If you want to save a few buck watch the classifieds on CN. Planetarium software package which provides easy-to-understand explanations and impressive visuals of all kinds. Easy solution found a very tiny dab of super lube on the threads and all was well and quiet.. This filter threads on to the rear cell of your Celestron or Meade SCT telescope. Completely stuck, completely frustrated. You need to be a member in order to leave a comment. 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. More important, its clear that the Antares is a reducer/corrector, just like the Celestron and not merely a reducer. Your price: $579.00. 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. Reducer - Corrector | Celestron That was fun. Reducer Lens .7x - EdgeHD 1100. Observing the microscopic world has never been easier! 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. Well done. 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. Perhaps not exactly- there will be some uncertainty because of manufacturing tolerances and so forth, but it will be close. This should not be the case if they have their purportedly different focal lengths. Style: Figure 2 shows the effective of a focal reducer on the light from a telescope objective. Copyright 2021 Stargazers Lounge How to Set the Correct Back Focus for Your Telescope (Guide) If I had to chose one, I would base my decision on your level of light pollution perhaps the Antares for its slightly higher transmission if you live under less light polluted skies, but the Celestron for its greater contrast if you are dealing with a suburban or urban light dome. We do not price match competitors if they are out of stock. 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). 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. We have placed cookies on your device to help make this website better. 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. Have always disliked the crude, noisy SCT threads, but I get it. 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. As a consequence, the standard f/6.3 and f/3.3 focal reducers for SCT scopes do not work. I've seen some older threads saying that the Celestron, Meade and Antares FRs are all the same and manufactured in the same factory. 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 working distance or required back focus, explained above, is usually specified and is far more important in practice. No negative issues to report. Most manufacturers provide this specification. Quite interestingly it bears the very same engravings of the Meade 4000 r/c (including "series 4000") except for "MEADE". Focal Reducer, 2", 0.7X - Antares The naming convention of SCT focal reducers is a little confusing. He tested this on an 8 Celestron , I have a Celestron 6SE. Thanks for any advice or experience you could share. Celestrons FREE planetarium app is an astronomy suite that redefines how you experience the night sky. He also holds a Ph.D. in engineering physics from McMaster University. I have both the Antares and the Celestron reducers. Many focal reducers are meant to be used within a few millimeters of the specified working distance to achieve the best possible image results. Who cares? More details are found in the Appendix of this article. 2023 Celestron, LLC. Fortunately, my neighbors are not out in their backyards at 11 pm, or they may have thought I was torturing a small mammal. This focal reducer is made to attach to the rear cell of Schmidt-Cassegrain or Maksutov-Cassegrain telescopes. JavaScript seems to be disabled in your browser. Now It only focuses near things, like some kind of macro zoom. So it provides a 0.63x design reduction factor when used with an f/10 SCT at the specified working distance. I'm going with the Celestron. However, manufacturers virtually never provide this specification. I use the Celestron version and it seems OK for both visual and imaging. Place the plastic covers on the lens when not in use to reduce the dust collection. 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. In terms of reduction and correction which are what reducer/correctors are supposed to do both are superb. Things change but when I rebought I got an Antares and it seems about the same to me. Celestrons award-winning Nature DX binocular gets a major upgrade with the addition of ED objective lenses. The Antares is supposed to be pretty comparable. The focal length and design working distance for this focal reducer were not available from the manufacturer. Antares f/6.3 Focal Reducer for SCTs - Awesome Astro InternetSales@optcorp.com. I use the same back spacing for both on a small 6" Celestron SCT. 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. I wonder whether, for example, Antares focal reducer for SCT belongs to the latter category. Our proprietary StarBright XLT optical coatings dramatically increase transmission, up to 97.4% on our Schmidt corrector lenses. I wont bother with differences in packaging, caps, etc. 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. My Celestron was made in China and the Antares in Canada. Edited by Tony Bonanno, 16 April 2021 - 06:44 PM. You attach the focal reducer to the rear port on a SCT and can keep it covered. This article explains the basics of how focal reducers work with an astronomy telescope. 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. 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. We have tested our current batch and it works with Meade, Celestron, and Baader SCT accessories. Once focused it's pretty good. I've only used it a few times but it looks good to me. 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. They usually have a 2" barrel that slides into the telescope focuser. This means that there must be sufficient travel on the telescope focuser to make up for this. If the focal reducer is to be used for visual observation, the visual back is threaded onto the eyepiece side of the reducer, and then a star diagonal and eyepiece are installed as usual. However, these will not impact optical performance. At least these two units I tested make the answer - whatever. It is not a corrector or flattener. However, the China 6.3 R/C has noticeable internal reflections that I haven't figured out yet. The reducer fits all Meade and Celestron . For example, a 0.8x reducer placed at the working distance provides a reduction of (1 0.8) x 100 = 20%. 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. * Not a Retail Store * 16313 Arthur StreetCerritos, CA 90703, USA. There are also third-party vendors such as Hotech. No small animals were harmed in making these observations. Stars in the corner of the image frame are indistinguishable between the Antares and the Celestron. To test this, I used three set-ups: 1. Is there likely to be any differences in performance between using these on an 8 or something smaller like my 6SE? Read our 101 article or get in touch. How about for visual observers? 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? Fumbling around in the dark, fine threads might be a problem. These RC reducers cannot be used with other types of telescopes. It can also be used with any other small chip CCD camera having a 1.25" nosepiece, such as the Celestron NexImage, Meade DSI . Celestron or Antares? Photographically you also get a wider field and much shorter exposures. Edited by bluewater, 05 September 2020 - 11:27 AM. Yellow and orange members of open clusters stood out a bit more as the various stars displayed their individuality. 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. When you said, "in some cases" a focal reducer also works as a flattener/corrector, are you saying that not all focal reducers are flatteners/corrector? The author finds differences in throughput and color balance, but then says he thinks the lenses are identical and he reaches his conclusions based on very long observing session. 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. 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. Torazz As a real-world example plot showing the above relationships, let's look at the 1.25" GSO focal reducer that provides a design reduction factor of 0.5x. Copyright 2003-2022 Agena AstroProducts. Agena's Guide to Focal Reducers - Agena Astro Easy solution found a very tiny dab of super lube on the threads and all was well and quiet. Upon close inspection, it was clear that the housing of Antares assembled in Canada version was a little more substantial than the Celestron. The Celestron f/6.3 is ~150 compared to the Antares at ~70. 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. Great report and verifies what I had thought all along, Fortunately, my neighbors are not out in their backyards at 11 pm, or they may have thought I was torturing a small mammal. Your mileage may vary. 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. Reproduction without permission prohibited. It is recommended for . 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. A slight nod to the Antares for heft and higher transmission, but points to the Celestron for nice threads and better contrast. We will be glad to help. 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. 3. 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. I've never found my 0.63 reducer causing CA when used with my SCT. Nowadays I tend to use the Celestron more with my refractors for imaging and viewing. There are many different types of focal reducers and they all effect. Images in the Celestron tended to appear ever-so-slightly dimmer (maybe? You currently have javascript disabled. Thanks guys, I'm trying to get my ZWO ASI120MC-S to work with my 90mm Meade. This focal reducer and field flattener consists of a four-element multicoated 40mm lens in a metal cell. The stars at the edge could be worse or better. Can you help me? 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. As one increases, the other decreases. Your eyepieces are the first accessories you should learn to use with your telescope. When using the diagonal, keep the field stops of the eyepieces under 20mm. It also leads to larger (although fainter) images of extended objects like the Moon or planets for astrophotographers or visual observers. As a Barlow's magnification increases with increasing distance from the Barlow, a focal reducer's reduction increases with increasing distance from the reducer. The previous post shows the reducer on what appear to be two different refractors. riklaunim Members 559 3,445 Location: Poland Posted October 11, 2010 They are reported as identical. The design reduction factor of a focal reducer is the relative amount by which the effective focal length of the telescope is reduced when the focal reducer is used at its specified working distance or back focus. Another factor to consider: focal reducers also increase the angle at which light approaches the focal plane. Reducer Lens .7x - EdgeHD 1100 - Celestron Will not focus with the stuff I have. However, this also came at a cost, as the sky background in the Antares was slightly brighter. Depending on the design of the telescope, they may require separate focal reducers if they require focal reducers at all. This "speeds up" the optical train by reducing the focal length and magnification of the scope, requiring less time to integrate the same signal. However, some focal reducers can be used on other models of telescopes, but this is not always possible. For the best experience on our site, be sure to turn on Javascript in your browser. Meade once made an f/3.3 focal reducer for SCT scopes. During check-out, you will be presented with several shipping choices and costs. More about this below. These reducers can also be used for visual observing with SCT scopes with eyepieces with a field stop as large as 24-27mm. Opticstar F6.3 Focal Reducer / Corrector. A few large telescopes and mounts are excluded from this free shipping offer. 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. Manish Panjwani has been an active amateur astronomer since before Halley's Comet last flew by our neighborhood. ), ASI Air Plus - Connected items are 'greyed out', Cost of ordering used equipment U.S. - Can can more than double figure, Tuthill Isostatic Mount and Star Trap Power Module. 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. However, in principle, the reduction factor of a focal reducer can be varied by changing the distance from the back of the focal reducer to the camera or eyepiece. The female end attaches to the rear cell of the telescope. The Celestron is both a corrector and focal reducer and the Antares is just a focal reducer. This would tell us exactly how well aberrations are corrected. The same illumination you have at the edge of a 27mm field, the C8 has at the edge of a 38mm field. However, it will not thread into William Optics accessories, and with GSO it is a hit or miss. The female end attaches to the rear cell of the telescope. This was most noticeable on the eyepiece end of the RC, where the metal rim surrounding the lens was about 1mm thicker than on the Celestron. But the diameter of the image circle decreases by a factor of 0.63 to about 24mm. CEL-94245. A few people have reported issues with the male SCT thread diameter on this item being a bit larger than necessary. Product Details. 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. It was used strictly for imaging, not visual observing. In such cases, we will be happy to take the item back as per our standard return terms. 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. 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. I also used several eyepieces including the ES 24mm/68, 17.5mm and 12.5mm Morpheuses, and a 10.5mm Pentax XL. You can adjust your cookie settings, otherwise we'll assume you're okay to continue. In this case, an additional T-adapter (with an optical length of 50mm) is needed to get the spacing correct for a DSLR or other camera with a 55mm back focus. Focal Reducer, 2", 0.7X. Most focal reducers are designed to operate optimally at the working distance in the optical path to achieve their specified reduction factor, which is usually between 0.5x and 0.8x. 0.5X focal reducer for Celestron, Meade, and Orion CCD imaging cameras I found both to be very good. This superb fully multi-coated multi-element focal reducer takes advantage of the latest computer aided design techniques to achieve the highest standards of performance set by the brand leaders at a fraction of the cost. Thks for that and its not for visual it for astrophotography. For example, an 8" SCT without a focal reducer has an illuminated field of 38mm at 50% fall-off. 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. Steve In some cases, focal reducers also act as field flatteners by correcting for field curvature and coma of the objective lens. There may have been an almost imperceptible difference, but the Antares and Celestron were producing precisely the same reduction. They never really recovered from selling a few 15 years back with element reversed. 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. Housings, threads, reduction, correction, blah, blah, blah. Equation 6 & 7 item two & three does not make sense, both say increase its reduction (one should say reduce its 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. I was originally hoping to do this with a made in Japan Celestron, but ended up with a newer China version but thats probably better in the end since it is the version now available, with the Japan ones rarer and only available used. 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. I think that the FRs made in Japan in the day may have been better. Celestron or Antares f/6.3 focal reducer for SCT? We have corrected # (iii) after equations 6 & 7. Whereas the Celestron threaded smoothly onto the scope, the Antares chattered and squeaked a bit more so when being removed. Please Log in to save it permanently. Orders placed over the weekend will be shipped on the following Monday. 160K views 9 years ago This video is a complete overview of focal reducers and how they function applying to telescopes. 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. Unlike . A f/10 focal ratio now achieves a f/6.3, while an f/11 focal ratio now achieves a f/7. USD $80.00. Get ready for a night of astroimaging with your mount faster than previously thought possible with All-Star Polar Alignment. Optically, it consists of a four-element lens that is fully multi-coated for high contrast and resolution. For visual use, this means you get lower power with the same eyepiece and a wider field of view. Most different was that the sky background was a little darker and more uniform, providing a tiny contrast boost for fainter objects. I happily cycle through LRGB filters to build the image rather than do a whole run of one filter at a time. In terms of reduction and correction - which are what reducer/correctors are supposed to do - both are superb. This standard distance is a consequence of the design of DSLR cameras for which the distance of the sensor to the outer edge of the flanges is about 45 mm, while the T-ring that attaches to the flange for astrophotography is about 10mm thick. 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 You may need spacers or a T-adapter to ensure the correcting working distance. If the reducer is placed elsewhere, at a position called the operating distance, the focal reduction factor will not be as advertised. 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. The faster f/ratio allows you to use slower film or shoot in lower light level situations and still properly expose your subject. Sign up for OPT news, exclusive offers, and updates on the latest gear! 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. This is a. Focal reducers also move the effective focal plane of the objective inward, that is, towards the objective (see Figure 1). 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. High power views will provide flatter fields all the way to the edge, both visually and photographically. So ab6110 is asking for a FR only without coma correction, there are a couple of brands who make special reducers for the ACF. Any comments gratefully received. Sign up for a new account in our community. All rights reserved. A reducer is a set of converging (or positive) lenses that cause the light from a telescope objective to converge at a steeper angle to the focal plane as if it were coming from an objective with a faster (lower) focal ratio and a shorter focal length. Thank you so much for the informative article, I now understand better how to integrate my reducer into my system to get better performance.