And when used in some refractors, the field flattening is not as accurate as it is in the f/10 SCTs. 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. Celestrons award-winning Nature DX binocular gets a major upgrade with the addition of ED objective lenses. Thanks for pointing this out. Focal reducer for 8SE - Celestron vs. Antares - Cloudy Nights Manish Panjwani has been an active amateur astronomer since before Halley's Comet last flew by our neighborhood. The most significant mechanical variation, however, is the quality and precision of the threading. 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. Meade and Celestron both sell such SCT-T adapters with the correct optical length. The reducer fits all Meade and Celestron . Thanks guys, I'm trying to get my ZWO ASI120MC-S to work with my 90mm Meade. ), but stars seemed a bit tighter and their colors were richer and more dramatic. 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. Celestron Nexstar+ 127 SLT, several budget plossl eyepieces, Celestron 8-24mm zoom EP and a 12.5mm illuminated double reticle EP, Svbony SV205 camera w/.5 focal reducer, Celestron SkyMaster 20x80 binos on a 40 yr old QuickSet PanHead tripod, Stellarium, Sharpcap and ManyCam on my laptop, SkyView and Nightshift on my phone and a dandy little $9 . Celestron Focus Motor for SCT, EdgeHD & 8" RASA, Celestron C6 0.63 reducer/flattener back focus. Copyright 2003-2022 Agena AstroProducts. The more focal reduction, the further inward the focal plane will be. However I've also read that the back focal distance on the Celestron is 105mm while the Antares is 81mm so they couldn't be identical. That was fun. Some coma is visible in the corners, but the image is quite good for EAA applications. I've heard and read all kinds of things about the Antares being only a reducer and not a corrector, etc. M44 was a perfect target for this, as its large size maxes out the FOV on a C8 with a corrector, and its bright stars make great targets for measuring the very edge of the visible field. I wont bother with differences in packaging, caps, etc. The nominal design reduction factor of these reducers is typically 0.5x. Is there likely to be any differences in performance between using these on an 8 or something smaller like my 6SE? Imagine having two telescopes in one a long focal length instrument for lunar and planetary work and a short focal length scope for deep sky observing and astrophotography. I have had the Japan unit on the back of my C5 since 1994 or thereabouts. Equation 6 & 7 item two & three does not make sense, both say increase its reduction (one should say reduce its reduction?). Please re-enable javascript to access full functionality. The Celestron f/6.3 is ~150 compared to the Antares at ~70. For the best experience on our site, be sure to turn on Javascript in your browser. With the Celestron Reducer/Corrector Lens, thats precisely what you get. 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. Reducer - Corrector Sign up for our newsletter to get exclusive deals, observing tips, and new product announcements. Well done. There will be no shipments on 3/1/2023, 3/2/2023, or 3/3/2023 (March 1st - March 3rd, 2023). I use the same back spacing for both on a small 6" Celestron SCT. Now, Celestron is using that same technology to allow star gazers to connect to the night sky and enhance their experience of the cosmos in fun and unique ways. Focal reducers for many SCTs and their flat-field equivalents usually have a back-focus distance of 105mm. I think that the FRs made in Japan in the day may have been better. Again, to my surprise, there was absolutely no difference between the Celestron and Antares on any star. You attach the focal reducer to the rear port on a SCT and can keep it covered. 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. The Celestron is both a corrector and focal reducer and the Antares is just a focal reducer. Despite never removing it no matter what I was looking at. There is a way to make subjective data more useful and that way is proper blind, or better still. Powered by Invision Community. First, let's have a look at some key optical parameters are needed to understand focal reducers. Another factor to consider: focal reducers also increase the angle at which light approaches the focal plane. Reducer Lens .7x - EdgeHD 1100. Thank you so much for the informative article, I now understand better how to integrate my reducer into my system to get better performance. 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. Focal Reducers | Celestron Since then, Agena has become one of the leading online retailers of telescopes and astronomical accessories worldwide. More important, its clear that the Antares is a reducer/corrector, just like the Celestron and not merely a reducer. In such cases, we will be happy to take the item back as per our standard return terms. We only send interesting emails and will never sell your data. The visual back must be removed first. The previous post shows the reducer on what appear to be two different refractors. Sign up to receive sale alerts, news about upcoming celestial events, and telescope tips from our experts! Dedicated focal reducers for refractors are intended primarily for imaging, not visual observation. Perfect for the serious student, professional scientist and discriminating hobbyist. The lens is housed in machined aluminum for are machined aluminum black anodized. 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. 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. With both, using the same diagonal set-up, the exact same stars were visible at the very edge of the FOV. 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. 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). 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. Never used one, but read the reviews here that suggest a coating problem. Right off the bat, I was struck by how similar the two R/Cs were. Reproduction without permission prohibited. 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. In some cases, focal reducers also act as field flatteners by correcting for field curvature and coma of the objective lens. In the 1960s, Celestrons founder, Tom Johnson, created groundbreaking new telescopes never before seen on the consumer market. I was referring to the C6 to answer you specifically. Brightness, color, and contrast were subtly different, but could be as much the day they were coated as any real difference in the two brands. They are also less expensive than many external focusers of similar build quality. The naming convention of SCT focal reducers is a little confusing. It's highly unlikely that they could be so precisely identical unless they were. Many focal reducers for refractors have a working distance (or back focus distance) of 55mm. Increase that distance, and greater reduction results and visa versa. As another example,GSO makes focal reducers for their line of Ritchey-Chretien imaging telescopes. I use the Celestron version and it seems OK for both visual and imaging. Focal Reducer for SCT - ACF - Stargazers Lounge My experience is that CN sellers are way above those listing elsewhere. 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. So Celestron buyers like Celestron, Meade buyers like the Meade and Antares buyer like the Antares. 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. This appendix summarizes how this works based on simple equations from the book Telescope Optics by Rutten and van Venrooij. We reserve the right to verify a competitor's advertised price and the availability of the item. 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. This telescope control software replaces the hand control and allows the user to remotely control their Celestron computerized telescope from their personal PC or laptop. 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. 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. But while the image gets brighter, the size of the image circle gets proportionately smaller. Unlike . Telescope Focal Reducers & Correctors - High Point Scientific 1.2" in that scope is a field stop of 43mm at f/10 and 27mm at f/6.3. Does anyone know if the Antares 4000 focal reducer is as good as the Celestron focal reducer. 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. I happily cycle through LRGB filters to build the image rather than do a whole run of one filter at a time. If it's positioned further from the eyepiece or camera and closer to the telescope objective, the reduction factor increases. Unscrew that wide angle lens and put it away, then attach the ASI120 to the nose-piece that came with the camera and fit that into the eyepiece holder. For the best experience on our site, be sure to turn on Javascript in your browser. Thks for that and its not for visual it for astrophotography. It was used strictly for imaging, not visual observing. I have both the Antares and the Celestron reducers. It must be in stock at the time of Price Match for us to make a guarantee. SKU: CEL-94245. (Note: Using the simple equations above, the focal length of this reducer can be estimated to be about 350mm). This means that there must be sufficient travel on the telescope focuser to make up for this. Thanks. Housings, threads, reduction, correction, blah, blah, blah. 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. A focal reducer does just the opposite of a Barlow lens or focal extender. Using one on such a scope would make demands on the eyepiece design and increase the exit pupil to an extent that focal reduction on fast Newts is not practical. However, these will not impact optical performance. 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. 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. However, manufacturers virtually never provide this specification. I've seen some older threads saying that the Celestron, Meade and Antares FRs are all the same and manufactured in the same factory. . USD $80.00. Can these economical focal reducers from GSO and other vendors result in good images? 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. This innovative software solves the time-consuming problem of trying to pinpoint the North Celestial Pole. You also wont be unhappy spending the few extra bucks on the Celestron for the pretty orange lettering, particularly if you can pick one up used, as I did. What an enjoyable read and detailed comparison. I wonder whether, for example, Antares focal reducer for SCT belongs to the latter category. 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. The lens has a knurled surface, providing a tremendous gripping surface for threading/unthreading. 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. Antares or Celestron? 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. So it provides a 0.63x design reduction factor when used with an f/10 SCT at the specified working distance. The Buyer's Guide To Eyepieces at the top of the Eyepieces forum has a column for this spec. You don't need to follow these equations to use a focal reducer, but they do show how the reduction factor changes with the placement of the reducer. 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. 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 focal length and design working distance for this focal reducer were not available from the manufacturer. 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. For me the Antares was a little brighter and had the least scatter by a bit so the better coatings won. The C8 has no noticeable vignetting with a 32mm Plssl in the f/6.3 reducer. But the diameter of the image circle decreases by a factor of 0.63 to about 24mm. Meade once made an f/3.3 focal reducer for SCT scopes. October 11, 2010 in Discussions - Scopes / Whole setups. The stars at the edge could be worse or better. The reduction factor MR can also be written in terms of d2 as: When the focal reducer is placed at the working distance, D, that is when d2=D, then the reduction factor MR is equal to the design reduction factor MRD: Equations (6) and (7) imply these important considerations: Most manufacturers do not publish the focal length of their focal reducers, so it is not usually possible to calculate the working distance and design reduction factor. An f/6.3 reducer is designed to reduce the focal ratio of an f/10 SCT to f/6.3. More aggressive reduction, or using these reducers with larger sensors, will result in aberrations and distortions near the edge of the image.