I think I remember hearing the reduction factor is slightly different, cant remember more or less reduction. 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. Very helpful, thanks a lot for this article! In such cases, we will be happy to take the item back as per our standard return terms. No retailers currently carry this product. 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. Since the focal length of the reducer, FR, is fixed, as d2 increases then MR decreases. If you do so, you will achieve the design reduction factor. This is the simplest way to attach your ASI121 to your telescope. 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. Increase that distance, and greater reduction results and visa versa. JavaScript seems to be disabled in your browser. Or, when the distance of the focal reducer to the focal plane of the objective d1 equals the focal length of the focal reducer FR, the reduction factor MR = 0.5x. First, let's have a look at some key optical parameters are needed to understand focal reducers. What I do know is that the Antares and the Celestron samples that I have perform exactly the same from the center right out to the edges. 2023 OPT Telescopes. 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. Reducer Lens .7x - EdgeHD 800 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. No small animals were harmed in making these observations. This innovative software solves the time-consuming problem of trying to pinpoint the North Celestial Pole. Can you help me? My experience is that CN sellers are way above those listing elsewhere. Sign up for our newsletter to get exclusive deals, observing tips, and new product announcements. He also holds a Ph.D. in engineering physics from McMaster University. Oceanside Photo & Telescope wants our customers to shop with confidence knowing that you will always get the best deal available. I really don't see any difference in the current crop except the "Meade" is usually the cheapest. Years ago, I bought the Antares version, and moved over to the Celestron. I wonder whether, for example, Antares focal reducer for SCT belongs to the latter category. Thank you so much for the informative article, I now understand better how to integrate my reducer into my system to get better performance. Your mileage may vary. Sharpness is essentially the same. 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 . Powered by Invision Community. and you will be fine. Again, these focal reducers are often provided by the telescope manufacturer. 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. I also used several eyepieces including the ES 24mm/68, 17.5mm and 12.5mm Morpheuses, and a 10.5mm Pentax XL. Bear in mind you can't squeeze blood out of a turnip, i.e. ED stands for "extra-low dispersion," which refers to the composition and optical properties of the glass used for the lenses. These scopes are compatibles with focal reducers. But in the end they both do pretty much the same thing and it sounds like any performance difference is subtle. 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. However, even though the imprint on the item states "Reducer / Corrector" please note that his is a reducer only. Several functions may not work. This filter threads on to the rear cell of your Celestron or Meade SCT telescope. The price for an item/offer must be listed and valid at the time of match. Hi - most interesting - may I ask .. the brighter guys - "if a camera sensor is too small for a n adaper, will a focal reduer allow me to get greater use from the camera? This focal reducer and field flattener consists of a four-element multicoated 40mm lens in a metal cell. When using the diagonal, keep the field stops of the eyepieces under 20mm. Upon close inspection, it was clear that the housing of Antares assembled in Canada version was a little more substantial than the Celestron. 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. Shipping will be via the cheapest shipping method which will vary depending on the items in your order. Because most modern Newtonians already have relatively fast focal ratios, these telescopes do not usually use focal reducers. No results, please adjust your filters. This appendix summarizes how this works based on simple equations from the book Telescope Optics by Rutten and van Venrooij. If you want to save a few buck watch the classifieds on CN. Looking forward to the day when I can do a shoot-out between a Japan and China Celestron, just for kicks. JavaScript seems to be disabled in your browser. control and Sky Viewer display makes selecting your target easy. InternetSales@optcorp.com, 800-483-6287 You may need spacers or a T-adapter to ensure the correcting working distance. 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. For example, a 0.8x reducer placed at the working distance provides a reduction of (1 0.8) x 100 = 20%. Focal reducers for refractors are easy to use. They are reported as identical. For imagers, the main purpose of a focal reducer is to increase the brightness of the image at the focal plane. Unleash the full pointing accuracy of your Celestron computerized telescope with a specialized telescope control software suite. This is very impressive performance given how hard this problem is to mitigate in general. In many cases, the answer is yes, especially for electronically-assisted astronomy (EAA). ED glass is specially formulated and contains rare-earth compounds that greatly reduce a visual defect called chromatic aberration. All rights reserved. The previous post shows the reducer on what appear to be two different refractors. Read our guide! There is a way to make subjective data more useful and that way is proper blind, or better still. Celestron or Antares? An image of about 24mm across, approximately, allows an observer to use a 1.25" eyepiece with a maximal field stop. 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. They are designed (assuming you are referring to the f/6.3 version) for the f/10 light cone. No difference. 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. Thanks for the extremely valuable article. Meade once made an f/3.3 focal reducer for SCT scopes. In some cases, focal reducers also act as field flatteners by correcting for field curvature and coma of the objective lens. And, the reality is that every F/6.3 RC out there Celestron, Hirsch, Astromania, etc., etc. As another example,GSO makes focal reducers for their line of Ritchey-Chretien imaging telescopes. One problem with getting opinions is that most of use do not have both reducers or have never done a side by side comparison. 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. 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 currently have javascript disabled. This should not be the case if they have their purportedly different focal lengths. 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. Some third-party vendors also make reducers for SCT scopes. The working distance or required back focus, explained above, is usually specified and is far more important in practice. What an enjoyable read and detailed comparison. Never used one, but read the reviews here that suggest a coating problem. 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. Edited by bluewater, 05 September 2020 - 11:27 AM. Fumbling around in the dark, fine threads might be a problem. Reviews. 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. There may have been an almost imperceptible difference, but the Antares and Celestron were producing precisely the same reduction. Ive owned Celestron, Meade, and Antares models over the years at least a couple of each. 3. I've heard and read all kinds of things about the Antares being only a reducer and not a corrector, etc. Besides observing from his heavily light polluted backyard in Los Angeles, Manish enjoys conducting astronomy outreach programs in local schools. Field stop diameters are one of the specified specs of eyepieces. 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. This also resulted in the clear aperture of the Antares being about 39-39.5mm, versus the Celestrons 41mm. 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. Start here to find the perfect telescope for you! 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. This focal reducer is made to attach to the rear cell of Schmidt-Cassegrain or Maksutov-Cassegrain telescopes. 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. Many focal reducers are meant to be used within a few millimeters of the specified working distance to achieve the best possible image results. Reducer - Corrector Learn More. The Reducer/Corrector can also be used for terrestrial digiscoping. The reducer features fully coated optics in an anodized aluminum filter ring with an ergonomic rubber grip. We have corrected # (iii) after equations 6 & 7. 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. Never noticed any anomalies with this unit. 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. The resultant reduction factor was measured to be 0.46x. 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. You need to be a member in order to leave a comment. Sign up for our newsletter to get exclusive deals, observing tips, and new product announcements. Turn it on and push Align. In about three minutes, youre ready to observe! The most popular accessories for your new telescope! All additional accessories mount onto the exterior/male threads. I am a purely visual observer, so will evaluate for visual use only. Meade and Celestron both sell such SCT-T adapters with the correct optical length. These reducers have a back focus (or design working distance) of 80mm. In both cases will end with a similar tfov. 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. Does anyone know if the Antares 4000 focal reducer is as good as the Celestron focal reducer.