create very inconsistent and funky-shaped stars. The other calculator is useful for determining where a dust particle is by measuring its resultant dust donut diameter in pixels. ASI 533, with given rings etc is 55mm back focus length. So a focused eyepiece means an out of focus camera. X Focal Ratio: f/ = Focal Length: mm. I hope my questions make sense)? Ive got a micro four thirds camera and a 130mm f/5 newt. - posted in Beginning Deep Sky Imaging: Hello all. My manual cites 61mm - multiple times. Does this happen with yours? What do you do about it? If I dont fully seat my 2 diagonal and eyepiece I can get to focus, but that doesnt make me very happy. Does that mean it is using up 85 mm of your scopes BF, so if your scope was 100mm BF, you would have 15mm left? Or is it adding 85mm of back focus, now making your scope 185mm BF which you would have to make up with t-rings and such. Jan 22, 2021 · 9. As per WO website, FLAT6111 (https://williamopticnt-not-included), back focus is 62. Visual Mode Imaging Mode Binocular Mode Choose Object. focal length x angular size (in radians) = size at image plane Reorder this to calculate angular size angular size (in radians) = size at image plane / focal length Feb 13, 2022 · Never attempt to collimate, focus, or adjust back focus during poor seeing conditions or while the OTA is equalizing to outdoor temperatures. 25 SCT and backfocus - posted in Cats & Casses: I have a 9. Aperture: mm. I have set the backfocus properly at 105MM. Mar 20, 2021 · The guider thickness seems to put the back focus farther back than it should assuming a 105mm back focus for the reducer but I can still get everything in focus including the ASI 174 mini guide camera ( which is awesome ). My original question was to ask what the expected focal length of an Edge HD 8 was, so that I could plate solve back to the right length in alternate image trains. 142857142857 . 3 FStop. If you have one those those latter telescopes, you can artificially extend your back focus using a lower magnification Barlow lens Nov 14, 2020 · Back focus. What happens if I get rid of the reducer in my setup and try and shoot at F10? Will I still be able to focus where the existing camera sensor is or do I need new spacers? I will Feb 28, 2021 · A Simple Solution to Determining Classic Cassegrain Baffle Length - posted in ATM, Optics and DIY Forum: If you have built or are building a Classic Cassegrain you may have encountered a very frustrating challenge in determining the proper baffle length for the primary mirror which is critical for good optical performance. My Aug 27, 2021 · How do you measure your back focus? - posted in Equipment (No astrophotography): I have always wondered how you guys calculate or work out the right back focus distance in your setups. This is probably t Feb 25, 2021 · Edge HD back focus - posted in Celestron Computerized Telescopes: Hi, Heres a recent support thread from Celestron. However, perfecting the focus can often prove challenging. The recess on the ASI2600 is 17. So if I calculate the camera Back focus plus the 10mm from the T-Ring plus the FF I get 114mm. Depth of focus describes focus at the film plane, and depth of field describes focus at the subject. Aug 21, 2020 · Page 1 of 2 - Back focus of SCT - posted in Cats & Casses: Hi, this is a newbie basic question. Specifically i am planning to use the SkyWatcher EVOSTAR 72ED DS PRO Apr 29, 2022 · Back focus is a term that causes much confusion among newcomers to astrophotography. 56mm • Light area: 122. Why would you want to do that? Feb 29, 2020 · HyperStar lenses are currently available for four telescopes: 6", 8", 9. For more information please visit NOIRLab Official Website for triplespec. This might be a stupid question but Im having trouble reaching focus with my 16 RC and an ASI2600MC Pro. Back-focus in astrophotography. Sep 29, 2023 · SV503 80ed and Uranus-C Back Focus Questions - posted in Refractors : Greeting all. Maksutov-Cassegrain Telescopes than focuse images by moving mirrors Jul 29, 2023 · Increased back focus. Is that right Jul 16, 2021 · The back focus length has been extended to 80-mm to allow for additional accessories to be placed in the optical path. Calculators already have sample data in them. Im trying to determine the correct backfocus for a flattener with my system, taking into account the thickness of the filters. com Search the The Critical Focus Zone (CFZ) of a telescope is the range within which the focus is acceptably sharp for astrophotography. Use this formula to calculate the resulting focal ratio when using a focal reducer with one of the 'classic' SCTs, note that the calcuations are only valid within 'sensible' ranges of focus. Is their a sticky explaining how you get the recommended back focus? How would you calculate in a focal reducer Dec 31, 2013 · Critical Focus Zone - posted in Experienced Deep Sky Imaging: Weather and work and all finally cooperating so I am working on some imaging again after a long break. Determining this distance can b A Barlow Lens, placed between the eyepiece and the telescope, will increase the Resulting Magnification by the power of the Barlow; i. 4″ (arc-second) Airy disc FWHM (or about 13 microns spot diameter for ~80% of encircled energy) in the visible (550nm), the inevitable atmospheric turbulence, or seeing, is usually much more than this. Sep 9, 2014 · Page 1 of 2 - Considering filter thickness when calculating backfocus - posted in Experienced Deep Sky Imaging: Im confusing myself here and could use some clarification. I got my brand spanking new 2600MC Pro and got to thinkingthis is the first unit I have owner with a built-in IR May 14, 2023 · Is there an APP or procedure to calculate the focus point for different telescope setups. 1. To this point, we have used 48. This makes it more difficult to get the telescope’s focus dialed incorrectly, so always start with low power (low magnification) and work your way up slowly. I believe the correct back focus for this unit is Apr 4, 2022 · When used to connect to M48 tubes, this adapter consumes an additional 4 mm of back focus. Apr 26, 2021 · In this episode of Back-Focus 101 I cover the basics for attaching a DSLR camera or CCD/CMOS style camera to either the Celestron C9. This is the distance from the camera's internal optical sensor to the face of the camera. 7x focal Oct 27, 2022 · Focusing a telescope may be, at times, challenging, as every telescope has a different focuser, and there could be slight differences in the procedure. Apr 14, 2021 · back focus with diagonal - posted in Beginning Deep Sky Imaging: Hi guys! just a quick question how does diagonal affects back focus? I know you shouldnt use diagonal for imaging, bu ti need to sometimes for clearance reasons. I may receive a commission for purchases made through these links. This is where the optical accessories like a reducer needs a certain distance behind it to ac The Critical Focus Zone: A common and popular figure of merit for focus accuracy is the Critical Focus Zone (CFZ). 5um Various adapters: M68/M54/M48 Dual speed (1:10) focuser. 5mm back focus, and eventually a filter drawer with 21. com The back focus for your telescope imaging train is the measured distance from the last optical component at the back of the telescope, whether it’s a coma corrector or field flattner / focal reducer and the focal plane of the telescope where the camera detector is. The design most heavily impacted is the Newtonian due to its short back focus; the only two possible fixes are to move the mirror and its cell up in Celestron RASA Back Focus - How to Calculate Back Focus - What are my Options. If this sounds familiar, I have a simple and straightforward approach Sep 17, 2016 · I could never get the telescope lens to focus with the camera. 25 EdgeHD, C11 EdgeHD, a 1) Diagram, Variables, and Design Formulae Cassegrain telescopes are built to reduce the physical length of the telescope tube. Im not entirely sure that I got an answer, but still r. It may or may not help. 1 extend. Common focal lengths for amateur telescopes range from 400mm to 3000mm, with larger telescopes often having longer focal lengths. Getting the proper back-focus for your imaging camera is a vital step in getting the best data possible out of your telescope imaging/research rig. However, we find 55 mm is still a good target for achieving focus with these scopes and encourage using the setups from this section (sans corrective elements, of course)!. 3 SCT focal reducer/corrector. ) Oct 25, 2020 · No "back focus" as such. 25" eyepiece barrel, and scopes with 2" focusers will usually cover the field of a 2" barrel (There are some exceptions where the field is bigger than 1. Supports both fine and coarse adjustment Self-flattening design. 5mm — the difference being the 5mm thickness of the tilt adjustment ring. 5mm. Aug 3, 2018 · Calculating Backfocus - posted in Beginning Deep Sky Imaging: I am extremely new to imaging and could use a bit of help. The focuser mechanism extends 55mm minimum from the OTA, and the adapter that connects the focuser tube to the camera is another 18mm. Note that depth of focus is different from depth of field. Back focus was not an issue. 63 = 1280mm) May 7, 2009 · Back focus directly impacts your ability to use accessories with your telescope. You may also change the binning to see the effect this has on pixel resolution. 5 mm Nov 4, 2012 · Take control of your telescope! Download the Celestron PWI Telescope Control Software. Last night was the first time I tried guiding and had no problems finding focus as well as finding guide stars. Beginning from the camera end, we do this: Consume 6. Your Flat73 requires an additional 11. 5mm extender and the M54-M48 21mm extender. I can in fact be any lens. Ive had the account forever though. Jun 26, 2022 · The back focus is specified by the manufacturer, no calculation is on the part of the user. Jan 7, 2021 · If the eyepiece connects in the middle or in the upper half of the body of the telescope (like most reflectors/Newtonians), your telescope has a low back focus and you might not benefit much from a binoviewer. Field 5 in the calculator is the sum of the back focus and the length of your camera’s nosepiece. See full list on agenaastro. - posted in Beginning Deep Sky Imaging: The meade f/6. Feb 25, 2021 · I've been playing around with Meade ACF with a Lepus Reducer 6. This works well. 3 focal reducer, I know it reduces the focal length of the scope by 0. In this article, we will explain what how to focus a telescope actually means, how focusers work, and why it’s important. Im currently using an SVBony SV503 80ed with its dedicated 0. Sep 26, 2024 · How many solutions are there for ASI6200MM Pro to get 55mm back focus length? If you are still stressed with these problems, then this tutorial is exactly what you are looking for. A flattener requiring 55mm of back focus means that the imaging chip must be 55mm behind the rear flange of the corrector for it to work properly. Someone mentioned recommended back focus, a google search revealed nothing helpful. With a standard Canon DSLR, the sensor is recessed much further back to make room for the flip mirror, this is why a Canon T-adaptor is so much thinner, but the optical length is the same 55mm. e. Here back on Earth we are seldom diffraction limited. Mar 25, 2015 · Back focus on Explore Scientific 127 APO - posted in Refractors : I just got a new ES 127 APO. 2mm as the back focus (most Takahashi telescopes, as example), the mechanical back focus needs to be 57. 3° For Dobsonian/Newtonian, use Paracorr to correct coma. Formulae used for these calculators Jun 25, 2009 · Take control of your telescope! Download the Celestron PWI Telescope Control Software. That's the reason why the highest-powered telescopes are such monsters with huge mirrors. Calculated data cannot be entered. (However, as mentioned previously, most Newtonian reflector telescopes will need a 2x Barlow or an amplifying lens for the binoviewer to reach focus. Click Calculate and the pixel resolution and field of view will be displayed below. We would like to show you a description here but the site won’t allow us. Feb 4, 2022 · Just looking at this calculator, but I assume it just is programmed with the correct back focus for a certain setup of camera, FW with a certain corrector or flattener, then adds on 1/3 thickness of the filter and then gives you the remaining spacers needed to make up that back focus, so nothing different to manually adding up all the elements and doing a bit of maths. In the picture, it seems incorrect. 3” adapter has only 2mm of optical thickness, this leaves 77mm of backfocus for your camera and accessories, also when used together with the Celestron EdgeHD . 3 focal reducer says it has 85mm of back focus. The flattener needs 95mm. I've read and seen videos saying that you have to get the back focus exactly right to achieve a sharp focus on the imager. 25", 11" and 14" Celestron Schmidt-Cassegrains. 4) With OAG-L and 2” filter: If you have an OAG-L, but do not have & want to use any filter wheel to reach 55mm back focal length. Quintuplet air-spaced APO design. I have recently acquired a few bits of kit that will be used with my 85 C8, and I want to make sure that I am following the correct procedure with them. A refractor is a telescope design that uses lenses to gather and focus light. Apr 10, 2021 · Correct procedure for setting focus and back focus with an SCT reducer - posted in Equipment (No astrophotography): Hello all. This calculator computes the spot diameter of a collimated Gaussian beam whose wavelength is and diameter at lens when it is focused with a lens having a focal length . Oct 30, 2005 · What is the FOV at prime focus? - posted in Film Astrophotography: Is the correct way to calculate the magnification at prime focus through a 35mm camera body the focal length of the scope, divided by 50? How do you calculate the FOV based on this info? How much of this FOV would you expect to actually capture on the film? If you enter an actual focal length and ratio then any selected telescope will be ignored and the extender/reducer factor will be applied to this entered value. Heres my attempt: 115÷805= . With these inputs, the diameter of the focal spot is Jun 17, 2021 · Focal Reducer Effect on Back Focus Distance - posted in Beginning Deep Sky Imaging: My Celestron Evolution 8 Edge HD has a back focus requirement of 133mm (back of scope to face of chip). With limited back focus, you may not be able to use Barlows, focal reducers, binoviewers, SLRs, and 2 in eyepieces. 8x field flattener\\reducer. The first light back-end instrument for this telescope will be a faint The optical ray drawing shows the telescope focus, the pupil plane and the 3305513-535. So, if the manufacturer specifies 56. Depth of field describes the range of focus that appears sharp in a photograph for subject planes in a scene for a given lens at a particular focal ratio. You "simply" focu the image on the sensor. The user does some arithmetic (back focus- sensor recess on camera = spacers required. So how to figure the mirrors? Calculate K values for the mirrors in your Cassegrain. Does the back focus point of a SCT telescope change position at all with the movement of the primary mirror? Or does the back focus length only have meaning when focusing at infinity? Thanks jk About this calculator. Calculator Instructions. Useful for getting that precise backfocus distance from a reducer or flattener when imaging and prevents binding between two M48 threaded parts. Read our guide! Nov 20, 2021 · Understanding back focus - posted in Beginning Deep Sky Imaging: Im upgrading to a ZWO 1600MM and Im trying to understand what Id need to achieve the correct back focus for my setup - but Im struggling to fully understand what it is - or more specifically why its so important. You need to place your camera (or eyepiece) at this point to see an in-focus image. This is because when people talk about back focus, they often mean different things: the back focus on a telescope, the required back focus for accessories such as field flatteners, or the flange focal distance of DSLRs and astro cameras. gooday@btinternet. (The standard nose piece supplied by ZWO is 30 mm in length). Dec 28, 2023 · Back focus is the distance from the last optical element of your telescope or accessory (such as a field flattener or a focal reducer) to the focal plane. Now I can focus the telescope and get someowhat decent pictures. This factor is designated by a power that is less than 1, and it usually lies between 0. Depth of Focus. In the beginning of my astrophotography journey, i just went with the standard 55mm which seems to be a standard measurement for more or less every OEM corrector/reducer. This is a Jun 26, 2023 · One of the biggest parts to astrophotography is the back focus. Oh, I did some years back, upgrade the manual focuser with the Peterson EZ Focus product. In a nut shell it is the smallest angle for which two star diffraction patterns (Airy disks) can Feb 4, 2017 · While appointing your telescope at a bright star, you simply place the Bahtinov focusing mask on your telescope’s objective lens and secure it into place using the provided rubber tabs. They are sure, 100%. However, if you now focus with an eyepiece, the eyepiece focal plane (usually the field stop) will then coincide with this new primary focal plane. 25 SCT with a Meade 4000 6. When I connect everything less the pictured lens to my 9. 25in adapter). IBF = 44 + 8 = 52 mm back focus (low profile configuration) Notice: T-ring adapters for most cameras are designed and made to lead to a 52mm back focus distance (like here for the Canon EOS). 5mm (red) and 1mm (gold). 5 mm of back focus. This is a Oct 7, 2021 · 11 Ways to Fix Telescope Focus Problems Start with a low magnification. 3” adapter for ESATTO 2" allows you to connect the ESATTO 2" to Celestron SCT (11" and 14") and EdgeHD (925, 1100, and 1400) models. 0 • Moon features: >5. So, for example, if your telescope has a backfocus of 100mm, the plane of the sensor should be 100mm from the end of the telescope. The main lens is 115mm. 25" but doesn't cover the full 2"). Reflectors often lack the back focus required by DSLR cameras and a barlow can fix this problem. Read our guide! Apr 13, 2022 · It uses approximately 3. Some are examples from my telescope, a C11 SCT with 279. This is known as the Rayleigh’s limit. • Prime focus magnification: 29x • Re-focus distance: 1. Its purpose is helping beginners to get an idea of what they can see in an amateur Aug 14, 2024 · Telescopes open our eyes to the marvel of the cosmos: the telescope field of view calculator will tell you exactly how much! Here you will learn: The basics of telescopes and eyepieces; What are the mysterious numbers on an eyepiece?; What is the field of view of a telescope?; and; How to calculate the field of view of a telescope. Telescope used like telephoto lens; Field Angle = (Image Diameter ÷ Telescope Focal Length) x 57. Jul 27, 2021 · To be able to calculate the back focus distance whilst maintaining the optimal focal ratio you desire, you'd have to have precise data from the manufacturer, and use an iterative calculation that converges on the exact value you want. The distance between the rear of your telescope and the point where light is focussed is known as back-focus measurements. 5 - 55 = 7. djwnzb psst ffcvipr akio iajxlo goqq sudlj utc yev yry