First, let's have a look at some key optical parameters are needed to understand focal reducers. 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. 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. 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. 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. Celestron is considered better in terms of QA, less likely to come with free dust, hair or fingerprint. 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. Both exhibited consistent reduction, identical field flattening, and edge correction properties, and both were high quality optically and mechanically. Quite interestingly it bears the very same engravings of the Meade 4000 r/c (including "series 4000") except for "MEADE". The Reducer/Corrector can also be used for terrestrial digiscoping. Benefits limited to hardware and conditions? If I had to guess, the difference is maybe 10-15 grams. 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. No idea what the issue is. 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. More important, its clear that the Antares is a reducer/corrector, just like the Celestron and not merely a reducer. You may need spacers or a T-adapter to ensure the correcting working distance. 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). * Not a Retail Store * 16313 Arthur StreetCerritos, CA 90703, USA. This fully multi-coated lens provides maximum light transmission with near full-field illumination. Reducer Lens .7x - EdgeHD 800 Learn more about extra solar planets imagery, 3D Star rendering, observation planning, telescope control, multiple-panel printing, and much more. The focal length of a focal reducer is usually measured from the rear lens surface of the reducer (and not the reducer's housing). SKU: CEL-94245. Focal reducers are essential optical accessories for astrophotography, electronically-assisted astronomy (EAA), and in some cases, for visual observation with long focal ratio telescopes. The Antares f6.3 focal reducer screws directly to the visual-back thread of all popular SCTs and converts f10 instruments to f6.3. This filter threads on to the rear cell of your Celestron or Meade SCT telescope. 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. One of the most important factors in a telescope is its transmissionthe percentage of light that reaches the focal plane. 2023 OPT Telescopes. Thanks Peter! More aggressive reduction, or using these reducers with larger sensors, will result in aberrations and distortions near the edge of the image. Years ago, I bought the Antares version, and moved over to the Celestron. The nominal design reduction factor of these reducers is typically 0.5x. They are commonly available in 1.25" and 2" threaded cells that conveniently thread into the nosepiece of a compatible camera or the barrel of an eyepiece. Celestrons award-winning Nature DX binocular gets a major upgrade with the addition of ED objective lenses. Wonder how they would stack up with a Japanese 6.3. I've looked through one from Meade and first impression was that it was like the Celestron version. The more focal reduction, the further inward the focal plane will be. 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. Never noticed any anomalies with this unit. The same illumination you have at the edge of a 27mm field, the C8 has at the edge of a 38mm field. For Ritchey-Chretien telescopes such as those manufactured by GSO, there are also dedicated focal reducers with a reduction factor of 0.7x to 0.8x. Besides observing from his heavily light polluted backyard in Los Angeles, Manish enjoys conducting astronomy outreach programs in local schools. The problem with those SCT reducers is that they cause chromatic aberration and require refocusing when using parfocal RGB/other filters. 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. Specially-designed focal reducers are available for use with these telescopes. I have a made in Japan 6.3 R/C and a made in China 6.3 R/C. The reducer features fully coated optics in an anodized aluminum filter ring with an ergonomic rubber grip. That is definitely a 2" eyepiece, but it is not a large or long focal length 2" eyepiece. 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. 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 both the Antares and the Celestron reducers. It has only one cover, which surprised me. 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. Photographically you also get a wider field and much shorter exposures. Each focal reducer has a fixed specification called the working distance or required back focus. In terms of reduction and correction which are what reducer/correctors are supposed to do both are superb. The brightness, shape, and distortion of specific stars in the exact same position at the edge of the field was precisely identical in both reducers. 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 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. It's easy! For imagers using longer focal-length refractors and SCTs, especially when using smaller sensors that place less demand on the focal reducer, there are economical alternatives for focal reducers from manufacturers such as GSO, Agena, and Antares. 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. . Celestron Solar Safe filter technology is GUARANTEED SAFE for direct solar observation and has been independently tested by SAI Global Assurance Services. 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 . ), but stars seemed a bit tighter and their colors were richer and more dramatic. Thank you so much for the informative article, I now understand better how to integrate my reducer into my system to get better performance. As a result, the smaller tube may cut into the light cone and effectively reduce the working aperture of the telescope. 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. Focal reducers for refractors are easy to use. If yes, what kind of focal reducers can I use? The C8 has no noticeable vignetting with a 32mm Plssl in the f/6.3 reducer. 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. Given the results of Test #1, I wanted to see if there was any truth to this assumption. Things change but when I rebought I got an Antares and it seems about the same to me. 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. (Note: Using the simple equations above, the focal length of this reducer can be estimated to be about 350mm). 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! JavaScript seems to be disabled in your browser. But I am rusty, can you condense a bit for me please? A slight nod to the Antares for heft and higher transmission, but points to the Celestron for nice threads and better contrast. The Reduction Factor and the Amount of Reduction are inversely related. 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. The reducer fits all Meade and Celestron . Unleash the full pointing accuracy of your Celestron computerized telescope with a specialized telescope control software suite. 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 for our newsletter to get exclusive deals, observing tips, and new product announcements. DUE TO EXTREMELY HIGH DEMAND, WE WILL NOT BE TAKING NEW ORDERS UNTIL MONDAY, DECEMBER 14. Reducer Lens .7x - EdgeHD 925 Ive owned Celestron, Meade, and Antares models over the years at least a couple of each. How does it look thats what matters. It's important to match the back focus to within a millimeter or two to get an optimal image, especially with cameras with larger sensors. Since the focal length of the reducer, FR, is fixed, as d2 increases then MR decreases. Wow, that is a very detailed discussion! It is recommended for . 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. It's highly unlikely that they could be so precisely identical unless they were. riklaunim Members 559 3,445 Location: Poland Posted October 11, 2010 They are reported as identical. Not one detectable iota of discernable difference. 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. Even though they may have been slightly dimmer, galaxies were a bit easier to tease out of the urban light soup I deal with. Generally, views through the Antares seemed a little more transparent and brighter. 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? I am a purely visual observer, so will evaluate for visual use only. 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. Despite never removing it no matter what I was looking at. Sign up for OPT news, exclusive offers, and updates on the latest gear! The amount of reduction is simply the percentage by which a reducer shortens the effective focal length of a telescope and is calculated as (1 Reduction Factor) x 100%. The internal surfaces are blackened and glare-threaded to provide the highest contrast. This focal reducer and field flattener consists of a four-element multicoated 40mm lens in a metal cell. Celestron Focus Motor for SCT, EdgeHD & 8" RASA, Celestron C6 0.63 reducer/flattener back focus. But when not in the box or on the telescope, there is no cover for the other end. The Antares focal reducer comes in small box. External Focusers for Schmidt-Cassegrain Telescopes 3.1 The Basics of SCT Threads This innovative software solves the time-consuming problem of trying to pinpoint the North Celestial Pole. ED stands for "extra-low dispersion," which refers to the composition and optical properties of the glass used for the lenses. We will be glad to help. 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. 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. All rights reserved. I wish there was. 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? Any comments gratefully received. I would not use the reducer with a 2" diagonal or eyepiece in the C6. 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. Torazz For imagers, the main purpose of a focal reducer is to increase the brightness of the image at the focal plane. We have placed cookies on your device to help make this website better. Reproduction without permission prohibited. We will match any online price that we confirm as valid. 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. 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. Such an image circle is still large enough to encompass the relatively large sensor of many deep-sky astronomy cameras. Better images are also obtained when using these focal reducers at a reduction factor of 0.5x 0.8x, approximately. By using this site, you agree to our Terms of Use. Get ready for a night of astroimaging with your mount faster than previously thought possible with All-Star Polar Alignment. 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"). I use it on my C8 SCT with a 1000d, and it seems to do everything written on the tin. Thanks for pointing this out. 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. The resultant reduction factor was measured to be 0.46x. The price for an item/offer must be listed and valid at the time of match. If you do so, you will achieve the design reduction factor. WiFi technology encircles the globe in a web of connectivity, knowledge, and information. Request stock alerts and we'll let you know when the item is back in stock. 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. That includes, for example, a 1.25" eyepiece with an apparent field of view of 68 and a focal length of 24mm (eg. 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. Stars had a tiny bit more sparkle and pop. Telescope Optics, Rutten and van Venrooij, Chapter 15, Willman-Bell (1988). A longer effective focal length leads to higher magnification with a given eyepiece for visual observers. Sign up for our newsletter to get exclusive deals, observing tips, and new product announcements. 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. I use the same back spacing for both on a small 6" Celestron SCT. Since the Celestron and Antares are supposed to have different focal lengths and spacing specs, I expected different results. 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. Place the plastic covers on the lens when not in use to reduce the dust collection. Yet, the Antares still easily and fully threaded without any hitches. Add a 0.63x reducer, and the brightness of extended objects increases by (1/0.63)2 = 2.5. Read our 101 article or get in touch. Not a bit. It also leads to larger (although fainter) images of extended objects like the Moon or planets for astrophotographers or visual observers. So it provides a 0.63x design reduction factor when used with an f/10 SCT at the specified working distance. Optically, it consists of a four-element lens that is fully multi-coated for high contrast and resolution. For me the Antares was a little brighter and had the least scatter by a bit so the better coatings won. It seems right to put some distance between the camera and the focal reducer, right? Download the Celestron PWI Telescope Control Software. Start Chat These reducers can also be used for visual observing with SCT scopes with eyepieces with a field stop as large as 24-27mm. 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. If the reducer is placed elsewhere, at a position called the operating distance, the focal reduction factor will not be as advertised. 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. This "speeds up" the optical train by reducing the focal length and magnification of the scope, requiring less time to integrate the same signal. OPT Product Number: AE-SCTFR specifications Warranty 2 Year Warranty Works as advertised! In your opinion, is the Celestron is worth the added cost ($150 vs. $90)? The focus barely shifts between filters and I suspect any shifts I do get are down to the filters and changes in temp. I found both to be very good. 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. 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. Steve If used before or beyond the working distance, unwanted image distortion may result. 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. The Antares f/6.3 Focal Reducer for Schmidt-Cassegrain Telescopes is a low-price option for reducing the focal length of your Schmidt-Cassegrain telescope from f/10 to f/6.3. Fortunately, my neighbors are not out in their backyards at 11 pm, or they may have thought I was torturing a small mammal. Not noticed any optical problems. Reducer Lens .7x - EdgeHD 1100 Learn More. Theres a long-running debate in these forums and even statements from some reputable dealers that the Antares is just a reducer (even though it is labeled Reducer/Corrector), whereas the Celestron is a true R/C, which flattens the SCTs naturally curved field and provides some edge correction. Will not focus with the stuff I have. If used before or beyond the working distance, unwanted image distortion may result, especially when using cameras with larger sensors. 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. 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. Our proprietary StarBright XLT optical coatings dramatically increase transmission, up to 97.4% on our Schmidt corrector lenses. . Check out our 2022 telescope buying guide here! Most Feather Touch focusers cost between $300-$350. Sky recognition technology that has revolutionized the manual telescope by eliminating the confusion common among beginners and enhancing the user experience for even seasoned telescope users. This filter threads on to the rear cell of your Celestron or Meade SCT telescope. That was fun. Unlike . 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. 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. It can also be used with any other small chip CCD camera having a 1.25" nosepiece, such as the Celestron NexImage, Meade DSI . I wonder whether, for example, Antares focal reducer for SCT belongs to the latter category.