Not noticed any optical problems. Some third-party vendors also make reducers for SCT scopes. 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. Sharpness is essentially the same. Things change but when I rebought I got an Antares and it seems about the same to me. I'm going with the Celestron. Theoretically each of these combinations all varied-length light paths should have resulted in slightly different reductions between the Celestron and Antares, since they supposedly have different focal lengths. 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. 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. More important, its clear that the Antares is a reducer/corrector, just like the Celestron and not merely a reducer. 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. looks virtually identical, except for the lettering. Despite never removing it no matter what I was looking at. We only send interesting emails and will never sell your data. 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. Stars had a tiny bit more sparkle and pop. 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. Rather than a direct side-by-side, I swapped the reducers so that I was using them on the exact same, well-collimated instrument. control and Sky Viewer display makes selecting your target easy. Again, to my surprise, there was absolutely no difference between the Celestron and Antares on any star. Now It only focuses near things, like some kind of macro zoom. Thanks guys, I'm trying to get my ZWO ASI120MC-S to work with my 90mm Meade. Antares f/6.3 Focal Reducer for Schmidt-Cassegrain Telescopes - Agena Astro No rainchecks will be issued for items out of stock at OPTcorp.com to match a competitor's price. Right off the bat, I was struck by how similar the two R/Cs were. They are reported as identical. Hmmm . riklaunim Members 559 3,445 Location: Poland Posted October 11, 2010 They are reported as identical. Your mileage may vary. I have the Antares and have no complaints. Once installed, you can add additional accessories like T-Adapters, 1.25 Visual Back, Star Diagonal, or Off-Axis Guider. Please note, orders placed after 10am on 2/28/2023 will be delayed. I even lost track of which reducer I was using. The EdgeHD .7x Focal Reducer Lens makes your EdgeHD 1100 one full F-Stop faster than f/10, reducing your exposure time by half to capture the same brightness of object . Celestron Focus Motor for SCT, EdgeHD & 8" RASA, Celestron C6 0.63 reducer/flattener back focus. As another example,GSO makes focal reducers for their line of Ritchey-Chretien imaging telescopes. During check-out, you will be presented with several shipping choices and costs. Therefore, a 55mm back focus with a filter that is 3mm thick added to the imaging train would become 56mm. However, these will not impact optical performance. With both, using the same diagonal set-up, the exact same stars were visible at the very edge of the FOV. F6.3 Focal reducer for F/10 or higher telescopes, 43mm aperture, 4-Element, Fully Multicoated. Photographically you also get a wider field and much shorter exposures. One of the most important factors in a telescope is its transmissionthe percentage of light that reaches the focal plane. I use the same back spacing for both on a small 6" Celestron SCT. 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. Celestron Reducer Lens .7x - EdgeHD 925 The EdgeHD .7x Focal Reducer Lens makes your EdgeHD 925 one full F-Stop faster than f/10, reducing your exposure time by half to capture the same brightness of object 5-element lens design Maintains similar. As per the OP I still can't see any reason to buy the Celestron for significantly more $$$. I would not use the reducer with a 2" diagonal or eyepiece in the C6. Still not sure what is the right gear for you? I have a Raspberry HQ camera, a Sony TV Zoom 12.5-75mm f1.8 and a Astromania 1,25" 0.5x focal reducer. The two samples I have PERFORM IDENTICALLY. For this test, I used a single configuration R/C, Click-lock, and 1.25 diagonal with the adapter. External Focusers for Schmidt-Cassegrain Telescopes 3.1 The Basics of SCT Threads Our patented SkyAlign alignment technology makes setting up a computerized telescope simple, fast, and accurate. Assuming you use the reducer with the stock 1.25" diagonal, it will operate at f/6.3. I have/had both the Celestron (Japan) and Antares units. I wonder whether, for example, Antares focal reducer for SCT belongs to the latter category. 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. Antares Click Lock Visual Back - Cats & Casses - Cloudy Nights I use the Celestron version and it seems OK for both visual and imaging. An eyepiece with a 27mm field stop yields a true field of 1.03 in the C6 at f/10. Some faster refractors with a focal ratio of f/6, for example, only require field flatteners and not focal reducers. But while the image gets brighter, the size of the image circle gets proportionately smaller. 160K views 9 years ago This video is a complete overview of focal reducers and how they function applying to telescopes. CEL-94245. Can you help me? So it provides a 0.63x design reduction factor when used with an f/10 SCT at the specified working distance. They never really recovered from selling a few 15 years back with element reversed. You attach the focal reducer to the rear port on a SCT and can keep it covered. Using an eyepiece with a 27mm field stop with the reducer will illuminate the edge the same as using an eyepieces with a 42.9mm field stop without it. I am new to these optic topics, and I want to ask you what happens with Masutov like SW or Celestron 4 or 7 inches. No small animals were harmed in making these observations. In every configuration, there were essentially parfocal, requiring only a tiny fine focus adjustment when changing correctors. All Rights Reserved. I really don't see any difference in the current crop except the "Meade" is usually the cheapest. 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. Please Log in to save it permanently. It must be in stock at the time of Price Match for us to make a guarantee. If the reducer is placed closer to the eyepiece or camera than the distance D, the reduction factor decreases. Performance wise what differences might there be using the reducer on a smaller scope. Any comments gratefully received. This filter threads on to the rear cell of your Celestron or Meade SCT telescope. Focal Reducer for SCT - ACF - Stargazers Lounge Once focused it's pretty good. In this case, d2 = FR/2, which means the back of the focal reducer is located at a distance FR/2 from the camera or eyepiece. 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 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. No experience with the Antares reducers, but I haven't personally seen a difference between Celestron and my current pair of made in Japan Meade reducers. We have tested our current batch and it works with Meade, Celestron, and Baader SCT accessories. Copyright 2021 Stargazers Lounge The key points are as follows: So just remember that a smaller distance (from the camera or eyepiece) means a lower amount of reduction (and vice versa). That includes, for example, a 1.25" eyepiece with an apparent field of view of 68 and a focal length of 24mm (eg. But the diameter of the image circle decreases by a factor of 0.63 to about 24mm. The author finds differences in throughput and color balance, but then says he thinks the lenses are identical and he reaches his conclusions based on very long observing session. Wonder how they would stack up with a Japanese 6.3. 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. In most cases, the easiest option is to choose the focal reducer made specifically for your telescope. 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). There are also third-party vendors such as Hotech. To test this, I used three set-ups: 1. ED glass is specially formulated and contains rare-earth compounds that greatly reduce a visual defect called chromatic aberration. Does anyone know if the Antares 4000 focal reducer is as good as the Celestron focal reducer. If it's positioned further from the eyepiece or camera and closer to the telescope objective, the reduction factor increases. Manish Panjwani has been an active amateur astronomer since before Halley's Comet last flew by our neighborhood. Celestron or Antares f/6.3 focal reducer for SCT? A few people have reported issues with the male SCT thread diameter on this item being a bit larger than necessary. Reducer Lens .7x - EdgeHD 925 Learn More. 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. That means the base of the mounting threads of the focal reducer needs to be 55mm from the camera sensor to achieve the design reduction factor, which is usually 0.8x or 0.85x. F 6.3 focal reducer/corrector. - Discussions - Stargazers Lounge 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. Get ready for a night of astroimaging with your mount faster than previously thought possible with All-Star Polar Alignment. Optically, it consists of a four-element lens that is fully multi-coated for high contrast and resolution. The distances d1 andd2 can also be expressed in terms of the focal length of the focal reducer FR with the lens equation: Using Equation 2, Equation 1 can also be expressed in terms of d2: The focal reduction factor of the focal reducer depends on its focal length and its distance from the focal plane of the objective as shown by Equation 4: Again, for example, when the focal reducer is placed at the original focal plane of the objective, d1=0 and MR=1, which means there is no focal reduction.