2.2 Using a Focal Reducer at the Working Distance, 2.3 Adjusting the Reduction Factor of a Focal Reducer, 3.3 Focal Reducers for Compound Telescopes, 3.5 Focal Reducers for Ritchey-Chretien and Field Flattened Scopes, 3.6 Focal Reducers in 1.25" and 2" Barrel Formats, 4. 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. Rather than a direct side-by-side, I swapped the reducers so that I was using them on the exact same, well-collimated instrument. Reducer Lens .7x - EdgeHD 1100 - Celestron No idea what the issue is. We process your personal data as stated in our. JavaScript seems to be disabled in your browser. Looking forward to the day when I can do a shoot-out between a Japan and China Celestron, just for kicks. In practice, it's important to remember that you will rarely operate at the exact working distance and at the exact reduction factor that is specified. 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. The faster f/ratio allows you to use slower film or shoot in lower light level situations and still properly expose your subject. In terms of reduction and correction - which are what reducer/correctors are supposed to do - both are superb. Quite interestingly it bears the very same engravings of the Meade 4000 r/c (including "series 4000") except for "MEADE". . Explore Scientific - Keys to the Universe Sale. As a Barlow's magnification increases with increasing distance from the Barlow, a focal reducer's reduction increases with increasing distance from the reducer. For example, an 8" SCT without a focal reducer has an illuminated field of 38mm at 50% fall-off. This means that there must be sufficient travel on the telescope focuser to make up for this. Brian Ventrudo is a writer, scientist, and astronomy educator. I had a Celestron, Antares and Hirsch for awhile and compared them over about a year. But the smaller image circle means there is a limit to the field stop of an eyepiece that can achieve an unvignetted image. Figure 2 shows the effective of a focal reducer on the light from a telescope objective. 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. Explore Scientific Keys to the Universe Sale, Antares f/6.3 Focal Reducer for Schmidt-Cassegrain Telescopes, Skip to the beginning of the images gallery. I focus using a moonlight electronic focuser and focusmax. But in the end they both do pretty much the same thing and it sounds like any performance difference is subtle. Once focused it's pretty good. Wonder how they would stack up with a Japanese 6.3. 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. 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). The telescope side of the barrel is often threaded with an M48 x 0.75 thread for standard 2" astronomy filters. Figure 7 shows an example of an image of the Dumbbell Nebula taken with a 1.25" GSO focal reducer at a reduction factor of 0.63x with an 85mm f/7 refractor and a QHY5III-290M camera with a sensor with a 6.4mm diagonal. The most significant mechanical variation, however, is the quality and precision of the threading. Read our guide! 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. Whereas the Celestron threaded smoothly onto the scope, the Antares chattered and squeaked a bit more so when being removed. and you will be fine. The stock Celestron visualback is just under 2 long. We do not price match competitors if they are out of stock. For example, a 0.8x reducer placed at the working distance provides a reduction of (1 0.8) x 100 = 20%. Now It only focuses near things, like some kind of macro zoom. 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). These reducers can also be used for visual observing with SCT scopes with eyepieces with a field stop as large as 24-27mm. This focal reducer and field flattener consists of a four-element multicoated 40mm lens in a metal cell. Celestrons FREE planetarium app is an astronomy suite that redefines how you experience the night sky. 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. 800-483-6287 Focal Reducers | Celestron 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. 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. Both exhibited consistent reduction, identical field flattening, and edge correction properties, and both were high quality optically and mechanically. Your eyepieces are the first accessories you should learn to use with your telescope. Turn it on and push Align. In about three minutes, youre ready to observe! Reproduction without permission prohibited. Try & buy if you like - usual mates rates. Optically, it consists of a four-element lens that is fully multi-coated for high contrast and resolution. There is a way to make subjective data more useful and that way is proper blind, or better still. That includes, for example, a 1.25" eyepiece with an apparent field of view of 68 and a focal length of 24mm (eg. I've looked through one from Meade and first impression was that it was like the Celestron version. Our proprietary StarBright XLT optical coatings dramatically increase transmission, up to 97.4% on our Schmidt corrector lenses. It works fine but you should stick with 1.25 EPs; or can use 2" EPs without corrector. I think I remember hearing the reduction factor is slightly different, cant remember more or less reduction. However, doesn't fit in the telescope and even if it did wouldn't work. Several functions may not work. It's easy! How to Set the Correct Back Focus for Your Telescope (Guide) And, the reality is that every F/6.3 RC out there Celestron, Hirsch, Astromania, etc., etc. I use it on my C8 SCT with a 1000d, and it seems to do everything written on the tin. A useful thing to know is how far from the objective lens (for a refractor) is the focal reducer located. However, the export of some items may be restricted outside the US due to size or manufacturer restrictions. Over the course of a several nights of general observing, I swapped back and forth between the Antares and Celestron R/Cs on a wide variety of objects open clusters, brighter galaxies, a couple of nebulae, and globular clusters as well. It is recommended for . riklaunim Members 559 3,445 Location: Poland Posted October 11, 2010 They are reported as identical. 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. For the best experience on our site, be sure to turn on Javascript in your browser. Meade and Celestron both sell such SCT-T adapters with the correct optical length. SKU: CEL-94245. Place the plastic covers on the lens when not in use to reduce the dust collection. Generally, views through the Antares seemed a little more transparent and brighter. So ab6110 is asking for a FR only without coma correction, there are a couple of brands who make special reducers for the ACF. In terms of reduction and correction which are what reducer/correctors are supposed to do both are superb. No difference. External Focusers for Schmidt-Cassegrain Telescopes 3.1 The Basics of SCT Threads Housings, threads, reduction, correction, blah, blah, blah. Reducer Lens .7x - EdgeHD 1400 Perfect for the serious student, professional scientist and discriminating hobbyist. Reducer Lens .7x - EdgeHD 800 Learn More. Nowadays I tend to use the Celestron more with my refractors for imaging and viewing. 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. Not noticed any optical problems. Reducer Lens .7x - EdgeHD 925 I've seen some older threads saying that the Celestron, Meade and Antares FRs are all the same and manufactured in the same factory. Focal reducers for these relatively fast ED refractors are generally for imaging only, not for visual observation. 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. Yellow and orange members of open clusters stood out a bit more as the various stars displayed their individuality. Copyright 2003-2022 Agena AstroProducts. 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. 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. 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. Can you help me? All Rights Reserved. Dedicated focal reducers for refractors are intended primarily for imaging, not visual observation. The distance d2, which measures the position of the new focal plane of the objective from the back of the focal reducer is given by Equation 5: In these equations, d1, d2, and MR are all variables that depend on each other through Equations 2 and 4. If you want to save a few buck watch the classifieds on CN. More important, its clear that the Antares is a reducer/corrector, just like the Celestron and not merely a reducer. A slight nod to the Antares for heft and higher transmission, but points to the Celestron for nice threads and better contrast. I use the same back spacing for both on a small 6" Celestron SCT. If used before or beyond the working distance, unwanted image distortion may result. Celestron is considered better in terms of QA, less likely to come with free dust, hair or fingerprint. 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. Is that distance D= Fo-d1=Fo-(d2/MR)? I only have the Celestron f/6.3. The working distance or required back focus, explained above, is usually specified and is far more important in practice. 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. Is there likely to be any differences in performance between using these on an 8 or something smaller like my 6SE? Besides observing from his heavily light polluted backyard in Los Angeles, Manish enjoys conducting astronomy outreach programs in local schools. Celestron Solar Safe filter technology is GUARANTEED SAFE for direct solar observation and has been independently tested by SAI Global Assurance Services. The internal surfaces are blackened and glare-threaded to provide the highest contrast. Reducer - Corrector Learn More. Community Forum Software by IP.BoardLicensed to: Cloudy Nights, E of San Francisco Bay and W of the Awahnee, This is not recommended for shared computers, reviews here that suggest a coating problem, Back to Celestron Computerized Telescopes, Looking for advice on first refractor and camera. The lens has a knurled surface, providing a tremendous gripping surface for threading/unthreading. This appendix summarizes how this works based on simple equations from the book Telescope Optics by Rutten and van Venrooij. Designed distancing using the reducer with a 1.25 visual back and 1.25 Televue mirror diagonal; I have an 8SE, and am thinking about getting a focal reducer. Start Chat 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 equations and argument in the Appendix of this article shows the relationship between the working distance and the reduction factor.