Such an image circle is still large enough to encompass the relatively large sensor of many deep-sky astronomy cameras. In some cases, focal reducers also act as field flatteners by correcting for field curvature and coma of the objective lens. 800-483-6287 Yet, the Antares still easily and fully threaded without any hitches. We process your personal data as stated in our. They both are great and I doubt my eyes could detect a difference in any one of them including the Japan version. I use the same back spacing for both on a small 6" Celestron SCT. Stars had a tiny bit more sparkle and pop. Reducer Lens .7x - EdgeHD 800 The previous post shows the reducer on what appear to be two different refractors. This is the simplest way to attach your ASI121 to your telescope. One problem with getting opinions is that most of use do not have both reducers or have never done a side by side comparison. Focal reducers are essential optical accessories for astrophotography, electronically-assisted astronomy (EAA), and in some cases, for visual observation with long focal ratio telescopes. Some are available in 1.25" barrel format but with C threads. 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. ), 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. 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. 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). This Antares 1.25" 0.5x focal reducer lens (tele-compressor) is used under the Orion brand name to thread into the nosepiece of Orion StarShoot Solar System cameras and StarShoot Deep Space Color Imaging Camera. I was referring to the C6 to answer you specifically. 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. A former wireless communications consulting engineer and management consultant to various Fortune 500 companies, Manish started Agena AstroProducts in 2003. 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. 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. For example, an 8" SCT without a focal reducer has an illuminated field of 38mm at 50% fall-off. No small animals were harmed in making these observations. You can probably eke out 1.2 without noticing serious vignetting, which is a field stop of 31.5mm. An image of about 24mm across, approximately, allows an observer to use a 1.25" eyepiece with a maximal field stop. Given past experience with them, I decided not to include the Meade version in my little experiment, as I have never met one I liked from getting one of the too-short focal length models, to one with some overflow cement in the doublet, to focus difficulties with some eyepieces. By External Focusers for Schmidt-Cassegrain Telescopes 3.1 The Basics of SCT Threads Antares or Celestron? Fortunately, my neighbors are not out in their backyards at 11 pm, or they may have thought I was torturing a small mammal. Both exhibited consistent reduction, identical field flattening, and edge correction properties, and both were high quality optically and mechanically. . 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. Easy solution found a very tiny dab of super lube on the threads and all was well and quiet. As another example,GSO makes focal reducers for their line of Ritchey-Chretien imaging telescopes. The visual back must be removed first. I think I remember hearing the reduction factor is slightly different, cant remember more or less reduction. I own both and concur heartily. Reducer - Corrector Antares Click Lock Visual Back - posted in Cats & Casses: Here is the situation:I bought a Celestron CPC 1100 for visual use.Want to put on the scope simulteanously a6.3 focal reducer, filter wheel, and aneyepiece turret. 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. Most Feather Touch focusers cost between $300-$350. This filter threads on to the rear cell of your Celestron or Meade SCT telescope. 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). For example, a 0.8x reducer placed at the working distance provides a reduction of (1 0.8) x 100 = 20%. The C8 has no noticeable vignetting with a 32mm Plssl in the f/6.3 reducer. Nebula Filters. ), but stars seemed a bit tighter and their colors were richer and more dramatic. Check out our 2022 telescope buying guide here! 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. Field stop diameters are one of the specified specs of eyepieces. The stock Celestron visualback is just under 2 long. 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. Thanks guys, I'm trying to get my ZWO ASI120MC-S to work with my 90mm Meade. Explore Scientific - Keys to the Universe Sale. 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). A longer effective focal length leads to higher magnification with a given eyepiece for visual observers. In terms of reduction and correction - which are what reducer/correctors are supposed to do - both are superb. 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. More aggressive reduction, or using these reducers with larger sensors, will result in aberrations and distortions near the edge of the image. At least these two units I tested make the answer - whatever. Can you help me? Still not sure what is the right gear for you? Housings, threads, reduction, correction, blah, blah, blah. Planetarium software package which provides easy-to-understand explanations and impressive visuals of all kinds. Ive owned Celestron, Meade, and Antares models over the years at least a couple of each. Things change but when I rebought I got an Antares and it seems about the same to me. Read our guide! I really don't see any difference in the current crop except the "Meade" is usually the cheapest. The focal length of a focal reducer is usually measured from the rear lens surface of the reducer (and not the reducer's housing). riklaunim Members 559 3,445 Location: Poland Posted October 11, 2010 They are reported as identical. However, the export of some items may be restricted outside the US due to size or manufacturer restrictions. That is definitely a 2" eyepiece, but it is not a large or long focal length 2" eyepiece. Focal reducers for many SCTs and their flat-field equivalents usually have a back-focus distance of 105mm. It's easy! Your eyepieces are the first accessories you should learn to use with your telescope. Figure 2 shows the effective of a focal reducer on the light from a telescope objective. Enter it during checkout! 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. Does anyone know if the Antares 4000 focal reducer is as good as the Celestron focal reducer. 2023 Celestron, LLC. 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. More about this below. The new Lithium Phosphate (LiFePO4) battery chemistry has significant advantages over other battery chemistries, great for for those Astronomers on the go. 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. Meade once made an f/3.3 focal reducer for SCT scopes. Can you tell me about the use of reducers in Maksutov-Cassegrain telescopes? But in the end they both do pretty much the same thing and it sounds like any performance difference is subtle. Try & buy if you like - usual mates rates. 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. 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. These reducers can also be used for visual observing with SCT scopes with eyepieces with a field stop as large as 24-27mm. 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. 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. Images in the Celestron tended to appear ever-so-slightly dimmer (maybe? As per the OP I still can't see any reason to buy the Celestron for significantly more $$$. Shipping will be via the cheapest shipping method which will vary depending on the items in your order. 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). Yellow and orange members of open clusters stood out a bit more as the various stars displayed their individuality. I'm going with the Celestron. 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. 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. 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. 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. ED glass is specially formulated and contains rare-earth compounds that greatly reduce a visual defect called chromatic aberration. 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). 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. It features a standard male SCT thread (2" OD, 24 TPI) on one side and a standard SCT female thread on the other. 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. If the reducer is placed closer to the eyepiece or camera than the distance D, the reduction factor decreases. This factor is designated by a power that is less than 1, and it usually lies between 0.5x or 0.8x. 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. Bear in mind you can't squeeze blood out of a turnip, i.e. 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. There may have been an almost imperceptible difference, but the Antares and Celestron were producing precisely the same reduction. Newtonian reflectors will seldom be able to accommodate the in-focus travel demanded by focal reducers. Looking forward to the day when I can do a shoot-out between a Japan and China Celestron, just for kicks. 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. Optically, it consists of a four-element lens that is fully multi-coated for high contrast and resolution. This focal reducer is made to attach to the rear cell of Schmidt-Cassegrain or Maksutov-Cassegrain 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. There is one difference though the Antares came with only one lens cap whereas the Celestron had a cap for both ends. With the barrel 1.25 reducer won't focus, all I get is fuzzy snowballs. Celestron or Antares f/6.3 focal reducer for SCT? Equation 6 & 7 item two & three does not make sense, both say increase its reduction (one should say reduce its reduction?). The Antares f6.3 focal reducer screws directly to the visual-back thread of all popular SCTs and converts f10 instruments to f6.3. An f/6.3 reducer is designed to reduce the focal ratio of an f/10 SCT to f/6.3. Learn more about extra solar planets imagery, 3D Star rendering, observation planning, telescope control, multiple-panel printing, and much more. Some third-party vendors also make reducers for SCT scopes. If you want to use them for visual - try maybe long focal length eyepieces rather than the reducer. 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. We do not price match competitors if they are out of stock. I happily cycle through LRGB filters to build the image rather than do a whole run of one filter at a time. . However, it will not thread into William Optics accessories, and with GSO it is a hit or miss. How does it look thats what matters. However, because the field curvatures in refractors and SCTs vary a lot, I would predict unpredictable effects inre: field curvature. 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. However, even though the imprint on the item states "Reducer / Corrector" please note that his is a reducer only. I wish there was. Years ago, I bought the Antares version, and moved over to the Celestron. Its a good thing I have the super lube handy or my neighbors wont be happy with me.come to think of it, Im sure the small mammals here wouldnt be thrilled either! Copyright 2021 Stargazers Lounge I am a purely visual observer, so will evaluate for visual use only. Michael 1 ronin Members We have placed cookies on your device to help make this website better. The brightness, shape, and distortion of specific stars in the exact same position at the edge of the field was precisely identical in both reducers. The Celestron is both a corrector and focal reducer and the Antares is just a focal reducer. Brian Ventrudo is a writer, scientist, and astronomy educator. It's an either/or proposition: reducer and 1.25", or 2", but not 2" and reducer. 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. 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. It works fine but you should stick with 1.25 EPs; or can use 2" EPs without corrector. It seems right to put some distance between the camera and the focal reducer, right? With both, using the same diagonal set-up, the exact same stars were visible at the very edge of the FOV. Right off the bat, I was struck by how similar the two R/Cs were. They are designed (assuming you are referring to the f/6.3 version) for the f/10 light cone. These reducers can also be used for visual observing with SCT scopes with eyepieces with a field stop as large as 24-27mm. We only send interesting emails and will never sell your data. No retailers currently carry this product. They never really recovered from selling a few 15 years back with element reversed. 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. All rights reserved. The Antares f/6.3 Focal Reducer for Schmidt-Cassegrain Telescopes is a low-price option for reducing the focal length of your Schmidt-Cassegrain telescope from f/10 to f/6.3. Sharpness is essentially the same. A focal reducer does just the opposite of a Barlow lens or focal extender. 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. This focal reducer is made to attach to the rear cell of Schmidt-Cassegrain or Maksutov-Cassegrain telescopes. Designed distancing using the reducer with a 1.25 visual back and 1.25 Televue mirror diagonal; If you do so, you will achieve the design reduction factor. JavaScript seems to be disabled in your browser. Reducer - Corrector Learn More. We reserve the right to verify a competitor's advertised price and the availability of the item. Figure 1 shows the relationship between the focal reduction factor MR and the position of the reducer in the optical path. 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. 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. Since then, Agena has become one of the leading online retailers of telescopes and astronomical accessories worldwide. Any comments gratefully received. Unlike . Perfect for the serious student, professional scientist and discriminating hobbyist. Clearly cost is a big factor for satisfied users. Thanks for the extremely valuable article. Not noticed any optical problems. The threads were similar on the eyepiece end, but a bit smoother. They are also less expensive than many external focusers of similar build quality. 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. I have had the Japan unit on the back of my C5 since 1994 or thereabouts. Equation (4) shows the relationship between the distance d2 and the reduction factor MR. 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. But I am rusty, can you condense a bit for me please? To calculate how much back focus spacing you need to add, take the thickness of the filter and divide it by 3. Thanks guys, appreciate the feedback. And when used in some refractors, the field flattening is not as accurate as it is in the f/10 SCTs. In such cases, we will be happy to take the item back as per our standard return terms. 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. Many focal reducers for refractors have a working distance (or back focus distance) of 55mm. Not a bit. Sign up for OPT news, exclusive offers, and updates on the latest gear! 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. Quite interestingly it bears the very same engravings of the Meade 4000 r/c (including "series 4000") except for "MEADE". 3. 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). Our proprietary StarBright XLT optical coatings dramatically increase transmission, up to 97.4% on our Schmidt corrector lenses. What I do know is that the Antares and the Celestron samples that I have perform exactly the same from the center right out to the edges. When using the diagonal, keep the field stops of the eyepieces under 20mm. All additional accessories mount onto the exterior/male threads. Given the results of Test #1, I wanted to see if there was any truth to this assumption. if the illuminated field is 27mm wide without the reducer, it will be 27 x 0.63 = 17mm with it in place. You may need spacers or a T-adapter to ensure the correcting working distance. 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%. Theres a long-running debate in these forums and even statements from some reputable dealers that the Antares is just a reducer (even though it is labeled Reducer/Corrector), whereas the Celestron is a true R/C, which flattens the SCTs naturally curved field and provides some edge correction.