They usually have a 2" barrel that slides into the telescope focuser. All Rights Reserved. However, some focal reducers can be used on other models of telescopes, but this is not always possible. Can you help me? Your wishlist has been temporarily saved. Sign up for our newsletter to get exclusive deals, observing tips, and new product announcements. Explore Scientific - Keys to the Universe Sale. Given the results of Test #1, I wanted to see if there was any truth to this assumption. which looks like the same one. 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. We only send interesting emails and will never sell your data. 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. These reducers can also be used for visual observing with SCT scopes with eyepieces with a field stop as large as 24-27mm. When using the diagonal, keep the field stops of the eyepieces under 20mm. This means that there must be sufficient travel on the telescope focuser to make up for this. ), but stars seemed a bit tighter and their colors were richer and more dramatic. Thanks guys, I'm trying to get my ZWO ASI120MC-S to work with my 90mm Meade. The threads were similar on the eyepiece end, but a bit smoother. Contiguous US Customers:All items we sell ship for free within the Contiguous US. During check-out, you will be presented with several shipping choices and costs. Perhaps not exactly- there will be some uncertainty because of manufacturing tolerances and so forth, but it will be close. 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. 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. 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. Because of their distinct optical design, slower Schmidt-Cassegrain telescopes (SCT) with focal ratios of f/10 require a different design of focal reducer compared to refractors. Celestron is considered better in terms of QA, less likely to come with free dust, hair or fingerprint. 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. Just one question. He received his first telescope at the age of 5 and completed his first university course in astronomy at the age of 12, eventually receiving a master's degree in the subject. 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. I have this one Opticstar F6.3 Focal 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. Request stock alerts and we'll let you know when the item is back in stock. Reducer - Corrector 2023 Celestron, LLC. Place the plastic covers on the lens when not in use to reduce the dust collection. Equation 6 & 7 item two & three does not make sense, both say increase its reduction (one should say reduce its reduction?). Increasing the operating distance, that is, moving a focal reducer away from the eyepiece or camera reduces its reduction factor, or conversely increases the amount of reduction. This is the simplest way to attach your ASI121 to your telescope. Thanks Peter! ED stands for "extra-low dispersion," which refers to the composition and optical properties of the glass used for the lenses. Focal reducers for refractors with focal ratio of f/7 to f/9, roughly, have a design reduction factor of about 0.75x to 0.8x and produce a flat field by correcting for the curvature of the objective lens. However, this also came at a cost, as the sky background in the Antares was slightly brighter. It's highly unlikely that they could be so precisely identical unless they were. Astro-Tech Schmidt-Cassegrain f/6.3 Focal Reducer Field Flattener Another factor to consider: focal reducers also increase the angle at which light approaches the focal plane. 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. However, the export of some items may be restricted outside the US due to size or manufacturer restrictions. 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. I've heard and read all kinds of things about the Antares being only a reducer and not a corrector, etc. There will be no shipments on 3/1/2023, 3/2/2023, or 3/3/2023 (March 1st - March 3rd, 2023). Agena's Guide to Focal Reducers - Agena Astro Reducer Lens .7x - EdgeHD 925 With the Celestron Reducer/Corrector Lens, thats precisely what you get. Each focal reducer has a fixed specification called the working distance or required back focus. They are also less expensive than many external focusers of similar build quality. 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. For visual use, this means you get lower power with the same eyepiece and a wider field of view. My experience is that CN sellers are way above those listing elsewhere. CEL-94245. These scopes are compatibles with focal reducers. Also read the reviews here, including those at 4 stars. Optically, it consists of a four-element lens that is fully multi-coated for high contrast and resolution. Focal reducers for these relatively fast ED refractors are generally for imaging only, not for visual observation. 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. For example, the focal reducer for an 8-inch Celestron EdgeHD telescope has a design reduction factor of 0.7x and a specified working distance (or back focus) of 105mm. You currently have javascript disabled. Stars had a tiny bit more sparkle and pop. 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. I've seen some older threads saying that the Celestron, Meade and Antares FRs are all the same and manufactured in the same factory. Therefore, a 55mm back focus with a filter that is 3mm thick added to the imaging train would become 56mm. JavaScript seems to be disabled in your browser. This appendix summarizes how this works based on simple equations from the book Telescope Optics by Rutten and van Venrooij. WiFi technology encircles the globe in a web of connectivity, knowledge, and information. 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. 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. Any comments gratefully received. We will be glad to help. As a consequence, the standard f/6.3 and f/3.3 focal reducers for SCT scopes do not work. If I had to go out on a very thick limb, I would have to say that these two reducers/correctors are, indeed, identical the exact same glass in slightly different housings with different lettering. Focal Reducer, 2", 0.7X. No results, please adjust your filters. 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! But the smaller image circle means there is a limit to the field stop of an eyepiece that can achieve an unvignetted image. a Tele Vue Panoptic), or a Plossl eyepiece with an apparent field of view of 50 and a focal length of 32mm. 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). The telescope side of the barrel is often threaded with an M48 x 0.75 thread for standard 2" astronomy filters. It is not a corrector or flattener. 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. Equation (4) shows the relationship between the distance d2 and the reduction factor MR. Most refractor manufacturers such as William Optics, Tele Vue Optics, Explore Scientific, Sky-Watcher, William Optics, and Stellarvue make their own focal reducers optimized for use with their telescopes. 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. 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. What an enjoyable read and detailed comparison. 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. The faster f/ratio allows you to use slower film or shoot in lower light level situations and still properly expose your subject. Figure 2 shows the effective of a focal reducer on the light from a telescope objective. Easy solution found a very tiny dab of super lube on the threads and all was well and quiet. 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. In terms of reduction and correction - which are what reducer/correctors are supposed to do - both are superb. Your price: $579.00. These reducers have a back focus (or design working distance) of 80mm. Reproduction without permission prohibited. If the reducer is placed elsewhere, at a position called the operating distance, the focal reduction factor will not be as advertised. A useful thing to know is how far from the objective lens (for a refractor) is the focal reducer located. Celestron Solar Safe filter technology is GUARANTEED SAFE for direct solar observation and has been independently tested by SAI Global Assurance Services. But in the end they both do pretty much the same thing and it sounds like any performance difference is subtle. I've only used it a few times but it looks good to me. Obviously bright objects like Jupiter or The Moon show the reflections. Now It only focuses near things, like some kind of macro zoom. The focal length and design working distance for this focal reducer were not available from the manufacturer. When the camera sensor is placed at this distance, the reduction factor of these reducers is 0.75x. 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. Also, the focusers of most Newtonians do not have enough in-travel to accommodate a focal reducer. Thanks for pointing this out. If you want to save a few buck watch the classifieds on CN. 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. 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. Have a promo code? Orders placed over the weekend will be shipped on the following Monday. Refractors, or SCTs with external focusers, may not have sufficient in-travel to reach focus in some configurations. Hello! Focal reducers for refractors are easy to use. USD $80.00. 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. Celestron & Antares f/6.3 Reducer/Corrector Shoot-out Antares F/6.3 SCT Focal Reducer | OPT Telescopes F 6.3 focal reducer/corrector. - Discussions - Stargazers Lounge I would pay slightly more for the Japan produced version, just because Hirsch was not bad either but sold it since I had 2 already. Antares f/6.3 SCT Focal Reducer - Rother Valley Optics Ltd 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. Quite interestingly it bears the very same engravings of the Meade 4000 r/c (including "series 4000") except for "MEADE". 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. Again, to my surprise, there was absolutely no difference between the Celestron and Antares on any star. Celestrons aplanatic EdgeHD optics revolutionized astroimaging. Explore Scientific Keys to the Universe Sale. Not one detectable iota of discernable difference. 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. Still not sure what is the right gear for you? Regardless, the difference was miniscule and is more than adequate on both and exceeds a 8 or 6 SCTs baffle tube diameter. Fortunately, my neighbors are not out in their backyards at 11 pm, or they may have thought I was torturing a small mammal. 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. A little longer light path with a 2 Baader click-lock, low profile 1.25 adapter, and the 1.25 diagonal; If it's positioned further from the eyepiece or camera and closer to the telescope objective, the reduction factor increases. The nominal design reduction factor of these reducers is typically 0.5x. It covers the basic optics and design specifications of a focal reducer, and goes through some practical factors to consider when selecting and using a focal reducer. 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. Hmmm . The Antares f6.3 focal reducer screws directly to the visual-back thread of all popular SCTs and converts f10 instruments to f6.3. 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. Torazz All rights reserved. Copyright 2021 Stargazers Lounge In some cases, focal reducers also act as field flatteners by correcting for field curvature and coma of the objective lens. The new Lithium Phosphate (LiFePO4) battery chemistry has significant advantages over other battery chemistries, great for for those Astronomers on the go. Download the Celestron PWI Telescope Control Software. However, these will not impact optical performance. - thanks. They only publish the value of D, the working distance (sometimes called the back focus distance) and the design reduction factor MRD. Start here to find the perfect telescope for you! It can also be used with any other small chip CCD camera having a 1.25" nosepiece, such as the Celestron NexImage, Meade DSI . For the best experience on our site, be sure to turn on Javascript in your browser. 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. Figure 6 shows a 1.25" focal reducer from GSO configured with a ZWO ASI224MC camera. You attach the focal reducer to the rear port on a SCT and can keep it covered. 3. 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. 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. Such an image circle is still large enough to encompass the relatively large sensor of many deep-sky astronomy cameras. 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. 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 have placed cookies on your device to help make this website better. 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. 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. The designed reduction factor (0.5x in the case of the GSO reducer example above) should be considered a rule of thumb or approximate value in most cases, rather than a very precise number. This should not be the case if they have their purportedly different focal lengths. 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. If you want to use them for visual - try maybe long focal length eyepieces rather than the reducer. More important, its clear that the Antares is a reducer/corrector, just like the Celestron and not merely a reducer. The reducer fits all Meade and Celestron . 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. 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. Learn more about extra solar planets imagery, 3D Star rendering, observation planning, telescope control, multiple-panel printing, and much more. You can adjust your cookie settings, otherwise we'll assume you're okay to continue. You need to be a member in order to leave a comment. The review is a subjective visual impression, which is interesting but not best evidence. Celestron or Antares f/6.3 focal reducer for SCT? As a Barlow's magnification increases with increasing distance from the Barlow, a focal reducer's reduction increases with increasing distance from the reducer. Celestrons patented StarSense Technology makes it easier than ever to locate objects in the night sky, even if youve never used a telescope before. 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. I must admit, as well, that I no longer place a lot of stock in the notion that Chinese optics are inferior to Japanese or Taiwanese any longer, as manufacturing technology has really leveled the playing field today, with most Chinese optics being excellent. It has only one cover, which surprised me. Focal Reducers | Celestron ED glass is specially formulated and contains rare-earth compounds that greatly reduce a visual defect called chromatic aberration. Reducer - Corrector | Celestron Well done. I was going to measure the difference in grams, but my lovely wife caught me trying to use her precious, high-tech kitchen scale for the cause, and put the kibosh on it. Whereas the Celestron threaded smoothly onto the scope, the Antares chattered and squeaked a bit more so when being removed.

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