Meade and Celestron both sell such SCT-T adapters with the correct optical length. Well done. That was fun. 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. If yes, what kind of focal reducers can I use? The two samples I have PERFORM IDENTICALLY. How about for visual observers? Figure 6 shows a 1.25" focal reducer from GSO configured with a ZWO ASI224MC camera. Check out our 2022 telescope buying guide here! This article explains the basics of how focal reducers work with an astronomy telescope. October 11, 2010 in Discussions - Scopes / Whole setups. This was most noticeable on the eyepiece end of the RC, where the metal rim surrounding the lens was about 1mm thicker than on the Celestron. More aggressive reduction, or using these reducers with larger sensors, will result in aberrations and distortions near the edge of the image. Figure 1 shows the relationship between the focal reduction factor MR and the position of the reducer in the optical path. Many focal reducers are meant to be used within a few millimeters of the specified working distance to achieve the best possible image results. Fortunately, my neighbors are not out in their backyards at 11 pm, or they may have thought I was torturing a small mammal. Melotte 15 - First Process in PixInsight (easy! Wow, that is a very detailed discussion! 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. Most reducers have a design reduction factor, MRD, that assumes the reducer is placed at a specific working distance, D, from the back surface of the focal reducer itself. 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. It features a standard male SCT thread (2" OD, 24 TPI) on one side and a standard SCT female thread on the other. The female end attaches to the rear cell of the telescope. How does it look thats what matters. Optically, it consists of a four-element lens that is fully multi-coated for high contrast and resolution. Performance wise what differences might there be using the reducer on a smaller scope. For the best experience on our site, be sure to turn on Javascript in your browser. Optically, it consists of a four-element lens that is fully multi-coated for high contrast and resolution. We do not price match competitors if they are out of stock. I really don't see any difference in the current crop except the "Meade" is usually the cheapest. By Using this same example of an 8" SCT and a 0.63x reducer, a visual observer can also enjoy brighter images and a wider field of view. The lens that the ZWO comes with give a perfect wide angle image of what is in front of it. 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. Sign up for our newsletter to get exclusive deals, observing tips, and new product announcements. Go behind the scenes with Celestrons product development team and learn more about our award-winning and patented innovations. Unlike SCT telescopes, Ritchey-Chretien telescopes and Celestron Edge HD or Meade ACF scopes have internal optics that provide an inherently flat field, so these telescopes require a special focal reducer than does not provide additional correction for field curvature. Reducer Lens .7x - EdgeHD 800 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. You may need spacers or a T-adapter to ensure the correcting working distance. I was going to measure the difference in grams, but my lovely wife caught me trying to use her precious, high-tech kitchen scale for the cause, and put the kibosh on it. DUE TO EXTREMELY HIGH DEMAND, WE WILL NOT BE TAKING NEW ORDERS UNTIL MONDAY, DECEMBER 14. I have Hirsch focal reducer, which is yet another clone of the Celestron reducer. Thanks guys, appreciate the feedback. Reducer Lens .7x - EdgeHD 1400 Learn More. Sign up for a new account in our community. The threads were similar on the eyepiece end, but a bit smoother. The Reduction Factor and the Amount of Reduction are inversely related. With spring galaxy season here, I decided to pick up a couple more to compare in a head-to-head shoot out. Bear in mind you can't squeeze blood out of a turnip, i.e. Focus misses by about 1 turnof the focus knob.Here is my solution:Buy a shorter 1.25 visual back for my scope. Right off the bat, I was struck by how similar the two R/Cs were. You need to be a member in order to leave a comment. I use it on my C8 SCT with a 1000d, and it seems to do everything written on the tin. The visual back must be removed first. It's easy! Today, our world-class team of optical and electronic engineers continues to push the boundaries of technology. There is one difference though the Antares came with only one lens cap whereas the Celestron had a cap for both ends. It's usually specified from the base of the mounting threads on the reducer's housing, and this is the most practical way of providing this specification. In some cases, focal reducers also act as field flatteners by correcting for field curvature and coma of the objective lens. It might work but it does not tell us anything about how well or to what extent the product works to correct the field of an SCT. When you said, "in some cases" a focal reducer also works as a flattener/corrector, are you saying that not all focal reducers are flatteners/corrector? It was used strictly for imaging, not visual observing. It's usually specified in millimeters. Equation 6 & 7 item two & three does not make sense, both say increase its reduction (one should say reduce its reduction?). 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. Focal Reducer, 2", 0.7X. The working distance of the GSO 0.5x focal reducer with 1.25" barrel and the GSO 0.5x focal reducer with 2" barrel is about 51mm to 53mm, approximately, from the middle of the metal cell that holds the lens. I focus using a moonlight electronic focuser and focusmax. Figure 2 shows the effective of a focal reducer on the light from a telescope objective. InternetSales@optcorp.com, 800-483-6287 JavaScript seems to be disabled in your browser. 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. Hi. An f/6.3 reducer is designed to reduce the focal ratio of an f/10 SCT to f/6.3. What an enjoyable read and detailed comparison. 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. This focal reducer and field flattener consists of a four-element multicoated 40mm lens in a metal cell. Many Ritchey-Chretien telescopes available today are made by GSO. 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. But when not in the box or on the telescope, there is no cover for the other end. Very helpful, thanks a lot for this article! However, these will not impact optical performance. This is very impressive performance given how hard this problem is to mitigate in general. I only have the Celestron f/6.3. You can probably eke out 1.2 without noticing serious vignetting, which is a field stop of 31.5mm. You can adjust your cookie settings, otherwise we'll assume you're okay to continue. The female end attaches to the rear cell of the telescope. I think I remember hearing the reduction factor is slightly different, cant remember more or less reduction. 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. OPT Product Number: AE-SCTFR specifications Warranty 2 Year Warranty Works as advertised! My Celestron was made in China and the Antares in Canada. control and Sky Viewer display makes selecting your target easy. We have placed cookies on your device to help make this website better. However, the China 6.3 R/C has noticeable internal reflections that I haven't figured out yet. control and Sky Viewer display makes selecting your target easy. The nominal design reduction factor of these reducers is typically 0.5x. However, because the field curvatures in refractors and SCTs vary a lot, I would predict unpredictable effects inre: field curvature. CPWI has an extensive object database, employs PointXP mount modeling, and more. Reducer Lens .7x - EdgeHD 1100. This appendix summarizes how this works based on simple equations from the book Telescope Optics by Rutten and van Venrooij. Description. Possibly the design of the Antares was changed .. Unlike . Your price: $579.00. I don't know. More important, its clear that the Antares is a reducer/corrector, just like the Celestron and not merely a reducer. Reproduction without permission prohibited. Celestron Solar Safe filter technology is GUARANTEED SAFE for direct solar observation and has been independently tested by SAI Global Assurance Services. Who cares? EclipSmart solar products feature Solar Safe filter technology providing the ultimate protection from harmful solar radiation, including both IR and UV light, and filters 99.999% of visible light. I own both and concur heartily. 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. Not noticed any optical problems. Please Log in to save it permanently. If I had to guess, the difference is maybe 10-15 grams. Perfect for the serious student, professional scientist and discriminating hobbyist. One focal reducer will not achieve optimum results with all types of telescopes, so there is no universal' focal reducer. I would not use the reducer with a 2" diagonal or eyepiece in the C6. 3. riklaunim Members 559 3,445 Location: Poland Posted October 11, 2010 They are reported as identical. Completely stuck, completely frustrated. 800-483-6287 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. 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 working distance or required back focus, explained above, is usually specified and is far more important in practice. All rights reserved. 2023 OPT Telescopes. If you want to save a few buck watch the classifieds on CN. if the illuminated field is 27mm wide without the reducer, it will be 27 x 0.63 = 17mm with it in place. Things change but when I rebought I got an Antares and it seems about the same to me. Celestrons aplanatic EdgeHD optics revolutionized astroimaging. - thanks. Many focal reducers for refractors have a working distance (or back focus distance) of 55mm.