1.2" in that scope is a field stop of 43mm at f/10 and 27mm at f/6.3. Given the results of Test #1, I wanted to see if there was any truth to this assumption. I wonder whether, for example, Antares focal reducer for SCT belongs to the latter category. For the best experience on our site, be sure to turn on Javascript in your browser. 0.63x Starizona Focal Reducer for SCTs- Awesome Astrophotography 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. CPWI has an extensive object database, employs PointXP mount modeling, and more. The new Lithium Phosphate (LiFePO4) battery chemistry has significant advantages over other battery chemistries, great for for those Astronomers on the go. For this shoot-out, I used a standard Celestron C8 with Starbright coatings. 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. Our patented SkyAlign alignment technology makes setting up a computerized telescope simple, fast, and accurate. If it's positioned further from the eyepiece or camera and closer to the telescope objective, the reduction factor increases. Hello! We process your personal data as stated in our. F 6.3 focal reducer/corrector. - Discussions - Stargazers Lounge 160K views 9 years ago This video is a complete overview of focal reducers and how they function applying to telescopes. 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. I was originally hoping to do this with a made in Japan Celestron, but ended up with a newer China version but thats probably better in the end since it is the version now available, with the Japan ones rarer and only available used. How does it look thats what matters. I had a Celestron, Antares and Hirsch for awhile and compared them over about a year. This fully multi-coated lens provides maximum light transmission with near full-field illumination. 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. It has only one cover, which surprised me. More about this below. Very helpful, thanks a lot for this article! Hmmm . 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. But nearly every observer who installs one of these devices is pleased with their performance. In every configuration, there were essentially parfocal, requiring only a tiny fine focus adjustment when changing correctors. 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. Perfect for the serious student, professional scientist and discriminating hobbyist. 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. Focal Reducer, 2", 0.7X. If you want to save a few buck watch the classifieds on CN. 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. However, this also came at a cost, as the sky background in the Antares was slightly brighter. Focal Reducer for SCT - ACF - Stargazers Lounge Can these economical focal reducers from GSO and other vendors result in good images? 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. Right off the bat, I was struck by how similar the two R/Cs were. 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 . Celestron Solar Safe filter technology is GUARANTEED SAFE for direct solar observation and has been independently tested by SAI Global Assurance Services. Focal reducers for these relatively fast ED refractors are generally for imaging only, not for visual observation. Meade and Celestron both sell such SCT-T adapters with the correct optical length. 2023 OPT Telescopes. The stock Celestron visualback is just under 2 long. 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. 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 visual back must be removed first. looks virtually identical, except for the lettering. Fumbling around in the dark, fine threads might be a problem. It's an either/or proposition: reducer and 1.25", or 2", but not 2" and reducer. No rainchecks will be issued for items out of stock at OPTcorp.com to match a competitor's price. 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. 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. Reducer Lens .7x - EdgeHD 800 Learn More. 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. We have placed cookies on your device to help make this website better. One problem with getting opinions is that most of use do not have both reducers or have never done a side by side comparison. 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. The Buyer's Guide To Eyepieces at the top of the Eyepieces forum has a column for this spec. Now It only focuses near things, like some kind of macro zoom. Since the Celestron and Antares are supposed to have different focal lengths and spacing specs, I expected different results. Once installed, you can add additional accessories like T-Adapters, 1.25 Visual Back, Star Diagonal, or Off-Axis Guider. Wonder how they would stack up with a Japanese 6.3. Edited by Tony Bonanno, 16 April 2021 - 06:44 PM. 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 have this one Opticstar F6.3 Focal Reducer / Corrector. Yet, the Antares still easily and fully threaded without any hitches. This filter threads on to the rear cell of your Celestron or Meade SCT telescope. 3. Nebula Filters. So, if you have a filter that is 3mm thick, you need to add 1mm of spacing to your imaging train to retain the correct back focus. In terms of reduction and correction which are what reducer/correctors are supposed to do both are superb. The reducer is we might presume designed to correct to some as yet un-measured extent, the image of a standard SCT. 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. 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. It's highly unlikely that they could be so precisely identical unless they were. But the diameter of the image circle decreases by a factor of 0.63 to about 24mm. But I am rusty, can you condense a bit for me please? 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. How about for visual observers? Benefits limited to hardware and conditions? 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. As a result, the smaller tube may cut into the light cone and effectively reduce the working aperture of the telescope. Brian Ventrudo is a writer, scientist, and astronomy educator. But when not in the box or on the telescope, there is no cover for the other end. By Sign up for our newsletter to get exclusive deals, observing tips, and new product announcements. It seems right to put some distance between the camera and the focal reducer, right? It's easy! In this case, an additional T-adapter (with an optical length of 50mm) is needed to get the spacing correct for a DSLR or other camera with a 55mm back focus. The internal surfaces are blackened and glare-threaded to provide the highest contrast. Years ago, I bought the Antares version, and moved over to the Celestron. 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. Thanks for the extremely valuable article. Start here to find the perfect telescope for you! In many cases, the answer is yes, especially for electronically-assisted astronomy (EAA). Images made with my ZWO 533 camera testing both show them to be essentially the same. The threads were similar on the eyepiece end, but a bit smoother. 0.5X focal reducer for Celestron, Meade, and Orion CCD imaging cameras It is not a corrector or flattener. Refractors, or SCTs with external focusers, may not have sufficient in-travel to reach focus in some configurations. This article explains the basics of how focal reducers work with an astronomy telescope. Some third-party vendors also make reducers for SCT scopes. Using an eyepiece with a 27mm field stop with the reducer will illuminate the edge the same as using an eyepieces with a 42.9mm field stop without it. CPWI has an extensive object database, employs PointXP mount modeling, and more. Thanks. 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. Watch this before you buy Celestron 8SE SCT, or a Focal Reducer or a I've only used it a few times but it looks good to me. More details are found in the Appendix of this article. My Celestron was made in China and the Antares in Canada. Reducer Lens .7x - EdgeHD 925 Learn More. Explore Scientific - Keys to the Universe Sale. 800-483-6287 And when d1 = FR, that is, when the focal reducer is placed at a distance from the focal plane of the objective that's equal to the reducer's focal length, the focal length of the combined optical system is Fo, so it acts as a 0.5x reducer. Again, these focal reducers are often provided by the telescope manufacturer. To test this, I used three set-ups: 1. We do not price match competitors if they are out of stock. When placed in the focal plane in front of a camera or eyepiece, a focal reducer leads to a wider field of view and a brighter image of extended objects, which is important for reducing the exposure times when imaging faint extended objects like nebulae or galaxies. Antares F/6.3 SCT Focal Reducer | OPT Telescopes 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. Completely stuck, completely frustrated. Hi. No small animals were harmed in making these observations. . However, some focal reducers can be used on other models of telescopes, but this is not always possible. 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. Easy solution found a very tiny dab of super lube on the threads and all was well and quiet. 3. Manish holds a Master's degree in Electrical Engineering from Virginia Tech and an MBA from the Kellogg School of Management at Northwestern University. 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. Here, there was a subtle difference . October 11, 2010 in Discussions - Scopes / Whole setups. However, with appropriate spacers and a camera with a known back-focus, it is easy to determine the exact amount of focal reduction for a given setup (some imaging software packages will also let you derive this from images). The lens that the ZWO comes with give a perfect wide angle image of what is in front of it. As one increases, the other decreases. 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. WiFi technology encircles the globe in a web of connectivity, knowledge, and information. 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. Reproduction without permission prohibited. 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. If you want to use them for visual - try maybe long focal length eyepieces rather than the reducer. I am a purely visual observer, so will evaluate for visual use only. 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. Have a promo code? They are reported as identical. 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. How to Set the Correct Back Focus for Your Telescope (Guide) 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) Share Customers Also Purchased Description Your wishlist has been temporarily saved. This innovative software solves the time-consuming problem of trying to pinpoint the North Celestial Pole. In the 1960s, Celestrons founder, Tom Johnson, created groundbreaking new telescopes never before seen on the consumer market. control and Sky Viewer display makes selecting your target easy. Thanks guys, I'm trying to get my ZWO ASI120MC-S to work with my 90mm Meade. 2023 Celestron, LLC. I have had the Japan unit on the back of my C5 since 1994 or thereabouts. 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. You attach the focal reducer to the rear port on a SCT and can keep it covered. 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. Generally, views through the Antares seemed a little more transparent and brighter. Please note, orders placed after 10am on 2/28/2023 will be delayed. The telescope side of the barrel is often threaded with an M48 x 0.75 thread for standard 2" astronomy filters. Fortunately, my neighbors are not out in their backyards at 11 pm, or they may have thought I was torturing a small mammal. Reducer Lens .7x - EdgeHD 1100. This part is no longer in production, but it is sometimes available used and may be used with cameras with smaller sensors. You need to be a member in order to leave a comment. More aggressive reduction, or using these reducers with larger sensors, will result in aberrations and distortions near the edge of the image. 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. 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. Reducer Lens .7x - EdgeHD 1100 - Celestron For this test, I used a single configuration R/C, Click-lock, and 1.25 diagonal with the adapter. Telescope Optics, Rutten and van Venrooij, Chapter 15, Willman-Bell (1988). In terms of reduction and correction - which are what reducer/correctors are supposed to do - both are superb. 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. I've never found my 0.63 reducer causing CA when used with my SCT. So it provides a 0.63x design reduction factor when used with an f/10 SCT at the specified working distance. Back-Focus 101: DSLR Cameras & the Celestron f/6.3 Reducer - YouTube Who cares? This is very impressive performance given how hard this problem is to mitigate in general. I have Hirsch focal reducer, which is yet another clone of the Celestron reducer. 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. Focal reducer for 8SE - Celestron vs. Antares - Cloudy Nights . 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. 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. Assuming you use the reducer with the stock 1.25" diagonal, it will operate at f/6.3. 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. . However, because the field curvatures in refractors and SCTs vary a lot, I would predict unpredictable effects inre: field curvature. I really don't see any difference in the current crop except the "Meade" is usually the cheapest. Reviews. What an enjoyable read and detailed comparison. 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"). . Thanks for pointing this out. Shipping will be via the cheapest shipping method which will vary depending on the items in your order. High power views will provide flatter fields all the way to the edge, both visually and photographically. It was also a little brighter in the center of the field with subtle darkening in the outer 20% or so. Because I have not heard any complaints about the made in China R/C. To calculate how much back focus spacing you need to add, take the thickness of the filter and divide it by 3. I only have the Celestron f/6.3. A slight nod to the Antares for heft and higher transmission, but points to the Celestron for nice threads and better contrast. Overall, this reducer does a phenomenal job at preventing gradients due to internal reflections from the camera sensor back to the glass in the reducer, as I suffered with the Antares reducer. When placed in the focal plane in front of a camera or eyepiece, a focal reducer leads to a wider field of view and a brighter image of extended objects, which is important for reducing the exposure times when imaging faint extended objects like nebulae or galaxies. 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. 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? * Not a Retail Store * 16313 Arthur StreetCerritos, CA 90703, USA. Meade once made an f/3.3 focal reducer for SCT scopes. 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. 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. It can also be used with any other small chip CCD camera having a 1.25" nosepiece, such as the Celestron NexImage, Meade DSI . This means that there must be sufficient travel on the telescope focuser to make up for this. Never used one, but read the reviews here that suggest a coating problem. Performance wise what differences might there be using the reducer on a smaller scope. They provide 0.75x focal reducers for these telescopes that takes an f/8 instrument down to f/6. But the smaller image circle means there is a limit to the field stop of an eyepiece that can achieve an unvignetted image. Since the focal length of the reducer, FR, is fixed, as d2 increases then MR decreases. This standard distance is a consequence of the design of DSLR cameras for which the distance of the sensor to the outer edge of the flanges is about 45 mm, while the T-ring that attaches to the flange for astrophotography is about 10mm thick. The Celestron f/6.3 is ~150 compared to the Antares at ~70. Celestron is considered better in terms of QA, less likely to come with free dust, hair or fingerprint. Regardless, the difference was miniscule and is more than adequate on both and exceeds a 8 or 6 SCTs baffle tube diameter. Torazz Ive owned Celestron, Meade, and Antares models over the years at least a couple of each. My experience is that CN sellers are way above those listing elsewhere. Housings, threads, reduction, correction, blah, blah, blah. if the illuminated field is 27mm wide without the reducer, it will be 27 x 0.63 = 17mm with it in place. Even though they may have been slightly dimmer, galaxies were a bit easier to tease out of the urban light soup I deal with. Just one question. Oceanside Photo & Telescope wants our customers to shop with confidence knowing that you will always get the best deal available. 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. 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). Focal reducers are essential optical accessories for astrophotography, electronically-assisted astronomy (EAA), and in some cases, for visual observation with long focal ratio telescopes. Each focal reducer has a fixed specification called the working distance or required back focus. Free shipping $189.95 Sharpness is essentially the same. Dedicated focal reducers for refractors are intended primarily for imaging, not visual observation. I use it on my C8 SCT with a 1000d, and it seems to do everything written on the tin. 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. I've seen some older threads saying that the Celestron, Meade and Antares FRs are all the same and manufactured in the same factory. That said any comparison reviews are helpful. As per the OP I still can't see any reason to buy the Celestron for significantly more $$$. But while the image gets brighter, the size of the image circle gets proportionately smaller. No retailers currently carry this product. Some coma is visible in the corners, but the image is quite good for EAA applications. Is there likely to be any differences in performance between using these on an 8 or something smaller like my 6SE? The problem with those SCT reducers is that they cause chromatic aberration and require refocusing when using parfocal RGB/other filters. DUE TO EXTREMELY HIGH DEMAND, WE WILL NOT BE TAKING NEW ORDERS UNTIL MONDAY, DECEMBER 14. For me the Antares was a little brighter and had the least scatter by a bit so the better coatings won. because they really dont matter. Weasner's Meade and Antares Focal Reducers Review This focal reducer is made to attach to the rear cell of Schmidt-Cassegrain or Maksutov-Cassegrain telescopes. Orders placed over the weekend will be shipped on the following Monday. Also read the reviews here, including those at 4 stars. 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. He also holds a Ph.D. in engineering physics from McMaster University. 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. During check-out, you will be presented with several shipping choices and costs. Your mileage may vary. Figure 2 shows the effective of a focal reducer on the light from a telescope objective. Edited by bluewater, 05 September 2020 - 11:27 AM. Antares f/6.3 Focal Reducer for SCTs - Awesome Astro I'd favor the Japanese Celestron version over the others that are commercially available. Whereas the Celestron threaded smoothly onto the scope, the Antares chattered and squeaked a bit more so when being removed. Looking forward to the day when I can do a shoot-out between a Japan and China Celestron, just for kicks. I was referring to the C6 to answer you specifically. The same illumination you have at the edge of a 27mm field, the C8 has at the edge of a 38mm field. We have tested our current batch and it works with Meade, Celestron, and Baader SCT accessories.

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