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SKU: CEL-94245. For visual use, this means you get lower power with the same eyepiece and a wider field of view. The lens has a knurled surface, providing a tremendous gripping surface for threading/unthreading. 0.63x Starizona Focal Reducer for SCTs- Awesome Astrophotography Very helpful, thanks a lot for this article! 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. Antares F/6.3 SCT Focal Reducer | OPT Telescopes Completely stuck, completely frustrated. For me, I was looking for, and planning to keep, the one that yielded the greatest reduction. 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. 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. The Antares is supposed to be pretty comparable. With both, using the same diagonal set-up, the exact same stars were visible at the very edge of the FOV. It must be in stock at the time of Price Match for us to make a guarantee. Reducer Lens .7x - EdgeHD 1100 Learn More. Add a 0.63x reducer, and the brightness of extended objects increases by (1/0.63)2 = 2.5. For imagers, the main purpose of a focal reducer is to increase the brightness of the image at the focal plane. 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). 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. Even though they may have been slightly dimmer, galaxies were a bit easier to tease out of the urban light soup I deal with. Yet, the Antares still easily and fully threaded without any hitches. 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. Your wishlist has been temporarily saved. I use the same back spacing for both on a small 6" Celestron SCT. Antares or Celestron? 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. 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. However, because the field curvatures in refractors and SCTs vary a lot, I would predict unpredictable effects inre: field curvature. 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. 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. Better images are also obtained when using these focal reducers at a reduction factor of 0.5x 0.8x, approximately. But in the end they both do pretty much the same thing and it sounds like any performance difference is subtle. So Celestron buyers like Celestron, Meade buyers like the Meade and Antares buyer like the Antares. When using the diagonal, keep the field stops of the eyepieces under 20mm. In most cases, the easiest option is to choose the focal reducer made specifically for your telescope. We will be glad to help. I've seen some older threads saying that the Celestron, Meade and Antares FRs are all the same and manufactured in the same factory. No results, please adjust your filters. 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. Does anyone know if the Antares 4000 focal reducer is as good as the Celestron focal reducer. 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. 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! Details: The item must be the identical item, brand name, size, weight, color, quantity and model number. 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. Will not focus with the stuff I have. Read our guide! I only have the Celestron f/6.3. The EdgeHD .7x Focal Reducer Lens makes your EdgeHD 1100 one full F-Stop faster than f/10, reducing your exposure time by half to capture the same brightness of object . Years ago, I bought the Antares version, and moved over to the Celestron. They never really recovered from selling a few 15 years back with element reversed. Copyright 2021 Stargazers Lounge 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. So ab6110 is asking for a FR only without coma correction, there are a couple of brands who make special reducers for the ACF. However, this also came at a cost, as the sky background in the Antares was slightly brighter. It has only one cover, which surprised me. No retailers currently carry this product. It can also be used with any other small chip CCD camera having a 1.25" nosepiece, such as the Celestron NexImage, Meade DSI . Sharpness is essentially the same. 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. Brightness, color, and contrast were subtly different, but could be as much the day they were coated as any real difference in the two brands. Clean, fun jokes the tradition continues - Page 106 Refractors, or SCTs with external focusers, may not have sufficient in-travel to reach focus in some configurations. But when not in the box or on the telescope, there is no cover for the other end. It also leads to larger (although fainter) images of extended objects like the Moon or planets for astrophotographers or visual observers. 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. I have this one Opticstar F6.3 Focal Reducer / Corrector. A useful thing to know is how far from the objective lens (for a refractor) is the focal reducer located. Upgrading the Focuser of Your Schmidt-Cassegrain Telescope - Agena Astro Agena's Guide to Focal Reducers - Agena Astro Celestron or Antares? All rights reserved. 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. All rights reserved. The telescope side of the barrel is often threaded with an M48 x 0.75 thread for standard 2" astronomy filters. Thanks. Both exhibited consistent reduction, identical field flattening, and edge correction properties, and both were high quality optically and mechanically. Focal reducers for these relatively fast ED refractors are generally for imaging only, not for visual observation. For me the Antares was a little brighter and had the least scatter by a bit so the better coatings won. Generally, views through the Antares seemed a little more transparent and brighter. Thanks for any advice or experience you could share. I don't know. Observing the microscopic world has never been easier! The more focal reduction, the further inward the focal plane will be. 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. 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. 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. And when used in some refractors, the field flattening is not as accurate as it is in the f/10 SCTs. 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. If I had to guess, the difference is maybe 10-15 grams. Explore Scientific - Keys to the Universe Sale. control and Sky Viewer display makes selecting your target easy. Unlike SCT telescopes, Ritchey-Chretien telescopes and Celestron Edge HD or Meade ACF scopes have internal optics that provide an inherently flat field, so these telescopes require a special focal reducer than does not provide additional correction for field curvature. The review is a subjective visual impression, which is interesting but not best evidence. In terms of reduction and correction - which are what reducer/correctors are supposed to do - both are superb. We have tested our current batch and it works with Meade, Celestron, and Baader SCT accessories. Orders placed after 12:00 PM Pacific Time will be shipped the next business day. Is there likely to be any differences in performance between using these on an 8 or something smaller like my 6SE? When the camera sensor is placed at this distance, the reduction factor of these reducers is 0.75x. Steve 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. For example, a 0.8x reducer placed at the working distance provides a reduction of (1 0.8) x 100 = 20%. Try & buy if you like - usual mates rates. More aggressive reduction, or using these reducers with larger sensors, will result in aberrations and distortions near the edge of the image. If you place your camera at a different working distance, you will get a different reduction factor and perhaps unwanted distortion in the image. They provide 0.75x focal reducers for these telescopes that takes an f/8 instrument down to f/6. The stars at the edge could be worse or better. The Buyer's Guide To Eyepieces at the top of the Eyepieces forum has a column for this spec. Thank you so much for the informative article, I now understand better how to integrate my reducer into my system to get better performance. 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). One of the most important factors in a telescope is its transmissionthe percentage of light that reaches the focal plane. Reproduction without permission prohibited. 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. A slight nod to the Antares for heft and higher transmission, but points to the Celestron for nice threads and better contrast. It was also a little brighter in the center of the field with subtle darkening in the outer 20% or so. Housings, threads, reduction, correction, blah, blah, blah. 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. But the diameter of the image circle decreases by a factor of 0.63 to about 24mm. 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. 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. October 11, 2010 in Discussions - Scopes / Whole setups. 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. 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. The female end attaches to the rear cell of the telescope. 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. Your mileage may vary. A reducer is a set of converging (or positive) lenses that cause the light from a telescope objective to converge at a steeper angle to the focal plane as if it were coming from an objective with a faster (lower) focal ratio and a shorter focal length. 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 price for an item/offer must be listed and valid at the time of match. StevieDvd Members 1,182 1,812 Location: Stevenage, UK Posted March 9, 2021 (edited) Don't know but your welcome to try out my Meade 6.3 sct reducer next time you are passing. InternetSales@optcorp.com, 800-483-6287 Focal reducers are essential optical accessories for astrophotography, electronically-assisted astronomy (EAA), and in some cases, for visual observation with long focal ratio telescopes. Focal reducers also move the effective focal plane of the objective inward, that is, towards the objective (see Figure 1). The faster f/ratio allows you to use slower film or shoot in lower light level situations and still properly expose your subject. The Antares focal reducer comes in small box. 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. These RC reducers cannot be used with other types of telescopes. Each focal reducer has a fixed specification called the working distance or required back focus. 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.