A wider field of view and a lower magnification is also useful, with some focal reducers and with some eyepieces, for visual observers with telescopes with long focal ratios. 800-483-6287 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. 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. Celestron or Antares f/6.3 focal reducer for SCT? However, because the field curvatures in refractors and SCTs vary a lot, I would predict unpredictable effects inre: field curvature. So it provides a 0.63x design reduction factor when used with an f/10 SCT at the specified working distance. I had a Celestron, Antares and Hirsch for awhile and compared them over about a year. I found both to be very good. Performance wise what differences might there be using the reducer on a smaller scope. For this shoot-out, I used a standard Celestron C8 with Starbright coatings. With both, using the same diagonal set-up, the exact same stars were visible at the very edge of the FOV. We will match any online price that we confirm as valid. However, some focal reducers can be used on other models of telescopes, but this is not always possible. 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. Rather than a direct side-by-side, I swapped the reducers so that I was using them on the exact same, well-collimated instrument. Looking forward to the day when I can do a shoot-out between a Japan and China Celestron, just for kicks. 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. Focal Reducers - Complete Overview and Function - YouTube In some cases, focal reducers also act as field flatteners by correcting for field curvature and coma of the objective lens. A former wireless communications consulting engineer and management consultant to various Fortune 500 companies, Manish started Agena AstroProducts in 2003. Start here to find the perfect telescope for you! I happily cycle through LRGB filters to build the image rather than do a whole run of one filter at a time. Agena's Guide to Focal Reducers - Agena Astro The problem with those SCT reducers is that they cause chromatic aberration and require refocusing when using parfocal RGB/other filters. Stars had a tiny bit more sparkle and pop. Orders placed after 12:00 PM Pacific Time will be shipped the next business day. If you do so, you will achieve the design reduction factor. 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. CPWI has an extensive object database, employs PointXP mount modeling, and more. Not one detectable iota of discernable difference. Celestrons award-winning Nature DX binocular gets a major upgrade with the addition of ED objective lenses. 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. CEL-94245. A useful thing to know is how far from the objective lens (for a refractor) is the focal reducer located. A longer effective focal length leads to higher magnification with a given eyepiece for visual observers. But is there a difference in quality between the Antares and the Celestron or Meade focal reducers? A few people have reported issues with the male SCT thread diameter on this item being a bit larger than necessary. Each focal reducer has a fixed specification called the working distance or required back focus. High power views will provide flatter fields all the way to the edge, both visually and photographically. Some are available in 1.25" barrel format but with C threads. This focal reducer is made to attach to the rear cell of Schmidt-Cassegrain or Maksutov-Cassegrain telescopes. Celestron's EdgeHD reducers feature a custom 5 element optical design engineered to maintain the flat-field performance of our award-winning EdgeHD optical system. 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). Once installed, you can add additional accessories like T-Adapters, 1.25 Visual Back, Star Diagonal, or Off-Axis Guider. 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. JavaScript seems to be disabled in your browser. Go behind the scenes with Celestrons product development team and learn more about our award-winning and patented innovations. 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. The Celestron f/6.3 is ~150 compared to the Antares at ~70. Opticstar F6.3 Focal Reducer / Corrector. However, even though the imprint on the item states "Reducer / Corrector" please note that his is a reducer only. Who cares? You currently have javascript disabled. So ab6110 is asking for a FR only without coma correction, there are a couple of brands who make special reducers for the ACF. Your wishlist has been temporarily saved. 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. It has only one cover, which surprised me. How does it look thats what matters. Copyright 2003-2022 Agena AstroProducts. Better images are also obtained when using these focal reducers at a reduction factor of 0.5x 0.8x, approximately. Images in the Celestron tended to appear ever-so-slightly dimmer (maybe? These scopes are compatibles with focal reducers. 2023 Celestron, LLC. 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. With spring galaxy season here, I decided to pick up a couple more to compare in a head-to-head shoot out. 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. In this configuration, the 29.5mm camera nosepiece and a 6mm extension ring positions the reducer at a working distance of 53.5mm from the camera sensor, which is located 12.5mm inside the front edge of the camera. Add a 0.63x reducer, and the brightness of extended objects increases by (1/0.63)2 = 2.5. 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. For me, I was looking for, and planning to keep, the one that yielded the greatest reduction. Regardless, the difference was miniscule and is more than adequate on both and exceeds a 8 or 6 SCTs baffle tube diameter. 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. Orders placed over the weekend will be shipped on the following Monday. 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. Focal reducers for refractors are easy to use. Shipping will be via the cheapest shipping method which will vary depending on the items in your order. A few large telescopes and mounts are excluded from this free shipping offer. Product Details. 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). Reducer - Corrector | Celestron In these equations: The combined focal length of the objective and focal reducer is given by Equation 1: For example, when d1=0, that is, the focal reducer is at the focal plane of the objective, Fcomb=Fo, so the focal reducer has no effect. Does anyone know if the Antares 4000 focal reducer is as good as the Celestron focal reducer. Sign up for our newsletter to get exclusive deals, observing tips, and new product announcements. More aggressive reduction, or using these reducers with larger sensors, will result in aberrations and distortions near the edge of the image. In such cases, we will be happy to take the item back as per our standard return terms. None of this was offensive, nor did it interfere with views in any significant way. However, it will not thread into William Optics accessories, and with GSO it is a hit or miss. With the barrel 1.25 reducer won't focus, all I get is fuzzy snowballs. We have tested our current batch and it works with Meade, Celestron, and Baader SCT accessories. The Celestron is both a corrector and focal reducer and the Antares is just a focal reducer. Thanks for pointing this out. For this test, I used a single configuration R/C, Click-lock, and 1.25 diagonal with the adapter. * Not a Retail Store * 16313 Arthur StreetCerritos, CA 90703, USA, Availability: Item has been discontinued by Agena and we no longer carry this item. Just one question. riklaunim Members 559 3,445 Location: Poland Posted October 11, 2010 They are reported as identical. 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. 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. 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. But I am rusty, can you condense a bit for me please? Download the Celestron PWI Telescope Control Software. Turn it on and push Align. In about three minutes, youre ready to observe! What an enjoyable read and detailed comparison. Sign up for a new account in our community. As mentioned in Section 2 of this guide, the reduction factor of a focal reducer depends on its position in the optical path relative to the eyepiece or camera. Many focal reducers are meant to be used within a few millimeters of the specified working distance to achieve the best possible image results. Sign up to receive sale alerts, news about upcoming celestial events, and telescope tips from our experts! It also leads to larger (although fainter) images of extended objects like the Moon or planets for astrophotographers or visual observers. Reducer - Corrector Learn More. They both are great and I doubt my eyes could detect a difference in any one of them including the Japan version. No rainchecks will be issued for items out of stock at OPTcorp.com to match a competitor's price. Equation 6 & 7 item two & three does not make sense, both say increase its reduction (one should say reduce its reduction?). Have always disliked the crude, noisy SCT threads, but I get it. 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 should not be the case if they have their purportedly different focal lengths. 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. They are designed (assuming you are referring to the f/6.3 version) for the f/10 light cone. Thanks for the extremely valuable article. More important, its clear that the Antares is a reducer/corrector, just like the Celestron and not merely a reducer. 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. When using the diagonal, keep the field stops of the eyepieces under 20mm. 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. 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. They are reported as identical. 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 . More details are found in the Appendix of this article. Article Agena AstroProducts, 2019. Manish holds a Master's degree in Electrical Engineering from Virginia Tech and an MBA from the Kellogg School of Management at Northwestern University. 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. 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. This rugged, 3-in-1 device features a true tactical 3-mode flashlight, a hand warmer, and a portable power bank for recharging your personal electronics on the go. I have the Antares and have no complaints. This article explains the basics of how focal reducers work with an astronomy telescope. This would tell us exactly how well aberrations are corrected. Please note, orders placed after 10am on 2/28/2023 will be delayed. It works fine but you should stick with 1.25 EPs; or can use 2" EPs without corrector. Thanks guys, I'm trying to get my ZWO ASI120MC-S to work with my 90mm Meade. But the smaller image circle means there is a limit to the field stop of an eyepiece that can achieve an unvignetted image. 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. Celestron makes a series of focal reducers for the Edge HD line that are matched to the 8", 9.25", 11", and 14" apertures of these scopes. I also used several eyepieces including the ES 24mm/68, 17.5mm and 12.5mm Morpheuses, and a 10.5mm Pentax XL. Perhaps not exactly- there will be some uncertainty because of manufacturing tolerances and so forth, but it will be close. If yes, what kind of focal reducers can I use? No retailers currently carry this product. The Antares focal reducer comes in small box. But in the end they both do pretty much the same thing and it sounds like any performance difference is subtle. I doubt there is any difference between the Antares and the Celestron except price. Reducer Lens .7x - EdgeHD 925 Learn More. Not a bit. And when d1 = FR, that is, when the focal reducer is placed at a distance from the focal plane of the objective that's equal to the reducer's focal length, the focal length of the combined optical system is Fo, so it acts as a 0.5x reducer. Just point the telescope at any three bright objectsstars, bright planets, or even the Moonand your telescope can orient itself with the night sky. Besides observing from his heavily light polluted backyard in Los Angeles, Manish enjoys conducting astronomy outreach programs in local schools. 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. ), 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. A slight nod to the Antares for heft and higher transmission, but points to the Celestron for nice threads and better contrast. How about for visual observers? For the best experience on our site, be sure to turn on Javascript in your browser. Celestrons patented StarSense Technology makes it easier than ever to locate objects in the night sky, even if youve never used a telescope before. Celestron Focus Motor for SCT, EdgeHD & 8" RASA, Celestron C6 0.63 reducer/flattener back focus. 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. Dedicated focal reducers for refractors are intended primarily for imaging, not visual observation. 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). And, the reality is that every F/6.3 RC out there Celestron, Hirsch, Astromania, etc., etc. A focal reducer does just the opposite of a Barlow lens or focal extender. 1.2" in that scope is a field stop of 43mm at f/10 and 27mm at f/6.3. 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 . The C8 has no noticeable vignetting with a 32mm Plssl in the f/6.3 reducer. 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. 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. Meade once made an f/3.3 focal reducer for SCT scopes. I wont bother with differences in packaging, caps, etc. Reducer Lens .7x - EdgeHD 800 The review is a subjective visual impression, which is interesting but not best evidence. It's usually specified in millimeters. 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. I really don't see any difference in the current crop except the "Meade" is usually the cheapest. 3. As one increases, the other decreases. The two samples I have PERFORM IDENTICALLY. Therefore, a 55mm back focus with a filter that is 3mm thick added to the imaging train would become 56mm. But the diameter of the image circle decreases by a factor of 0.63 to about 24mm. All Rights Reserved. I have Hirsch focal reducer, which is yet another clone of the Celestron reducer. As a consequence, the standard f/6.3 and f/3.3 focal reducers for SCT scopes do not work. 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. 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. Its a good thing I have the super lube handy or my neighbors wont be happy with me.come to think of it, Im sure the small mammals here wouldnt be thrilled either! Reducer Lens .7x - EdgeHD 800 Learn More. For example, with a 0.8x focal reducer, a telescope with a focal length of 800mm will operate at 800 x 0.8 = 640mm when the reducer is placed at the working distance specified by the manufacturer. It's an either/or proposition: reducer and 1.25", or 2", but not 2" and reducer. I don't know. Best evidence would by obtained by using a camera and evaluating the image both by eye and with a computer analysis. Obviously bright objects like Jupiter or The Moon show the reflections. Celestron Solar Safe filter technology is GUARANTEED SAFE for direct solar observation and has been independently tested by SAI Global Assurance Services. That is definitely a 2" eyepiece, but it is not a large or long focal length 2" eyepiece. Today, our world-class team of optical and electronic engineers continues to push the boundaries of technology. Reviews. 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. Fastar Technology allows imagers the option of drastically increasing the speed and sensitivity of their Celestron optical tube, allowing bright, detailed images with short exposures. 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. The equations and argument in the Appendix of this article shows the relationship between the working distance and the reduction factor. External Focusers for Schmidt-Cassegrain Telescopes 3.1 The Basics of SCT Threads These reducers can also be used for visual observing with SCT scopes with eyepieces with a field stop as large as 24-27mm. This focal reducer is made to attach to the rear cell of Schmidt-Cassegrain or Maksutov-Cassegrain telescopes. 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. The Reduction Factor and the Amount of Reduction are inversely related. 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. Explore Scientific - Keys to the Universe Sale. These RC reducers cannot be used with other types of telescopes. Both exhibited consistent reduction, identical field flattening, and edge correction properties, and both were high quality optically and mechanically. 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. The new Lithium Phosphate (LiFePO4) battery chemistry has significant advantages over other battery chemistries, great for for those Astronomers on the go. I use the Celestron version and it seems OK for both visual and imaging. 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. Is there likely to be any differences in performance between using these on an 8 or something smaller like my 6SE? The distance d2, which measures the position of the new focal plane of the objective from the back of the focal reducer is given by Equation 5: In these equations, d1, d2, and MR are all variables that depend on each other through Equations 2 and 4.
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