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). I even lost track of which reducer I was using. 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. I have Hirsch focal reducer, which is yet another clone of the Celestron reducer. More aggressive reduction, or using these reducers with larger sensors, will result in aberrations and distortions near the edge of the image. 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. As one increases, the other decreases. Perfect for the serious student, professional scientist and discriminating hobbyist. 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. 3. Can these economical focal reducers from GSO and other vendors result in good images? 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. Given past experience with them, I decided not to include the Meade version in my little experiment, as I have never met one I liked from getting one of the too-short focal length models, to one with some overflow cement in the doublet, to focus difficulties with some eyepieces. Reviews. A useful thing to know is how far from the objective lens (for a refractor) is the focal reducer located. Manish holds a Master's degree in Electrical Engineering from Virginia Tech and an MBA from the Kellogg School of Management at Northwestern University. 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. 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. Yet, the Antares still easily and fully threaded without any hitches. It is recommended for . If yes, what kind of focal reducers can I use? You can adjust your cookie settings, otherwise we'll assume you're okay to continue. 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. I wish there was. What an enjoyable read and detailed comparison. ), 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. Sign up to receive sale alerts, news about upcoming celestial events, and telescope tips from our experts! Have always disliked the crude, noisy SCT threads, but I get it. Celestron Solar Safe filter technology is GUARANTEED SAFE for direct solar observation and has been independently tested by SAI Global Assurance Services. All rights reserved. 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. Clearly cost is a big factor for satisfied users. My Celestron was made in China and the Antares in Canada. An eyepiece with a 27mm field stop yields a true field of 1.03 in the C6 at f/10. Obviously bright objects like Jupiter or The Moon show the reflections. Does anyone know if the Antares 4000 focal reducer is as good as the Celestron focal reducer. These scopes are compatibles with focal reducers. 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. Unleash the full pointing accuracy of your Celestron computerized telescope with a specialized telescope control software suite. However, this also came at a cost, as the sky background in the Antares was slightly brighter. 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. Telescope Optics, Rutten and van Venrooij, Chapter 15, Willman-Bell (1988). Several functions may not work. Read our 101 article or get in touch. CEL-94245. 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. 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. 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. In the 1960s, Celestrons founder, Tom Johnson, created groundbreaking new telescopes never before seen on the consumer market. 2023 OPT Telescopes. 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. 1.2" in that scope is a field stop of 43mm at f/10 and 27mm at f/6.3. You need to be a member in order to leave a comment. However, some focal reducers can be used on other models of telescopes, but this is not always possible. But in the Japan version I have never noticed any anomaly like the ghosting in the China R/C. 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. They only publish the value of D, the working distance (sometimes called the back focus distance) and the design reduction factor MRD. The Reducer/Corrector is easy to install by threading the unit onto the rear cell of your Schmidt-Cassegrain telescope (or the reducer plate of the C11 and C14). Again, swapping back and forth for a couple of hours on M44, M35, and several brighter stars, I examined the shape of specific stars near the edge of the field with both correctors. 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. Things change but when I rebought I got an Antares and it seems about the same to me. In some cases, focal reducers also act as field flatteners by correcting for field curvature and coma of the objective lens. I have a made in Japan 6.3 R/C and a made in China 6.3 R/C. However, manufacturers virtually never provide this specification. I've heard and read all kinds of things about the Antares being only a reducer and not a corrector, etc. This means that there must be sufficient travel on the telescope focuser to make up for this. Shipping will be via the cheapest shipping method which will vary depending on the items in your order. Copyright 2003-2022 Agena AstroProducts. 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. In terms of reduction and correction which are what reducer/correctors are supposed to do both are superb. InternetSales@optcorp.com. They are also less expensive than many external focusers of similar build quality. 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. Most reducers have a design reduction factor, MRD, that assumes the reducer is placed at a specific working distance, D, from the back surface of the focal reducer itself. Figure 1 shows the relationship between the focal reduction factor MR and the position of the reducer in the optical path. Reproduction without permission prohibited. Because I have not heard any complaints about the made in China R/C. For Stephen Wilkerson: The ZWO ASI120MC-S does come with a wide angle lens, HOWEVER, it is NOT intended to used when you are using the ASI120 camera attached to your telescope. First, let's have a look at some key optical parameters are needed to understand focal reducers. This also resulted in the clear aperture of the Antares being about 39-39.5mm, versus the Celestrons 41mm. To test this, I used three set-ups: 1. Some manufacturers will specify the working distance from the middle of the rear lens surface, and this number must then be converted into a practical working distance number by subtracting the amount by which the rear lens surface is recessed in its housing. * Not a Retail Store * 16313 Arthur StreetCerritos, CA 90703, USA. 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. ED glass is specially formulated and contains rare-earth compounds that greatly reduce a visual defect called chromatic aberration. The Celestron f/6.3 is ~150 compared to the Antares at ~70. External Focusers for Schmidt-Cassegrain Telescopes 3.1 The Basics of SCT Threads For visual use, this means you get lower power with the same eyepiece and a wider field of view. Both exhibited consistent reduction, identical field flattening, and edge correction properties, and both were high quality optically and mechanically. 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. 2.2 Using a Focal Reducer at the Working Distance, 2.3 Adjusting the Reduction Factor of a Focal Reducer, 3.3 Focal Reducers for Compound Telescopes, 3.5 Focal Reducers for Ritchey-Chretien and Field Flattened Scopes, 3.6 Focal Reducers in 1.25" and 2" Barrel Formats, 4. 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. However, the China 6.3 R/C has noticeable internal reflections that I haven't figured out yet. Your mileage may vary. I must admit, as well, that I no longer place a lot of stock in the notion that Chinese optics are inferior to Japanese or Taiwanese any longer, as manufacturing technology has really leveled the playing field today, with most Chinese optics being excellent. Now It only focuses near things, like some kind of macro zoom. Celestrons FREE planetarium app is an astronomy suite that redefines how you experience the night sky. Since then, Agena has become one of the leading online retailers of telescopes and astronomical accessories worldwide. Celestron or Antares f/6.3 focal reducer for SCT? These reducers can also be used for visual observing with SCT scopes with eyepieces with a field stop as large as 24-27mm. 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. But I am rusty, can you condense a bit for me please? 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. Also, the focusers of most Newtonians do not have enough in-travel to accommodate a focal reducer. Since the Celestron and Antares are supposed to have different focal lengths and spacing specs, I expected different results. Sign up to get exclusive deals, observing tips, and new product announcements. I have both the Antares and the Celestron reducers. That said any comparison reviews are helpful. You attach the focal reducer to the rear port on a SCT and can keep it covered. Most manufacturers provide this specification. . The lens that the ZWO comes with give a perfect wide angle image of what is in front of it. The naming convention of SCT focal reducers is a little confusing. 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. Images made with my ZWO 533 camera testing both show them to be essentially the same. Focal reducers (and focal reducer/field flatteners combos) are usually used with two types of telescopes, refractors and compound telescopes such as Schmidt-Cassegrain or Ritchey-Chretien. 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. It seems right to put some distance between the camera and the focal reducer, right? An image of about 24mm across, approximately, allows an observer to use a 1.25" eyepiece with a maximal field stop. Reducer - Corrector That is definitely a 2" eyepiece, but it is not a large or long focal length 2" eyepiece. The female end attaches to the rear cell of the telescope. 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. With spring galaxy season here, I decided to pick up a couple more to compare in a head-to-head shoot out. 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. The Celestron is both a corrector and focal reducer and the Antares is just a focal reducer. Also read the reviews here, including those at 4 stars. 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. The nominal design reduction factor of these reducers is typically 0.5x. 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 Celestron f/6.3 is ~150 compared to the Antares at ~70. My experience is that CN sellers are way above those listing elsewhere. 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. 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. None of this was offensive, nor did it interfere with views in any significant way. The Antares f6.3 focal reducer screws directly to the visual-back thread of all popular SCTs and converts f10 instruments to f6.3. Photographically you also get a wider field and much shorter exposures. The stars at the edge could be worse or better. To further factor out my natural astigmatism (I normally wear glasses while observing), I did the tests with my regular progressive lenses, single vision glasses I use when observing, and naked eye. Oceanside Photo & Telescope wants our customers to shop with confidence knowing that you will always get the best deal available. 2023 Celestron, LLC. They both are great and I doubt my eyes could detect a difference in any one of them including the Japan version. This is one of our best-selling items, and customers have reported that this product is at least as good as, and probably better than, other leading f/6.3 focal reducers sold on the market for a lot more. Yellow and orange members of open clusters stood out a bit more as the various stars displayed their individuality. If I had to guess, the difference is maybe 10-15 grams. Reducer Lens .7x - EdgeHD 1100. riklaunim Members 559 3,445 Location: Poland Posted October 11, 2010 They are reported as identical. And when used in some refractors, the field flattening is not as accurate as it is in the f/10 SCTs. I use the Celestron version and it seems OK for both visual and imaging. 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. Hi. 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. 3. . 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. A focal reducer does just the opposite of a Barlow lens or focal extender. 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. Observing the microscopic world has never been easier! If you want to save a few buck watch the classifieds on CN. Therefore, a 55mm back focus with a filter that is 3mm thick added to the imaging train would become 56mm. Perhaps not exactly- there will be some uncertainty because of manufacturing tolerances and so forth, but it will be close. Thanks for any advice or experience you could share. Any comments gratefully received. 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. Thanks for the extremely valuable article. For the best experience on our site, be sure to turn on Javascript in your browser. GSO, for example, has a 0.75x reducer for RC scopes with a back focus of 80mm, which is usually enough room for a wide range of astronomy cameras and accessories and spacers as needed. 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. Since the focal length of the reducer, FR, is fixed, as d2 increases then MR decreases. SKU: CEL-94245. Most different was that the sky background was a little darker and more uniform, providing a tiny contrast boost for fainter objects. looks virtually identical, except for the lettering. Nada. The new Lithium Phosphate (LiFePO4) battery chemistry has significant advantages over other battery chemistries, great for for those Astronomers on the go. 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. This focal reducer and field flattener consists of a four-element multicoated 40mm lens in a metal cell. The focal length of a focal reducer is usually measured from the rear lens surface of the reducer (and not the reducer's housing). 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). Copyright 2003-2022 Agena AstroProducts. 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. Despite never removing it no matter what I was looking at. The two samples I have PERFORM IDENTICALLY. If you want to use them for visual - try maybe long focal length eyepieces rather than the reducer. This would tell us exactly how well aberrations are corrected. 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. As a Barlow's magnification increases with increasing distance from the Barlow, a focal reducer's reduction increases with increasing distance from the reducer. Your eyepieces are the first accessories you should learn to use with your telescope. Steve 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. 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. Powered by Invision Community. Not a bit. Focal reducers for these relatively fast ED refractors are generally for imaging only, not for visual observation. We process your personal data as stated in our. He also holds a Ph.D. in engineering physics from McMaster University. Dedicated focal reducers for refractors are intended primarily for imaging, not visual observation. Easy solution found a very tiny dab of super lube on the threads and all was well and quiet. 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. Such an image circle is still large enough to encompass the relatively large sensor of many deep-sky astronomy cameras. 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. Since 2008, Brian has taught astronomy to tens of thousands of stargazers through his websites OneMinuteAstronomer.com and CosmicPursuits.com.