Never noticed any anomalies with this unit. 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. 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. No negative issues to report. 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. Much to my surprise, swapping back and forth between the two correctors using all three diagonal configurations, I also could detect absolutely no change in reduction between the two reducers. With the barrel 1.25 reducer won't focus, all I get is fuzzy snowballs. Many focal reducers for refractors have a working distance (or back focus distance) of 55mm. This was most noticeable on the eyepiece end of the RC, where the metal rim surrounding the lens was about 1mm thicker than on the Celestron. 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. 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! For me, I was looking for, and planning to keep, the one that yielded the greatest reduction. Possibly the design of the Antares was changed .. Celestron is considered better in terms of QA, less likely to come with free dust, hair or fingerprint. However, these will not impact optical performance. Images made with my ZWO 533 camera testing both show them to be essentially the same. I have/had both the Celestron (Japan) and Antares units. 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. I own both and concur heartily. Have always disliked the crude, noisy SCT threads, but I get it. 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. Equation (4) shows the relationship between the distance d2 and the reduction factor MR. My Celestron was made in China and the Antares in Canada. The internal surfaces are blackened and glare-threaded to provide the highest contrast. Some faster refractors with a focal ratio of f/6, for example, only require field flatteners and not focal reducers. CPWI has an extensive object database, employs PointXP mount modeling, and more. I have a made in Japan 6.3 R/C and a made in China 6.3 R/C. 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 . Imaging - Focal Reducers and Flatteners - Page 1 - KW Telescope Figure 1 shows the relationship between the focal reduction factor MR and the position of the reducer in the optical path. However, because the field curvatures in refractors and SCTs vary a lot, I would predict unpredictable effects inre: field curvature. Thks for that and its not for visual it for astrophotography. Since then, Agena has become one of the leading online retailers of telescopes and astronomical accessories worldwide. Photographically you also get a wider field and much shorter exposures. Such an image circle is still large enough to encompass the relatively large sensor of many deep-sky astronomy cameras. Telescope Optics, Rutten and van Venrooij, Chapter 15, Willman-Bell (1988). But I am rusty, can you condense a bit for me please? Easy solution found a very tiny dab of super lube on the threads and all was well and quiet.. Because I have not heard any complaints about the made in China R/C. Reducer - Corrector | Celestron Just point the telescope at any three bright objectsstars, bright planets, or even the Moonand your telescope can orient itself with the night sky. Our patented SkyAlign alignment technology makes setting up a computerized telescope simple, fast, and accurate. 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. So, this past week I challenged the Antares and Celestron models to a head-to-hear on my C8 on some decent nights of good seeing and transparency in my Bortle 5-6 urban skies. Images in the Celestron tended to appear ever-so-slightly dimmer (maybe? Thank you so much for the informative article, I now understand better how to integrate my reducer into my system to get better performance. Celestrons award-winning Nature DX binocular gets a major upgrade with the addition of ED objective lenses. * Not a Retail Store * 16313 Arthur StreetCerritos, CA 90703, USA, Availability: Item has been discontinued by Agena and we no longer carry this item. This also resulted in the clear aperture of the Antares being about 39-39.5mm, versus the Celestrons 41mm. This is the distance at which the reducer must be placed in front of the eyepiece or camera focal plane in order to operate at the design reduction factor. InternetSales@optcorp.com. Practical Considerations of Focal Reducers, 4.2 Back Focus Requirements of Focal Reducers, GSO makes focal reducers for their line of Ritchey-Chretien, Celestron makes a series of focal reducers for the Edge HD line, 0.75x focal reducers for these telescopes, focal reducer for an 8-inch Celestron EdgeHD, A Primer on T-Rings and T-Adapters for Astronomy and Astrophotography, Choosing the Best Telescope for Beginners 2023, Top Night Sky & Astronomy Events in August 2022, Top Night Sky & Astronomy Events in July 2022, Selecting a Baader Planetarium Star Diagonal, A Guide to Choosing Astronomy Eyepieces for Binoviewers, Choosing a Magnifying Finder Scope for Your Telescope, A focal reducer will provide its design reduction factor only when it is placed at the exact working distance from the focal plane of the eyepiece or camera, Reducing the operating distance, that is, moving a focal reducer closer to the eyepiece or camera increases its reduction factor, or conversely reduces the amount of focal reduction. Most refractor manufacturers such as William Optics, Tele Vue Optics, Explore Scientific, Sky-Watcher, William Optics, and Stellarvue make their own focal reducers optimized for use with their telescopes. 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. There is a way to make subjective data more useful and that way is proper blind, or better still. First, let's have a look at some key optical parameters are needed to understand focal reducers. It's usually specified in millimeters. It works fine but you should stick with 1.25 EPs; or can use 2" EPs without corrector. Antares Click Lock Visual Back - Cats & Casses - Cloudy Nights If the reducer is placed closer to the eyepiece or camera than the distance D, the reduction factor decreases. It is recommended for . I'm going with the Celestron. The new Lithium Phosphate (LiFePO4) battery chemistry has significant advantages over other battery chemistries, great for for those Astronomers on the go. And, the reality is that every F/6.3 RC out there Celestron, Hirsch, Astromania, etc., etc. Meade and Celestron both sell such SCT-T adapters with the correct optical length. Reviews. I use the Celestron version and it seems OK for both visual and imaging. In the 1960s, Celestrons founder, Tom Johnson, created groundbreaking new telescopes never before seen on the consumer market. Therefore, a 55mm back focus with a filter that is 3mm thick added to the imaging train would become 56mm. Explore Scientific - Keys to the Universe Sale. Thanks. I have the Antares and have no complaints. Please re-enable javascript to access full functionality. 1.2" in that scope is a field stop of 43mm at f/10 and 27mm at f/6.3. It's highly unlikely that they could be so precisely identical unless they were. 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. 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. 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. Also read the reviews here, including those at 4 stars. 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. My application is mostly visual now, but I'm looking to do more astrophotography over time. riklaunim Members 559 3,445 Location: Poland Posted October 11, 2010 They are reported as identical. However, I noticed immediately that the Antares had a bit more of an heft to it, giving it a solid feel the Celestron didnt possess. Many focal reducers are meant to be used within a few millimeters of the specified working distance to achieve the best possible image results. https://www.celestron.com/products/reducer-corrector, //cdn.shopify.com/s/files/1/1935/4371/products/94175_reducer_corrector_01.jpg?v=1603736883, //cdn.shopify.com/s/files/1/1935/4371/products/94175_reducer_corrector_01_medium.jpg?v=1603736883, Popular Science by Celestron StarSense Explorer DX 5" Smartphone App-Enabled Schmidt Cassegrain Telescope, Advanced VX 8" Schmidt-Cassegrain Telescope, C9.25 Optical Tube Assembly (CGE Dovetail), Advanced VX 6" Schmidt-Cassegrain Telescope, Advanced VX 700 Maksutov Cassegrain Telescope, CGX-L Equatorial 925 Schmidt-Cassegrain Telescope, CPC 1100 GPS (XLT) Computerized Telescope, CGX-L Equatorial 1400 Schmidt-Cassegrain Telescope, CGX-L Equatorial 1100 Schmidt-Cassegrain Telescope, CGX Equatorial 925 Schmidt-Cassegrain Telescope, CGX Equatorial 800 Schmidt-Cassegrain Telescope, CGX Equatorial 1100 Schmidt-Cassegrain Telescope, CGEM II 1100 Schmidt-Cassegrain Telescope, Advanced VX 9.25" Schmidt-Cassegrain Telescope, Advanced VX 11" Schmidt-Cassegrain Telescope, Not compatible with #93648 Off-Axis Guider, not compatible with #93519 2" Mirror Diagonal (discontinued), Currently not compatible due to mechanical interferences. With this telescope and this focal reducer, it does not help to move to a 2" eyepiece and a 2" diagonal as the visual view will be akin to looking through a porthole within the larger apparent field of view of the eyepiece. Have a promo code? No retailers currently carry this product. I wont bother with differences in packaging, caps, etc. Unlike . 2023 OPT Telescopes. It seems right to put some distance between the camera and the focal reducer, right? And when used in some refractors, the field flattening is not as accurate as it is in the f/10 SCTs. 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! 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. Reducer Lens .7x - EdgeHD 1400 Learn More. What an enjoyable read and detailed comparison. That was fun. 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. Still not sure what is the right gear for you? 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. 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. One of the most important factors in a telescope is its transmissionthe percentage of light that reaches the focal plane. Right off the bat, I was struck by how similar the two R/Cs were. The working distance (backfocus) of the Celestron f/6.3 reducer is specified to be 105mm from the base of the male SCT thread on the camera side. This means that there must be sufficient travel on the telescope focuser to make up for this. Orders placed after 12:00 PM Pacific Time will be shipped the next business day. 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. 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. This fully multi-coated lens provides maximum light transmission with near full-field illumination. Clearly cost is a big factor for satisfied users. Depending on the design of the telescope, they may require separate focal reducers if they require focal reducers at all. 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. External Focusers for Schmidt-Cassegrain Telescopes 3.1 The Basics of SCT Threads 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. All rights reserved. No difference. If used before or beyond the working distance, unwanted image distortion may result. 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. Since the Celestron and Antares are supposed to have different focal lengths and spacing specs, I expected different results. 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. Explore Scientific Keys to the Universe Sale. It's easy! As per the OP I still can't see any reason to buy the Celestron for significantly more $$$. Is that distance D= Fo-d1=Fo-(d2/MR)? Manish Panjwani has been an active amateur astronomer since before Halley's Comet last flew by our neighborhood. More aggressive reduction, or using these reducers with larger sensors, will result in aberrations and distortions near the edge of the image. This appendix summarizes how this works based on simple equations from the book Telescope Optics by Rutten and van Venrooij. You attach the focal reducer to the rear port on a SCT and can keep it covered. Most Feather Touch focusers cost between $300-$350. 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. October 11, 2010 in Discussions - Scopes / Whole setups. Thanks for the extremely valuable article. Stars in the corner of the image frame are indistinguishable between the Antares and the Celestron. All Rights Reserved. USD $80.00. Fumbling around in the dark, fine threads might be a problem. That includes, for example, a 1.25" eyepiece with an apparent field of view of 68 and a focal length of 24mm (eg. They are reported as identical. If it's positioned further from the eyepiece or camera and closer to the telescope objective, the reduction factor increases. The focal length and design working distance for this focal reducer were not available from the manufacturer. The previous post shows the reducer on what appear to be two different refractors. They are designed (assuming you are referring to the f/6.3 version) for the f/10 light cone. As one increases, the other decreases. If you do so, you will achieve the design reduction factor. Add a 0.63x reducer, and the brightness of extended objects increases by (1/0.63)2 = 2.5. However, in principle, the reduction factor of a focal reducer can be varied by changing the distance from the back of the focal reducer to the camera or eyepiece. Not one detectable iota of discernable difference. Quite interestingly it bears the very same engravings of the Meade 4000 r/c (including "series 4000") except for "MEADE". Can you tell me about the use of reducers in Maksutov-Cassegrain telescopes? Whereas the Celestron threaded smoothly onto the scope, the Antares chattered and squeaked a bit more so when being removed. Regardless, the difference was miniscule and is more than adequate on both and exceeds a 8 or 6 SCTs baffle tube diameter. The female end attaches to the rear cell of the telescope. We do not price match competitors if they are out of stock. 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. Reducer Lens .7x - EdgeHD 800 Learn More. Thanks Peter! 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. Some coma is visible in the corners, but the image is quite good for EAA applications. Upon close inspection, it was clear that the housing of Antares assembled in Canada version was a little more substantial than the Celestron. 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. This "speeds up" the optical train by reducing the focal length and magnification of the scope, requiring less time to integrate the same signal. During check-out, you will be presented with several shipping choices and costs. With both, using the same diagonal set-up, the exact same stars were visible at the very edge of the FOV. The equations in the Appendix show how this all works. looks virtually identical, except for the lettering. 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. It's an either/or proposition: reducer and 1.25", or 2", but not 2" and reducer. Take control of your telescope! 2. 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). 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. 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. The same illumination you have at the edge of a 27mm field, the C8 has at the edge of a 38mm field. 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. The Antares is supposed to be pretty comparable. You can adjust your cookie settings, otherwise we'll assume you're okay to continue. Can these economical focal reducers from GSO and other vendors result in good images? Assuming you use the reducer with the stock 1.25" diagonal, it will operate at f/6.3. which looks like the same one. Each focal reducer has a fixed specification called the working distance or required back focus. For the best experience on our site, be sure to turn on Javascript in your browser. Hence, there is a chance that you may not be able to thread your SCT diagonal or other SCT accessory on to this reducer for these or for any other brand. 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. Read our guide! Antares or Celestron? Will not focus with the stuff I have. control and Sky Viewer display makes selecting your target easy. 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. High power views will provide flatter fields all the way to the edge, both visually and photographically. 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. 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. 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. Get ready for a night of astroimaging with your mount faster than previously thought possible with All-Star Polar Alignment. Your wishlist has been temporarily saved. The focal length of a focal reducer is usually measured from the rear lens surface of the reducer (and not the reducer's housing). Thanks for pointing this out. The most popular accessories for your new telescope! 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. I've never found my 0.63 reducer causing CA when used with my SCT. 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. For visual use, this means you get lower power with the same eyepiece and a wider field of view. OPT Product Number: AE-SCTFR specifications Warranty 2 Year Warranty Works as advertised! 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. 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. But the smaller image circle means there is a limit to the field stop of an eyepiece that can achieve an unvignetted image. 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. However, manufacturers virtually never provide this specification. 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. If I had to chose one, I would base my decision on your level of light pollution perhaps the Antares for its slightly higher transmission if you live under less light polluted skies, but the Celestron for its greater contrast if you are dealing with a suburban or urban light dome.
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