First, I wanted to compare the actual reduction provided by these competitors, as many threads here cite different ideal spacing from the reducer to eyepiece focal plane to achieve the correct f/6.3 result. There are many different types of focal reducers and they all effect. 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. Theoretically each of these combinations all varied-length light paths should have resulted in slightly different reductions between the Celestron and Antares, since they supposedly have different focal lengths. riklaunim Members 559 3,445 Location: Poland Posted October 11, 2010 They are reported as identical. Will not focus with the stuff I have. Sign up to receive sale alerts, news about upcoming celestial events, and telescope tips from our experts! 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. Celestron or Antares? InternetSales@optcorp.com. 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. I think that the FRs made in Japan in the day may have been better. More details are found in the Appendix of this article. Description. Rather than a direct side-by-side, I swapped the reducers so that I was using them on the exact same, well-collimated instrument. However, the China 6.3 R/C has noticeable internal reflections that I haven't figured out yet. Fortunately, my neighbors are not out in their backyards at 11 pm, or they may have thought I was torturing a small mammal. I'm going with the Celestron. A f/10 focal ratio now achieves a f/6.3, while an f/11 focal ratio now achieves a f/7. The most significant mechanical variation, however, is the quality and precision of the threading. I own both and concur heartily. 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. Celestron or Antares f/6.3 focal reducer for SCT? 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. Have a promo code? Celestron Solar Safe filter technology is GUARANTEED SAFE for direct solar observation and has been independently tested by SAI Global Assurance Services. I have the Antares and am not unhappy with it, but for AP I would want more back focal distance if those numbers are accurate. I use the same back spacing for both on a small 6" Celestron SCT. Take control of your telescope! Photographically you also get a wider field and much shorter exposures. 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. I would not use the reducer with a 2" diagonal or eyepiece in the C6. The visual back must be removed first. It's an either/or proposition: reducer and 1.25", or 2", but not 2" and reducer. 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. For me, I was looking for, and planning to keep, the one that yielded the greatest reduction. There are also third-party vendors such as Hotech. The Buyer's Guide To Eyepieces at the top of the Eyepieces forum has a column for this spec. 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. ED stands for "extra-low dispersion," which refers to the composition and optical properties of the glass used for the lenses. However, it will not thread into William Optics accessories, and with GSO it is a hit or miss. Blue Fireball M42 T/T2 Thread Camera Adapter for Prime Focus Photography - 2" # P-06, Celestron T-Ring for Canon EOS Camera # 93419, GSO 2" Crayford Focuser for SCTs - Dual Speed, Length of male SCT thread = 5mm (0.2") but this is preceded by an unthreaded part on the eyepiece side making the total length = 8.8mm (0.35"), Length of female SCT thread = 7.5mm (0.3"). As a Barlow's magnification increases with increasing distance from the Barlow, a focal reducer's reduction increases with increasing distance from the reducer. 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. Edited by Tony Bonanno, 16 April 2021 - 06:44 PM. Since the focal length of the reducer, FR, is fixed, as d2 increases then MR decreases. 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. A slight nod to the Antares for heft and higher transmission, but points to the Celestron for nice threads and better contrast. That is definitely a 2" eyepiece, but it is not a large or long focal length 2" eyepiece. Just point the telescope at any three bright objectsstars, bright planets, or even the Moonand your telescope can orient itself with the night sky. The focal length of a focal reducer is usually measured from the rear lens surface of the reducer (and not the reducer's housing). But while the image gets brighter, the size of the image circle gets proportionately smaller. The new Lithium Phosphate (LiFePO4) battery chemistry has significant advantages over other battery chemistries, great for for those Astronomers on the go. Nebula Filters. * Not a Retail Store * 16313 Arthur StreetCerritos, CA 90703, USA. Nowadays I tend to use the Celestron more with my refractors for imaging and viewing. The previous post shows the reducer on what appear to be two different refractors. It covers the basic optics and design specifications of a focal reducer, and goes through some practical factors to consider when selecting and using a focal reducer. I've never found my 0.63 reducer causing CA when used with my SCT. 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. I have both the Antares and the Celestron reducers. A few large telescopes and mounts are excluded from this free shipping offer. 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. In both cases will end with a similar tfov. Explore Scientific Keys to the Universe Sale, Antares f/6.3 Focal Reducer for Schmidt-Cassegrain Telescopes, Skip to the beginning of the images gallery. Your price: $579.00. Meade and Celestron both sell such SCT-T adapters with the correct optical length. Brian Ventrudo is a writer, scientist, and astronomy educator. Nada. Explore Scientific Keys to the Universe Sale. This also resulted in the clear aperture of the Antares being about 39-39.5mm, versus the Celestrons 41mm. The most popular accessories for your new telescope! Most different was that the sky background was a little darker and more uniform, providing a tiny contrast boost for fainter objects. No difference. I have Hirsch focal reducer, which is yet another clone of the Celestron reducer. A focal reducer does just the opposite of a Barlow lens or focal extender. Even though they may have been slightly dimmer, galaxies were a bit easier to tease out of the urban light soup I deal with. Copyright 2021 Stargazers Lounge But is there a difference in quality between the Antares and the Celestron or Meade focal reducers? Not noticed any optical problems. 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. When the camera sensor is placed at this distance, the reduction factor of these reducers is 0.75x. How does it look thats what matters. 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. . 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. 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 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 every configuration, there were essentially parfocal, requiring only a tiny fine focus adjustment when changing correctors. In terms of reduction and correction - which are what reducer/correctors are supposed to do - both are superb. 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. Please note, orders placed after 10am on 2/28/2023 will be delayed. The same illumination you have at the edge of a 27mm field, the C8 has at the edge of a 38mm field. No negative issues to report. Manish holds a Master's degree in Electrical Engineering from Virginia Tech and an MBA from the Kellogg School of Management at Northwestern University. If used before or beyond the working distance, unwanted image distortion may result, especially when using cameras with larger sensors. 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. However, some focal reducers can be used on other models of telescopes, but this is not always possible. 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. First, let's have a look at some key optical parameters are needed to understand focal reducers. With the Celestron Reducer/Corrector Lens, thats precisely what you get. 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. All Rights Reserved. Thanks Peter! This fully multi-coated lens provides maximum light transmission with near full-field illumination. 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 . 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. If used with other f/ratios, the field flattening characteristic may be unpredictable. If the reducer is placed elsewhere, at a position called the operating distance, the focal reduction factor will not be as advertised. I only have the Celestron f/6.3. 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. The two samples I have PERFORM IDENTICALLY. During check-out, you will be presented with several shipping choices and costs. 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. Keep in mind that these differences were very subtle, and could be due to normal variations in coatings among different runs, and not necessarily unique to the brands. Some faster refractors with a focal ratio of f/6, for example, only require field flatteners and not focal reducers. I focus using a moonlight electronic focuser and focusmax. Since the Celestron and Antares are supposed to have different focal lengths and spacing specs, I expected different results. What an enjoyable read and detailed comparison. You can adjust your cookie settings, otherwise we'll assume you're okay to continue. This part is no longer in production, but it is sometimes available used and may be used with cameras with smaller sensors. 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. This is very impressive performance given how hard this problem is to mitigate in general. We only send interesting emails and will never sell your data. 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. None of this was offensive, nor did it interfere with views in any significant way. Please Log in to save it permanently. In many cases, the answer is yes, especially for electronically-assisted astronomy (EAA). Assuming you use the reducer with the stock 1.25" diagonal, it will operate at f/6.3. For the best experience on our site, be sure to turn on Javascript in your browser. 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 Check out our 2022 telescope buying guide here! 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. and you will be fine. because they really dont matter. A longer effective focal length leads to higher magnification with a given eyepiece for visual observers. Benefits limited to hardware and conditions? Hi. 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. Reducer Lens .7x - EdgeHD 925 Learn More. Thanks guys, appreciate the feedback. When you said, "in some cases" a focal reducer also works as a flattener/corrector, are you saying that not all focal reducers are flatteners/corrector? Sign up to get exclusive deals, observing tips, and new product announcements. Please re-enable javascript to access full functionality. They never really recovered from selling a few 15 years back with element reversed. Therefore, a 55mm back focus with a filter that is 3mm thick added to the imaging train would become 56mm. OPT Product Number: AE-SCTFR specifications Warranty 2 Year Warranty Works as advertised! These RC reducers cannot be used with other types of telescopes. The reducer features fully coated optics in an anodized aluminum filter ring with an ergonomic rubber grip. Article Agena AstroProducts, 2019. Yet, the Antares still easily and fully threaded without any hitches. Possibly the design of the Antares was changed .. 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. Many focal reducers are meant to be used within a few millimeters of the specified working distance to achieve the best possible image results. For example, an 8" SCT without a focal reducer has an illuminated field of 38mm at 50% fall-off. Celestron Focus Motor for SCT, EdgeHD & 8" RASA, Celestron C6 0.63 reducer/flattener back focus. I think I remember hearing the reduction factor is slightly different, cant remember more or less reduction. But the diameter of the image circle decreases by a factor of 0.63 to about 24mm. a Tele Vue Panoptic), or a Plossl eyepiece with an apparent field of view of 50 and a focal length of 32mm. 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. For visual use, this means you get lower power with the same eyepiece and a wider field of view. 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. These scopes are compatibles with focal reducers. In the 1960s, Celestrons founder, Tom Johnson, created groundbreaking new telescopes never before seen on the consumer market. The female end attaches to the rear cell of the telescope. 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. 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. Our patented SkyAlign alignment technology makes setting up a computerized telescope simple, fast, and accurate. 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. Many Ritchey-Chretien telescopes available today are made by GSO. 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. Focal reducers for many SCTs and their flat-field equivalents usually have a back-focus distance of 105mm. 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. 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. 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. The threads were similar on the eyepiece end, but a bit smoother. This focal reducer from Celestron reduces the effective focal length by 0.63X Enjoy the wider field of view & faster exposure times at f/6.3 with f/10 telescopes f/11 telescopes, such as the C14 will perform at f/7 The Celestron f/6.3 Reducer has four fully-multicoated elements Reduce your exposure times by a factor of 3!
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