The stars at the edge could be worse or better. Telescope Optics, Rutten and van Venrooij, Chapter 15, Willman-Bell (1988). I also used several eyepieces including the ES 24mm/68, 17.5mm and 12.5mm Morpheuses, and a 10.5mm Pentax XL. 2023 Celestron, LLC. A few large telescopes and mounts are excluded from this free shipping offer. Is that distance D= Fo-d1=Fo-(d2/MR)? Sharpness is essentially the same. Besides observing from his heavily light polluted backyard in Los Angeles, Manish enjoys conducting astronomy outreach programs in local schools. Reducer - Corrector The nominal design reduction factor of these reducers is typically 0.5x. EclipSmart solar products feature Solar Safe filter technology providing the ultimate protection from harmful solar radiation, including both IR and UV light, and filters 99.999% of visible light. Things change but when I rebought I got an Antares and it seems about the same to me. Benefits limited to hardware and conditions? OPT Product Number: AE-SCTFR specifications Warranty 2 Year Warranty Works as advertised! There are many different types of focal reducers and they all effect. Performance wise what differences might there be using the reducer on a smaller scope. During check-out, you will be presented with several shipping choices and costs. Our proprietary StarBright XLT optical coatings dramatically increase transmission, up to 97.4% on our Schmidt corrector lenses. This superb fully multi-coated multi-element focal reducer takes advantage of the latest computer aided design techniques to achieve the highest standards of performance set by the brand leaders at a fraction of the cost. However, these will not impact optical performance. Perhaps not exactly- there will be some uncertainty because of manufacturing tolerances and so forth, but it will be close. Place the plastic covers on the lens when not in use to reduce the dust collection. 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. How about for visual observers? 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. All rights reserved. SKU: CEL-94245. Some faster refractors with a focal ratio of f/6, for example, only require field flatteners and not focal reducers. 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. 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. 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. 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. 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. Scope size might influence choice as well, as a C6 might benefit from the Antares' transparency, while larger scopes might benefit from the Celestron's higher contrast. They are also less expensive than many external focusers of similar build quality. 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. 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. Please re-enable javascript to access full functionality. I use the Celestron version and it seems OK for both visual and imaging. In some cases, focal reducers also act as field flatteners by correcting for field curvature and coma of the objective lens. The reducer is we might presume designed to correct to some as yet un-measured extent, the image of a standard SCT. 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 distances d1 andd2 can also be expressed in terms of the focal length of the focal reducer FR with the lens equation: Using Equation 2, Equation 1 can also be expressed in terms of d2: The focal reduction factor of the focal reducer depends on its focal length and its distance from the focal plane of the objective as shown by Equation 4: Again, for example, when the focal reducer is placed at the original focal plane of the objective, d1=0 and MR=1, which means there is no focal reduction. 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. In this configuration, the 29.5mm camera nosepiece and a 6mm extension ring positions the reducer at a working distance of 53.5mm from the camera sensor, which is located 12.5mm inside the front edge of the camera. Does anyone know if the Antares 4000 focal reducer is as good as the Celestron focal reducer. . Images in the Celestron tended to appear ever-so-slightly dimmer (maybe? When you said, "in some cases" a focal reducer also works as a flattener/corrector, are you saying that not all focal reducers are flatteners/corrector? The 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. He also holds a Ph.D. in engineering physics from McMaster University. Hi. The resultant reduction factor was measured to be 0.46x. No experience with the Antares reducers, but I haven't personally seen a difference between Celestron and my current pair of made in Japan Meade reducers. Explore Scientific - Keys to the Universe Sale. Stock focusers in an SCT move the mirror of the scope to change the position of the focal plane, and they have sufficient travel to accommodate a focal reducer. I would not use the reducer with a 2" diagonal or eyepiece in the C6. Style: Also read the reviews here, including those at 4 stars. It's easy! We have tested our current batch and it works with Meade, Celestron, and Baader SCT accessories. control and Sky Viewer display makes selecting your target easy. It must be in stock at the time of Price Match for us to make a guarantee. 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. 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. However, even though the imprint on the item states "Reducer / Corrector" please note that his is a reducer only. So ab6110 is asking for a FR only without coma correction, there are a couple of brands who make special reducers for the ACF. Getting the proper back-focus for your imaging camera is a vital step in getting the best data possible out of your telescope imaging/research rig. But while the image gets brighter, the size of the image circle gets proportionately smaller. We will be glad to help. It's an either/or proposition: reducer and 1.25", or 2", but not 2" and reducer. This focal reducer and field flattener consists of a four-element multicoated 40mm lens in a metal cell. Start here to find the perfect telescope for you! More about this below. Antares or Celestron? There will be no shipments on 3/1/2023, 3/2/2023, or 3/3/2023 (March 1st - March 3rd, 2023). We process your personal data as stated in our. But the diameter of the image circle decreases by a factor of 0.63 to about 24mm. 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. An image of about 24mm across, approximately, allows an observer to use a 1.25" eyepiece with a maximal field stop. This filter threads on to the rear cell of your Celestron or Meade SCT telescope. It is not a corrector or flattener. 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. By using this site, you agree to our Terms of Use. Easy solution found a very tiny dab of super lube on the threads and all was well and quiet. Stars in the corner of the image frame are indistinguishable between the Antares and the Celestron. - thanks. With the Celestron Reducer/Corrector Lens, thats precisely what you get. But is there a difference in quality between the Antares and the Celestron or Meade focal reducers? Contiguous US Customers:All items we sell ship for free within the Contiguous US. These scopes are compatibles with focal reducers. The working distance or required back focus, explained above, is usually specified and is far more important in practice. These reducers can also be used for visual observing with SCT scopes with eyepieces with a field stop as large as 24-27mm. 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. 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. Unleash the full pointing accuracy of your Celestron computerized telescope with a specialized telescope control software suite. The Reduction Factor and the Amount of Reduction are inversely related. This factor is designated by a power that is less than 1, and it usually lies between 0.5x or 0.8x. Enter it during checkout! Again, to my surprise, there was absolutely no difference between the Celestron and Antares on any star. Even though they may have been slightly dimmer, galaxies were a bit easier to tease out of the urban light soup I deal with. 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. Powered by Invision Community. They are designed (assuming you are referring to the f/6.3 version) for the f/10 light cone. First, let's have a look at some key optical parameters are needed to understand focal reducers. Brian Ventrudo is a writer, scientist, and astronomy educator. Once focused it's pretty good. Request stock alerts and we'll let you know when the item is back in stock. I wish there was. Rather than a direct side-by-side, I swapped the reducers so that I was using them on the exact same, well-collimated instrument. Article Agena AstroProducts, 2019. We have corrected # (iii) after equations 6 & 7. One of the most important factors in a telescope is its transmissionthe percentage of light that reaches the focal plane. 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. Designed distancing using the reducer with a 1.25 visual back and 1.25 Televue mirror diagonal;
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