Check out our 2022 telescope buying guide here! 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. 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. Many focal reducers are meant to be used within a few millimeters of the specified working distance to achieve the best possible image results. Most Feather Touch focusers cost between $300-$350. 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 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. No idea what the issue is. Thanks Peter! 800-483-6287 Things change but when I rebought I got an Antares and it seems about the same to me. This article explained the basics of how focal reducers work with various kinds of telescopes and how their working distance affects their reduction factor, and it provided sufficient detail to help amateur astronomer choose and use the right focal reducer for a particular application. Please note, orders placed after 10am on 2/28/2023 will be delayed. Your mileage may vary. Description. 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. and you will be fine. I am a purely visual observer, so will evaluate for visual use only. However, manufacturers virtually never provide this specification. By using this site, you agree to our Terms of Use. I really don't see any difference in the current crop except the "Meade" is usually the cheapest. Depending on the design of the telescope, they may require separate focal reducers if they require focal reducers at all. That's partly because focal reducers correct for field curvature, which itself depends on the focal ratio and other optical design factors of the telescope. 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. They are reported as identical. 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. Stars had a tiny bit more sparkle and pop. Explore Scientific Keys to the Universe Sale. Obviously bright objects like Jupiter or The Moon show the reflections. The new Lithium Phosphate (LiFePO4) battery chemistry has significant advantages over other battery chemistries, great for for those Astronomers on the go. However, it will not thread into William Optics accessories, and with GSO it is a hit or miss. Both exhibited consistent reduction, identical field flattening, and edge correction properties, and both were high quality optically and mechanically. A f/10 focal ratio now achieves a f/6.3, while an f/11 focal ratio now achieves a f/7. I own both and concur heartily. control and Sky Viewer display makes selecting your target easy. There is one difference though the Antares came with only one lens cap whereas the Celestron had a cap for both ends. I also used several eyepieces including the ES 24mm/68, 17.5mm and 12.5mm Morpheuses, and a 10.5mm Pentax XL. 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). As I understand it, compared to the old Meade SCT's, the ACF is already "coma corrected", so the standard Meade, Celestron etc F6.3 focal reducers are not suitable and will only worsen the images. Fortunately, my neighbors are not out in their backyards at 11 pm, or they may have thought I was torturing a small mammal. 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. Using this same example of an 8" SCT and a 0.63x reducer, a visual observer can also enjoy brighter images and a wider field of view. 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? The resultant reduction factor was measured to be 0.46x. As a consequence, the standard f/6.3 and f/3.3 focal reducers for SCT scopes do not work. Your wishlist has been temporarily saved. 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. * Not a Retail Store * 16313 Arthur StreetCerritos, CA 90703, USA. Read our 101 article or get in touch. To test this, I used three set-ups: 1. Nebula Filters. Download the Celestron PWI Telescope Control Software. 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. Refractors, or SCTs with external focusers, may not have sufficient in-travel to reach focus in some configurations. But I am rusty, can you condense a bit for me please? I'm going with the Celestron. I wish there was. * Not a Retail Store * 16313 Arthur StreetCerritos, CA 90703, USA, Availability: Item has been discontinued by Agena and we no longer carry this item. Reproduction without permission prohibited. If used before or beyond the working distance, unwanted image distortion may result. 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. 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. If the reducer is placed elsewhere, at a position called the operating distance, the focal reduction factor will not be as advertised. Hmmm . 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. Nowadays I tend to use the Celestron more with my refractors for imaging and viewing. 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. Better images are also obtained when using these focal reducers at a reduction factor of 0.5x 0.8x, approximately. 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. Can these economical focal reducers from GSO and other vendors result in good images? I've only used it a few times but it looks good to me. This fully multi-coated lens provides maximum light transmission with near full-field illumination. ED stands for "extra-low dispersion," which refers to the composition and optical properties of the glass used for the lenses. And when used in some refractors, the field flattening is not as accurate as it is in the f/10 SCTs. As one increases, the other decreases. Request stock alerts and we'll let you know when the item is back in stock. Focus misses by about 1 turnof the focus knob.Here is my solution:Buy a shorter 1.25 visual back for my scope. If it's positioned further from the eyepiece or camera and closer to the telescope objective, the reduction factor increases. 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. Celestrons award-winning Nature DX binocular gets a major upgrade with the addition of ED objective lenses. Today, our world-class team of optical and electronic engineers continues to push the boundaries of technology. 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. 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. 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. Most manufacturers provide this specification. 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. Planetarium software package which provides easy-to-understand explanations and impressive visuals of all kinds. Does anyone know if the Antares 4000 focal reducer is as good as the Celestron focal reducer. 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. You need to be a member in order to leave a comment. In terms of reduction and correction - which are what reducer/correctors are supposed to do - both are superb. Maybe I got a lemon. You may need spacers or a T-adapter to ensure the correcting working distance. Meade and Celestron both sell such SCT-T adapters with the correct optical length. It's highly unlikely that they could be so precisely identical unless they were. If the focal reducer is to be used for visual observation, the visual back is threaded onto the eyepiece side of the reducer, and then a star diagonal and eyepiece are installed as usual. Sign up for a new account in our community. A little longer light path with a 2 Baader click-lock, low profile 1.25 adapter, and the 1.25 diagonal; The lens has a knurled surface, providing a tremendous gripping surface for threading/unthreading. However, the China 6.3 R/C has noticeable internal reflections that I haven't figured out yet. You attach the focal reducer to the rear port on a SCT and can keep it covered. This should not be the case if they have their purportedly different focal lengths. 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. The lens that the ZWO comes with give a perfect wide angle image of what is in front of it. The equations and argument in the Appendix of this article shows the relationship between the working distance and the reduction factor. Perhaps not exactly- there will be some uncertainty because of manufacturing tolerances and so forth, but it will be close. I am new to these optic topics, and I want to ask you what happens with Masutov like SW or Celestron 4 or 7 inches. 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. There will be no shipments on 3/1/2023, 3/2/2023, or 3/3/2023 (March 1st - March 3rd, 2023). For the best experience on our site, be sure to turn on Javascript in your browser. I found both to be very good. 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. Celestron or Antares? Imagine having two telescopes in one a long focal length instrument for lunar and planetary work and a short focal length scope for deep sky observing and astrophotography. Meade once made an f/3.3 focal reducer for SCT scopes. Several functions may not work. But in the end they both do pretty much the same thing and it sounds like any performance difference is subtle. The focal length and design working distance for this focal reducer were not available from the manufacturer. 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. Place the plastic covers on the lens when not in use to reduce the dust collection. A longer effective focal length leads to higher magnification with a given eyepiece for visual observers. I doubt there is any difference between the Antares and the Celestron except price. They are also less expensive than many external focusers of similar build quality. Optically, it consists of a four-element lens that is fully multi-coated for high contrast and resolution. For the best experience on our site, be sure to turn on Javascript in your browser. Meade once made an f/3.3 focal reducer for SCT scopes. Sign up for our newsletter to get exclusive deals, observing tips, and new product announcements. Figure 6 shows a 1.25" focal reducer from GSO configured with a ZWO ASI224MC camera. 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 1100 Learn More. For visual use, this means you get lower power with the same eyepiece and a wider field of view. In some cases, focal reducers also act as field flatteners by correcting for field curvature and coma of the objective lens. The f/6.3 reducer is operating at f/5-f/5.5 with a 2" diagonal, depending on the back focus length of the diagonal. They never really recovered from selling a few 15 years back with element reversed. Start Chat It's an either/or proposition: reducer and 1.25", or 2", but not 2" and reducer. Upon close inspection, it was clear that the housing of Antares assembled in Canada version was a little more substantial than the Celestron. looks virtually identical, except for the lettering. WiFi technology encircles the globe in a web of connectivity, knowledge, and information. 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. Copyright 2003-2022 Agena AstroProducts. Advanced designs for Schmidt-Cassegrain scopes such as the Meade ACF or Celestron Edge HD have optical elements in the tube to correct for coma and field flatness. I have this one Opticstar F6.3 Focal Reducer / Corrector. In your opinion, is the Celestron is worth the added cost ($150 vs. $90)? 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. However, even though the imprint on the item states "Reducer / Corrector" please note that his is a reducer only. 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. In both cases will end with a similar tfov. 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. Images in the Celestron tended to appear ever-so-slightly dimmer (maybe? 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). OPT Product Number: AE-SCTFR specifications Warranty 2 Year Warranty Works as advertised! At least these two units I tested make the answer - whatever. This also resulted in the clear aperture of the Antares being about 39-39.5mm, versus the Celestrons 41mm. Newtonian reflectors will seldom be able to accommodate the in-focus travel demanded by focal reducers. I'd favor the Japanese Celestron version over the others that are commercially available. Sign up for OPT news, exclusive offers, and updates on the latest gear! Learn more about extra solar planets imagery, 3D Star rendering, observation planning, telescope control, multiple-panel printing, and much more. The Reduction Factor and the Amount of Reduction are inversely related. 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. Also, the focusers of most Newtonians do not have enough in-travel to accommodate a focal reducer. If you place your camera at a different working distance, you will get a different reduction factor and perhaps unwanted distortion in the image. Can you help me? Telescope Optics, Rutten and van Venrooij, Chapter 15, Willman-Bell (1988). Article Agena AstroProducts, 2019. 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. 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 How does it look thats what matters. Hello! Celestrons aplanatic EdgeHD optics revolutionized astroimaging. 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. 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. 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. First, let's have a look at some key optical parameters are needed to understand focal reducers. Ive owned Celestron, Meade, and Antares models over the years at least a couple of each. Turn it on and push Align. In about three minutes, youre ready to observe! We have tested our current batch and it works with Meade, Celestron, and Baader SCT accessories. 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. For this test, I used a single configuration R/C, Click-lock, and 1.25 diagonal with the adapter. InternetSales@optcorp.com, 800-483-6287 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. Since 2008, Brian has taught astronomy to tens of thousands of stargazers through his websites OneMinuteAstronomer.com and CosmicPursuits.com. Have always disliked the crude, noisy SCT threads, but I get it. That includes, for example, a 1.25" eyepiece with an apparent field of view of 68 and a focal length of 24mm (eg. We only send interesting emails and will never sell your data. 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. 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. The naming convention of SCT focal reducers is a little confusing. Designed distancing using the reducer with a 1.25 visual back and 1.25 Televue mirror diagonal; We will match any online price that we confirm as valid. These reducers can also be used for visual observing with SCT scopes with eyepieces with a field stop as large as 24-27mm. Perfect for the serious student, professional scientist and discriminating hobbyist. They are designed (assuming you are referring to the f/6.3 version) for the f/10 light cone. No negative issues to report. Antares or Celestron? The lens is housed in machined aluminum for are machined aluminum black anodized. Wow, that is a very detailed discussion! 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. 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. 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. But while the image gets brighter, the size of the image circle gets proportionately smaller. More about this below. No difference. The stock Celestron visualback is just under 2 long. Benefits limited to hardware and conditions? The Best Dedicated Astronomy Cameras for Beginners, Astronomik OIII 12nm CCD Filter - T-Threads, Pegasus Astro Dual Motor Focus Controller, 10 Micron 12kg (26.45lbs) Stainless Steel Counterweight- GM 2000, I would like more information regarding stock availability dates. Assuming you use the reducer with the stock 1.25" diagonal, it will operate at f/6.3. However, because the field curvatures in refractors and SCTs vary a lot, I would predict unpredictable effects inre: field curvature. Since then, Agena has become one of the leading online retailers of telescopes and astronomical accessories worldwide. Looking forward to the day when I can do a shoot-out between a Japan and China Celestron, just for kicks. if the illuminated field is 27mm wide without the reducer, it will be 27 x 0.63 = 17mm with it in place.

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