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. 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. Antares f/6.3 SCT Focal Reducer - Rother Valley Optics Ltd because they really dont matter. Focal reducers for refractors are easy to use. 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. 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. We only send interesting emails and will never sell your data. 0.5X focal reducer for Celestron, Meade, and Orion CCD imaging cameras Request stock alerts and we'll let you know when the item is back in stock. Hi. The lens that the ZWO comes with give a perfect wide angle image of what is in front of it. Unlike SCT telescopes, Ritchey-Chretien telescopes and Celestron Edge HD or Meade ACF scopes have internal optics that provide an inherently flat field, so these telescopes require a special focal reducer than does not provide additional correction for field curvature. Besides observing from his heavily light polluted backyard in Los Angeles, Manish enjoys conducting astronomy outreach programs in local schools. I've seen some older threads saying that the Celestron, Meade and Antares FRs are all the same and manufactured in the same factory. Sign up for OPT news, exclusive offers, and updates on the latest gear! Focus misses by about 1 turnof the focus knob.Here is my solution:Buy a shorter 1.25 visual back for my scope. So it provides a 0.63x design reduction factor when used with an f/10 SCT at the specified working distance. As a Barlow's magnification increases with increasing distance from the Barlow, a focal reducer's reduction increases with increasing distance from the reducer. 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. Focal reducer for 8SE - Celestron vs. Antares - Cloudy Nights In every configuration, there were essentially parfocal, requiring only a tiny fine focus adjustment when changing correctors. 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. Astro-Tech Schmidt-Cassegrain f/6.3 Focal Reducer Field Flattener Go behind the scenes with Celestrons product development team and learn more about our award-winning and patented innovations. 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. 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. 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. ), 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. 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. However, some focal reducers can be used on other models of telescopes, but this is not always possible. They are reported as identical. Photographically you also get a wider field and much shorter exposures. Antares or Celestron? More aggressive reduction, or using these reducers with larger sensors, will result in aberrations and distortions near the edge of the image. I use the Celestron version and it seems OK for both visual and imaging. 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%. Therefore, a 55mm back focus with a filter that is 3mm thick added to the imaging train would become 56mm. And, the reality is that every F/6.3 RC out there Celestron, Hirsch, Astromania, etc., etc. CPWI has an extensive object database, employs PointXP mount modeling, and more. Have a promo code? The review is a subjective visual impression, which is interesting but not best evidence. This filter threads on to the rear cell of your Celestron or Meade SCT telescope. A f/10 focal ratio now achieves a f/6.3, while an f/11 focal ratio now achieves a f/7. I happily cycle through LRGB filters to build the image rather than do a whole run of one filter at a time. But is there a difference in quality between the Antares and the Celestron or Meade focal reducers? Manish Panjwani has been an active amateur astronomer since before Halley's Comet last flew by our neighborhood. 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. 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. However, the China 6.3 R/C has noticeable internal reflections that I haven't figured out yet. 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. 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. Images made with my ZWO 533 camera testing both show them to be essentially the same. 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. Thanks guys, appreciate the feedback. Dedicated focal reducers for refractors are intended primarily for imaging, not visual observation. 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. Telescope Optics, Rutten and van Venrooij, Chapter 15, Willman-Bell (1988). The naming convention of SCT focal reducers is a little confusing. Reducer - Corrector 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 working distance or required back focus, explained above, is usually specified and is far more important in practice. If used with other f/ratios, the field flattening characteristic may be unpredictable. . ED stands for "extra-low dispersion," which refers to the composition and optical properties of the glass used for the lenses. The female end attaches to the rear cell of the telescope. Turn it on and push Align. In about three minutes, youre ready to observe! It seems right to put some distance between the camera and the focal reducer, right? Ive owned Celestron, Meade, and Antares models over the years at least a couple of each. Brian Ventrudo is a writer, scientist, and astronomy educator. Once focused it's pretty good. 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. 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. 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. Check out our 2022 telescope buying guide here! a Tele Vue Panoptic), or a Plossl eyepiece with an apparent field of view of 50 and a focal length of 32mm. This focal reducer from Celestron reduces the effective focal length by 0.63X Enjoy the wider field of view & faster exposure times at f/6.3 with f/10 telescopes f/11 telescopes, such as the C14 will perform at f/7 The Celestron f/6.3 Reducer has four fully-multicoated elements Reduce your exposure times by a factor of 3! 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). So Celestron buyers like Celestron, Meade buyers like the Meade and Antares buyer like the Antares. Thanks guys, I'm trying to get my ZWO ASI120MC-S to work with my 90mm Meade. 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. 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. No negative issues to report. 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. Maybe I got a lemon. He also holds a Ph.D. in engineering physics from McMaster University. Some are available in 1.25" barrel format but with C threads. I use it on my C8 SCT with a 1000d, and it seems to do everything written on the tin. 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 most commonly available focal reducers for SCTs are the f/6.3 reducers from Celestron and a similar f/6.3 focal reducer from Meade. None of this was offensive, nor did it interfere with views in any significant way. Celestrons award-winning Nature DX binocular gets a major upgrade with the addition of ED objective lenses. One of the most important factors in a telescope is its transmissionthe percentage of light that reaches the focal plane. To test this, I used three set-ups: 1. Meade once made an f/3.3 focal reducer for SCT scopes. 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. (Note: Using the simple equations above, the focal length of this reducer can be estimated to be about 350mm). An f/6.3 reducer is designed to reduce the focal ratio of an f/10 SCT to f/6.3. Shipping will be via the cheapest shipping method which will vary depending on the items in your order. Steve The visual back must be removed first. Some coma is visible in the corners, but the image is quite good for EAA applications. Generally, views through the Antares seemed a little more transparent and brighter. No idea what the issue is. Copyright 2003-2022 Agena AstroProducts. 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? These reducers have a back focus (or design working distance) of 80mm. 3. There is one difference though the Antares came with only one lens cap whereas the Celestron had a cap for both ends. 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. This is a. Add a 0.63x reducer, and the brightness of extended objects increases by (1/0.63)2 = 2.5. The most significant mechanical variation, however, is the quality and precision of the threading. This would tell us exactly how well aberrations are corrected. And when d1 = FR, that is, when the focal reducer is placed at a distance from the focal plane of the objective that's equal to the reducer's focal length, the focal length of the combined optical system is Fo, so it acts as a 0.5x reducer. We will be glad to help. This is very impressive performance given how hard this problem is to mitigate in general. SKU: CEL-94245. Because I have not heard any complaints about the made in China R/C. 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. In your opinion, is the Celestron is worth the added cost ($150 vs. $90)? It's an either/or proposition: reducer and 1.25", or 2", but not 2" and reducer. Due to the design, the Reducer/Corrector lens does diminish a small amount of field curvature common to all Schmidt Cassegrain telescopes but does not eliminate it. Product Details. If I had to guess, the difference is maybe 10-15 grams. The telescope side of the barrel is often threaded with an M48 x 0.75 thread for standard 2" astronomy filters. As a result, the smaller tube may cut into the light cone and effectively reduce the working aperture of the telescope. It's usually specified in millimeters. 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 am a purely visual observer, so will evaluate for visual use only. The two samples I have PERFORM IDENTICALLY. 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. I have this one Opticstar F6.3 Focal Reducer / Corrector. Focal reducers are essential optical accessories for astrophotography, electronically-assisted astronomy (EAA), and in some cases, for visual observation with long focal ratio telescopes. For the best experience on our site, be sure to turn on Javascript in your browser. Reducer Lens .7x - EdgeHD 1400 Oceanside Photo & Telescope wants our customers to shop with confidence knowing that you will always get the best deal available. 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. These scopes are compatibles with focal 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. They are designed (assuming you are referring to the f/6.3 version) for the f/10 light cone. However, this also came at a cost, as the sky background in the Antares was slightly brighter. Field stop diameters are one of the specified specs of eyepieces. 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. Reviews. I've heard and read all kinds of things about the Antares being only a reducer and not a corrector, etc. Since then, Agena has become one of the leading online retailers of telescopes and astronomical accessories worldwide. In most cases, the easiest option is to choose the focal reducer made specifically for your telescope. Nada. I have/had both the Celestron (Japan) and Antares units. When using the diagonal, keep the field stops of the eyepieces under 20mm. 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. The female end attaches to the rear cell of the telescope. An image of about 24mm across, approximately, allows an observer to use a 1.25" eyepiece with a maximal field stop. The faster f/ratio allows you to use slower film or shoot in lower light level situations and still properly expose your subject. Can these economical focal reducers from GSO and other vendors result in good images? For these items, please contact us to obtain a shipping quote before you check out using the online shopping cart.International Customers:Free shipping does not apply to international orders. 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.
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