The threads were similar on the eyepiece end, but a bit smoother. 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. * Not a Retail Store * 16313 Arthur StreetCerritos, CA 90703, USA, Availability: Item has been discontinued by Agena and we no longer carry this item. Again, to my surprise, there was absolutely no difference between the Celestron and Antares on any star. Reducer Lens .7x - EdgeHD 925 Learn More. This fully multi-coated lens provides maximum light transmission with near full-field illumination. If you want to use them for visual - try maybe long focal length eyepieces rather than the reducer. 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. In every configuration, there were essentially parfocal, requiring only a tiny fine focus adjustment when changing correctors. 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. Figure 6 shows a 1.25" focal reducer from GSO configured with a ZWO ASI224MC camera. 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. Planetarium software package which provides easy-to-understand explanations and impressive visuals of all kinds. Today, our world-class team of optical and electronic engineers continues to push the boundaries of technology. These RC reducers cannot be used with other types of telescopes. I doubt there is any difference between the Antares and the Celestron except price. 2023 Celestron, LLC. One of the most important factors in a telescope is its transmissionthe percentage of light that reaches the focal plane. Style: The Antares f6.3 focal reducer screws directly to the visual-back thread of all popular SCTs and converts f10 instruments to f6.3. If I had to guess, the difference is maybe 10-15 grams. Wow, that is a very detailed discussion! Sign up for our newsletter to get exclusive deals, observing tips, and new product announcements. Reducer Lens .7x - EdgeHD 1100 Learn More. More details are found in the Appendix of this article. Completely stuck, completely frustrated. They are reported as identical. SKU: CEL-94245. Whereas the Celestron threaded smoothly onto the scope, the Antares chattered and squeaked a bit more so when being removed. 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. I was referring to the C6 to answer you specifically. Celestron or Antares f/6.3 focal reducer for SCT? 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. Unique focal reducer and field corrector lens accessory, Reduces the focal length and f/ ratio of your Schmidt-Cassegrain telescope by 37%, Provides a dual focal ratio instrument, without sacrificing image quality, Compatible with all Schmidt-Cassegrain telescopes (see compatible list in description). It was used strictly for imaging, not visual observing. Also, the focusers of most Newtonians do not have enough in-travel to accommodate a focal reducer. Celestrons award-winning Nature DX binocular gets a major upgrade with the addition of ED objective lenses. I have the Antares and have no complaints. I have this one Opticstar F6.3 Focal Reducer / Corrector. It also leads to larger (although fainter) images of extended objects like the Moon or planets for astrophotographers or visual observers. If you do so, you will achieve the design reduction factor. Ive owned Celestron, Meade, and Antares models over the years at least a couple of each. Increase that distance, and greater reduction results and visa versa. Easy solution found a very tiny dab of super lube on the threads and all was well and quiet.. It works fine but you should stick with 1.25 EPs; or can use 2" EPs without corrector. There are many different types of focal reducers and they all effect. Any comments gratefully received. This is the simplest way to attach your ASI121 to your telescope. Perfect for the serious student, professional scientist and discriminating hobbyist. All rights reserved. Images in the Celestron tended to appear ever-so-slightly dimmer (maybe? The two samples I have PERFORM IDENTICALLY. Oceanside Photo & Telescope wants our customers to shop with confidence knowing that you will always get the best deal available. Meade once made an f/3.3 focal reducer for SCT scopes. 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. 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. We will match any online price that we confirm as valid. 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. This article explained the basics of how focal reducers work with various kinds of telescopes and how their working distance affects their reduction factor, and it provided sufficient detail to help amateur astronomer choose and use the right focal reducer for a particular application. I am a purely visual observer, so will evaluate for visual use only. The previous post shows the reducer on what appear to be two different refractors. For example, a 0.8x reducer placed at the working distance provides a reduction of (1 0.8) x 100 = 20%. 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. This was most noticeable on the eyepiece end of the RC, where the metal rim surrounding the lens was about 1mm thicker than on the Celestron. I've heard and read all kinds of things about the Antares being only a reducer and not a corrector, etc. 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. One focal reducer will not achieve optimum results with all types of telescopes, so there is no universal' focal reducer. The Reduction Factor and the Amount of Reduction are inversely related. M44 was a perfect target for this, as its large size maxes out the FOV on a C8 with a corrector, and its bright stars make great targets for measuring the very edge of the visible field. Start here to find the perfect telescope for you! No negative issues to report. 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. Rather than a direct side-by-side, I swapped the reducers so that I was using them on the exact same, well-collimated instrument. Your price: $579.00. Very helpful, thanks a lot for this article! 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. Never noticed any anomalies with this unit. 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. Brian Ventrudo is a writer, scientist, and astronomy educator. Place the plastic covers on the lens when not in use to reduce the dust collection. The Celestron f/6.3 is ~150 compared to the Antares at ~70. 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. The focal length and design working distance for this focal reducer were not available from the manufacturer. 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? Orders placed over the weekend will be shipped on the following Monday. Unique focal reducer and field corrector lens accessory Reduces the focal length and f/ ratio of your Schmidt-Cassegrain telescope by 37% Provides a dual focal ratio instrument, without sacrificing image quality Compatible with all Schmidt-Cassegrain telescopes (see compatible list in description) Share Customers Also Purchased Description 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. This article explains the basics of how focal reducers work with an astronomy telescope. These reducers can also be used for visual observing with SCT scopes with eyepieces with a field stop as large as 24-27mm. Some third-party vendors also make reducers for SCT scopes. For imagers, the main purpose of a focal reducer is to increase the brightness of the image at the focal plane. Yet, the Antares still easily and fully threaded without any hitches. Some faster refractors with a focal ratio of f/6, for example, only require field flatteners and not focal reducers. I am new to these optic topics, and I want to ask you what happens with Masutov like SW or Celestron 4 or 7 inches. Celestrons patented StarSense Technology makes it easier than ever to locate objects in the night sky, even if youve never used a telescope before. I've seen some older threads saying that the Celestron, Meade and Antares FRs are all the same and manufactured in the same factory. External Focusers for Schmidt-Cassegrain Telescopes 3.1 The Basics of SCT Threads The resultant reduction factor was measured to be 0.46x. I don't know. Focal Reducer, 2", 0.7X. To test this, I used three set-ups: 1. Learn more about extra solar planets imagery, 3D Star rendering, observation planning, telescope control, multiple-panel printing, and much more. Wonder how they would stack up with a Japanese 6.3. The focal length of a focal reducer is usually measured from the rear lens surface of the reducer (and not the reducer's housing). If it's positioned further from the eyepiece or camera and closer to the telescope objective, the reduction factor increases. However, manufacturers virtually never provide this specification. Great report and verifies what I had thought all along, Fortunately, my neighbors are not out in their backyards at 11 pm, or they may have thought I was torturing a small mammal. An f/6.3 reducer is designed to reduce the focal ratio of an f/10 SCT to f/6.3. No difference. What an enjoyable read and detailed comparison. Since the focal length of the reducer, FR, is fixed, as d2 increases then MR decreases. As one increases, the other decreases. For this test, I used a single configuration R/C, Click-lock, and 1.25 diagonal with the adapter. Depending on the design of the telescope, they may require separate focal reducers if they require focal reducers at all. Many reducers, such as the Celestron HD focal reducer mentioned above, and many focal reducers for apochromatic refractors, are meant to be used within a few millimeters (or less) of the specified working distance to achieve the best possible image results. 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. 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. The camera side of the focal reducer is threaded for a T-adapter with wide M48 threads, or in some cases, with smaller M42 threads. Newtonian reflectors will seldom be able to accommodate the in-focus travel demanded by focal reducers. They provide 0.75x focal reducers for these telescopes that takes an f/8 instrument down to f/6. We reserve the right to verify a competitor's advertised price and the availability of the item. Figure 1 shows the relationship between the focal reduction factor MR and the position of the reducer in the optical path. because they really dont matter. If the reducer is placed elsewhere, at a position called the operating distance, the focal reduction factor will not be as advertised. Field stop diameters are one of the specified specs of eyepieces. Go behind the scenes with Celestrons product development team and learn more about our award-winning and patented innovations. Manish holds a Master's degree in Electrical Engineering from Virginia Tech and an MBA from the Kellogg School of Management at Northwestern University. 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. Who cares? Turn it on and push Align. In about three minutes, youre ready to observe! This factor is designated by a power that is less than 1, and it usually lies between 0.5x or 0.8x. With spring galaxy season here, I decided to pick up a couple more to compare in a head-to-head shoot out. 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. Refractors, or SCTs with external focusers, may not have sufficient in-travel to reach focus in some configurations. Reviews. looks virtually identical, except for the lettering. You currently have javascript disabled. Such an image circle is still large enough to encompass the relatively large sensor of many deep-sky astronomy cameras. Much to my surprise, swapping back and forth between the two correctors using all three diagonal configurations, I also could detect absolutely no change in reduction between the two reducers. 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. 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. Right off the bat, I was struck by how similar the two R/Cs were. When the camera sensor is placed at this distance, the reduction factor of these reducers is 0.75x.
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