Details: The item must be the identical item, brand name, size, weight, color, quantity and model number. I've only used it a few times but it looks good to me. One focal reducer will not achieve optimum results with all types of telescopes, so there is no universal' focal reducer. 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. Just point the telescope at any three bright objectsstars, bright planets, or even the Moonand your telescope can orient itself with the night sky. More important, its clear that the Antares is a reducer/corrector, just like the Celestron and not merely a reducer. But nearly every observer who installs one of these devices is pleased with their performance. You can adjust your cookie settings, otherwise we'll assume you're okay to continue. I've never found my 0.63 reducer causing CA when used with my SCT. Reproduction without permission prohibited. There are many different types of focal reducers and they all effect. 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. For me the Antares was a little brighter and had the least scatter by a bit so the better coatings won. Newtonian reflectors will seldom be able to accommodate the in-focus travel demanded by focal reducers. Once installed, you can add additional accessories like T-Adapters, 1.25 Visual Back, Star Diagonal, or Off-Axis Guider. These scopes are compatibles with focal reducers. Our proprietary StarBright XLT optical coatings dramatically increase transmission, up to 97.4% on our Schmidt corrector lenses. Practical Considerations of Focal Reducers, 4.2 Back Focus Requirements of Focal Reducers, GSO makes focal reducers for their line of Ritchey-Chretien, Celestron makes a series of focal reducers for the Edge HD line, 0.75x focal reducers for these telescopes, focal reducer for an 8-inch Celestron EdgeHD, A Primer on T-Rings and T-Adapters for Astronomy and Astrophotography, Choosing the Best Telescope for Beginners 2023, Top Night Sky & Astronomy Events in August 2022, Top Night Sky & Astronomy Events in July 2022, Selecting a Baader Planetarium Star Diagonal, A Guide to Choosing Astronomy Eyepieces for Binoviewers, Choosing a Magnifying Finder Scope for Your Telescope, A focal reducer will provide its design reduction factor only when it is placed at the exact working distance from the focal plane of the eyepiece or camera, Reducing the operating distance, that is, moving a focal reducer closer to the eyepiece or camera increases its reduction factor, or conversely reduces the amount of focal reduction. 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. The internal surfaces are blackened and glare-threaded to provide the highest contrast. 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. First, let's have a look at some key optical parameters are needed to understand focal reducers. The stock Celestron visualback is just under 2 long. Check out our 2022 telescope buying guide here! The focus barely shifts between filters and I suspect any shifts I do get are down to the filters and changes in temp. 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. Therefore, a 55mm back focus with a filter that is 3mm thick added to the imaging train would become 56mm. The most popular accessories for your new telescope! 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. A longer effective focal length leads to higher magnification with a given eyepiece for visual observers. Since the focal length of the reducer, FR, is fixed, as d2 increases then MR decreases. But I am rusty, can you condense a bit for me please? Thanks guys, appreciate the feedback. GSO, for example, has a 0.75x reducer for RC scopes with a back focus of 80mm, which is usually enough room for a wide range of astronomy cameras and accessories and spacers as needed. I think that the FRs made in Japan in the day may have been better. This appendix summarizes how this works based on simple equations from the book Telescope Optics by Rutten and van Venrooij. 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. 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. Brian Ventrudo is a writer, scientist, and astronomy educator. 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). 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. This article explains the basics of how focal reducers work with an astronomy telescope. Clearly cost is a big factor for satisfied users. More about this below. Michael 1 ronin Members Designed distancing using the reducer with a 1.25 visual back and 1.25 Televue mirror diagonal; Quite interestingly it bears the very same engravings of the Meade 4000 r/c (including "series 4000") except for "MEADE". There are also third-party vendors such as Hotech. So, this past week I challenged the Antares and Celestron models to a head-to-hear on my C8 on some decent nights of good seeing and transparency in my Bortle 5-6 urban skies. Focal reducers also move the effective focal plane of the objective inward, that is, towards the objective (see Figure 1). It seems right to put some distance between the camera and the focal reducer, right? Meade once made an f/3.3 focal reducer for SCT scopes. 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. No idea what the issue is. Not noticed any optical problems. Copyright 2003-2022 Agena AstroProducts. The previous post shows the reducer on what appear to be two different refractors. 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. I've heard and read all kinds of things about the Antares being only a reducer and not a corrector, etc. 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 in the Appendix show how this all works. No retailers currently carry this product. As a Barlow's magnification increases with increasing distance from the Barlow, a focal reducer's reduction increases with increasing distance from the reducer. As mentioned in Section 2 of this guide, the reduction factor of a focal reducer depends on its position in the optical path relative to the eyepiece or camera. 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. If yes, what kind of focal reducers can I use? For imagers using longer focal-length refractors and SCTs, especially when using smaller sensors that place less demand on the focal reducer, there are economical alternatives for focal reducers from manufacturers such as GSO, Agena, and Antares. 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. Better images are also obtained when using these focal reducers at a reduction factor of 0.5x 0.8x, approximately. This focal reducer is made to attach to the rear cell of Schmidt-Cassegrain or Maksutov-Cassegrain telescopes. To test this, I used three set-ups: 1. Housings, threads, reduction, correction, blah, blah, blah. 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. Observing the microscopic world has never been easier! Add a 0.63x reducer, and the brightness of extended objects increases by (1/0.63)2 = 2.5. In terms of reduction and correction which are what reducer/correctors are supposed to do both are superb. We will be glad to help. The faster f/ratio allows you to use slower film or shoot in lower light level situations and still properly expose your subject. During check-out, you will be presented with several shipping choices and costs. 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 . Celestrons aplanatic EdgeHD optics revolutionized astroimaging. Thks for that and its not for visual it for astrophotography. Stars had a tiny bit more sparkle and pop. A few people have reported issues with the male SCT thread diameter on this item being a bit larger than necessary. Antares or Celestron? Wonder how they would stack up with a Japanese 6.3. The more focal reduction, the further inward the focal plane will be. 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. This is very impressive performance given how hard this problem is to mitigate in general. 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. Planetarium software package which provides easy-to-understand explanations and impressive visuals of all kinds. The most significant mechanical variation, however, is the quality and precision of the threading. Your eyepieces are the first accessories you should learn to use with your telescope. Focal reducers for these relatively fast ED refractors are generally for imaging only, not for visual observation. 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. This should not be the case if they have their purportedly different focal lengths. 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. However, manufacturers virtually never provide this specification. I read another thread in a different forum about F6.3 reducer correctors and one amateur posted an image about glue coming out of an astromania f6.3 reducer which he planned to return. However, some focal reducers can be used on other models of telescopes, but this is not always possible. This is one of our best-selling items, and customers have reported that this product is at least as good as, and probably better than, other leading f/6.3 focal reducers sold on the market for a lot more. Like you, I am primarily visually observing but I have everything together now that so I am going to start experimenting with photography so we'll see how it does there. In both cases will end with a similar tfov. The telescope side of the barrel is often threaded with an M48 x 0.75 thread for standard 2" astronomy filters. SKU: CEL-94245. 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! 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. For the best experience on our site, be sure to turn on Javascript in your browser. But when not in the box or on the telescope, there is no cover for the other end. In every configuration, there were essentially parfocal, requiring only a tiny fine focus adjustment when changing correctors. My experience is that CN sellers are way above those listing elsewhere. You can probably eke out 1.2 without noticing serious vignetting, which is a field stop of 31.5mm. This "speeds up" the optical train by reducing the focal length and magnification of the scope, requiring less time to integrate the same signal. The price for an item/offer must be listed and valid at the time of match. 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. No negative issues to report. CEL-94245. In terms of reduction and correction - which are what reducer/correctors are supposed to do - both are superb. With both, using the same diagonal set-up, the exact same stars were visible at the very edge of the FOV. Wow, that is a very detailed discussion! Many Ritchey-Chretien telescopes available today are made by GSO. For example, a 0.8x reducer placed at the working distance provides a reduction of (1 0.8) x 100 = 20%. 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. 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. 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 have tested our current batch and it works with Meade, Celestron, and Baader SCT accessories. 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. 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. 3. I think I remember hearing the reduction factor is slightly different, cant remember more or less reduction. I have the Japanese version and although I haven't used it in quite awhile, the views through it were superb with no internal reflections at all. There will be no shipments on 3/1/2023, 3/2/2023, or 3/3/2023 (March 1st - March 3rd, 2023). 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 . Most reducers have a design reduction factor, MRD, that assumes the reducer is placed at a specific working distance, D, from the back surface of the focal reducer itself. Request stock alerts and we'll let you know when the item is back in stock. Celestron or Antares? 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. Things change but when I rebought I got an Antares and it seems about the same to me. The Celestron is both a corrector and focal reducer and the Antares is just a focal reducer. The review is a subjective visual impression, which is interesting but not best evidence. (Note: Using the simple equations above, the focal length of this reducer can be estimated to be about 350mm). Please note, orders placed after 10am on 2/28/2023 will be delayed. I use the Celestron version and it seems OK for both visual and imaging. It's usually specified in millimeters. As another example,GSO makes focal reducers for their line of Ritchey-Chretien imaging telescopes. A focal reducer does just the opposite of a Barlow lens or focal extender. It is recommended for . 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. The lens is housed in machined aluminum for are machined aluminum black anodized. Reducer Lens .7x - EdgeHD 925 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. Learn more about extra solar planets imagery, 3D Star rendering, observation planning, telescope control, multiple-panel printing, and much more. 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. because they really dont matter. A useful thing to know is how far from the objective lens (for a refractor) is the focal reducer located. Based on Test 1 and Test 2, I think there is perhaps more validity to opposing statements here in these forums that the Antares and current China-made Celestron do, indeed, have exactly the same optics just with different housings and branding. There is one difference though the Antares came with only one lens cap whereas the Celestron had a cap for both ends. Have always disliked the crude, noisy SCT threads, but I get it. 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. InternetSales@optcorp.com. Some manufacturers will specify the working distance from the middle of the rear lens surface, and this number must then be converted into a practical working distance number by subtracting the amount by which the rear lens surface is recessed in its housing. This is the distance at which the reducer must be placed in front of the eyepiece or camera focal plane in order to operate at the design reduction factor. If the reducer is placed closer to the eyepiece or camera than the distance D, the reduction factor decreases. 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. This fully multi-coated lens provides maximum light transmission with near full-field illumination. We do not price match competitors if they are out of stock. Copyright 2021 Stargazers Lounge For imagers, the main purpose of a focal reducer is to increase the brightness of the image at the focal plane. The easiest way to use a focal reducer is to make sure you place it at the specified working distance in front of your camera or eyepiece. In this case, d2 = FR/2, which means the back of the focal reducer is located at a distance FR/2 from the camera or eyepiece. An image of about 24mm across, approximately, allows an observer to use a 1.25" eyepiece with a maximal field stop. 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 innovative software solves the time-consuming problem of trying to pinpoint the North Celestial Pole. Using an eyepiece with a 27mm field stop with the reducer will illuminate the edge the same as using an eyepieces with a 42.9mm field stop without it. In the 1960s, Celestrons founder, Tom Johnson, created groundbreaking new telescopes never before seen on the consumer market. Go behind the scenes with Celestrons product development team and learn more about our award-winning and patented innovations. 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. Hello! 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. October 11, 2010 in Discussions - Scopes / Whole setups. At least these two units I tested make the answer - whatever. Get ready for a night of astroimaging with your mount faster than previously thought possible with All-Star Polar Alignment. The Antares is supposed to be pretty comparable. I use it on my C8 SCT with a 1000d, and it seems to do everything written on the tin. And when used in some refractors, the field flattening is not as accurate as it is in the f/10 SCTs. In many cases, the answer is yes, especially for electronically-assisted astronomy (EAA). Several functions may not work. Most manufacturers provide this specification. If used before or beyond the working distance, unwanted image distortion may result, especially when using cameras with larger sensors. Besides observing from his heavily light polluted backyard in Los Angeles, Manish enjoys conducting astronomy outreach programs in local schools. 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. However, it will not thread into William Optics accessories, and with GSO it is a hit or miss. 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. Any comments gratefully received. ED stands for "extra-low dispersion," which refers to the composition and optical properties of the glass used for the lenses. 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. Celestrons award-winning Nature DX binocular gets a major upgrade with the addition of ED objective lenses. 160K views 9 years ago This video is a complete overview of focal reducers and how they function applying to telescopes.