Thanks for any advice or experience you could share. 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. 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. It has only one cover, which surprised me. Please note, orders placed after 10am on 2/28/2023 will be delayed. Some faster refractors with a focal ratio of f/6, for example, only require field flatteners and not focal reducers. I've never found my 0.63 reducer causing CA when used with my SCT. This innovative software solves the time-consuming problem of trying to pinpoint the North Celestial Pole. Product Details 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. Figure 2 shows the effective of a focal reducer on the light from a telescope objective. He also holds a Ph.D. in engineering physics from McMaster University. 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. But nearly every observer who installs one of these devices is pleased with their performance. Your price: $579.00. None of this was offensive, nor did it interfere with views in any significant way. I've seen some older threads saying that the Celestron, Meade and Antares FRs are all the same and manufactured in the same factory. riklaunim Members 559 3,445 Location: Poland Posted October 11, 2010 They are reported as identical. I've heard and read all kinds of things about the Antares being only a reducer and not a corrector, etc. Quite interestingly it bears the very same engravings of the Meade 4000 r/c (including "series 4000") except for "MEADE". Celestrons patented StarSense Technology makes it easier than ever to locate objects in the night sky, even if youve never used a telescope before. 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. 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. But is there a difference in quality between the Antares and the Celestron or Meade focal reducers? Stars in the corner of the image frame are indistinguishable between the Antares and the Celestron. I had a Celestron, Antares and Hirsch for awhile and compared them over about a year. A longer effective focal length leads to higher magnification with a given eyepiece for visual observers. I have/had both the Celestron (Japan) and Antares units. The same illumination you have at the edge of a 27mm field, the C8 has at the edge of a 38mm field. The more focal reduction, the further inward the focal plane will be. JavaScript seems to be disabled in your browser. This focal reducer and field flattener consists of a four-element multicoated 40mm lens in a metal cell. Celestrons aplanatic EdgeHD optics revolutionized astroimaging. 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. Again, to my surprise, there was absolutely no difference between the Celestron and Antares on any star. 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. Some third-party vendors also make reducers for SCT scopes. Check out our 2022 telescope buying guide here! This filter threads on to the rear cell of your Celestron or Meade SCT telescope. Looking forward to the day when I can do a shoot-out between a Japan and China Celestron, just for kicks. The Celestron is both a corrector and focal reducer and the Antares is just a focal reducer. I only have the Celestron f/6.3. Watch this before you buy Celestron 8SE SCT, or a Focal Reducer or a Hyperstar 7,758 views Mar 28, 2018 145 Dislike Share Ray's Astrophotography 42.3K subscribers Note: I am not paid or. This superb fully multi-coated multi-element focal reducer takes advantage of the latest computer aided design techniques to achieve the highest standards of performance set by the brand leaders at a fraction of the cost. A useful thing to know is how far from the objective lens (for a refractor) is the focal reducer located. By using this site, you agree to our Terms of Use. The threads were similar on the eyepiece end, but a bit smoother. 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. 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. Sign up for our newsletter to get exclusive deals, observing tips, and new product announcements. 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. If you want to save a few buck watch the classifieds on CN. Can these economical focal reducers from GSO and other vendors result in good images? As one increases, the other decreases. We tested GSO's 1.25" 0.5x focal reducer at a variety of operating distances and calculated the field of view through a telescope to derive the actual reduction factor that is plotted below. Never used one, but read the reviews here that suggest a coating problem. If I had to guess, the difference is maybe 10-15 grams. They are designed (assuming you are referring to the f/6.3 version) for the f/10 light cone. Any comments gratefully received. The internal surfaces are blackened and glare-threaded to provide the highest contrast. If yes, what kind of focal reducers can I use? Not noticed any optical problems. Once focused it's pretty good. 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. Based on Test 1 and Test 2, I think there is perhaps more validity to opposing statements here in these forums that the Antares and current China-made Celestron do, indeed, have exactly the same optics just with different housings and branding. 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. As a Barlow's magnification increases with increasing distance from the Barlow, a focal reducer's reduction increases with increasing distance from the reducer. This part is no longer in production, but it is sometimes available used and may be used with cameras with smaller sensors. There are many different types of focal reducers and they all effect. 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. a Tele Vue Panoptic), or a Plossl eyepiece with an apparent field of view of 50 and a focal length of 32mm. 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. You may need spacers or a T-adapter to ensure the correcting working distance. 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. Style: 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. 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. Possibly the design of the Antares was changed .. But the smaller image circle means there is a limit to the field stop of an eyepiece that can achieve an unvignetted image. ), ASI Air Plus - Connected items are 'greyed out', Cost of ordering used equipment U.S. - Can can more than double figure, Tuthill Isostatic Mount and Star Trap Power Module. Get ready for a night of astroimaging with your mount faster than previously thought possible with All-Star Polar Alignment. 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? This is the simplest way to attach your ASI121 to your telescope. But in the end they both do pretty much the same thing and it sounds like any performance difference is subtle. 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. Focal Reducer, 2", 0.7X. Also, the focusers of most Newtonians do not have enough in-travel to accommodate a focal reducer. Your eyepieces are the first accessories you should learn to use with your telescope. As a real-world example plot showing the above relationships, let's look at the 1.25" GSO focal reducer that provides a design reduction factor of 0.5x. Images in the Celestron tended to appear ever-so-slightly dimmer (maybe? The telescope side of the barrel is often threaded with an M48 x 0.75 thread for standard 2" astronomy filters. The reducer fits all Meade and Celestron . Your wishlist has been temporarily saved. 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. This filter threads on to the rear cell of your Celestron or Meade SCT telescope. With spring galaxy season here, I decided to pick up a couple more to compare in a head-to-head shoot out. Reducer - Corrector 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. I was referring to the C6 to answer you specifically. Fumbling around in the dark, fine threads might be a problem. 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. 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 . 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. It's easy! Clearly cost is a big factor for satisfied users. 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 are also less expensive than many external focusers of similar build quality. Photographically you also get a wider field and much shorter exposures. External Focusers for Schmidt-Cassegrain Telescopes 3.1 The Basics of SCT Threads 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. If the reducer is placed closer to the eyepiece or camera than the distance D, the reduction factor decreases. 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. Opticstar F6.3 Focal Reducer / Corrector. If you place your camera at a different working distance, you will get a different reduction factor and perhaps unwanted distortion in the image. 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. . Thanks for the extremely valuable article. And when used in some refractors, the field flattening is not as accurate as it is in the f/10 SCTs. However, some focal reducers can be used on other models of telescopes, but this is not always possible. Copyright 2003-2022 Agena AstroProducts. 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. My Celestron was made in China and the Antares in Canada. My application is mostly visual now, but I'm looking to do more astrophotography over time. Fortunately, my neighbors are not out in their backyards at 11 pm, or they may have thought I was torturing a small mammal. During check-out, you will be presented with several shipping choices and costs. Fastar Technology allows imagers the option of drastically increasing the speed and sensitivity of their Celestron optical tube, allowing bright, detailed images with short exposures. Start here to find the perfect telescope for you! Reducer - Corrector Learn More. It's usually specified from the base of the mounting threads on the reducer's housing, and this is the most practical way of providing this specification. Free shipping $189.95 Michael 1 ronin Members I am a purely visual observer, so will evaluate for visual use only. The previous post shows the reducer on what appear to be two different refractors. 800-483-6287 Completely stuck, completely frustrated. Reducer Lens .7x - EdgeHD 1400 The nominal design reduction factor of these reducers is typically 0.5x. 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. For example, an 8" SCT without a focal reducer has an illuminated field of 38mm at 50% fall-off. Upon close inspection, it was clear that the housing of Antares assembled in Canada version was a little more substantial than the Celestron. Please let us know what topics you are interested in. 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. The lens has a knurled surface, providing a tremendous gripping surface for threading/unthreading. Take control of your telescope! 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. 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. As a consequence, the standard f/6.3 and f/3.3 focal reducers for SCT scopes do not work. 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. No idea what the issue is. Another factor to consider: focal reducers also increase the angle at which light approaches the focal plane. 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. First, let's have a look at some key optical parameters are needed to understand focal reducers. . 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). The equations and argument in the Appendix of this article shows the relationship between the working distance and the reduction factor. But while the image gets brighter, the size of the image circle gets proportionately smaller. You currently have javascript disabled. Focal reducers also move the effective focal plane of the objective inward, that is, towards the objective (see Figure 1). Many Ritchey-Chretien telescopes available today are made by GSO. 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. Newtonian reflectors will seldom be able to accommodate the in-focus travel demanded by focal reducers. Increasing the operating distance, that is, moving a focal reducer away from the eyepiece or camera reduces its reduction factor, or conversely increases the amount of reduction. 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. We reserve the right to verify a competitor's advertised price and the availability of the item. Thanks Peter! But when not in the box or on the telescope, there is no cover for the other end. Edited by bluewater, 05 September 2020 - 11:27 AM. Hi. Enter it during checkout! Focus misses by about 1 turnof the focus knob.Here is my solution:Buy a shorter 1.25 visual back for my scope. 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. For this test, I used a single configuration R/C, Click-lock, and 1.25 diagonal with the adapter. 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. Our patented SkyAlign alignment technology makes setting up a computerized telescope simple, fast, and accurate. There is one difference though the Antares came with only one lens cap whereas the Celestron had a cap for both ends. This Antares 1.25" 0.5x focal reducer lens (tele-compressor) is used under the Orion brand name to thread into the nosepiece of Orion StarShoot Solar System cameras and StarShoot Deep Space Color Imaging Camera. For the best experience on our site, be sure to turn on Javascript in your browser. Depending on the design of the telescope, they may require separate focal reducers if they require focal reducers at all. My experience is that CN sellers are way above those listing elsewhere. 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. In the 1960s, Celestrons founder, Tom Johnson, created groundbreaking new telescopes never before seen on the consumer market. But the diameter of the image circle decreases by a factor of 0.63 to about 24mm. With the Celestron Reducer/Corrector Lens, thats precisely what you get. However, manufacturers virtually never provide this specification. 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. It's an either/or proposition: reducer and 1.25", or 2", but not 2" and reducer. You need to be a member in order to leave a comment. They are reported as identical. Edited by Tony Bonanno, 16 April 2021 - 06:44 PM. An f/6.3 reducer is designed to reduce the focal ratio of an f/10 SCT to f/6.3. Also read the reviews here, including those at 4 stars. 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. In most cases, the easiest option is to choose the focal reducer made specifically for your telescope. 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. The stock Celestron visualback is just under 2 long. Best evidence would by obtained by using a camera and evaluating the image both by eye and with a computer analysis. If used with other f/ratios, the field flattening characteristic may be unpredictable. Such an image circle is still large enough to encompass the relatively large sensor of many deep-sky astronomy cameras. It is not a corrector or flattener. 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. The lens that the ZWO comes with give a perfect wide angle image of what is in front of it. One problem with getting opinions is that most of use do not have both reducers or have never done a side by side comparison. 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. No retailers currently carry this product. Yet, the Antares still easily and fully threaded without any hitches. With both, using the same diagonal set-up, the exact same stars were visible at the very edge of the FOV. How about for visual observers? WiFi technology encircles the globe in a web of connectivity, knowledge, and information. 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.