When the camera sensor is placed at this distance, the reduction factor of these reducers is 0.75x. Newtonian reflectors will seldom be able to accommodate the in-focus travel demanded by focal reducers. In the 1960s, Celestrons founder, Tom Johnson, created groundbreaking new telescopes never before seen on the consumer market. In many cases, the answer is yes, especially for electronically-assisted astronomy (EAA). As a real-world example plot showing the above relationships, let's look at the 1.25" GSO focal reducer that provides a design reduction factor of 0.5x. The Antares f/6.3 Focal Reducer for Schmidt-Cassegrain Telescopes is a low-price option for reducing the focal length of your Schmidt-Cassegrain telescope from f/10 to f/6.3. The focal length of a focal reducer is usually measured from the rear lens surface of the reducer (and not the reducer's housing). I have/had both the Celestron (Japan) and Antares units. The Celestron f/6.3 is ~150 compared to the Antares at ~70. Obviously bright objects like Jupiter or The Moon show the reflections. I would not use the reducer with a 2" diagonal or eyepiece in the C6. This means that there must be sufficient travel on the telescope focuser to make up for this. Not noticed any optical problems. We have tested our current batch and it works with Meade, Celestron, and Baader SCT accessories. Add a 0.63x reducer, and the brightness of extended objects increases by (1/0.63)2 = 2.5. Steve If I had to chose one, I would base my decision on your level of light pollution perhaps the Antares for its slightly higher transmission if you live under less light polluted skies, but the Celestron for its greater contrast if you are dealing with a suburban or urban light dome. This factor is designated by a power that is less than 1, and it usually lies between 0.5x or 0.8x. Here, there was a subtle difference . The problem with those SCT reducers is that they cause chromatic aberration and require refocusing when using parfocal RGB/other filters. Many focal reducers are meant to be used within a few millimeters of the specified working distance to achieve the best possible image results. Perhaps not exactly- there will be some uncertainty because of manufacturing tolerances and so forth, but it will be close. These reducers can also be used for visual observing with SCT scopes with eyepieces with a field stop as large as 24-27mm. It's usually specified in millimeters. It works fine but you should stick with 1.25 EPs; or can use 2" EPs without corrector. How does it look thats what matters. Most focal reducers are designed to operate optimally at the working distance in the optical path to achieve their specified reduction factor, which is usually between 0.5x and 0.8x. Focal reducers for refractors are easy to use. One problem with getting opinions is that most of use do not have both reducers or have never done a side by side comparison. We have placed cookies on your device to help make this website better. WiFi technology encircles the globe in a web of connectivity, knowledge, and information. In your opinion, is the Celestron is worth the added cost ($150 vs. $90)? As one increases, the other decreases. Figure 7 shows an example of an image of the Dumbbell Nebula taken with a 1.25" GSO focal reducer at a reduction factor of 0.63x with an 85mm f/7 refractor and a QHY5III-290M camera with a sensor with a 6.4mm diagonal. Never used one, but read the reviews here that suggest a coating problem. It's important to match the back focus to within a millimeter or two to get an optimal image, especially with cameras with larger sensors. During checkout, you may also be shown other optional faster shipping choices.US Customers in Hawaii and Alaska: Free shipping applies to almost all products. I think I remember hearing the reduction factor is slightly different, cant remember more or less reduction. Even though they may have been slightly dimmer, galaxies were a bit easier to tease out of the urban light soup I deal with. The Buyer's Guide To Eyepieces at the top of the Eyepieces forum has a column for this spec. I was originally hoping to do this with a made in Japan Celestron, but ended up with a newer China version but thats probably better in the end since it is the version now available, with the Japan ones rarer and only available used. Optically, it consists of a four-element lens that is fully multi-coated for high contrast and resolution. It is not a corrector or flattener. Celestrons FREE planetarium app is an astronomy suite that redefines how you experience the night sky. If you want to save a few buck watch the classifieds on CN. A few people have reported issues with the male SCT thread diameter on this item being a bit larger than necessary. The Antares FR2-0.7X is the same 4-element f/6.3 lens system used for f/10 Schmidt-Cassegrain telescopes but in a 2" barrel threaded for standard filters. No small animals were harmed in making these observations. Focal reducers for many SCTs and their flat-field equivalents usually have a back-focus distance of 105mm. No rainchecks will be issued for items out of stock at OPTcorp.com to match a competitor's price. I read another thread in a different forum about F6.3 reducer correctors and one amateur posted an image about glue coming out of an astromania f6.3 reducer which he planned to return. A longer effective focal length leads to higher magnification with a given eyepiece for visual observers. An f/6.3 reducer is designed to reduce the focal ratio of an f/10 SCT to f/6.3. It seems right to put some distance between the camera and the focal reducer, right? A couple of tiny dust particles between lens elements, uneven lens edge blackening, very minor coating blemishes, or even a very small fine lens scratch or two are very common in this Antares product and must be accepted as normal for this item. A reducer is a set of converging (or positive) lenses that cause the light from a telescope objective to converge at a steeper angle to the focal plane as if it were coming from an objective with a faster (lower) focal ratio and a shorter focal length. It's an either/or proposition: reducer and 1.25", or 2", but not 2" and reducer. Focal reducers also move the effective focal plane of the objective inward, that is, towards the objective (see Figure 1). They provide 0.75x focal reducers for these telescopes that takes an f/8 instrument down to f/6. Dedicated focal reducers for refractors are intended primarily for imaging, not visual observation. In this case, an additional T-adapter (with an optical length of 50mm) is needed to get the spacing correct for a DSLR or other camera with a 55mm back focus. It also leads to larger (although fainter) images of extended objects like the Moon or planets for astrophotographers or visual observers. To further factor out my natural astigmatism (I normally wear glasses while observing), I did the tests with my regular progressive lenses, single vision glasses I use when observing, and naked eye. Looking forward to the day when I can do a shoot-out between a Japan and China Celestron, just for kicks. Watch this before you buy Celestron 8SE SCT, or a Focal Reducer or a Hyperstar 7,758 views Mar 28, 2018 145 Dislike Share Ray's Astrophotography 42.3K subscribers Note: I am not paid or. But when not in the box or on the telescope, there is no cover for the other end. Nowadays I tend to use the Celestron more with my refractors for imaging and viewing. Celestron or Antares f/6.3 focal reducer for SCT? The equations and argument in the Appendix of this article shows the relationship between the working distance and the reduction factor. Well done. However, doesn't fit in the telescope and even if it did wouldn't work. Read our guide! For the best experience on our site, be sure to turn on Javascript in your browser. Easy solution found a very tiny dab of super lube on the threads and all was well and quiet. Sign up for a new account in our community. With both, using the same diagonal set-up, the exact same stars were visible at the very edge of the FOV. First, let's have a look at some key optical parameters are needed to understand focal reducers. Field stop diameters are one of the specified specs of eyepieces. Does anyone have any experience with the Celestron and Antares focal reducers? The focal length and design working distance for this focal reducer were not available from the manufacturer. Whereas the Celestron threaded smoothly onto the scope, the Antares chattered and squeaked a bit more so when being removed. So ab6110 is asking for a FR only without coma correction, there are a couple of brands who make special reducers for the ACF. Blue Fireball M42 T/T2 Thread Camera Adapter for Prime Focus Photography - 2" # P-06, Celestron T-Ring for Canon EOS Camera # 93419, GSO 2" Crayford Focuser for SCTs - Dual Speed, Length of male SCT thread = 5mm (0.2") but this is preceded by an unthreaded part on the eyepiece side making the total length = 8.8mm (0.35"), Length of female SCT thread = 7.5mm (0.3"). It threads onto the rear cell of 5" to 16" Celestron and Meade Schmidt-Cassegrain telescopes, making it possible to have a dual focal ratio instrument without sacrificing image quality. The two samples I have PERFORM IDENTICALLY. Antares or Celestron? Yet, the Antares still easily and fully threaded without any hitches. ), ASI Air Plus - Connected items are 'greyed out', Cost of ordering used equipment U.S. - Can can more than double figure, Tuthill Isostatic Mount and Star Trap Power Module. When placed in the focal plane in front of a camera or eyepiece, a focal reducer leads to a wider field of view and a brighter image of extended objects, which is important for reducing the exposure times when imaging faint extended objects like nebulae or galaxies. Many reducers, such as the Celestron HD focal reducer mentioned above, and many focal reducers for apochromatic refractors, are meant to be used within a few millimeters (or less) of the specified working distance to achieve the best possible image results. If used with other f/ratios, the field flattening characteristic may be unpredictable. 3. Because of their distinct optical design, slower Schmidt-Cassegrain telescopes (SCT) with focal ratios of f/10 require a different design of focal reducer compared to refractors. Normal shipments will resume on Monday, March 6, 2023. nleash the full pointing accuracy of your Celestron computerized telescope with a specialized telescope control software suite. This is one of our best-selling items, and customers have reported that this product is at least as good as, and probably better than, other leading f/6.3 focal reducers sold on the market for a lot more. Thanks guys, appreciate the feedback. In some cases, focal reducers also act as field flatteners by correcting for field curvature and coma of the objective lens. These 0.63x focal reducers were originally designed to optimize for an image circle to match 36mm x 24mm film or its digital equivalent for astrophotography. Start here to find the perfect telescope for you! As I understand it, compared to the old Meade SCT's, the ACF is already "coma corrected", so the standard Meade, Celestron etc F6.3 focal reducers are not suitable and will only worsen the images. I have the Japanese version and although I haven't used it in quite awhile, the views through it were superb with no internal reflections at all. We process your personal data as stated in our. Celestrons patented StarSense Technology makes it easier than ever to locate objects in the night sky, even if youve never used a telescope before. (Note: Using the simple equations above, the focal length of this reducer can be estimated to be about 350mm). Both exhibited consistent reduction, identical field flattening, and edge correction properties, and both were high quality optically and mechanically. More about this below. Some manufacturers will specify the working distance from the middle of the rear lens surface, and this number must then be converted into a practical working distance number by subtracting the amount by which the rear lens surface is recessed in its housing. At least these two units I tested make the answer - whatever. This filter threads on to the rear cell of your Celestron or Meade SCT telescope. Advanced designs for Schmidt-Cassegrain scopes such as the Meade ACF or Celestron Edge HD have optical elements in the tube to correct for coma and field flatness. And, the reality is that every F/6.3 RC out there Celestron, Hirsch, Astromania, etc., etc. So, if you have a filter that is 3mm thick, you need to add 1mm of spacing to your imaging train to retain the correct back focus. I have the Antares and have no complaints. All Rights Reserved. You need to be a member in order to leave a comment. The most significant mechanical variation, however, is the quality and precision of the threading. I doubt there is any difference between the Antares and the Celestron except price. The amount of reduction is simply the percentage by which a reducer shortens the effective focal length of a telescope and is calculated as (1 Reduction Factor) x 100%. I have the Antares and am not unhappy with it, but for AP I would want more back focal distance if those numbers are accurate. It features a standard male SCT thread (2" OD, 24 TPI) on one side and a standard SCT female thread on the other. I own both and concur heartily. The Reduction Factor and the Amount of Reduction are inversely related. Increase that distance, and greater reduction results and visa versa. I also used several eyepieces including the ES 24mm/68, 17.5mm and 12.5mm Morpheuses, and a 10.5mm Pentax XL. Is that distance D= Fo-d1=Fo-(d2/MR)? Focal reducers for SCT, RC, and field-flattened Edge HD or ACF telescopes thread onto the back of the telescope tube with 2"-24 or 3"-28 SCT threads. * Not a Retail Store * 16313 Arthur StreetCerritos, CA 90703, USA, Availability: Item has been discontinued by Agena and we no longer carry this item. The working distance (backfocus) of the Celestron f/6.3 reducer is specified to be 105mm from the base of the male SCT thread on the camera side. DUE TO EXTREMELY HIGH DEMAND, WE WILL NOT BE TAKING NEW ORDERS UNTIL MONDAY, DECEMBER 14. If the reducer is placed elsewhere, at a position called the operating distance, the focal reduction factor will not be as advertised. Reducer - Corrector Most refractor manufacturers such as William Optics, Tele Vue Optics, Explore Scientific, Sky-Watcher, William Optics, and Stellarvue make their own focal reducers optimized for use with their telescopes. Celestron makes a series of focal reducers for the Edge HD line that are matched to the 8", 9.25", 11", and 14" apertures of these scopes. With the barrel 1.25 reducer won't focus, all I get is fuzzy snowballs. I use the same back spacing for both on a small 6" Celestron SCT. No retailers currently carry this product. As a consequence, the standard f/6.3 and f/3.3 focal reducers for SCT scopes do not work. This award-winning optical system reduces visual defects like field curvature and coma, creating an ultra-flat field for pinpoint stars all the way to the edge of todays largest imaging sensors. Great for home, classroom, or home-school use, this kit includes all the essential items youll need to begin exploring the wonders of the microscopic world. In practice, it's important to remember that you will rarely operate at the exact working distance and at the exact reduction factor that is specified. Hmmm . I have Hirsch focal reducer, which is yet another clone of the Celestron reducer. Best evidence would by obtained by using a camera and evaluating the image both by eye and with a computer analysis. Antares' f/6.3 focal reducer provides a faster f/6.3 system for imaging or visual use when used with an f/10 SCT or other compatible telescopes. Focal reducers for refractors with focal ratio of f/7 to f/9, roughly, have a design reduction factor of about 0.75x to 0.8x and produce a flat field by correcting for the curvature of the objective lens. In such cases, we will be happy to take the item back as per our standard return terms. This superb fully multi-coated multi-element focal reducer takes advantage of the latest computer aided design techniques to achieve the highest standards of performance set by the brand leaders at a fraction of the cost. All Rights Reserved. Reducer Lens .7x - EdgeHD 925 Does anyone know if the Antares 4000 focal reducer is as good as the Celestron focal reducer. The reducer features fully coated optics in an anodized aluminum filter ring with an ergonomic rubber grip. Antares Click Lock Visual Back - posted in Cats & Casses: Here is the situation:I bought a Celestron CPC 1100 for visual use.Want to put on the scope simulteanously a6.3 focal reducer, filter wheel, and aneyepiece turret. Community Forum Software by IP.BoardLicensed to: Cloudy Nights, E of San Francisco Bay and W of the Awahnee, This is not recommended for shared computers, reviews here that suggest a coating problem, Back to Celestron Computerized Telescopes, Looking for advice on first refractor and camera. Thanks Peter! However, this also came at a cost, as the sky background in the Antares was slightly brighter. This appendix summarizes how this works based on simple equations from the book Telescope Optics by Rutten and van Venrooij. Powered by Invision Community. For imaging, a T-adapter is threaded to the camera side of the focal reducer, which in turns connects to the camera with the appropriate hardware. Images in the Celestron tended to appear ever-so-slightly dimmer (maybe? But in the end they both do pretty much the same thing and it sounds like any performance difference is subtle. Hi - most interesting - may I ask .. the brighter guys - "if a camera sensor is too small for a n adaper, will a focal reduer allow me to get greater use from the camera? Right off the bat, I was struck by how similar the two R/Cs were. 800-483-6287 This "speeds up" the optical train by reducing the focal length and magnification of the scope, requiring less time to integrate the same signal. JavaScript seems to be disabled in your browser. But is there a difference in quality between the Antares and the Celestron or Meade focal reducers? Bear in mind you can't squeeze blood out of a turnip, i.e. Article Agena AstroProducts, 2019. A wider field of view and a lower magnification is also useful, with some focal reducers and with some eyepieces, for visual observers with telescopes with long focal ratios. ED stands for "extra-low dispersion," which refers to the composition and optical properties of the glass used for the lenses. The camera side of the focal reducer is threaded for a T-adapter with wide M48 threads, or in some cases, with smaller M42 threads. This Antares 1.25" 0.5x focal reducer lens (tele-compressor) is used under the Orion brand name to thread into the nosepiece of Orion StarShoot Solar System cameras and StarShoot Deep Space Color Imaging Camera. Therefore, a 55mm back focus with a filter that is 3mm thick added to the imaging train would become 56mm. If the focal reducer is to be used for visual observation, the visual back is threaded onto the eyepiece side of the reducer, and then a star diagonal and eyepiece are installed as usual. However, these will not impact optical performance. Like many of us with SCTs, I have bought and sold a number of f/6.3 reducer/correctors over the years, and I have always been curious how they really stack up to each other. Celestron or Antares? They are reported as identical. Things change but when I rebought I got an Antares and it seems about the same to me. 2. This should not be the case if they have their purportedly different focal lengths. Given the results of Test #1, I wanted to see if there was any truth to this assumption. Overall, this reducer does a phenomenal job at preventing gradients due to internal reflections from the camera sensor back to the glass in the reducer, as I suffered with the Antares reducer. The brightness, shape, and distortion of specific stars in the exact same position at the edge of the field was precisely identical in both reducers. This article explained the basics of how focal reducers work with various kinds of telescopes and how their working distance affects their reduction factor, and it provided sufficient detail to help amateur astronomer choose and use the right focal reducer for a particular application. This is the distance at which the reducer must be placed in front of the eyepiece or camera focal plane in order to operate at the design reduction factor. Some are available in 1.25" barrel format but with C threads. Explicitly designed for Celestron Schmidt-Cassegrain telescopes, this unique lens reduces your telescopes focal length and f/ ratio by 37%, turning your long focal length telescope into a fast, short focal length instrument. Figure 1 shows the relationship between the focal reduction factor MR and the position of the reducer in the optical path. Very helpful, thanks a lot for this article! Like you, I am primarily visually observing but I have everything together now that so I am going to start experimenting with photography so we'll see how it does there. Meade does not make an equivalent line of focal reducers for the ACF scopes, although some models of Meade ACF are already at f/8, faster than the f/10 ratio of Celestron Edge HD scopes. Sign up to receive sale alerts, news about upcoming celestial events, and telescope tips from our experts! How about for visual observers? The lens has a knurled surface, providing a tremendous gripping surface for threading/unthreading. I use it on my C8 SCT with a 1000d, and it seems to do everything written on the tin. Most amateur astronomers are familiar with a Barlow lens (or a focal extender), a negative or diverging lens that effectively increases the focal length and the focal ratio of a telescope's objective lens. For the best experience on our site, be sure to turn on Javascript in your browser. Ive owned Celestron, Meade, and Antares models over the years at least a couple of each. Maybe I got a lemon. 1.2" in that scope is a field stop of 43mm at f/10 and 27mm at f/6.3. At a significantly lower price point, the Antares is a steal, and theres no need to upgrade to the Celestron if you already have one. If I had to go out on a very thick limb, I would have to say that these two reducers/correctors are, indeed, identical the exact same glass in slightly different housings with different lettering. Copyright 2021 Stargazers Lounge Place the plastic covers on the lens when not in use to reduce the dust collection. The female end attaches to the rear cell of the telescope. However, the China 6.3 R/C has noticeable internal reflections that I haven't figured out yet. Edited by Tony Bonanno, 16 April 2021 - 06:44 PM. The designed reduction factor (0.5x in the case of the GSO reducer example above) should be considered a rule of thumb or approximate value in most cases, rather than a very precise number. However, in principle, the reduction factor of a focal reducer can be varied by changing the distance from the back of the focal reducer to the camera or eyepiece. Keep in mind that these differences were very subtle, and could be due to normal variations in coatings among different runs, and not necessarily unique to the brands. However, manufacturers virtually never provide this specification. The stock Celestron visualback is just under 2 long. You can probably eke out 1.2 without noticing serious vignetting, which is a field stop of 31.5mm. Stock focusers in an SCT move the mirror of the scope to change the position of the focal plane, and they have sufficient travel to accommodate a focal reducer. Have always disliked the crude, noisy SCT threads, but I get it. Learn more about extra solar planets imagery, 3D Star rendering, observation planning, telescope control, multiple-panel printing, and much more. The Antares focal reducer comes in small box. Your mileage may vary. I have a Raspberry HQ camera, a Sony TV Zoom 12.5-75mm f1.8 and a Astromania 1,25" 0.5x focal reducer. For example, the focal reducer for an 8-inch Celestron EdgeHD telescope has a design reduction factor of 0.7x and a specified working distance (or back focus) of 105mm. I focus using a moonlight electronic focuser and focusmax. Sky recognition technology that has revolutionized the manual telescope by eliminating the confusion common among beginners and enhancing the user experience for even seasoned telescope users. I've looked through one from Meade and first impression was that it was like the Celestron version. So Celestron buyers like Celestron, Meade buyers like the Meade and Antares buyer like the Antares. However, some focal reducers can be used over a wider range of working distances, especially those with simpler optical design, and especially when used with cameras with smaller sensors. If yes, what kind of focal reducers can I use? The reducer fits all Meade and Celestron . That said any comparison reviews are helpful. One focal reducer will not achieve optimum results with all types of telescopes, so there is no universal' focal reducer. Reviews. I'd favor the Japanese Celestron version over the others that are commercially available. He received his first telescope at the age of 5 and completed his first university course in astronomy at the age of 12, eventually receiving a master's degree in the subject. This standard distance is a consequence of the design of DSLR cameras for which the distance of the sensor to the outer edge of the flanges is about 45 mm, while the T-ring that attaches to the flange for astrophotography is about 10mm thick. The most commonly available focal reducers for SCTs are the f/6.3 reducers from Celestron and a similar f/6.3 focal reducer from Meade. The faster f/ratio allows you to use slower film or shoot in lower light level situations and still properly expose your subject. CPWI has an extensive object database, employs PointXP mount modeling, and more. Can these economical focal reducers from GSO and other vendors result in good images? There is one difference though the Antares came with only one lens cap whereas the Celestron had a cap for both ends. I don't know. Turn it on and push Align. In about three minutes, youre ready to observe! GSO, for example, has a 0.75x reducer for RC scopes with a back focus of 80mm, which is usually enough room for a wide range of astronomy cameras and accessories and spacers as needed. Each focal reducer has a fixed specification called the working distance or required back focus. This is the simplest way to attach your ASI121 to your telescope. That includes, for example, a 1.25" eyepiece with an apparent field of view of 68 and a focal length of 24mm (eg. Orders placed over the weekend will be shipped on the following Monday. It has only one cover, which surprised me. By using this site, you agree to our Terms of Use. A slight nod to the Antares for heft and higher transmission, but points to the Celestron for nice threads and better contrast. Check out our 2022 telescope buying guide here! No difference. Details: The item must be the identical item, brand name, size, weight, color, quantity and model number. For example, with a 0.8x focal reducer, a telescope with a focal length of 800mm will operate at 800 x 0.8 = 640mm when the reducer is placed at the working distance specified by the manufacturer. 2023 Celestron, LLC. If you place your camera at a different working distance, you will get a different reduction factor and perhaps unwanted distortion in the image. I've heard and read all kinds of things about the Antares being only a reducer and not a corrector, etc. And when d1 = FR, that is, when the focal reducer is placed at a distance from the focal plane of the objective that's equal to the reducer's focal length, the focal length of the combined optical system is Fo, so it acts as a 0.5x reducer. Stars had a tiny bit more sparkle and pop. Due to the design, the Reducer/Corrector lens does diminish a small amount of field curvature common to all Schmidt Cassegrain telescopes but does not eliminate it. However, with appropriate spacers and a camera with a known back-focus, it is easy to determine the exact amount of focal reduction for a given setup (some imaging software packages will also let you derive this from images). The internal surfaces are blackened and glare-threaded to provide the highest contrast. I think there may be some confusion here, because Antares makes a variety of reducers for eyepieces and scopes in addition to this SCT R/C but this definitely is a reducer/corrector. Many focal reducers for refractors have a working distance (or back focus distance) of 55mm. One of the most important factors in a telescope is its transmissionthe percentage of light that reaches the focal plane. Theres a long-running debate in these forums and even statements from some reputable dealers that the Antares is just a reducer (even though it is labeled Reducer/Corrector), whereas the Celestron is a true R/C, which flattens the SCTs naturally curved field and provides some edge correction. I use the Celestron version and it seems OK for both visual and imaging. Designed distancing using the reducer with a 1.25 visual back and 1.25 Televue mirror diagonal; External Focusers for Schmidt-Cassegrain Telescopes 3.1 The Basics of SCT Threads Or, when the distance of the focal reducer to the focal plane of the objective d1 equals the focal length of the focal reducer FR, the reduction factor MR = 0.5x. Style: Over the course of a several nights of general observing, I swapped back and forth between the Antares and Celestron R/Cs on a wide variety of objects open clusters, brighter galaxies, a couple of nebulae, and globular clusters as well. A f/10 focal ratio now achieves a f/6.3, while an f/11 focal ratio now achieves a f/7. Housings, threads, reduction, correction, blah, blah, blah. Once focused it's pretty good.

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