You need to be a member in order to leave a comment. Unscrew that wide angle lens and put it away, then attach the ASI120 to the nose-piece that came with the camera and fit that into the eyepiece holder. The camera side of the focal reducer is threaded for a T-adapter with wide M48 threads, or in some cases, with smaller M42 threads. If used with other f/ratios, the field flattening characteristic may be unpredictable. It's usually specified in millimeters. 3. This is very impressive performance given how hard this problem is to mitigate in general. Thanks Peter! 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. Read our guide! A f/10 focal ratio now achieves a f/6.3, while an f/11 focal ratio now achieves a f/7. They only publish the value of D, the working distance (sometimes called the back focus distance) and the design reduction factor MRD. Oceanside Photo & Telescope wants our customers to shop with confidence knowing that you will always get the best deal available. Celestron Focus Motor for SCT, EdgeHD & 8" RASA, Celestron C6 0.63 reducer/flattener back focus. However, doesn't fit in the telescope and even if it did wouldn't work. The click-lock with a 2 dielectric diagonal with a somewhat shorter light path, using both a 2 ES 28mm/68 and the same low-profile adapter with a 1.25 ES 24mm/68. The female end attaches to the rear cell of the telescope. Focal Reducer, 2", 0.7X. Figure 6 shows a 1.25" focal reducer from GSO configured with a ZWO ASI224MC camera. However I've also read that the back focal distance on the Celestron is 105mm while the Antares is 81mm so they couldn't be identical. These reducers can also be used for visual observing with SCT scopes with eyepieces with a field stop as large as 24-27mm. If you do so, you will achieve the design reduction factor.
[email protected], 800-483-6287 Contiguous US Customers:All items we sell ship for free within the Contiguous US. We have corrected # (iii) after equations 6 & 7. 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. Reducer Lens .7x - EdgeHD 925 With the barrel 1.25 reducer won't focus, all I get is fuzzy snowballs. Equation (4) shows the relationship between the distance d2 and the reduction factor MR. The working distance (backfocus) of the Celestron f/6.3 reducer is specified to be 105mm from the base of the male SCT thread on the camera side. Focal reducers for refractors are easy to use. The equations and argument in the Appendix of this article shows the relationship between the working distance and the reduction factor. The Celestron f/6.3 is ~150 compared to the Antares at ~70. Some faster refractors with a focal ratio of f/6, for example, only require field flatteners and not focal reducers. 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. I really don't see any difference in the current crop except the "Meade" is usually the cheapest. I was referring to the C6 to answer you specifically. https://www.celestron.com/products/reducer-corrector, //cdn.shopify.com/s/files/1/1935/4371/products/94175_reducer_corrector_01.jpg?v=1603736883, //cdn.shopify.com/s/files/1/1935/4371/products/94175_reducer_corrector_01_medium.jpg?v=1603736883, Popular Science by Celestron StarSense Explorer DX 5" Smartphone App-Enabled Schmidt Cassegrain Telescope, Advanced VX 8" Schmidt-Cassegrain Telescope, C9.25 Optical Tube Assembly (CGE Dovetail), Advanced VX 6" Schmidt-Cassegrain Telescope, Advanced VX 700 Maksutov Cassegrain Telescope, CGX-L Equatorial 925 Schmidt-Cassegrain Telescope, CPC 1100 GPS (XLT) Computerized Telescope, CGX-L Equatorial 1400 Schmidt-Cassegrain Telescope, CGX-L Equatorial 1100 Schmidt-Cassegrain Telescope, CGX Equatorial 925 Schmidt-Cassegrain Telescope, CGX Equatorial 800 Schmidt-Cassegrain Telescope, CGX Equatorial 1100 Schmidt-Cassegrain Telescope, CGEM II 1100 Schmidt-Cassegrain Telescope, Advanced VX 9.25" Schmidt-Cassegrain Telescope, Advanced VX 11" Schmidt-Cassegrain Telescope, Not compatible with #93648 Off-Axis Guider, not compatible with #93519 2" Mirror Diagonal (discontinued), Currently not compatible due to mechanical interferences. A useful thing to know is how far from the objective lens (for a refractor) is the focal reducer located. Now, Celestron is using that same technology to allow star gazers to connect to the night sky and enhance their experience of the cosmos in fun and unique ways. Designed distancing using the reducer with a 1.25 visual back and 1.25 Televue mirror diagonal; That said any comparison reviews are helpful. The reducer features fully coated optics in an anodized aluminum filter ring with an ergonomic rubber grip. For me, I was looking for, and planning to keep, the one that yielded the greatest reduction. The designed reduction factor (0.5x in the case of the GSO reducer example above) should be considered a rule of thumb or approximate value in most cases, rather than a very precise number. Copyright 2003-2022 Agena AstroProducts. I am a purely visual observer, so will evaluate for visual use only. Please re-enable javascript to access full functionality. In the 1960s, Celestrons founder, Tom Johnson, created groundbreaking new telescopes never before seen on the consumer market. They usually have a 2" barrel that slides into the telescope focuser. Also read the reviews here, including those at 4 stars. The most significant mechanical variation, however, is the quality and precision of the threading. 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. Reviews. 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. But I am rusty, can you condense a bit for me please? I wish there was. 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. Does anyone have any experience with the Celestron and Antares focal reducers? You currently have javascript disabled. Celestrons aplanatic EdgeHD optics revolutionized astroimaging. The reduction factor MR can also be written in terms of d2 as: When the focal reducer is placed at the working distance, D, that is when d2=D, then the reduction factor MR is equal to the design reduction factor MRD: Equations (6) and (7) imply these important considerations: Most manufacturers do not publish the focal length of their focal reducers, so it is not usually possible to calculate the working distance and design reduction factor. 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. To calculate how much back focus spacing you need to add, take the thickness of the filter and divide it by 3. ED glass is specially formulated and contains rare-earth compounds that greatly reduce a visual defect called chromatic aberration. Even though they may have been slightly dimmer, galaxies were a bit easier to tease out of the urban light soup I deal with. If you are using a camera that has a back focus of less than 55mm, additional spacer rings will be required between the reducer and the camera. Focal reducers are essential optical accessories for astrophotography, electronically-assisted astronomy (EAA), and in some cases, for visual observation with long focal ratio telescopes. . Please Log in to save it permanently. That was fun. 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. There is a way to make subjective data more useful and that way is proper blind, or better still. No small animals were harmed in making these observations. 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. 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. Best evidence would by obtained by using a camera and evaluating the image both by eye and with a computer analysis. Copyright 2003-2022 Agena AstroProducts. Brightness, color, and contrast were subtly different, but could be as much the day they were coated as any real difference in the two brands. I happily cycle through LRGB filters to build the image rather than do a whole run of one filter at a time. However, this also came at a cost, as the sky background in the Antares was slightly brighter. ), 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. 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 eyepieces are the first accessories you should learn to use with your telescope. Shipping will be via the cheapest shipping method which will vary depending on the items in your order. A former wireless communications consulting engineer and management consultant to various Fortune 500 companies, Manish started Agena AstroProducts in 2003. However, because the field curvatures in refractors and SCTs vary a lot, I would predict unpredictable effects inre: field curvature. which looks like the same one. 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. 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. Using these numbers in equation 4 in the Appendix, below, we can easily calculate that the focal length of this unit is approximately103mm (it will be 103mm plus the small amount by which the rear lens surface of the reducer is recessed beneath the reducer housing). It must be in stock at the time of Price Match for us to make a guarantee. I am new to these optic topics, and I want to ask you what happens with Masutov like SW or Celestron 4 or 7 inches. Obviously bright objects like Jupiter or The Moon show the reflections. because they really dont matter. Get ready for a night of astroimaging with your mount faster than previously thought possible with All-Star Polar Alignment. In terms of reduction and correction - which are what reducer/correctors are supposed to do - both are superb. 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. 800-483-6287 In some cases, focal reducers also act as field flatteners by correcting for field curvature and coma of the objective lens. Still not sure what is the right gear for you? 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. A slight nod to the Antares for heft and higher transmission, but points to the Celestron for nice threads and better contrast. In most cases, the easiest option is to choose the focal reducer made specifically for your telescope. Reducer Lens .7x - EdgeHD 800 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. If the reducer is placed closer to the eyepiece or camera than the distance D, the reduction factor decreases. You may need spacers or a T-adapter to ensure the correcting working distance. Also, the focusers of most Newtonians do not have enough in-travel to accommodate a focal reducer. For this shoot-out, I used a standard Celestron C8 with Starbright coatings. 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. 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. Reducer Lens .7x - EdgeHD 1400 It is not a corrector or flattener. Sign up for a new account in our community. This "speeds up" the optical train by reducing the focal length and magnification of the scope, requiring less time to integrate the same signal. Take control of your telescope! We will be glad to help. When using the diagonal, keep the field stops of the eyepieces under 20mm. if the illuminated field is 27mm wide without the reducer, it will be 27 x 0.63 = 17mm with it in place. However, even though the imprint on the item states "Reducer / Corrector" please note that his is a reducer only. Today, our world-class team of optical and electronic engineers continues to push the boundaries of technology. control and Sky Viewer display makes selecting your target easy. He also holds a Ph.D. in engineering physics from McMaster University. One focal reducer will not achieve optimum results with all types of telescopes, so there is no universal' focal reducer. 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. However, it will not thread into William Optics accessories, and with GSO it is a hit or miss. For example, an 8" SCT without a focal reducer has an illuminated field of 38mm at 50% fall-off. 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. Wow, that is a very detailed discussion! 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. Most Feather Touch focusers cost between $300-$350. They are reported as identical. Stars had a tiny bit more sparkle and pop. It was also a little brighter in the center of the field with subtle darkening in the outer 20% or so. Hello! Celestrons award-winning Nature DX binocular gets a major upgrade with the addition of ED objective lenses. Not one detectable iota of discernable difference. This telescope control software replaces the hand control and allows the user to remotely control their Celestron computerized telescope from their personal PC or laptop. 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. I focus using a moonlight electronic focuser and focusmax. Once focused it's pretty good. In some cases, focal reducers also act as field flatteners by correcting for field curvature and coma of the objective lens. M44 was a perfect target for this, as its large size maxes out the FOV on a C8 with a corrector, and its bright stars make great targets for measuring the very edge of the visible field. It also leads to larger (although fainter) images of extended objects like the Moon or planets for astrophotographers or visual observers. I also used several eyepieces including the ES 24mm/68, 17.5mm and 12.5mm Morpheuses, and a 10.5mm Pentax XL. During check-out, you will be presented with several shipping choices and costs. Here, there was a subtle difference . . WiFi technology encircles the globe in a web of connectivity, knowledge, and information. This article explains the basics of how focal reducers work with an astronomy 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. 2023 Celestron, LLC. For Stephen Wilkerson: The ZWO ASI120MC-S does come with a wide angle lens, HOWEVER, it is NOT intended to used when you are using the ASI120 camera attached to your telescope. I own both and concur heartily. He tested this on an 8 Celestron , I have a Celestron 6SE. There are also third-party vendors such as Hotech. Can you tell me about the use of reducers in Maksutov-Cassegrain telescopes? They are commonly available in 1.25" and 2" threaded cells that conveniently thread into the nosepiece of a compatible camera or the barrel of an eyepiece. Celestron Solar Safe filter technology is GUARANTEED SAFE for direct solar observation and has been independently tested by SAI Global Assurance Services. CPWI has an extensive object database, employs PointXP mount modeling, and more. Benefits limited to hardware and conditions? They never really recovered from selling a few 15 years back with element reversed. 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. 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. Focal reducers for these relatively fast ED refractors are generally for imaging only, not for visual observation. I've heard and read all kinds of things about the Antares being only a reducer and not a corrector, etc. Antares or Celestron? 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. First, I wanted to compare the actual reduction provided by these competitors, as many threads here cite different ideal spacing from the reducer to eyepiece focal plane to achieve the correct f/6.3 result. The price for an item/offer must be listed and valid at the time of match. 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. They both are great and I doubt my eyes could detect a difference in any one of them including the Japan version. I have the Antares and have no complaints. 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 details are found in the Appendix of this article. As a Barlow's magnification increases with increasing distance from the Barlow, a focal reducer's reduction increases with increasing distance from the reducer. Please let us know what topics you are interested in. Thank you so much for the informative article, I now understand better how to integrate my reducer into my system to get better performance. Reducer Lens .7x - EdgeHD 800 Learn More. 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. There is one difference though the Antares came with only one lens cap whereas the Celestron had a cap for both ends. Performance wise what differences might there be using the reducer on a smaller scope. With this telescope and this focal reducer, it does not help to move to a 2" eyepiece and a 2" diagonal as the visual view will be akin to looking through a porthole within the larger apparent field of view of the eyepiece. Very helpful, thanks a lot for this article! This innovative software solves the time-consuming problem of trying to pinpoint the North Celestial Pole. 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. You attach the focal reducer to the rear port on a SCT and can keep it covered. There will be no shipments on 3/1/2023, 3/2/2023, or 3/3/2023 (March 1st - March 3rd, 2023). Sign up to get exclusive deals, observing tips, and new product announcements. Wonder how they would stack up with a Japanese 6.3. 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. Not noticed any optical problems. Start here to find the perfect telescope for you! 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. control and Sky Viewer display makes selecting your target easy. Whereas the Celestron threaded smoothly onto the scope, the Antares chattered and squeaked a bit more so when being removed. I use the Celestron version and it seems OK for both visual and imaging. 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. Thanks guys, appreciate the feedback. The review is a subjective visual impression, which is interesting but not best evidence. In your opinion, is the Celestron is worth the added cost ($150 vs. $90)? Hence, there is a chance that you may not be able to thread your SCT diagonal or other SCT accessory on to this reducer for these or for any other brand. But nearly every observer who installs one of these devices is pleased with their performance. 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. ED stands for "extra-low dispersion," which refers to the composition and optical properties of the glass used for the lenses. Bear in mind you can't squeeze blood out of a turnip, i.e. It works fine but you should stick with 1.25 EPs; or can use 2" EPs without corrector. For example, a 0.8x reducer placed at the working distance provides a reduction of (1 0.8) x 100 = 20%. October 11, 2010 in Discussions - Scopes / Whole setups. The amount of reduction is simply the percentage by which a reducer shortens the effective focal length of a telescope and is calculated as (1 Reduction Factor) x 100%. I think that the FRs made in Japan in the day may have been better. High power views will provide flatter fields all the way to the edge, both visually and photographically. This appendix summarizes how this works based on simple equations from the book Telescope Optics by Rutten and van Venrooij. Edited by Tony Bonanno, 16 April 2021 - 06:44 PM. Rather than a direct side-by-side, I swapped the reducers so that I was using them on the exact same, well-collimated instrument. The focal length and design working distance for this focal reducer were not available from the manufacturer. With spring galaxy season here, I decided to pick up a couple more to compare in a head-to-head shoot out. 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. 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. It's an either/or proposition: reducer and 1.25", or 2", but not 2" and reducer. I only have the Celestron f/6.3. Reducer Lens .7x - EdgeHD 1100. I'm going with the Celestron. You can probably eke out 1.2 without noticing serious vignetting, which is a field stop of 31.5mm. Orders placed after 12:00 PM Pacific Time will be shipped the next business day. For the best experience on our site, be sure to turn on Javascript in your browser. In many cases, the answer is yes, especially for electronically-assisted astronomy (EAA). Clearly cost is a big factor for satisfied users. Such an image circle is still large enough to encompass the relatively large sensor of many deep-sky astronomy cameras. The same illumination you have at the edge of a 27mm field, the C8 has at the edge of a 38mm field. You also wont be unhappy spending the few extra bucks on the Celestron for the pretty orange lettering, particularly if you can pick one up used, as I did. Besides observing from his heavily light polluted backyard in Los Angeles, Manish enjoys conducting astronomy outreach programs in local schools. 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. Is there likely to be any differences in performance between using these on an 8 or something smaller like my 6SE? Dedicated focal reducers for refractors are intended primarily for imaging, not visual observation. Upon close inspection, it was clear that the housing of Antares assembled in Canada version was a little more substantial than the Celestron. 1.2" in that scope is a field stop of 43mm at f/10 and 27mm at f/6.3. When the camera sensor is placed at this distance, the reduction factor of these reducers is 0.75x. The key points are as follows: So just remember that a smaller distance (from the camera or eyepiece) means a lower amount of reduction (and vice versa). Go behind the scenes with Celestrons product development team and learn more about our award-winning and patented innovations. 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. Blue Fireball M42 T/T2 Thread Camera Adapter for Prime Focus Photography - 2" # P-06, Celestron T-Ring for Canon EOS Camera # 93419, GSO 2" Crayford Focuser for SCTs - Dual Speed, Length of male SCT thread = 5mm (0.2") but this is preceded by an unthreaded part on the eyepiece side making the total length = 8.8mm (0.35"), Length of female SCT thread = 7.5mm (0.3"). 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. 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. The working distance or required back focus, explained above, is usually specified and is far more important in practice. My Celestron was made in China and the Antares in Canada. Sign up to receive sale alerts, news about upcoming celestial events, and telescope tips from our experts! I would not use the reducer with a 2" diagonal or eyepiece in the C6. Celestron's EdgeHD reducers feature a custom 5 element optical design engineered to maintain the flat-field performance of our award-winning EdgeHD optical system. Unlike . We only send interesting emails and will never sell your data. Figure 2 shows the effective of a focal reducer on the light from a telescope objective. Thanks for any advice or experience you could share. However, some focal reducers can be used on other models of telescopes, but this is not always possible. That includes, for example, a 1.25" eyepiece with an apparent field of view of 68 and a focal length of 24mm (eg. The threads were similar on the eyepiece end, but a bit smoother. Torazz 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. looks virtually identical, except for the lettering. Explicitly designed for Celestron Schmidt-Cassegrain telescopes, this unique lens reduces your telescopes focal length and f/ ratio by 37%, turning your long focal length telescope into a fast, short focal length instrument. 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. For imagers, the main purpose of a focal reducer is to increase the brightness of the image at the focal plane. 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. Article Agena AstroProducts, 2019. It threads onto the rear cell of 5" to 16" Celestron and Meade Schmidt-Cassegrain telescopes, making it possible to have a dual focal ratio instrument without sacrificing image quality. Watch this before you buy Celestron 8SE SCT, or a Focal Reducer or a Hyperstar 7,758 views Mar 28, 2018 145 Dislike Share Ray's Astrophotography 42.3K subscribers Note: I am not paid or. If I had to go out on a very thick limb, I would have to say that these two reducers/correctors are, indeed, identical the exact same glass in slightly different housings with different lettering.