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This filter threads on to the rear cell of your Celestron or Meade SCT telescope. But the smaller image circle means there is a limit to the field stop of an eyepiece that can achieve an unvignetted image. So Celestron buyers like Celestron, Meade buyers like the Meade and Antares buyer like the Antares. Not noticed any optical problems. 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. Anyway, when purchased my R/C the "original" Celestron unit was not readily available and was offered instead the one sold under the shop's own label (in my case Tecnosky, but I saw the same product offered under TS label). It's an either/or proposition: reducer and 1.25", or 2", but not 2" and reducer. It was used strictly for imaging, not visual observing. Therefore, a 55mm back focus with a filter that is 3mm thick added to the imaging train would become 56mm. Thanks for the extremely valuable article. They provide 0.75x focal reducers for these telescopes that takes an f/8 instrument down to f/6. Sharpness is essentially the same. Our proprietary StarBright XLT optical coatings dramatically increase transmission, up to 97.4% on our Schmidt corrector lenses. Sign up for OPT news, exclusive offers, and updates on the latest gear! 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. Since the focal plane of an eyepiece is rarely precisely known(except for some brands such as Baader Planetarium and Tele Vue), and because the nosepiece of an eyepiece is of a fixed length, the actual reduction factor will be close to, but not exactly at, its designed reduction factor. CEL-94245. If the reducer is placed closer to the eyepiece or camera than the distance D, the reduction factor decreases. It's highly unlikely that they could be so precisely identical unless they were. All additional accessories mount onto the exterior/male threads. This is the simplest way to attach your ASI121 to your telescope. Most Feather Touch focusers cost between $300-$350. I don't know. Easy solution found a very tiny dab of super lube on the threads and all was well and quiet. Specially-designed focal reducers are available for use with these telescopes. Clearly cost is a big factor for satisfied users. https://www.celestron.com/products/reducer-corrector, //cdn.shopify.com/s/files/1/1935/4371/products/94175_reducer_corrector_01.jpg?v=1603736883, //cdn.shopify.com/s/files/1/1935/4371/products/94175_reducer_corrector_01_medium.jpg?v=1603736883, Popular Science by Celestron StarSense Explorer DX 5" Smartphone App-Enabled Schmidt Cassegrain Telescope, Advanced VX 8" Schmidt-Cassegrain Telescope, C9.25 Optical Tube Assembly (CGE Dovetail), Advanced VX 6" Schmidt-Cassegrain Telescope, Advanced VX 700 Maksutov Cassegrain Telescope, CGX-L Equatorial 925 Schmidt-Cassegrain Telescope, CPC 1100 GPS (XLT) Computerized Telescope, CGX-L Equatorial 1400 Schmidt-Cassegrain Telescope, CGX-L Equatorial 1100 Schmidt-Cassegrain Telescope, CGX Equatorial 925 Schmidt-Cassegrain Telescope, CGX Equatorial 800 Schmidt-Cassegrain Telescope, CGX Equatorial 1100 Schmidt-Cassegrain Telescope, CGEM II 1100 Schmidt-Cassegrain Telescope, Advanced VX 9.25" Schmidt-Cassegrain Telescope, Advanced VX 11" Schmidt-Cassegrain Telescope, Not compatible with #93648 Off-Axis Guider, not compatible with #93519 2" Mirror Diagonal (discontinued), Currently not compatible due to mechanical interferences. If it's positioned further from the eyepiece or camera and closer to the telescope objective, the reduction factor increases. The lens has a knurled surface, providing a tremendous gripping surface for threading/unthreading. Celestron or Antares? Very helpful, thanks a lot for this article! I own both and concur heartily. The more focal reduction, the further inward the focal plane will be. Many focal reducers are meant to be used within a few millimeters of the specified working distance to achieve the best possible image results. 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. In many cases, the answer is yes, especially for electronically-assisted astronomy (EAA). 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. These reducers can also be used for visual observing with SCT scopes with eyepieces with a field stop as large as 24-27mm. If used before or beyond the working distance, unwanted image distortion may result. OPT Product Number: AE-SCTFR specifications Warranty 2 Year Warranty Works as advertised! In some cases, focal reducers also act as field flatteners by correcting for field curvature and coma of the objective lens. Edited by Tony Bonanno, 16 April 2021 - 06:44 PM. No retailers currently carry this product. This part is no longer in production, but it is sometimes available used and may be used with cameras with smaller sensors. It's easy! This is a. Meade once made an f/3.3 focal reducer for SCT scopes. There is one difference though the Antares came with only one lens cap whereas the Celestron had a cap for both ends. Brian Ventrudo is a writer, scientist, and astronomy educator. 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. Thank you so much for the informative article, I now understand better how to integrate my reducer into my system to get better performance. No idea what the issue is. I've heard and read all kinds of things about the Antares being only a reducer and not a corrector, etc. Much to my surprise, swapping back and forth between the two correctors using all three diagonal configurations, I also could detect absolutely no change in reduction between the two reducers. Take control of your telescope! However, doesn't fit in the telescope and even if it did wouldn't work. One focal reducer will not achieve optimum results with all types of telescopes, so there is no universal' focal reducer. I've seen some older threads saying that the Celestron, Meade and Antares FRs are all the same and manufactured in the same factory. Focal reducers (and focal reducer/field flatteners combos) are usually used with two types of telescopes, refractors and compound telescopes such as Schmidt-Cassegrain or Ritchey-Chretien. 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. 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. There will be no shipments on 3/1/2023, 3/2/2023, or 3/3/2023 (March 1st - March 3rd, 2023). External Focusers for Schmidt-Cassegrain Telescopes 3.1 The Basics of SCT Threads I focus using a moonlight electronic focuser and focusmax. For these items, please contact us to obtain a shipping quote before you check out using the online shopping cart.International Customers:Free shipping does not apply to international orders. Celestron is considered better in terms of QA, less likely to come with free dust, hair or fingerprint. I found both to be very good. The visual back must be removed first. Wonder how they would stack up with a Japanese 6.3. The resultant reduction factor was measured to be 0.46x. During a twenty-year scientific career, he developed laser systems to detect molecules found in interstellar space and planetary atmospheres, and leveraged his expertise to create laser technology for optical communications networks. I've seen some older threads saying that the Celestron, Meade and Antares FRs are all the same and manufactured in the same factory. As often noted in reviews and forum threads, Antares products tend to have threads that are a little less precise, and this specimen certainly demonstrated this. For imagers, the main purpose of a focal reducer is to increase the brightness of the image at the focal plane. Reducer Lens .7x - EdgeHD 1100 Learn More. Several functions may not work. Reducer Lens .7x - EdgeHD 1400 Learn More. * Not a Retail Store * 16313 Arthur StreetCerritos, CA 90703, USA. 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. Never used one, but read the reviews here that suggest a coating problem. 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. As mentioned in Section 2.3, the reduction factor for these focal reducers can be varied by adding spacers to move the reducer further from the camera sensor or eyepiece. 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. 800-483-6287 Meade once made an f/3.3 focal reducer for SCT scopes. Refractors, or SCTs with external focusers, may not have sufficient in-travel to reach focus in some configurations. But in the end they both do pretty much the same thing and it sounds like any performance difference is subtle. if the illuminated field is 27mm wide without the reducer, it will be 27 x 0.63 = 17mm with it in place. 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. 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. Place the plastic covers on the lens when not in use to reduce the dust collection. For the best experience on our site, be sure to turn on Javascript in your browser. For both imaging and visual observing, these reducers also improve image sharpness at the edge of the field by correcting for coma and field curvature. Celestrons aplanatic EdgeHD optics revolutionized astroimaging. 1.2" in that scope is a field stop of 43mm at f/10 and 27mm at f/6.3. Equation (4) shows the relationship between the distance d2 and the reduction factor MR. Try & buy if you like - usual mates rates. An image of about 24mm across, approximately, allows an observer to use a 1.25" eyepiece with a maximal field stop. SKU: CEL-94245. The faster f/ratio allows you to use slower film or shoot in lower light level situations and still properly expose your subject. When using the diagonal, keep the field stops of the eyepieces under 20mm. . October 11, 2010 in Discussions - Scopes / Whole setups. For this shoot-out, I used a standard Celestron C8 with Starbright coatings. Michael 1 ronin Members Celestron Focus Motor for SCT, EdgeHD & 8" RASA, Celestron C6 0.63 reducer/flattener back focus. Using these numbers in equation 4 in the Appendix, below, we can easily calculate that the focal length of this unit is approximately103mm (it will be 103mm plus the small amount by which the rear lens surface of the reducer is recessed beneath the reducer housing). However, I noticed immediately that the Antares had a bit more of an heft to it, giving it a solid feel the Celestron didnt possess. Stars had a tiny bit more sparkle and pop. Again, swapping back and forth for a couple of hours on M44, M35, and several brighter stars, I examined the shape of specific stars near the edge of the field with both correctors. USD $80.00. 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. 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. Read our 101 article or get in touch. Does anyone have any experience with the Celestron and Antares focal reducers? I have a made in Japan 6.3 R/C and a made in China 6.3 R/C. Hmmm . I am a purely visual observer, so will evaluate for visual use only. 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. I would pay slightly more for the Japan produced version, just because Hirsch was not bad either but sold it since I had 2 already. Start here to find the perfect telescope for you! If a stronger level of focal reduction is used, say 0.5x, then the image circle may be too small to fill the sensor of larger cameras. But the diameter of the image circle decreases by a factor of 0.63 to about 24mm. Celestron Solar Safe filter technology is GUARANTEED SAFE for direct solar observation and has been independently tested by SAI Global Assurance Services. Possibly the design of the Antares was changed .. control and Sky Viewer display makes selecting your target easy. Yellow and orange members of open clusters stood out a bit more as the various stars displayed their individuality. The click-lock with a 2 dielectric diagonal with a somewhat shorter light path, using both a 2 ES 28mm/68 and the same low-profile adapter with a 1.25 ES 24mm/68. This is especially true when these reducers are used with cameras with smaller sensors with a dimension of about 1/4 to 1/3 the diameter of the reducer, and with telescopes with a focal ratio of f/7 or larger. Increasing the operating distance, that is, moving a focal reducer away from the eyepiece or camera reduces its reduction factor, or conversely increases the amount of reduction. 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. For example, many focal reducers designed for f/7 or f/8 ED refractors such as those from Tele Vue, William Optics, Sky-Watcher, and Meade are designed to have a working distance (or back focus) of 55mm. What an enjoyable read and detailed comparison. 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. I use it on my C8 SCT with a 1000d, and it seems to do everything written on the tin. Not a bit. The naming convention of SCT focal reducers is a little confusing. But nearly every observer who installs one of these devices is pleased with their performance. There may have been an almost imperceptible difference, but the Antares and Celestron were producing precisely the same reduction. WiFi technology encircles the globe in a web of connectivity, knowledge, and information. I wish there was. The female end attaches to the rear cell of the telescope. We will be glad to help. You cannot, for example, use a 0.63x focal reducer intended for a standard Celestron or Meade SCT and use it on a Celestron Edge HD or a Meade ACF. Benefits limited to hardware and conditions? Stars in the corner of the image frame are indistinguishable between the Antares and the Celestron. Copyright 2021 Stargazers Lounge Any comments gratefully received. Torazz Based on Test 1 and Test 2, I think there is perhaps more validity to opposing statements here in these forums that the Antares and current China-made Celestron do, indeed, have exactly the same optics just with different housings and branding. More important, its clear that the Antares is a reducer/corrector, just like the Celestron and not merely a reducer. 2023 OPT Telescopes. To calculate how much back focus spacing you need to add, take the thickness of the filter and divide it by 3. They both are great and I doubt my eyes could detect a difference in any one of them including the Japan version. I even lost track of which reducer I was using. The problem with those SCT reducers is that they cause chromatic aberration and require refocusing when using parfocal RGB/other filters. Manish Panjwani has been an active amateur astronomer since before Halley's Comet last flew by our neighborhood. 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. With spring galaxy season here, I decided to pick up a couple more to compare in a head-to-head shoot out. . What I do know is that the Antares and the Celestron samples that I have perform exactly the same from the center right out to the edges. For Ritchey-Chretien telescopes such as those manufactured by GSO, there are also dedicated focal reducers with a reduction factor of 0.7x to 0.8x. So, this past week I challenged the Antares and Celestron models to a head-to-hear on my C8 on some decent nights of good seeing and transparency in my Bortle 5-6 urban skies. Add a 0.63x reducer, and the brightness of extended objects increases by (1/0.63)2 = 2.5. Each focal reducer has a fixed specification called the working distance or required back focus. The Reduction Factor and the Amount of Reduction are inversely related. Learn more about extra solar planets imagery, 3D Star rendering, observation planning, telescope control, multiple-panel printing, and much more. However, even though the imprint on the item states "Reducer / Corrector" please note that his is a reducer only. We only send interesting emails and will never sell your data. . I have the Antares and have no complaints. Please let us know what topics you are interested in. This focal reducer from Celestron reduces the effective focal length by 0.63X Enjoy the wider field of view & faster exposure times at f/6.3 with f/10 telescopes f/11 telescopes, such as the C14 will perform at f/7 The Celestron f/6.3 Reducer has four fully-multicoated elements Reduce your exposure times by a factor of 3! CPWI has an extensive object database, employs PointXP mount modeling, and more. The Buyer's Guide To Eyepieces at the top of the Eyepieces forum has a column for this spec. Can you tell me about the use of reducers in Maksutov-Cassegrain telescopes? Thanks for pointing this out.