But while the image gets brighter, the size of the image circle gets proportionately smaller. Sign up to get exclusive deals, observing tips, and new product announcements. 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. 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. The faster f/ratio allows you to use slower film or shoot in lower light level situations and still properly expose your subject. Meade once made an f/3.3 focal reducer for SCT scopes. Sky recognition technology that has revolutionized the manual telescope by eliminating the confusion common among beginners and enhancing the user experience for even seasoned telescope users. Style: It was also a little brighter in the center of the field with subtle darkening in the outer 20% or so. However, even though the imprint on the item states "Reducer / Corrector" please note that his is a reducer only. Article Agena AstroProducts, 2019. Can you tell me about the use of reducers in Maksutov-Cassegrain telescopes? That includes, for example, a 1.25" eyepiece with an apparent field of view of 68 and a focal length of 24mm (eg. 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. 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. Years ago, I bought the Antares version, and moved over to the Celestron. These reducers have a back focus (or design working distance) of 80mm. I have/had both the Celestron (Japan) and Antares units. I have Hirsch focal reducer, which is yet another clone of the Celestron 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! However, this also came at a cost, as the sky background in the Antares was slightly brighter. Because most modern Newtonians already have relatively fast focal ratios, these telescopes do not usually use focal reducers. . Focal reducers for refractors are easy to use. I've only used it a few times but it looks good to me. Edited by Tony Bonanno, 16 April 2021 - 06:44 PM. 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). Details: The item must be the identical item, brand name, size, weight, color, quantity and model number. The focal length and design working distance for this focal reducer were not available from the manufacturer. 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. They both are great and I doubt my eyes could detect a difference in any one of them including the Japan version. Also read the reviews here, including those at 4 stars. A former wireless communications consulting engineer and management consultant to various Fortune 500 companies, Manish started Agena AstroProducts in 2003. Sharpness is essentially the same. 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. The problem with those SCT reducers is that they cause chromatic aberration and require refocusing when using parfocal RGB/other filters. In terms of reduction and correction - which are what reducer/correctors are supposed to do - both are superb. Celestron Focus Motor for SCT, EdgeHD & 8" RASA, Celestron C6 0.63 reducer/flattener back focus. No results, please adjust your filters. For example, a 0.8x reducer placed at the working distance provides a reduction of (1 0.8) x 100 = 20%. 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. The review is a subjective visual impression, which is interesting but not best evidence. Thanks for the extremely valuable article. 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. These reducers can also be used for visual observing with SCT scopes with eyepieces with a field stop as large as 24-27mm. Again, to my surprise, there was absolutely no difference between the Celestron and Antares on any star. And, the reality is that every F/6.3 RC out there Celestron, Hirsch, Astromania, etc., etc. Reducer Lens .7x - EdgeHD 800 Learn More. It's usually specified in millimeters. 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. If you want to save a few buck watch the classifieds on CN. Another factor to consider: focal reducers also increase the angle at which light approaches the focal plane. I wont bother with differences in packaging, caps, etc. Performance wise what differences might there be using the reducer on a smaller scope. 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. 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. 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. I had a Celestron, Antares and Hirsch for awhile and compared them over about a year. I happily cycle through LRGB filters to build the image rather than do a whole run of one filter at a time. This focal reducer and field flattener consists of a four-element multicoated 40mm lens in a metal cell. 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. Reviews. They are designed (assuming you are referring to the f/6.3 version) for the f/10 light cone. You don't need to follow these equations to use a focal reducer, but they do show how the reduction factor changes with the placement of the reducer. They never really recovered from selling a few 15 years back with element reversed. Hello! 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"). These reducers can also be used for visual observing with SCT scopes with eyepieces with a field stop as large as 24-27mm. - thanks. How about for visual observers? Never used one, but read the reviews here that suggest a coating problem. No negative issues to report. The price for an item/offer must be listed and valid at the time of match. As one increases, the other decreases. 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. 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. Specially-designed focal reducers are available for use with these telescopes. With this telescope and this focal reducer, it does not help to move to a 2" eyepiece and a 2" diagonal as the visual view will be akin to looking through a porthole within the larger apparent field of view of the eyepiece. During check-out, you will be presented with several shipping choices and costs. 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. This factor is designated by a power that is less than 1, and it usually lies between 0.5x or 0.8x. and you will be fine. 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. For me the Antares was a little brighter and had the least scatter by a bit so the better coatings won. But I am rusty, can you condense a bit for me please? 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. They usually have a 2" barrel that slides into the telescope focuser. SKU: CEL-94245. The threads were similar on the eyepiece end, but a bit smoother. As per the OP I still can't see any reason to buy the Celestron for significantly more $$$. Quite interestingly it bears the very same engravings of the Meade 4000 r/c (including "series 4000") except for "MEADE". Maybe I got a lemon. Most manufacturers provide this specification. Read our guide! An eyepiece with a 27mm field stop yields a true field of 1.03 in the C6 at f/10. 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. Celestron or Antares f/6.3 focal reducer for SCT? More about this below. Dedicated focal reducers for refractors are intended primarily for imaging, not visual observation. Reducer Lens .7x - EdgeHD 1100 Learn More. The lens is housed in machined aluminum for are machined aluminum black anodized. In your opinion, is the Celestron is worth the added cost ($150 vs. $90)? Now It only focuses near things, like some kind of macro zoom. Learn more about extra solar planets imagery, 3D Star rendering, observation planning, telescope control, multiple-panel printing, and much more. Thanks Peter! As often noted in reviews and forum threads, Antares products tend to have threads that are a little less precise, and this specimen certainly demonstrated this. But is there a difference in quality between the Antares and the Celestron or Meade focal reducers? But the diameter of the image circle decreases by a factor of 0.63 to about 24mm. 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. The female end attaches to the rear cell of the telescope. 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. Celestron or Antares? My Celestron was made in China and the Antares in Canada. The previous post shows the reducer on what appear to be two different refractors. 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. Orders placed over the weekend will be shipped on the following Monday. Brian Ventrudo is a writer, scientist, and astronomy educator. 800-483-6287 They only publish the value of D, the working distance (sometimes called the back focus distance) and the design reduction factor MRD. They are commonly available in 1.25" and 2" threaded cells that conveniently thread into the nosepiece of a compatible camera or the barrel of an eyepiece. . Right off the bat, I was struck by how similar the two R/Cs were. 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 focal reducer is made to attach to the rear cell of Schmidt-Cassegrain or Maksutov-Cassegrain telescopes. Optically, it consists of a four-element lens that is fully multi-coated for high contrast and resolution. The new Lithium Phosphate (LiFePO4) battery chemistry has significant advantages over other battery chemistries, great for for those Astronomers on the go. My application is mostly visual now, but I'm looking to do more astrophotography over time. 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. 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. Both exhibited consistent reduction, identical field flattening, and edge correction properties, and both were high quality optically and mechanically. Bear in mind you can't squeeze blood out of a turnip, i.e. 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. But in the end they both do pretty much the same thing and it sounds like any performance difference is subtle. All Rights Reserved. Nada. 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. I really don't see any difference in the current crop except the "Meade" is usually the cheapest. Melotte 15 - First Process in PixInsight (easy! Refractors, or SCTs with external focusers, may not have sufficient in-travel to reach focus in some configurations. Read our 101 article or get in touch. Reducer Lens .7x - EdgeHD 1400 Learn More. So Celestron buyers like Celestron, Meade buyers like the Meade and Antares buyer like the Antares. 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. Check out our 2022 telescope buying guide here! Whereas the Celestron threaded smoothly onto the scope, the Antares chattered and squeaked a bit more so when being removed. 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. Sign up for a new account in our community. We only send interesting emails and will never sell your data. Nebula Filters. In some cases, focal reducers also act as field flatteners by correcting for field curvature and coma of the objective lens. Things change but when I rebought I got an Antares and it seems about the same to me. Clearly cost is a big factor for satisfied users. Focal Reducer, 2", 0.7X. 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. As a consequence, the standard f/6.3 and f/3.3 focal reducers for SCT scopes do not work. If I had to guess, the difference is maybe 10-15 grams. I don't know. 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. If used with other f/ratios, the field flattening characteristic may be unpredictable. Newtonian reflectors will seldom be able to accommodate the in-focus travel demanded by focal reducers. 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. 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. We reserve the right to verify a competitor's advertised price and the availability of the item. Photographically you also get a wider field and much shorter exposures. Given the results of Test #1, I wanted to see if there was any truth to this assumption. You may need spacers or a T-adapter to ensure the correcting working distance. Due to the design, the Reducer/Corrector lens does diminish a small amount of field curvature common to all Schmidt Cassegrain telescopes but does not eliminate it. 1.2" in that scope is a field stop of 43mm at f/10 and 27mm at f/6.3. I have this one Opticstar F6.3 Focal Reducer / Corrector. Free shipping $189.95 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. I must admit, as well, that I no longer place a lot of stock in the notion that Chinese optics are inferior to Japanese or Taiwanese any longer, as manufacturing technology has really leveled the playing field today, with most Chinese optics being excellent. 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. Many Ritchey-Chretien telescopes available today are made by GSO. 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. I think there may be some confusion here, because Antares makes a variety of reducers for eyepieces and scopes in addition to this SCT R/C but this definitely is a reducer/corrector. A focal reducer does just the opposite of a Barlow lens or focal extender. The Reduction Factor and the Amount of Reduction are inversely related. 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. 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. control and Sky Viewer display makes selecting your target easy. Some are available in 1.25" barrel format but with C threads. Reducer - Corrector Celestrons patented StarSense Technology makes it easier than ever to locate objects in the night sky, even if youve never used a telescope before. Explore Scientific - Keys to the Universe Sale. It can also be used with any other small chip CCD camera having a 1.25" nosepiece, such as the Celestron NexImage, Meade DSI . Thks for that and its not for visual it for astrophotography. Reducer Lens .7x - EdgeHD 925 Learn More. Figure 2 shows the effective of a focal reducer on the light from a telescope objective. This should not be the case if they have their purportedly different focal lengths. In such cases, we will be happy to take the item back as per our standard return terms. Celestron's EdgeHD reducers feature a custom 5 element optical design engineered to maintain the flat-field performance of our award-winning EdgeHD optical system. 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. CEL-94245. Therefore, a 55mm back focus with a filter that is 3mm thick added to the imaging train would become 56mm. Stars had a tiny bit more sparkle and pop. 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. Still not sure what is the right gear for you? How does it look thats what matters. At least these two units I tested make the answer - whatever. ), but stars seemed a bit tighter and their colors were richer and more dramatic. A few people have reported issues with the male SCT thread diameter on this item being a bit larger than necessary. The Reducer/Corrector is easy to install by threading the unit onto the rear cell of your Schmidt-Cassegrain telescope (or the reducer plate of the C11 and C14). This fully multi-coated lens provides maximum light transmission with near full-field illumination. 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. Since the focal length of the reducer, FR, is fixed, as d2 increases then MR decreases. 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. A few large telescopes and mounts are excluded from this free shipping offer. This is the simplest way to attach your ASI121 to your telescope. Please re-enable javascript to access full functionality. I would not use the reducer with a 2" diagonal or eyepiece in the C6. 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.

Brazil Military Strength, Lucy Thomas Singer Photos, Great Gatsby True Or False, Famous Pastors In Orlando Florida, Articles A