In this configuration, the 29.5mm camera nosepiece and a 6mm extension ring positions the reducer at a working distance of 53.5mm from the camera sensor, which is located 12.5mm inside the front edge of the camera. The internal surfaces are blackened and glare-threaded to provide the highest contrast. Can these economical focal reducers from GSO and other vendors result in good images? But the smaller image circle means there is a limit to the field stop of an eyepiece that can achieve an unvignetted image. 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. 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. If you do so, you will achieve the design reduction factor. 160K views 9 years ago This video is a complete overview of focal reducers and how they function applying to telescopes. If used before or beyond the working distance, unwanted image distortion may result, especially when using cameras with larger sensors. Your mileage may vary. I use the same back spacing for both on a small 6" Celestron SCT. In such cases, we will be happy to take the item back as per our standard return terms. If used before or beyond the working distance, unwanted image distortion may result. 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. I have Hirsch focal reducer, which is yet another clone of the Celestron reducer. This should not be the case if they have their purportedly different focal lengths. They never really recovered from selling a few 15 years back with element reversed. 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. 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. In both cases will end with a similar tfov. If yes, what kind of focal reducers can I use? control and Sky Viewer display makes selecting your target easy. Manish holds a Master's degree in Electrical Engineering from Virginia Tech and an MBA from the Kellogg School of Management at Northwestern University. Figure 6 shows a 1.25" focal reducer from GSO configured with a ZWO ASI224MC camera. However, these will not impact optical performance. This focal reducer and field flattener consists of a four-element multicoated 40mm lens in a metal cell. 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. 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. Anyway, when purchased my R/C the "original" Celestron unit was not readily available and was offered instead the one sold under the shop's own label (in my case Tecnosky, but I saw the same product offered under TS label). F6.3 Focal reducer for F/10 or higher telescopes, 43mm aperture, 4-Element, Fully Multicoated. No negative issues to report. Using this same example of an 8" SCT and a 0.63x reducer, a visual observer can also enjoy brighter images and a wider field of view. 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. Now It only focuses near things, like some kind of macro zoom. Reducer Lens .7x - EdgeHD 925 Learn More. Newtonian reflectors will seldom be able to accommodate the in-focus travel demanded by focal reducers. I had a Celestron, Antares and Hirsch for awhile and compared them over about a year. This would tell us exactly how well aberrations are corrected. Weasner's Meade and Antares Focal Reducers Review 1.2" in that scope is a field stop of 43mm at f/10 and 27mm at f/6.3. Optically, it consists of a four-element lens that is fully multi-coated for high contrast and resolution. 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). 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. Does anyone know if the Antares 4000 focal reducer is as good as the Celestron focal reducer. 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. The new Lithium Phosphate (LiFePO4) battery chemistry has significant advantages over other battery chemistries, great for for those Astronomers on the go. In your opinion, is the Celestron is worth the added cost ($150 vs. $90)? 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? On the camera side, the focal reducer has male M42x0.75 or M48x0.75 threads that attach directly to the T-ring (with an M42-M48 adapter if necessary). For example, an 8" SCT without a focal reducer has an illuminated field of 38mm at 50% fall-off. The faster f/ratio allows you to use slower film or shoot in lower light level situations and still properly expose your subject. Completely stuck, completely frustrated. 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. And, the reality is that every F/6.3 RC out there Celestron, Hirsch, Astromania, etc., etc. WiFi technology encircles the globe in a web of connectivity, knowledge, and information. 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. It also leads to larger (although fainter) images of extended objects like the Moon or planets for astrophotographers or visual observers. I really don't see any difference in the current crop except the "Meade" is usually the cheapest. I've seen some older threads saying that the Celestron, Meade and Antares FRs are all the same and manufactured in the same factory. Antares f/6.3 SCT Focal Reducer - Rother Valley Optics Ltd It's highly unlikely that they could be so precisely identical unless they were. Explore Scientific Keys to the Universe Sale. Celestron or Antares f/6.3 focal reducer for SCT? Manish Panjwani has been an active amateur astronomer since before Halley's Comet last flew by our neighborhood. 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. How to Set the Correct Back Focus for Your Telescope (Guide) This fully multi-coated lens provides maximum light transmission with near full-field illumination. 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. This appendix summarizes how this works based on simple equations from the book Telescope Optics by Rutten and van Venrooij. 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. Start here to find the perfect telescope for you! They are also less expensive than many external focusers of similar build quality. But I am rusty, can you condense a bit for me please? For the best experience on our site, be sure to turn on Javascript in your browser. To calculate how much back focus spacing you need to add, take the thickness of the filter and divide it by 3. High power views will provide flatter fields all the way to the edge, both visually and photographically. Increase that distance, and greater reduction results and visa versa. Focal Reducer, 2", 0.7X. Orders placed after 12:00 PM Pacific Time will be shipped the next business day. 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. When the camera sensor is placed at this distance, the reduction factor of these reducers is 0.75x. 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. Our patented SkyAlign alignment technology makes setting up a computerized telescope simple, fast, and accurate. Like many of us with SCTs, I have bought and sold a number of f/6.3 reducer/correctors over the years, and I have always been curious how they really stack up to each other. Thank you so much for the informative article, I now understand better how to integrate my reducer into my system to get better performance. 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. Images in the Celestron tended to appear ever-so-slightly dimmer (maybe? Wow, that is a very detailed discussion! These reducers can also be used for visual observing with SCT scopes with eyepieces with a field stop as large as 24-27mm. 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. 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. October 11, 2010 in Discussions - Scopes / Whole setups.
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