Therefore, a 55mm back focus with a filter that is 3mm thick added to the imaging train would become 56mm. Fortunately, my neighbors are not out in their backyards at 11 pm, or they may have thought I was torturing a small mammal. If it's positioned further from the eyepiece or camera and closer to the telescope objective, the reduction factor increases. 160K views 9 years ago This video is a complete overview of focal reducers and how they function applying to telescopes. For me, I was looking for, and planning to keep, the one that yielded the greatest reduction. 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. In some cases, focal reducers also act as field flatteners by correcting for field curvature and coma of the objective lens. 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. So it provides a 0.63x design reduction factor when used with an f/10 SCT at the specified working distance. The two samples I have PERFORM IDENTICALLY. Astro-Tech Schmidt-Cassegrain f/6.3 Focal Reducer Field Flattener Stars had a tiny bit more sparkle and pop. The more focal reduction, the further inward the focal plane will be. It was used strictly for imaging, not visual observing. Bear in mind you can't squeeze blood out of a turnip, i.e. 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. Figure 2 shows the effective of a focal reducer on the light from a telescope objective. One of the most important factors in a telescope is its transmissionthe percentage of light that reaches the focal plane. 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. High power views will provide flatter fields all the way to the edge, both visually and photographically. During check-out, you will be presented with several shipping choices and costs. - thanks. As one increases, the other decreases. Observing the microscopic world has never been easier! Right off the bat, I was struck by how similar the two R/Cs were. If you want to use them for visual - try maybe long focal length eyepieces rather than the reducer. Yellow and orange members of open clusters stood out a bit more as the various stars displayed their individuality. 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. 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. 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. As per the OP I still can't see any reason to buy the Celestron for significantly more $$$. However, these will not impact optical performance. However, even though the imprint on the item states "Reducer / Corrector" please note that his is a reducer only. Refractors, or SCTs with external focusers, may not have sufficient in-travel to reach focus in some configurations. Learn more about extra solar planets imagery, 3D Star rendering, observation planning, telescope control, multiple-panel printing, and much more. This filter threads on to the rear cell of your Celestron or Meade SCT telescope. It features a standard male SCT thread (2" OD, 24 TPI) on one side and a standard SCT female thread on the other. If the reducer is placed closer to the eyepiece or camera than the distance D, the reduction factor decreases. 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. 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. Looking forward to the day when I can do a shoot-out between a Japan and China Celestron, just for kicks. 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. 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. These reducers can also be used for visual observing with SCT scopes with eyepieces with a field stop as large as 24-27mm. This is the simplest way to attach your ASI121 to your telescope. 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. Focal reducers are essential optical accessories for astrophotography, electronically-assisted astronomy (EAA), and in some cases, for visual observation with long focal ratio telescopes. 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. Fumbling around in the dark, fine threads might be a problem. 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. But in the end they both do pretty much the same thing and it sounds like any performance difference is subtle. It works fine but you should stick with 1.25 EPs; or can use 2" EPs without corrector. Our proprietary StarBright XLT optical coatings dramatically increase transmission, up to 97.4% on our Schmidt corrector lenses. 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. 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. 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. 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. First, let's have a look at some key optical parameters are needed to understand focal reducers. 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 most significant mechanical variation, however, is the quality and precision of the threading. Some are available in 1.25" barrel format but with C threads. We reserve the right to verify a competitor's advertised price and the availability of the item. The Celestron f/6.3 is ~150 compared to the Antares at ~70. That was fun. That is definitely a 2" eyepiece, but it is not a large or long focal length 2" eyepiece. SKU: CEL-94245. We will match any online price that we confirm as valid. 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. Many focal reducers are meant to be used within a few millimeters of the specified working distance to achieve the best possible image results. If used before or beyond the working distance, unwanted image distortion may result. This focal reducer is made to attach to the rear cell of Schmidt-Cassegrain or Maksutov-Cassegrain telescopes. Your price: $579.00. Thanks. Performance wise what differences might there be using the reducer on a smaller scope. For example, many focal reducers designed for f/7 or f/8 ED refractors such as those from Tele Vue, William Optics, Sky-Watcher, and Meade are designed to have a working distance (or back focus) of 55mm. However, because the field curvatures in refractors and SCTs vary a lot, I would predict unpredictable effects inre: field curvature. Images in the Celestron tended to appear ever-so-slightly dimmer (maybe? because they really dont matter. For example, a 0.8x reducer placed at the working distance provides a reduction of (1 0.8) x 100 = 20%. This filter threads on to the rear cell of your Celestron or Meade SCT telescope. In terms of reduction and correction which are what reducer/correctors are supposed to do both are superb. I have the Antares and am not unhappy with it, but for AP I would want more back focal distance if those numbers are accurate. Sign up to receive sale alerts, news about upcoming celestial events, and telescope tips from our experts! This means that there must be sufficient travel on the telescope focuser to make up for this. It's an either/or proposition: reducer and 1.25", or 2", but not 2" and reducer. 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). Does anyone know if the Antares 4000 focal reducer is as good as the Celestron focal reducer. The internal surfaces are blackened and glare-threaded to provide the highest contrast. I wonder whether, for example, Antares focal reducer for SCT belongs to the latter category. which looks like the same one. Focus misses by about 1 turnof the focus knob.Here is my solution:Buy a shorter 1.25 visual back for my scope. The most commonly available focal reducers for SCTs are the f/6.3 reducers from Celestron and a similar f/6.3 focal reducer from Meade. I own both and concur heartily. This innovative software solves the time-consuming problem of trying to pinpoint the North Celestial Pole. Can these economical focal reducers from GSO and other vendors result in good images? Reviews. Possibly the design of the Antares was changed .. They only publish the value of D, the working distance (sometimes called the back focus distance) and the design reduction factor MRD. Most Feather Touch focusers cost between $300-$350. Take control of your telescope! Meade once made an f/3.3 focal reducer for SCT scopes. These scopes are compatibles with focal reducers. Antares F/6.3 SCT Focal Reducer | OPT Telescopes If yes, what kind of focal reducers can I use? 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. All Rights Reserved. Details: The item must be the identical item, brand name, size, weight, color, quantity and model number. 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. Sign up for OPT news, exclusive offers, and updates on the latest gear! Hi. Agena's Guide to Focal Reducers - Agena Astro Most different was that the sky background was a little darker and more uniform, providing a tiny contrast boost for fainter objects. Can you tell me about the use of reducers in Maksutov-Cassegrain telescopes? In many cases, the answer is yes, especially for electronically-assisted astronomy (EAA). Our patented SkyAlign alignment technology makes setting up a computerized telescope simple, fast, and accurate. Best evidence would by obtained by using a camera and evaluating the image both by eye and with a computer analysis. 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. Things change but when I rebought I got an Antares and it seems about the same to me. I also used several eyepieces including the ES 24mm/68, 17.5mm and 12.5mm Morpheuses, and a 10.5mm Pentax XL. I happily cycle through LRGB filters to build the image rather than do a whole run of one filter at a time. Reducer - Corrector Manish holds a Master's degree in Electrical Engineering from Virginia Tech and an MBA from the Kellogg School of Management at Northwestern University. I'm going with the Celestron. Get ready for a night of astroimaging with your mount faster than previously thought possible with All-Star Polar Alignment. 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. 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. A few large telescopes and mounts are excluded from this free shipping offer. The new Lithium Phosphate (LiFePO4) battery chemistry has significant advantages over other battery chemistries, great for for those Astronomers on the go. I had a Celestron, Antares and Hirsch for awhile and compared them over about a year. Celestron Focus Motor for SCT, EdgeHD & 8" RASA, Celestron C6 0.63 reducer/flattener back focus. 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. ED stands for "extra-low dispersion," which refers to the composition and optical properties of the glass used for the lenses. No small animals were harmed in making these observations. In every configuration, there were essentially parfocal, requiring only a tiny fine focus adjustment when changing correctors. USD $80.00. 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. Thanks guys, appreciate the feedback. Stars in the corner of the image frame are indistinguishable between the Antares and the Celestron. Copyright 2003-2022 Agena AstroProducts. Celestrons patented StarSense Technology makes it easier than ever to locate objects in the night sky, even if youve never used a telescope before. This article explains the basics of how focal reducers work with an astronomy telescope. 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. For the best experience on our site, be sure to turn on Javascript in your browser. I've heard and read all kinds of things about the Antares being only a reducer and not a corrector, etc. F6.3 Focal reducer for F/10 or higher telescopes, 43mm aperture, 4-Element, Fully Multicoated. Stock focusers in an SCT move the mirror of the scope to change the position of the focal plane, and they have sufficient travel to accommodate a focal reducer. 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. The C8 has no noticeable vignetting with a 32mm Plssl in the f/6.3 reducer. The Buyer's Guide To Eyepieces at the top of the Eyepieces forum has a column for this spec. Focal reducers for these relatively fast ED refractors are generally for imaging only, not for visual observation. Watch this before you buy Celestron 8SE SCT, or a Focal Reducer or a 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. Celestrons award-winning Nature DX binocular gets a major upgrade with the addition of ED objective lenses. Not one detectable iota of discernable difference. It's highly unlikely that they could be so precisely identical unless they were. 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. Depending on the design of the telescope, they may require separate focal reducers if they require focal reducers at all. The Reduction Factor and the Amount of Reduction are inversely related. I have an 8SE, and am thinking about getting a focal reducer. The working distance or required back focus, explained above, is usually specified and is far more important in practice. 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. But in the Japan version I have never noticed any anomaly like the ghosting in the China R/C. This focal reducer is made to attach to the rear cell of Schmidt-Cassegrain or Maksutov-Cassegrain telescopes. 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. With the Celestron Reducer/Corrector Lens, thats precisely what you get. If used before or beyond the working distance, unwanted image distortion may result, especially when using cameras with larger sensors. Opticstar F6.3 Focal Reducer / Corrector. This factor is designated by a power that is less than 1, and it usually lies between 0.5x or 0.8x. Sign up for our newsletter to get exclusive deals, observing tips, and new product announcements. 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. This rugged, 3-in-1 device features a true tactical 3-mode flashlight, a hand warmer, and a portable power bank for recharging your personal electronics on the go. Here, there was a subtle difference . 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. 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. I focus using a moonlight electronic focuser and focusmax. 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. Have always disliked the crude, noisy SCT threads, but I get it. Unleash the full pointing accuracy of your Celestron computerized telescope with a specialized telescope control software suite. A focal reducer does just the opposite of a Barlow lens or focal extender. Read our 101 article or get in touch. . Upgrading the Focuser of Your Schmidt-Cassegrain Telescope - Agena Astro They are designed (assuming you are referring to the f/6.3 version) for the f/10 light cone. Focal Reducer for SCT - ACF - Stargazers Lounge Each focal reducer has a fixed specification called the working distance or required back focus. The reduction factor MR can also be written in terms of d2 as: When the focal reducer is placed at the working distance, D, that is when d2=D, then the reduction factor MR is equal to the design reduction factor MRD: Equations (6) and (7) imply these important considerations: Most manufacturers do not publish the focal length of their focal reducers, so it is not usually possible to calculate the working distance and design reduction factor. 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. 800-483-6287 For visual use, this means you get lower power with the same eyepiece and a wider field of view. Edited by Tony Bonanno, 16 April 2021 - 06:44 PM. Turn it on and push Align. In about three minutes, youre ready to observe! A little longer light path with a 2 Baader click-lock, low profile 1.25 adapter, and the 1.25 diagonal; Focal reducers for SCT, RC, and field-flattened Edge HD or ACF telescopes thread onto the back of the telescope tube with 2"-24 or 3"-28 SCT threads. No results, please adjust your filters. I've seen some older threads saying that the Celestron, Meade and Antares FRs are all the same and manufactured in the same factory. 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. Equation (4) shows the relationship between the distance d2 and the reduction factor MR. 1.2" in that scope is a field stop of 43mm at f/10 and 27mm at f/6.3. The Reducer/Corrector can also be used for terrestrial digiscoping. The stock Celestron visualback is just under 2 long. I would pay slightly more for the Japan produced version, just because Hirsch was not bad either but sold it since I had 2 already. You can adjust your cookie settings, otherwise we'll assume you're okay to continue. I wont bother with differences in packaging, caps, etc. I have a made in Japan 6.3 R/C and a made in China 6.3 R/C. Please re-enable javascript to access full functionality. Copyright 2003-2022 Agena AstroProducts. The previous post shows the reducer on what appear to be two different refractors. Reducer Lens .7x - EdgeHD 1400 Learn More. As a Barlow's magnification increases with increasing distance from the Barlow, a focal reducer's reduction increases with increasing distance from the reducer. He tested this on an 8 Celestron , I have a Celestron 6SE. If you place your camera at a different working distance, you will get a different reduction factor and perhaps unwanted distortion in the image. It's usually specified in millimeters. Does anyone have any experience with the Celestron and Antares focal reducers? Celestron or Antares f/6.3 focal reducer for SCT? Go behind the scenes with Celestrons product development team and learn more about our award-winning and patented innovations. To test this, I used three set-ups: 1. Antares Click Lock Visual Back - Cats & Casses - Cloudy Nights Thanks for the extremely valuable article. The focal length of a focal reducer is usually measured from the rear lens surface of the reducer (and not the reducer's housing). Optically, it consists of a four-element lens that is fully multi-coated for high contrast and resolution. Nowadays I tend to use the Celestron more with my refractors for imaging and viewing. At least these two units I tested make the answer - whatever. Imaging - Focal Reducers and Flatteners - Page 1 - KW Telescope Telescope Optics, Rutten and van Venrooij, Chapter 15, Willman-Bell (1988). Reducer Lens .7x - EdgeHD 800 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. This appendix summarizes how this works based on simple equations from the book Telescope Optics by Rutten and van Venrooij. Oceanside Photo & Telescope wants our customers to shop with confidence knowing that you will always get the best deal available. Sign up for a new account in our community. Some third-party vendors also make reducers for SCT scopes. More aggressive reduction, or using these reducers with larger sensors, will result in aberrations and distortions near the edge of the image. A former wireless communications consulting engineer and management consultant to various Fortune 500 companies, Manish started Agena AstroProducts in 2003. CPWI has an extensive object database, employs PointXP mount modeling, and more. I have this one Opticstar F6.3 Focal Reducer / Corrector. 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. You may need spacers or a T-adapter to ensure the correcting working distance. Michael 1 ronin Members Just point the telescope at any three bright objectsstars, bright planets, or even the Moonand your telescope can orient itself with the night sky. 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 . My Celestron was made in China and the Antares in Canada. Whereas the Celestron threaded smoothly onto the scope, the Antares chattered and squeaked a bit more so when being removed. InternetSales@optcorp.com, 800-483-6287 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. Style: Yet, the Antares still easily and fully threaded without any hitches. The price for an item/offer must be listed and valid at the time of match. It has only one cover, which surprised me. They both are great and I doubt my eyes could detect a difference in any one of them including the Japan version. You currently have javascript disabled. With both, using the same diagonal set-up, the exact same stars were visible at the very edge of the FOV. Shipping will be via the cheapest shipping method which will vary depending on the items in your order. Steve 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. Your mileage may vary. 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. Since the focal length of the reducer, FR, is fixed, as d2 increases then MR decreases. However, the export of some items may be restricted outside the US due to size or manufacturer restrictions. Reducer - Corrector Learn More. Thanks guys, I'm trying to get my ZWO ASI120MC-S to work with my 90mm Meade. Does anyone know if the Antares 4000 focal reducer is as good as the Celestron focal reducer. Never used one, but read the reviews here that suggest a coating problem.
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