Because most modern Newtonians already have relatively fast focal ratios, these telescopes do not usually use focal reducers. Reproduction without permission prohibited. These reducers have a back focus (or design working distance) of 80mm. Your wishlist has been temporarily saved. Images in the Celestron tended to appear ever-so-slightly dimmer (maybe? A couple of tiny dust particles between lens elements, uneven lens edge blackening, very minor coating blemishes, or even a very small fine lens scratch or two are very common in this Antares product and must be accepted as normal for this item. This appendix summarizes how this works based on simple equations from the book Telescope Optics by Rutten and van Venrooij. Read our 101 article or get in touch. The Celestron is both a corrector and focal reducer and the Antares is just a focal reducer. High power views will provide flatter fields all the way to the edge, both visually and photographically. And, the reality is that every F/6.3 RC out there Celestron, Hirsch, Astromania, etc., etc. No negative issues to report. 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. Figure 1 shows the relationship between the focal reduction factor MR and the position of the reducer in the optical path. 3. 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. No retailers currently carry this product. And when used in some refractors, the field flattening is not as accurate as it is in the f/10 SCTs. USD $80.00. Contiguous US Customers:All items we sell ship for free within the Contiguous US. It's highly unlikely that they could be so precisely identical unless they were. But the diameter of the image circle decreases by a factor of 0.63 to about 24mm. Celestrons FREE planetarium app is an astronomy suite that redefines how you experience the night sky. A slight nod to the Antares for heft and higher transmission, but points to the Celestron for nice threads and better contrast. 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. 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. Not noticed any optical problems. Focal reducers also move the effective focal plane of the objective inward, that is, towards the objective (see Figure 1). This is very impressive performance given how hard this problem is to mitigate in general. Many focal reducers are meant to be used within a few millimeters of the specified working distance to achieve the best possible image results. Not a bit. ), but stars seemed a bit tighter and their colors were richer and more dramatic. However, the China 6.3 R/C has noticeable internal reflections that I haven't figured out yet. Michael 1 ronin Members Since the focal length of the reducer, FR, is fixed, as d2 increases then MR decreases. 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. 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. This is the simplest way to attach your ASI121 to your telescope. SKU: CEL-94245. You can adjust your cookie settings, otherwise we'll assume you're okay to continue. 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. They provide 0.75x focal reducers for these telescopes that takes an f/8 instrument down to f/6. Designed distancing using the reducer with a 1.25 visual back and 1.25 Televue mirror diagonal; Both exhibited consistent reduction, identical field flattening, and edge correction properties, and both were high quality optically and mechanically. It features a standard male SCT thread (2" OD, 24 TPI) on one side and a standard SCT female thread on the other. Sign up to get exclusive deals, observing tips, and new product announcements. StevieDvd Members 1,182 1,812 Location: Stevenage, UK Posted March 9, 2021 (edited) Don't know but your welcome to try out my Meade 6.3 sct reducer next time you are passing. Celestron or Antares? Is that distance D= Fo-d1=Fo-(d2/MR)? Most manufacturers provide this specification. 2. Another factor to consider: focal reducers also increase the angle at which light approaches the focal plane. 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. Normal shipments will resume on Monday, March 6, 2023. nleash the full pointing accuracy of your Celestron computerized telescope with a specialized telescope control software suite. This is the distance at which the reducer must be placed in front of the eyepiece or camera focal plane in order to operate at the design reduction factor. 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. 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. 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. 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. Just one question. 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. This means that there must be sufficient travel on the telescope focuser to make up for this. 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"). Focus misses by about 1 turnof the focus knob.Here is my solution:Buy a shorter 1.25 visual back for my scope. 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. 2023 Celestron, LLC. 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. 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. For example, a 0.8x reducer placed at the working distance provides a reduction of (1 0.8) x 100 = 20%. 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? Optically, it consists of a four-element lens that is fully multi-coated for high contrast and resolution. But nearly every observer who installs one of these devices is pleased with their performance. I have a made in Japan 6.3 R/C and a made in China 6.3 R/C. That was fun. The lens is housed in machined aluminum for are machined aluminum black anodized. Product Details. Learn more about extra solar planets imagery, 3D Star rendering, observation planning, telescope control, multiple-panel printing, and much more. Have a promo code? ), 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. 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? For me, I was looking for, and planning to keep, the one that yielded the greatest reduction. 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. Reducer - Corrector Learn More. 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. Over the course of a several nights of general observing, I swapped back and forth between the Antares and Celestron R/Cs on a wide variety of objects open clusters, brighter galaxies, a couple of nebulae, and globular clusters as well. This factor is designated by a power that is less than 1, and it usually lies between 0.5x or 0.8x. Opticstar F6.3 Focal Reducer / Corrector. However, manufacturers virtually never provide this specification. Maybe I got a lemon. 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! The visual back must be removed first. Meade once made an f/3.3 focal reducer for SCT scopes. Focal reducers for refractors are easy to use. Check out our 2022 telescope buying guide here! Will not focus with the stuff I have. In both cases will end with a similar tfov. How about for visual observers? 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. The faster f/ratio allows you to use slower film or shoot in lower light level situations and still properly expose your subject. 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. Details: The item must be the identical item, brand name, size, weight, color, quantity and model number. In the 1960s, Celestrons founder, Tom Johnson, created groundbreaking new telescopes never before seen on the consumer market. 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. Style: In your opinion, is the Celestron is worth the added cost ($150 vs. $90)? Any comments gratefully received. All Rights Reserved. A f/10 focal ratio now achieves a f/6.3, while an f/11 focal ratio now achieves a f/7. The Celestron f/6.3 is ~150 compared to the Antares at ~70. One of the most important factors in a telescope is its transmissionthe percentage of light that reaches the focal plane. Today, our world-class team of optical and electronic engineers continues to push the boundaries of technology. Does anyone know if the Antares 4000 focal reducer is as good as the Celestron focal reducer. 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. 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. 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. Like you, I am primarily visually observing but I have everything together now that so I am going to start experimenting with photography so we'll see how it does there. Oceanside Photo & Telescope wants our customers to shop with confidence knowing that you will always get the best deal available. Besides observing from his heavily light polluted backyard in Los Angeles, Manish enjoys conducting astronomy outreach programs in local schools. control and Sky Viewer display makes selecting your target easy. However, these will not impact optical performance. I have Hirsch focal reducer, which is yet another clone of the Celestron reducer. 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. This filter threads on to the rear cell of your Celestron or Meade SCT telescope. These reducers can also be used for visual observing with SCT scopes with eyepieces with a field stop as large as 24-27mm. 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. looks virtually identical, except for the lettering. I found both to be very good. In some cases, focal reducers also act as field flatteners by correcting for field curvature and coma of the objective lens. As per the OP I still can't see any reason to buy the Celestron for significantly more $$$. Specially-designed focal reducers are available for use with these telescopes. Celestrons aplanatic EdgeHD optics revolutionized astroimaging. Possibly the design of the Antares was changed .. Some faster refractors with a focal ratio of f/6, for example, only require field flatteners and not focal reducers. Explore Scientific - Keys to the Universe Sale. As a result, the smaller tube may cut into the light cone and effectively reduce the working aperture of the telescope. However, some focal reducers can be used on other models of telescopes, but this is not always possible. Can you help me? You may need spacers or a T-adapter to ensure the correcting working distance. The reducer is we might presume designed to correct to some as yet un-measured extent, the image of a standard SCT. The Reducer/Corrector can also be used for terrestrial digiscoping. 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.
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