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Sign up to receive sale alerts, news about upcoming celestial events, and telescope tips from our experts! The stars at the edge could be worse or better. It's easy! However, some focal reducers can be used on other models of telescopes, but this is not always possible. 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. Therefore, a 55mm back focus with a filter that is 3mm thick added to the imaging train would become 56mm. 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. . But the diameter of the image circle decreases by a factor of 0.63 to about 24mm. While most Barlow lenses and focal extenders work with most kinds of telescopes available to amateur astronomers, focal reducers are designed to work in a narrow range of focal ratios of a telescope objective. Start Chat 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. More about this below. 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). Right off the bat, I was struck by how similar the two R/Cs were. But when not in the box or on the telescope, there is no cover for the other end. 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. If the reducer is placed elsewhere, at a position called the operating distance, the focal reduction factor will not be as advertised. Stars in the corner of the image frame are indistinguishable between the Antares and the Celestron. Several functions may not work. Nada. Many reducers, such as the Celestron HD focal reducer mentioned above, and many focal reducers for apochromatic refractors, are meant to be used within a few millimeters (or less) of the specified working distance to achieve the best possible image results. No results, please adjust your filters. 800-483-6287 This article explained the basics of how focal reducers work with various kinds of telescopes and how their working distance affects their reduction factor, and it provided sufficient detail to help amateur astronomer choose and use the right focal reducer for a particular application. Planetarium software package which provides easy-to-understand explanations and impressive visuals of all kinds. Hmmm . It works fine but you should stick with 1.25 EPs; or can use 2" EPs without corrector. 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. 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. The focal length of a focal reducer is usually measured from the rear lens surface of the reducer (and not the reducer's housing). In such cases, we will be happy to take the item back as per our standard return terms. It is not a corrector or flattener. 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. Easy solution found a very tiny dab of super lube on the threads and all was well and quiet.. Never noticed any anomalies with this unit. Refractors, or SCTs with external focusers, may not have sufficient in-travel to reach focus in some configurations. The equations and argument in the Appendix of this article shows the relationship between the working distance and the reduction factor. 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. CEL-94245. I think that the FRs made in Japan in the day may have been better. Manish Panjwani has been an active amateur astronomer since before Halley's Comet last flew by our neighborhood. For this shoot-out, I used a standard Celestron C8 with Starbright coatings. A couple of tiny dust particles between lens elements, uneven lens edge blackening, very minor coating blemishes, or even a very small fine lens scratch or two are very common in this Antares product and must be accepted as normal for this item. Once focused it's pretty good. Bear in mind you can't squeeze blood out of a turnip, i.e. Some refractors such the TeleVue Nagler-Petzval (NP), the Takahashi "FSQ", and the William Optics Redcat/WhiteCat 51 have inherently flat fields because of internal optical elements. Many focal reducers are meant to be used within a few millimeters of the specified working distance to achieve the best possible image results. riklaunim Members 559 3,445 Location: Poland Posted October 11, 2010 They are reported as identical. 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. OPT Product Number: AE-SCTFR specifications Warranty 2 Year Warranty Works as advertised! He tested this on an 8 Celestron , I have a Celestron 6SE. Can you help me? Edited by bluewater, 05 September 2020 - 11:27 AM. To test this, I used three set-ups: 1. 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 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. Clearly cost is a big factor for satisfied users. It features a standard male SCT thread (2" OD, 24 TPI) on one side and a standard SCT female thread on the other. 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. I have both the Antares and the Celestron reducers. Since then, Agena has become one of the leading online retailers of telescopes and astronomical accessories worldwide. 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. Reducer Lens .7x - EdgeHD 800 Check out our 2022 telescope buying guide here! A former wireless communications consulting engineer and management consultant to various Fortune 500 companies, Manish started Agena AstroProducts in 2003. Add a 0.63x reducer, and the brightness of extended objects increases by (1/0.63)2 = 2.5. A few people have reported issues with the male SCT thread diameter on this item being a bit larger than necessary. 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. Please note, orders placed after 10am on 2/28/2023 will be delayed. However, these will not impact optical performance. I happily cycle through LRGB filters to build the image rather than do a whole run of one filter at a time. Please re-enable javascript to access full functionality. 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. This fully multi-coated lens provides maximum light transmission with near full-field illumination. JavaScript seems to be disabled in your browser. With the Celestron Reducer/Corrector Lens, thats precisely what you get. For me, I was looking for, and planning to keep, the one that yielded the greatest reduction. This article explains the basics of how focal reducers work with an astronomy telescope. We have placed cookies on your device to help make this website better. Generally, views through the Antares seemed a little more transparent and brighter. How does it look thats what matters. Because most modern Newtonians already have relatively fast focal ratios, these telescopes do not usually use focal reducers. I have/had both the Celestron (Japan) and Antares units. 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). Focus misses by about 1 turnof the focus knob.Here is my solution:Buy a shorter 1.25 visual back for my scope. 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). 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. They usually have a 2" barrel that slides into the telescope focuser. I think I remember hearing the reduction factor is slightly different, cant remember more or less reduction. However, even though the imprint on the item states "Reducer / Corrector" please note that his is a reducer only. For this test, I used a single configuration R/C, Click-lock, and 1.25 diagonal with the adapter. 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 have the Antares and have no complaints. 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. Like you, I am primarily visually observing but I have everything together now that so I am going to start experimenting with photography so we'll see how it does there. 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. Take control of your telescope! 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. On the trail, at the job site, in the classroom, or simply sitting at home relaxing the Celestron Elements ThermoTank 3 will keep your hands toasty. 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. Learn more about extra solar planets imagery, 3D Star rendering, observation planning, telescope control, multiple-panel printing, and much more. In terms of reduction and correction which are what reducer/correctors are supposed to do both are superb. No negative issues to report. Upon close inspection, it was clear that the housing of Antares assembled in Canada version was a little more substantial than the Celestron. October 11, 2010 in Discussions - Scopes / Whole setups. 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. 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. Again, these focal reducers are often provided by the telescope manufacturer. 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. Over the course of a several nights of general observing, I swapped back and forth between the Antares and Celestron R/Cs on a wide variety of objects open clusters, brighter galaxies, a couple of nebulae, and globular clusters as well. The reducer features fully coated optics in an anodized aluminum filter ring with an ergonomic rubber grip. A few large telescopes and mounts are excluded from this free shipping offer. As a Barlow's magnification increases with increasing distance from the Barlow, a focal reducer's reduction increases with increasing distance from the reducer. Hi. Product Details. And when used in some refractors, the field flattening is not as accurate as it is in the f/10 SCTs. The more focal reduction, the further inward the focal plane will be. Based on Test 1 and Test 2, I think there is perhaps more validity to opposing statements here in these forums that the Antares and current China-made Celestron do, indeed, have exactly the same optics just with different housings and branding. As a result, the smaller tube may cut into the light cone and effectively reduce the working aperture of the telescope. These reducers can also be used for visual observing with SCT scopes with eyepieces with a field stop as large as 24-27mm. Is that distance D= Fo-d1=Fo-(d2/MR)? For the best experience on our site, be sure to turn on Javascript in your browser. 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. The visual back must be removed first. I had a Celestron, Antares and Hirsch for awhile and compared them over about a year. 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. That includes, for example, a 1.25" eyepiece with an apparent field of view of 68 and a focal length of 24mm (eg. and you will be fine. 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. My experience is that CN sellers are way above those listing elsewhere. Quite interestingly it bears the very same engravings of the Meade 4000 r/c (including "series 4000") except for "MEADE". The review is a subjective visual impression, which is interesting but not best evidence. The telescope side of the barrel is often threaded with an M48 x 0.75 thread for standard 2" astronomy filters. Assuming you use the reducer with the stock 1.25" diagonal, it will operate at f/6.3. Try & buy if you like - usual mates rates. A reducer is a set of converging (or positive) lenses that cause the light from a telescope objective to converge at a steeper angle to the focal plane as if it were coming from an objective with a faster (lower) focal ratio and a shorter focal length. All Rights Reserved. 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. Telescope Optics, Rutten and van Venrooij, Chapter 15, Willman-Bell (1988). Observing the microscopic world has never been easier! Dedicated focal reducers for refractors are intended primarily for imaging, not visual observation. I am a purely visual observer, so will evaluate for visual use only. So Celestron buyers like Celestron, Meade buyers like the Meade and Antares buyer like the Antares. Focal reducers for many SCTs and their flat-field equivalents usually have a back-focus distance of 105mm. Meade and Celestron both sell such SCT-T adapters with the correct optical length. In your opinion, is the Celestron is worth the added cost ($150 vs. $90)? This superb fully multi-coated multi-element focal reducer takes advantage of the latest computer aided design techniques to achieve the highest standards of performance set by the brand leaders at a fraction of the cost. This also resulted in the clear aperture of the Antares being about 39-39.5mm, versus the Celestrons 41mm. 160K views 9 years ago This video is a complete overview of focal reducers and how they function applying to telescopes. The same illumination you have at the edge of a 27mm field, the C8 has at the edge of a 38mm field. Since 2008, Brian has taught astronomy to tens of thousands of stargazers through his websites OneMinuteAstronomer.com and CosmicPursuits.com. I have a Raspberry HQ camera, a Sony TV Zoom 12.5-75mm f1.8 and a Astromania 1,25" 0.5x focal reducer. 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. 1.2" in that scope is a field stop of 43mm at f/10 and 27mm at f/6.3. Not noticed any optical problems. CPWI has an extensive object database, employs PointXP mount modeling, and more. These reducers can also be used for visual observing with SCT scopes with eyepieces with a field stop as large as 24-27mm. At least these two units I tested make the answer - whatever. Unleash the full pointing accuracy of your Celestron computerized telescope with a specialized telescope control software suite. This filter threads on to the rear cell of your Celestron or Meade SCT telescope. Celestrons patented StarSense Technology makes it easier than ever to locate objects in the night sky, even if youve never used a telescope before. We will match any online price that we confirm as valid. Melotte 15 - First Process in PixInsight (easy! Even though the manufacturer did not specify the working distance or focal length of this reducer, it is easy to see from this plot that this item provides its stated reduction of 0.5x when it is placed at a working distance of 51.5mm between the base of the threads on the mount and the focal plane of the eyepiece or camera. It can also be used with any other small chip CCD camera having a 1.25" nosepiece, such as the Celestron NexImage, Meade DSI . 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. Reducer - Corrector The new Lithium Phosphate (LiFePO4) battery chemistry has significant advantages over other battery chemistries, great for for those Astronomers on the go. CPWI has an extensive object database, employs PointXP mount modeling, and more. The lens is housed in machined aluminum for are machined aluminum black anodized. The two samples I have PERFORM IDENTICALLY. No small animals were harmed in making these observations. control and Sky Viewer display makes selecting your target easy. This Antares 1.25" 0.5x focal reducer lens (tele-compressor) is used under the Orion brand name to thread into the nosepiece of Orion StarShoot Solar System cameras and StarShoot Deep Space Color Imaging Camera. 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. Meade once made an f/3.3 focal reducer for SCT scopes. SKU: CEL-94245. The C8 has no noticeable vignetting with a 32mm Plssl in the f/6.3 reducer. But is there a difference in quality between the Antares and the Celestron or Meade focal reducers? Is there likely to be any differences in performance between using these on an 8 or something smaller like my 6SE? Have a promo code? As per the OP I still can't see any reason to buy the Celestron for significantly more $$$. 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. 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. Description. InternetSales@optcorp.com. We tested GSO's 1.25" 0.5x focal reducer at a variety of operating distances and calculated the field of view through a telescope to derive the actual reduction factor that is plotted below. By using this site, you agree to our Terms of Use.