But nearly every observer who installs one of these devices is pleased with their performance. You currently have javascript disabled. Most manufacturers provide this specification. The nominal design reduction factor of these reducers is typically 0.5x. 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. Reducer Lens .7x - EdgeHD 800 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. Orders placed over the weekend will be shipped on the following Monday. Because I have not heard any complaints about the made in China R/C. 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. No experience with the Antares reducers, but I haven't personally seen a difference between Celestron and my current pair of made in Japan Meade reducers. Check out our 2022 telescope buying guide here! EclipSmart solar products feature Solar Safe filter technology providing the ultimate protection from harmful solar radiation, including both IR and UV light, and filters 99.999% of visible light. Have always disliked the crude, noisy SCT threads, but I get it. 160K views 9 years ago This video is a complete overview of focal reducers and how they function applying to telescopes. 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 . High power views will provide flatter fields all the way to the edge, both visually and photographically. This is especially true when these reducers are used with cameras with smaller sensors with a dimension of about 1/4 to 1/3 the diameter of the reducer, and with telescopes with a focal ratio of f/7 or larger. I use the Celestron version and it seems OK for both visual and imaging. Increase that distance, and greater reduction results and visa versa. 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. The internal surfaces are blackened and glare-threaded to provide the highest contrast. Figure 6 shows a 1.25" focal reducer from GSO configured with a ZWO ASI224MC camera. The most significant mechanical variation, however, is the quality and precision of the threading. Celestron Solar Safe filter technology is GUARANTEED SAFE for direct solar observation and has been independently tested by SAI Global Assurance Services. A little longer light path with a 2 Baader click-lock, low profile 1.25 adapter, and the 1.25 diagonal; No results, please adjust your filters. Hello! I've never found my 0.63 reducer causing CA when used with my SCT. Some third-party vendors also make reducers for SCT scopes. This may be a problem if the focuser tube or the diagonal (for visual observing) is too narrow to accept light at this larger angle. 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. The amount of reduction is simply the percentage by which a reducer shortens the effective focal length of a telescope and is calculated as (1 Reduction Factor) x 100%. He received his first telescope at the age of 5 and completed his first university course in astronomy at the age of 12, eventually receiving a master's degree in the subject. Telescope Optics, Rutten and van Venrooij, Chapter 15, Willman-Bell (1988). looks virtually identical, except for the lettering. CEL-94245. Figure 1 shows the relationship between the focal reduction factor MR and the position of the reducer in the optical path. 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. I have/had both the Celestron (Japan) and Antares units. However, because the field curvatures in refractors and SCTs vary a lot, I would predict unpredictable effects inre: field curvature. Edited by Tony Bonanno, 16 April 2021 - 06:44 PM. Does anyone know if the Antares 4000 focal reducer is as good as the Celestron focal reducer. Possibly the design of the Antares was changed .. It was used strictly for imaging, not visual observing. In terms of reduction and correction which are what reducer/correctors are supposed to do both are superb. I really don't see any difference in the current crop except the "Meade" is usually the cheapest. Fortunately, my neighbors are not out in their backyards at 11 pm, or they may have thought I was torturing a small mammal. This also resulted in the clear aperture of the Antares being about 39-39.5mm, versus the Celestrons 41mm. That is definitely a 2" eyepiece, but it is not a large or long focal length 2" eyepiece. Not one detectable iota of discernable difference. Ive owned Celestron, Meade, and Antares models over the years at least a couple of each. If the reducer is placed elsewhere, at a position called the operating distance, the focal reduction factor will not be as advertised. 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. The resultant reduction factor was measured to be 0.46x. CPWI has an extensive object database, employs PointXP mount modeling, and more. Planetarium software package which provides easy-to-understand explanations and impressive visuals of all kinds. 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. Hmmm . The stock Celestron visualback is just under 2 long. ED stands for "extra-low dispersion," which refers to the composition and optical properties of the glass used for the lenses. Celestron or Antares? 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. a Tele Vue Panoptic), or a Plossl eyepiece with an apparent field of view of 50 and a focal length of 32mm. Is there likely to be any differences in performance between using these on an 8 or something smaller like my 6SE? Wonder how they would stack up with a Japanese 6.3. 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. But while the image gets brighter, the size of the image circle gets proportionately smaller. 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. This factor is designated by a power that is less than 1, and it usually lies between 0.5x or 0.8x. 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. 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. 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. As another example,GSO makes focal reducers for their line of Ritchey-Chretien imaging telescopes. I have an 8SE, and am thinking about getting a focal reducer. Once installed, you can add additional accessories like T-Adapters, 1.25 Visual Back, Star Diagonal, or Off-Axis Guider. 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. Celestrons patented StarSense Technology makes it easier than ever to locate objects in the night sky, even if youve never used a telescope before. Does anyone have any experience with the Celestron and Antares focal reducers? Field stop diameters are one of the specified specs of eyepieces. * Not a Retail Store * 16313 Arthur StreetCerritos, CA 90703, USA. Sign up for OPT news, exclusive offers, and updates on the latest gear! Copyright 2021 Stargazers Lounge Take control of your telescope! Completely stuck, completely frustrated. The most popular accessories for your new telescope! My Celestron was made in China and the Antares in Canada. A longer effective focal length leads to higher magnification with a given eyepiece for visual observers. The reducer fits all Meade and Celestron . All rights reserved. Focal reducers for refractors are easy to use. You attach the focal reducer to the rear port on a SCT and can keep it covered. In most cases, the easiest option is to choose the focal reducer made specifically for your telescope. Reducer Lens .7x - EdgeHD 925 Learn More. Read our guide! Refractors, or SCTs with external focusers, may not have sufficient in-travel to reach focus in some configurations. My application is mostly visual now, but I'm looking to do more astrophotography over time. DUE TO EXTREMELY HIGH DEMAND, WE WILL NOT BE TAKING NEW ORDERS UNTIL MONDAY, DECEMBER 14. An f/6.3 reducer is designed to reduce the focal ratio of an f/10 SCT to f/6.3. However, the China 6.3 R/C has noticeable internal reflections that I haven't figured out yet. I've heard and read all kinds of things about the Antares being only a reducer and not a corrector, etc. In both cases will end with a similar tfov. They are also less expensive than many external focusers of similar build quality. It's an either/or proposition: reducer and 1.25", or 2", but not 2" and reducer. 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. Still not sure what is the right gear for you? 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. 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"). An eyepiece with a 27mm field stop yields a true field of 1.03 in the C6 at f/10. Clearly cost is a big factor for satisfied users. Celestron Nexstar+ 127 SLT, several budget plossl eyepieces, Celestron 8-24mm zoom EP and a 12.5mm illuminated double reticle EP, Svbony SV205 camera w/.5 focal reducer, Celestron SkyMaster 20x80 binos on a 40 yr old QuickSet PanHead tripod, Stellarium, Sharpcap and ManyCam on my laptop, SkyView and Nightshift on my phone and a dandy little $9 . You cannot, for example, use a 0.63x focal reducer intended for a standard Celestron or Meade SCT and use it on a Celestron Edge HD or a Meade ACF. I only have the Celestron f/6.3. Sign up for a new account in our community. 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. Images made with my ZWO 533 camera testing both show them to be essentially the same. The two samples I have PERFORM IDENTICALLY. 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. Whereas the Celestron threaded smoothly onto the scope, the Antares chattered and squeaked a bit more so when being removed. This focal reducer and field flattener consists of a four-element multicoated 40mm lens in a metal cell. Besides observing from his heavily light polluted backyard in Los Angeles, Manish enjoys conducting astronomy outreach programs in local schools. I'm going with the Celestron. You can adjust your cookie settings, otherwise we'll assume you're okay to continue. There are also third-party vendors such as Hotech. If used with other f/ratios, the field flattening characteristic may be unpredictable. Just point the telescope at any three bright objectsstars, bright planets, or even the Moonand your telescope can orient itself with the night sky. A f/10 focal ratio now achieves a f/6.3, while an f/11 focal ratio now achieves a f/7. More details are found in the Appendix of this article. 800-483-6287 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 Brian Ventrudo is a writer, scientist, and astronomy educator. Our proprietary StarBright XLT optical coatings dramatically increase transmission, up to 97.4% on our Schmidt corrector lenses. Who cares? More aggressive reduction, or using these reducers with larger sensors, will result in aberrations and distortions near the edge of the image. Perhaps not exactly- there will be some uncertainty because of manufacturing tolerances and so forth, but it will be close. I'd favor the Japanese Celestron version over the others that are commercially available. 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. I have a Raspberry HQ camera, a Sony TV Zoom 12.5-75mm f1.8 and a Astromania 1,25" 0.5x focal reducer. 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. Thanks for pointing this out. It can also be used with any other small chip CCD camera having a 1.25" nosepiece, such as the Celestron NexImage, Meade DSI . That means the base of the mounting threads of the focal reducer needs to be 55mm from the camera sensor to achieve the design reduction factor, which is usually 0.8x or 0.85x. Best evidence would by obtained by using a camera and evaluating the image both by eye and with a computer analysis. The working distance of the GSO 0.5x focal reducer with 1.25" barrel and the GSO 0.5x focal reducer with 2" barrel is about 51mm to 53mm, approximately, from the middle of the metal cell that holds the lens. This focal reducer from Celestron reduces the effective focal length by 0.63X Enjoy the wider field of view & faster exposure times at f/6.3 with f/10 telescopes f/11 telescopes, such as the C14 will perform at f/7 The Celestron f/6.3 Reducer has four fully-multicoated elements Reduce your exposure times by a factor of 3! 1.2" in that scope is a field stop of 43mm at f/10 and 27mm at f/6.3. There is a way to make subjective data more useful and that way is proper blind, or better still. Meade and Celestron both sell such SCT-T adapters with the correct optical length. Oceanside Photo & Telescope wants our customers to shop with confidence knowing that you will always get the best deal available. For example, an 8" SCT without a focal reducer has an illuminated field of 38mm at 50% fall-off. Figure 2 shows the effective of a focal reducer on the light from a telescope objective. We have corrected # (iii) after equations 6 & 7. So it provides a 0.63x design reduction factor when used with an f/10 SCT at the specified working distance. Steve In every configuration, there were essentially parfocal, requiring only a tiny fine focus adjustment when changing correctors. 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. If used before or beyond the working distance, unwanted image distortion may result. 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. I wish there was. Place the plastic covers on the lens when not in use to reduce the dust collection. Turn it on and push Align. In about three minutes, youre ready to observe! 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. We have placed cookies on your device to help make this website better. The key points are as follows: So just remember that a smaller distance (from the camera or eyepiece) means a lower amount of reduction (and vice versa). As a Barlow's magnification increases with increasing distance from the Barlow, a focal reducer's reduction increases with increasing distance from the reducer. * Not a Retail Store * 16313 Arthur StreetCerritos, CA 90703, USA, Availability: Item has been discontinued by Agena and we no longer carry this item. Some faster refractors with a focal ratio of f/6, for example, only require field flatteners and not focal reducers. 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.
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