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. Can you tell me about the use of reducers in Maksutov-Cassegrain telescopes? Very helpful, thanks a lot for this article! I've seen some older threads saying that the Celestron, Meade and Antares FRs are all the same and manufactured in the same factory. 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. 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. Just point the telescope at any three bright objectsstars, bright planets, or even the Moonand your telescope can orient itself with the night sky. 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. Therefore, a 55mm back focus with a filter that is 3mm thick added to the imaging train would become 56mm. These RC reducers cannot be used with other types of telescopes. 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). Regardless, the difference was miniscule and is more than adequate on both and exceeds a 8 or 6 SCTs baffle tube diameter. A former wireless communications consulting engineer and management consultant to various Fortune 500 companies, Manish started Agena AstroProducts in 2003. One of the most important factors in a telescope is its transmissionthe percentage of light that reaches the focal plane. The most significant mechanical variation, however, is the quality and precision of the threading. As a Barlow's magnification increases with increasing distance from the Barlow, a focal reducer's reduction increases with increasing distance from the reducer. This means that there must be sufficient travel on the telescope focuser to make up for this. One focal reducer will not achieve optimum results with all types of telescopes, so there is no universal' focal reducer. As per the OP I still can't see any reason to buy the Celestron for significantly more $$$. 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. Since the focal length of the reducer, FR, is fixed, as d2 increases then MR decreases. Product Details 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. In both cases will end with a similar tfov. The Celestron is both a corrector and focal reducer and the Antares is just a focal reducer. Hello! For example, an 8" SCT without a focal reducer has an illuminated field of 38mm at 50% fall-off. Have a promo code? But nearly every observer who installs one of these devices is pleased with their performance. As mentioned in Section 2.3, the reduction factor for these focal reducers can be varied by adding spacers to move the reducer further from the camera sensor or eyepiece. 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. 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. ), 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. 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. For this shoot-out, I used a standard Celestron C8 with Starbright coatings. It also leads to larger (although fainter) images of extended objects like the Moon or planets for astrophotographers or visual observers. If I had to guess, the difference is maybe 10-15 grams. Figure 6 shows a 1.25" focal reducer from GSO configured with a ZWO ASI224MC camera. 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. 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. 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). (Note: Using the simple equations above, the focal length of this reducer can be estimated to be about 350mm). Thank you so much for the informative article, I now understand better how to integrate my reducer into my system to get better performance. Edited by Tony Bonanno, 16 April 2021 - 06:44 PM. 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. 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. 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. You attach the focal reducer to the rear port on a SCT and can keep it covered. In many cases, the answer is yes, especially for electronically-assisted astronomy (EAA). 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 used before or beyond the working distance, unwanted image distortion may result. Unlike . Again, to my surprise, there was absolutely no difference between the Celestron and Antares on any star. I have had the Japan unit on the back of my C5 since 1994 or thereabouts. 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. Sign up for OPT news, exclusive offers, and updates on the latest gear!
Depending on the design of the telescope, they may require separate focal reducers if they require focal reducers at all. 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. 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. Images in the Celestron tended to appear ever-so-slightly dimmer (maybe? On the trail, at the job site, in the classroom, or simply sitting at home relaxing the Celestron Elements ThermoTank 3 will keep your hands toasty. The Reducer/Corrector can also be used for terrestrial digiscoping. You currently have javascript disabled. We do not price match competitors if they are out of stock. Our patented SkyAlign alignment technology makes setting up a computerized telescope simple, fast, and accurate. 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. A focal reducer does just the opposite of a Barlow lens or focal extender. The Buyer's Guide To Eyepieces at the top of the Eyepieces forum has a column for this spec. Quite interestingly it bears the very same engravings of the Meade 4000 r/c (including "series 4000") except for "MEADE". Most Feather Touch focusers cost between $300-$350. 3. As another example,GSO makes focal reducers for their line of Ritchey-Chretien imaging telescopes. Details: The item must be the identical item, brand name, size, weight, color, quantity and model number. 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. I have an 8SE, and am thinking about getting a focal reducer. 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. It is recommended for . 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. Free shipping $189.95 Sign up for our newsletter to get exclusive deals, observing tips, and new product announcements. 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. Another factor to consider: focal reducers also increase the angle at which light approaches the focal plane. Well done. 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. 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! 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. 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. However, even though the imprint on the item states "Reducer / Corrector" please note that his is a reducer only. You may need spacers or a T-adapter to ensure the correcting working distance. 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. 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? I think I remember hearing the reduction factor is slightly different, cant remember more or less reduction. With both, using the same diagonal set-up, the exact same stars were visible at the very edge of the FOV. 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. 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. This would tell us exactly how well aberrations are corrected. We have tested our current batch and it works with Meade, Celestron, and Baader SCT accessories. 2023 OPT Telescopes. 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. The nominal design reduction factor of these reducers is typically 0.5x. Housings, threads, reduction, correction, blah, blah, blah. CEL-94245. For the best experience on our site, be sure to turn on Javascript in your browser. The faster f/ratio allows you to use slower film or shoot in lower light level situations and still properly expose your subject. Also, the focusers of most Newtonians do not have enough in-travel to accommodate a focal reducer. Article Agena AstroProducts, 2019. Read our 101 article or get in touch. 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. It's highly unlikely that they could be so precisely identical unless they were. But in the Japan version I have never noticed any anomaly like the ghosting in the China R/C. The same illumination you have at the edge of a 27mm field, the C8 has at the edge of a 38mm field. The stars at the edge could be worse or better. Like many of us with SCTs, I have bought and sold a number of f/6.3 reducer/correctors over the years, and I have always been curious how they really stack up to each other. Reducer Lens .7x - EdgeHD 925 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. So it provides a 0.63x design reduction factor when used with an f/10 SCT at the specified working distance. The two samples I have PERFORM IDENTICALLY. A useful thing to know is how far from the objective lens (for a refractor) is the focal reducer located. I have the Antares and have no complaints. A longer effective focal length leads to higher magnification with a given eyepiece for visual observers. To calculate how much back focus spacing you need to add, take the thickness of the filter and divide it by 3. 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. 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.
Antares f/6.3 SCT Focal Reducer - Rother Valley Optics Ltd The stock Celestron visualback is just under 2 long. Who cares? The female end attaches to the rear cell of the telescope. Some are available in 1.25" barrel format but with C threads. Celestron is considered better in terms of QA, less likely to come with free dust, hair or fingerprint. 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. I've never found my 0.63 reducer causing CA when used with my SCT. Can you help me? I've heard and read all kinds of things about the Antares being only a reducer and not a corrector, etc. 1.2" in that scope is a field stop of 43mm at f/10 and 27mm at f/6.3. 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. Our proprietary StarBright XLT optical coatings dramatically increase transmission, up to 97.4% on our Schmidt corrector lenses. Generally, views through the Antares seemed a little more transparent and brighter. Once focused it's pretty good. More important, its clear that the Antares is a reducer/corrector, just like the Celestron and not merely a reducer. One problem with getting opinions is that most of use do not have both reducers or have never done a side by side comparison. Upon close inspection, it was clear that the housing of Antares assembled in Canada version was a little more substantial than the Celestron. 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. Copyright 2021 Stargazers Lounge But while the image gets brighter, the size of the image circle gets proportionately smaller.
Watch this before you buy Celestron 8SE SCT, or a Focal Reducer or a Each focal reducer has a fixed specification called the working distance or required back focus. There is one difference though the Antares came with only one lens cap whereas the Celestron had a cap for both ends. This also resulted in the clear aperture of the Antares being about 39-39.5mm, versus the Celestrons 41mm. For the best experience on our site, be sure to turn on Javascript in your browser. From the SkyProdigy, a telescope so smart it can align itself, to our high-performance EdgeHD optical system, weve revolutionized the hobby of astronomy for beginners and advanced amateurs alike. The most popular accessories for your new telescope! Focal reducers for these relatively fast ED refractors are generally for imaging only, not for visual observation. The visual back must be removed first. Wonder how they would stack up with a Japanese 6.3.
Antares F/6.3 SCT Focal Reducer | OPT Telescopes This article explains the basics of how focal reducers work with an astronomy telescope. The review is a subjective visual impression, which is interesting but not best evidence.
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. Since the Celestron and Antares are supposed to have different focal lengths and spacing specs, I expected different results. 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. Completely stuck, completely frustrated. No results, please adjust your filters. Perfect for the serious student, professional scientist and discriminating hobbyist. 800-483-6287 Your price: $579.00. That was fun.
Agena's Guide to Focal Reducers - Agena Astro The Antares is supposed to be pretty comparable. 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. 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. The telescope side of the barrel is often threaded with an M48 x 0.75 thread for standard 2" astronomy filters. 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. By It's easy! Does anyone have any experience with the Celestron and Antares focal reducers? Because I have not heard any complaints about the made in China R/C. 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. Oceanside Photo & Telescope wants our customers to shop with confidence knowing that you will always get the best deal available. How does it look thats what matters. Nada. Assuming you use the reducer with the stock 1.25" diagonal, it will operate at f/6.3. Fortunately, my neighbors are not out in their backyards at 11 pm, or they may have thought I was torturing a small mammal. 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. It's usually specified in millimeters. Manish Panjwani has been an active amateur astronomer since before Halley's Comet last flew by our neighborhood. 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. However, some focal reducers can be used over a wider range of working distances, especially those with simpler optical design, and especially when used with cameras with smaller sensors. . Try & buy if you like - usual mates rates. 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. But in the end they both do pretty much the same thing and it sounds like any performance difference is subtle.
Focal Reducers | Celestron It is not a corrector or flattener. Steve In these equations: The combined focal length of the objective and focal reducer is given by Equation 1: For example, when d1=0, that is, the focal reducer is at the focal plane of the objective, Fcomb=Fo, so the focal reducer has no effect. Any comments gratefully received. 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. In terms of reduction and correction which are what reducer/correctors are supposed to do both are superb. It has only one cover, which surprised me. 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. Advanced designs for Schmidt-Cassegrain scopes such as the Meade ACF or Celestron Edge HD have optical elements in the tube to correct for coma and field flatness. Newtonian reflectors will seldom be able to accommodate the in-focus travel demanded by focal reducers. 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.
Weasner's Meade and Antares Focal Reducers Review 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. 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DUE TO EXTREMELY HIGH DEMAND, WE WILL NOT BE TAKING NEW ORDERS UNTIL MONDAY, DECEMBER 14. Start Chat This appendix summarizes how this works based on simple equations from the book Telescope Optics by Rutten and van Venrooij. Orders placed after 12:00 PM Pacific Time will be shipped the next business day. Explore Scientific Keys to the Universe Sale. No retailers currently carry this product. CPWI has an extensive object database, employs PointXP mount modeling, and more. 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. Some third-party vendors also make reducers for SCT scopes. This factor is designated by a power that is less than 1, and it usually lies between 0.5x or 0.8x. The reducer is we might presume designed to correct to some as yet un-measured extent, the image of a standard SCT. The Reduction Factor and the Amount of Reduction are inversely related. The focal length of a focal reducer is usually measured from the rear lens surface of the reducer (and not the reducer's housing). I really don't see any difference in the current crop except the "Meade" is usually the cheapest. Clearly cost is a big factor for satisfied users. However, it will not thread into William Optics accessories, and with GSO it is a hit or miss. In such cases, we will be happy to take the item back as per our standard return terms. 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. a Tele Vue Panoptic), or a Plossl eyepiece with an apparent field of view of 50 and a focal length of 32mm. Meade once made an f/3.3 focal reducer for SCT scopes. 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. 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. Brian Ventrudo is a writer, scientist, and astronomy educator. Maybe I got a lemon. Thanks Peter! We reserve the right to verify a competitor's advertised price and the availability of the item. The C8 has no noticeable vignetting with a 32mm Plssl in the f/6.3 reducer. 3. Sign up for a new account in our community. WiFi technology encircles the globe in a web of connectivity, knowledge, and information. This innovative software solves the time-consuming problem of trying to pinpoint the North Celestial Pole. So ab6110 is asking for a FR only without coma correction, there are a couple of brands who make special reducers for the ACF. Still not sure what is the right gear for you? 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. Celestron or Antares? Go behind the scenes with Celestrons product development team and learn more about our award-winning and patented innovations. Hi. I think that the FRs made in Japan in the day may have been better. . 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. Theoretically each of these combinations all varied-length light paths should have resulted in slightly different reductions between the Celestron and Antares, since they supposedly have different focal lengths. .
Antares Click Lock Visual Back - Cats & Casses - Cloudy Nights 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. This focal reducer is made to attach to the rear cell of Schmidt-Cassegrain or Maksutov-Cassegrain telescopes. Reducer Lens .7x - EdgeHD 1100. Keep in mind that these differences were very subtle, and could be due to normal variations in coatings among different runs, and not necessarily unique to the brands. The naming convention of SCT focal reducers is a little confusing. Please note, orders placed after 10am on 2/28/2023 will be delayed. Is that distance D= Fo-d1=Fo-(d2/MR)? In terms of reduction and correction - which are what reducer/correctors are supposed to do - both are superb. It's an either/or proposition: reducer and 1.25", or 2", but not 2" and reducer. If you want to use them for visual - try maybe long focal length eyepieces rather than the reducer.
F 6.3 focal reducer/corrector. - Discussions - Stargazers Lounge