. It seems right to put some distance between the camera and the focal reducer, right? Does anyone know if the Antares 4000 focal reducer is as good as the Celestron focal reducer. This is the simplest way to attach your ASI121 to your telescope. As per the OP I still can't see any reason to buy the Celestron for significantly more $$$. You can adjust your cookie settings, otherwise we'll assume you're okay to continue. Specially-designed focal reducers are available for use with these telescopes. This should not be the case if they have their purportedly different focal lengths. Can these economical focal reducers from GSO and other vendors result in good images? Many focal reducers are meant to be used within a few millimeters of the specified working distance to achieve the best possible image results. 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. This innovative software solves the time-consuming problem of trying to pinpoint the North Celestial Pole. 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. We will be glad to help. 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. I had a Celestron, Antares and Hirsch for awhile and compared them over about a year. What is likely is that fatigue sets in, and also that as the targets move toward or a way from the meridian there will be changes for that reason alone. Newtonian reflectors will seldom be able to accommodate the in-focus travel demanded by focal reducers. 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. 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. Focal reducers for many SCTs and their flat-field equivalents usually have a back-focus distance of 105mm. Sign up to get exclusive deals, observing tips, and new product announcements. Since then, Agena has become one of the leading online retailers of telescopes and astronomical accessories worldwide. Assuming you use the reducer with the stock 1.25" diagonal, it will operate at f/6.3. 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). * Not a Retail Store * 16313 Arthur StreetCerritos, CA 90703, USA. I wonder whether, for example, Antares focal reducer for SCT belongs to the latter category. 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. This focal reducer and field flattener consists of a four-element multicoated 40mm lens in a metal cell. 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. 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. 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. Just one question. 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. Thanks for the extremely valuable article. 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. Not noticed any optical problems. Getting the proper back-focus for your imaging camera is a vital step in getting the best data possible out of your telescope imaging/research rig. 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. 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. The naming convention of SCT focal reducers is a little confusing. The focal length and design working distance for this focal reducer were not available from the manufacturer. Thanks Peter! If you want to use them for visual - try maybe long focal length eyepieces rather than the reducer. I happily cycle through LRGB filters to build the image rather than do a whole run of one filter at a time. The same illumination you have at the edge of a 27mm field, the C8 has at the edge of a 38mm field. An image of about 24mm across, approximately, allows an observer to use a 1.25" eyepiece with a maximal field stop. Equation 6 & 7 item two & three does not make sense, both say increase its reduction (one should say reduce its reduction?). Planetarium software package which provides easy-to-understand explanations and impressive visuals of all kinds. Well done. Just point the telescope at any three bright objectsstars, bright planets, or even the Moonand your telescope can orient itself with the night sky. They only publish the value of D, the working distance (sometimes called the back focus distance) and the design reduction factor MRD. Easy solution found a very tiny dab of super lube on the threads and all was well and quiet.. 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. However, it will not thread into William Optics accessories, and with GSO it is a hit or miss. There may have been an almost imperceptible difference, but the Antares and Celestron were producing precisely the same reduction. Equation (4) shows the relationship between the distance d2 and the reduction factor MR. I've seen some older threads saying that the Celestron, Meade and Antares FRs are all the same and manufactured in the same factory. Still not sure what is the right gear for you? JavaScript seems to be disabled in your browser. The visual back must be removed first. The previous post shows the reducer on what appear to be two different refractors. So ab6110 is asking for a FR only without coma correction, there are a couple of brands who make special reducers for the ACF. 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. None of this was offensive, nor did it interfere with views in any significant way. You attach the focal reducer to the rear port on a SCT and can keep it covered. Wow, that is a very detailed discussion! 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. Reviews. If it's positioned further from the eyepiece or camera and closer to the telescope objective, the reduction factor increases. 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. No small animals were harmed in making these observations. 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. Here, there was a subtle difference . To test this, I used three set-ups: 1. There is a way to make subjective data more useful and that way is proper blind, or better still. 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. We have corrected # (iii) after equations 6 & 7. If you are using a camera that has a back focus of less than 55mm, additional spacer rings will be required between the reducer and the camera. Go behind the scenes with Celestrons product development team and learn more about our award-winning and patented innovations. 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. Hence, there is a chance that you may not be able to thread your SCT diagonal or other SCT accessory on to this reducer for these or for any other brand. It also leads to larger (although fainter) images of extended objects like the Moon or planets for astrophotographers or visual observers. OPT Product Number: AE-SCTFR specifications Warranty 2 Year Warranty Works as advertised! 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. Description. 2023 OPT Telescopes. They are reported as identical. The Celestron is both a corrector and focal reducer and the Antares is just a focal reducer. Each focal reducer has a fixed specification called the working distance or required back focus. Our proprietary StarBright XLT optical coatings dramatically increase transmission, up to 97.4% on our Schmidt corrector lenses. The review is a subjective visual impression, which is interesting but not best evidence. 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. Scope size might influence choice as well, as a C6 might benefit from the Antares' transparency, while larger scopes might benefit from the Celestron's higher contrast. Years ago, I bought the Antares version, and moved over to the Celestron. A focal reducer does just the opposite of a Barlow lens or focal extender. The focus barely shifts between filters and I suspect any shifts I do get are down to the filters and changes in temp. 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. 3. 2. The reducer fits all Meade and Celestron . Refractors, or SCTs with external focusers, may not have sufficient in-travel to reach focus in some configurations. For the best experience on our site, be sure to turn on Javascript in your browser. I found both to be very good. 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. 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. An f/6.3 reducer is designed to reduce the focal ratio of an f/10 SCT to f/6.3. looks virtually identical, except for the lettering. A few large telescopes and mounts are excluded from this free shipping offer. As one increases, the other decreases. Free shipping $189.95 Also, the focusers of most Newtonians do not have enough in-travel to accommodate a focal reducer. This may be a problem if the focuser tube or the diagonal (for visual observing) is too narrow to accept light at this larger angle. In some cases, focal reducers also act as field flatteners by correcting for field curvature and coma of the objective lens. High power views will provide flatter fields all the way to the edge, both visually and photographically. 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. These reducers can also be used for visual observing with SCT scopes with eyepieces with a field stop as large as 24-27mm. We have tested our current batch and it works with Meade, Celestron, and Baader SCT accessories. One problem with getting opinions is that most of use do not have both reducers or have never done a side by side comparison. Stars had a tiny bit more sparkle and pop. Some coma is visible in the corners, but the image is quite good for EAA applications. 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. We do not price match competitors if they are out of stock. My Celestron was made in China and the Antares in Canada. But the diameter of the image circle decreases by a factor of 0.63 to about 24mm. These scopes are compatibles with focal reducers. Explore Scientific Keys to the Universe Sale. There are many different types of focal reducers and they all effect. CPWI has an extensive object database, employs PointXP mount modeling, and more. I've only used it a few times but it looks good to me. Details: The item must be the identical item, brand name, size, weight, color, quantity and model number. In terms of reduction and correction which are what reducer/correctors are supposed to do both are superb. The more focal reduction, the further inward the focal plane will be. This filter threads on to the rear cell of your Celestron or Meade SCT telescope. Your eyepieces are the first accessories you should learn to use with your telescope. Performance wise what differences might there be using the reducer on a smaller scope. Celestrons FREE planetarium app is an astronomy suite that redefines how you experience the night sky. Thanks for pointing this out. Observing the microscopic world has never been easier! Sign up for a new account in our community. I would not use the reducer with a 2" diagonal or eyepiece in the C6. ED stands for "extra-low dispersion," which refers to the composition and optical properties of the glass used for the lenses. It's usually specified in millimeters. 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. Since the focal length of the reducer, FR, is fixed, as d2 increases then MR decreases. We process your personal data as stated in our. Most Feather Touch focusers cost between $300-$350. Article Agena AstroProducts, 2019. I think I remember hearing the reduction factor is slightly different, cant remember more or less reduction. Please note, orders placed after 10am on 2/28/2023 will be delayed. Hi. With both, using the same diagonal set-up, the exact same stars were visible at the very edge of the FOV. Can you help me? This focal reducer is made to attach to the rear cell of Schmidt-Cassegrain or Maksutov-Cassegrain telescopes. I'd favor the Japanese Celestron version over the others that are commercially available. 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. 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. 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. Sign up to receive sale alerts, news about upcoming celestial events, and telescope tips from our experts! We reserve the right to verify a competitor's advertised price and the availability of the item. Thanks guys, I'm trying to get my ZWO ASI120MC-S to work with my 90mm Meade. Reducer Lens .7x - EdgeHD 925 Learn More. The easiest way to use a focal reducer is to make sure you place it at the specified working distance in front of your camera or eyepiece. More aggressive reduction, or using these reducers with larger sensors, will result in aberrations and distortions near the edge of the image. And when used in some refractors, the field flattening is not as accurate as it is in the f/10 SCTs. The Celestron f/6.3 is ~150 compared to the Antares at ~70. 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). One focal reducer will not achieve optimum results with all types of telescopes, so there is no universal' focal reducer. The Reduction Factor and the Amount of Reduction are inversely related. In many cases, the answer is yes, especially for electronically-assisted astronomy (EAA). 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. Reducer - Corrector Benefits limited to hardware and conditions? In the 1960s, Celestrons founder, Tom Johnson, created groundbreaking new telescopes never before seen on the consumer market. Fumbling around in the dark, fine threads might be a problem. Can you tell me about the use of reducers in Maksutov-Cassegrain telescopes? No rainchecks will be issued for items out of stock at OPTcorp.com to match a competitor's price. October 11, 2010 in Discussions - Scopes / Whole setups. However, the export of some items may be restricted outside the US due to size or manufacturer restrictions. 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. For the best experience on our site, be sure to turn on Javascript in your browser. 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 . Easy solution found a very tiny dab of super lube on the threads and all was well and quiet. Manish Panjwani has been an active amateur astronomer since before Halley's Comet last flew by our neighborhood. It works fine but you should stick with 1.25 EPs; or can use 2" EPs without corrector. which looks like the same one. That's partly because focal reducers correct for field curvature, which itself depends on the focal ratio and other optical design factors of the telescope. The equations and argument in the Appendix of this article shows the relationship between the working distance and the reduction factor. 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. 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 have the Antares and have no complaints. Copyright 2003-2022 Agena AstroProducts. There are also third-party vendors such as Hotech. 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. Product Details. USD $80.00. With spring galaxy season here, I decided to pick up a couple more to compare in a head-to-head shoot out. Both exhibited consistent reduction, identical field flattening, and edge correction properties, and both were high quality optically and mechanically. Antares or Celestron? What an enjoyable read and detailed comparison. . 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. Maybe I got a lemon. In both cases will end with a similar tfov. 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. That is definitely a 2" eyepiece, but it is not a large or long focal length 2" eyepiece. Does anyone have any experience with the Celestron and Antares focal reducers? All Rights Reserved. If yes, what kind of focal reducers can I use? Unique focal reducer and field corrector lens accessory Reduces the focal length and f/ ratio of your Schmidt-Cassegrain telescope by 37% Provides a dual focal ratio instrument, without sacrificing image quality Compatible with all Schmidt-Cassegrain telescopes (see compatible list in description) Share Customers Also Purchased Description Your wishlist has been temporarily saved. 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. Start Chat 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. Any comments gratefully received. Who cares? Thank you so much for the informative article, I now understand better how to integrate my reducer into my system to get better performance. Celestron or Antares? The f/6.3 reducer is operating at f/5-f/5.5 with a 2" diagonal, depending on the back focus length of the diagonal. Focal Reducer, 2", 0.7X. If used with other f/ratios, the field flattening characteristic may be unpredictable. 3. 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. 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. Is that distance D= Fo-d1=Fo-(d2/MR)? If used before or beyond the working distance, unwanted image distortion may result. No difference. At least these two units I tested make the answer - whatever. ED glass is specially formulated and contains rare-earth compounds that greatly reduce a visual defect called chromatic aberration. He also holds a Ph.D. in engineering physics from McMaster University. 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. Thanks for any advice or experience you could share. The female end attaches to the rear cell of the telescope. The price for an item/offer must be listed and valid at the time of match. Another factor to consider: focal reducers also increase the angle at which light approaches the focal plane. Besides observing from his heavily light polluted backyard in Los Angeles, Manish enjoys conducting astronomy outreach programs in local schools. But when not in the box or on the telescope, there is no cover for the other end. As a result, the smaller tube may cut into the light cone and effectively reduce the working aperture of the telescope. For the best experience on our site, be sure to turn on Javascript in your browser. Some faster refractors with a focal ratio of f/6, for example, only require field flatteners and not focal reducers. ), but stars seemed a bit tighter and their colors were richer and more dramatic. All additional accessories mount onto the exterior/male threads. ), 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. Nebula Filters. Reproduction without permission prohibited. More about this below. The stars at the edge could be worse or better. Many focal reducers for refractors have a working distance (or back focus distance) of 55mm. You can probably eke out 1.2 without noticing serious vignetting, which is a field stop of 31.5mm. These reducers have a back focus (or design working distance) of 80mm. Brian Ventrudo is a writer, scientist, and astronomy educator. Great report and verifies what I had thought all along, Fortunately, my neighbors are not out in their backyards at 11 pm, or they may have thought I was torturing a small mammal. 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? Reducer Lens .7x - EdgeHD 800 Learn More. Obviously bright objects like Jupiter or The Moon show the reflections. I have an 8SE, and am thinking about getting a focal reducer. Fortunately, my neighbors are not out in their backyards at 11 pm, or they may have thought I was torturing a small mammal. Completely stuck, completely frustrated. 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. Request stock alerts and we'll let you know when the item is back in stock. When using the diagonal, keep the field stops of the eyepieces under 20mm. Once installed, you can add additional accessories like T-Adapters, 1.25 Visual Back, Star Diagonal, or Off-Axis Guider. 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). Therefore, a 55mm back focus with a filter that is 3mm thick added to the imaging train would become 56mm. Enter it during checkout! They both are great and I doubt my eyes could detect a difference in any one of them including the Japan version. 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. DUE TO EXTREMELY HIGH DEMAND, WE WILL NOT BE TAKING NEW ORDERS UNTIL MONDAY, DECEMBER 14. Again, to my surprise, there was absolutely no difference between the Celestron and Antares on any star. 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. Copyright 2021 Stargazers Lounge On the camera side, the focal reducer has male M42x0.75 or M48x0.75 threads that attach directly to the T-ring (with an M42-M48 adapter if necessary). If you do so, you will achieve the design reduction factor. From the SkyProdigy, a telescope so smart it can align itself, to our high-performance EdgeHD optical system, weve revolutionized the hobby of astronomy for beginners and advanced amateurs alike. However, doesn't fit in the telescope and even if it did wouldn't work. Practical Considerations of Focal Reducers, 4.2 Back Focus Requirements of Focal Reducers, GSO makes focal reducers for their line of Ritchey-Chretien, Celestron makes a series of focal reducers for the Edge HD line, 0.75x focal reducers for these telescopes, focal reducer for an 8-inch Celestron EdgeHD, A Primer on T-Rings and T-Adapters for Astronomy and Astrophotography, Choosing the Best Telescope for Beginners 2023, Top Night Sky & Astronomy Events in August 2022, Top Night Sky & Astronomy Events in July 2022, Selecting a Baader Planetarium Star Diagonal, A Guide to Choosing Astronomy Eyepieces for Binoviewers, Choosing a Magnifying Finder Scope for Your Telescope, A focal reducer will provide its design reduction factor only when it is placed at the exact working distance from the focal plane of the eyepiece or camera, Reducing the operating distance, that is, moving a focal reducer closer to the eyepiece or camera increases its reduction factor, or conversely reduces the amount of focal reduction. The threads were similar on the eyepiece end, but a bit smoother. The Best Dedicated Astronomy Cameras for Beginners, Astronomik OIII 12nm CCD Filter - T-Threads, Pegasus Astro Dual Motor Focus Controller, 10 Micron 12kg (26.45lbs) Stainless Steel Counterweight- GM 2000, I would like more information regarding stock availability dates. Your price: $579.00. For this shoot-out, I used a standard Celestron C8 with Starbright coatings. With this telescope and this focal reducer, it does not help to move to a 2" eyepiece and a 2" diagonal as the visual view will be akin to looking through a porthole within the larger apparent field of view of the eyepiece. CPWI has an extensive object database, employs PointXP mount modeling, and more. Again, these focal reducers are often provided by the telescope manufacturer. This is very impressive performance given how hard this problem is to mitigate in general. Clearly cost is a big factor for satisfied users. control and Sky Viewer display makes selecting your target easy. Now It only focuses near things, like some kind of macro zoom. Telescope Optics, Rutten and van Venrooij, Chapter 15, Willman-Bell (1988). For visual use, this means you get lower power with the same eyepiece and a wider field of view. Very helpful, thanks a lot for this article! However, even though the imprint on the item states "Reducer / Corrector" please note that his is a reducer only. Some third-party vendors also make reducers for SCT scopes. A useful thing to know is how far from the objective lens (for a refractor) is the focal reducer located. 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.