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Celestron

Celestron – Focal Reducer & Field Corrector Imaging Accessory – Reduces Focal Length & Ratio 37% – f/10 to f/6.3 – Ideal for Deep-Sky Observing & Astroimaging – Works w/Schmidt-Cassegrain Telescopes

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Style: Corrector


Features

  • LIKE HAVING TWO TELESCOPES IN ONE: Your long focal length Schmidt-Cassegrain is well suited to lunar and planetary work. Add the Reducer Corrector and you have a short focal length telescope perfect for deep sky observing and astrophotography.
  • REDUCES FOCAL LENGTH AND F/RATIO BY 37%: Simply thread the reducer onto your telescopes rear cell and an f/10 Schmidt-Cassegrain becomes f/6.3. An f/11 instrument becomes f/7.
  • COMPATIBLE WITH ALL YOUR ACCESSORIES: Once the reducer is installed, you can add accessories like a T-Adapter, visual back, star diagonal or off-axis guider as usual.
  • GREAT FOR TERRESTRIAL DIGISCOPING: The faster f/ratio allows you to shoot in dimmer lighting conditions and still properly expose your subject. This fully multi-coated lens provides maximum light transmission with near full-field illumination.
  • UNBEATABLE WARRANTY & SUPPORT: Buy with confidence from Celestron, a leading telescope brand in California since 1960. Your purchase includes a 2-Year US Warranty and unlimited support from our team of US-based experts.

Description

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. With the Celestron Reducer/Corrector Lens, that’s precisely what you get. Explicitly designed for Celestron Schmidt-Cassegrain telescopes, this unique lens reduces your telescope’s focal length and f/ ratio by 37%, turning your long focal length telescope into a fast, short focal length instrument. A f/10 focal ratio now achieves a f/6.3, while an f/11 focal ratio now achieves a f/7. For visual use, this means you get lower power with the same eyepiece and a wider field of view. Photographically you also get a wider field and much shorter exposures. The Reducer/Corrector is easy to install by threading the unit onto the rear cell of your Schmidt- Cassegrain telescope (or the reducer plate of the C11 and C14). Once installed, you can add additional accessories like T-Adapters, 1.25” Visual Back, Star Diagonal, or Off-Axis Guider. The Reducer/Corrector can also be used for terrestrial digiscoping. The faster f/ratio allows you to use slower film or shoot in lower light level situations and still properly expose your subject. This fully multi-coated lens provides maximum light transmission with near full-field illumination. The lens is housed in machined aluminum for are machined aluminum black anodized. The internal surfaces are blackened and glare-threaded to provide the highest contrast. The lens has a knurled surface, providing a tremendous gripping surface for threading/unthreading.

Brand: Celestron


Optical Tube Length: 105 Millimeters


Eye Piece Lens Description: Plossl


Objective Lens Diameter: 200 Millimeters


Telescope Mount Description: Equatorial Mount


Product Dimensions: 2"D x 2"W x 2"H


Focus Type: Manual Focus


Finderscope: Reflex


Item Weight: 150 Grams


Compatible Devices: Celestron Schmidt-Cassegrain telescopes (C5, C6, C8, C9.25, C11, C14)


Product Dimensions: 2 x 2 x 2 inches


Item Weight: 5.3 ounces


Item model number: 94175


Is Discontinued By Manufacturer: No


Date First Available: November 4, 2009


Manufacturer: Celestron


Frequently asked questions

If you place your order now, the estimated arrival date for this product is: Tuesday, Mar 3

Yes, absolutely! You may return this product for a full refund within 30 days of receiving it.

To initiate a return, please visit our Returns Center.

View our full returns policy here.

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Top Amazon Reviews

    • Visual or Video -A Great Accessory
Style: Corrector
I am sorry that I did not buy this accessory two years ago. It all began with a used Celestron C5. Then I bought a very nice used Nexstar 8SE and thought wow, I should have done this go-to thing sooner. After a year or so, I moved up to a new Celestron CPC925 and decided to explore video astronomy with an inexpensive Samsung SBC-2000 security cam. Most SCTs have a focal ratio of about f/10 (focal length divided by aperture) but a camera works better with a faster (shorter focal length) scope. The usual way to do that with a video camera is to screw on a small .5x reducer. So I bought on of those for $35 and was just amazed at the detail and colors in the Dumbbell Nebula. Then someone over at Cloudynights.com suggested that try adding a f/6.3 reducer (stacking reducers). So I bought the f/6.3, screwed in on the back of the CPC925, replaced the visual back and diagonal, mounted the camera (without the .5x) and stayed up until 2AM looking at the Orion Nebula. Before heading for bed, I pulled the camera, put in a 20MM 68 degree APOV eyepiece, and had another "Wow!" moment. The Celestron f/6.3 reducer-corrector really brightens the image, widens the field of view, improves contrast and detail, and flattens the image improving the look of stars near the edge of the field of view. Many people leave them on all of the time except when looking at the moon and planets or other high magnification situation. There are other and cheaper reducers on the market and they do work. However not all of them offer the same degree of improvement at the edge of the field of view. Rod Mollise writes "...6.3 r/cs are one of the best--if not the best--SCT accessories to ever come down the pike" and "I'll put it this way...the 6.3 rarely comes off the rear cell of the C8." ... show more
Reviewed in the United States on October 24, 2011 by Night Sky Fan
    • An essential accessory for deep sky viewing or photogrqphy with a Celestron SCT
Style: Corrector
Review Image by Chuck Chuck
The focal reducer is easy to screw on and of, and it fits snugly onto my Celestron 8SE. It provides a crisp, clear wider field of view, allowing me to see or photograph a larger area of the sky. It feels sturdy and well-built, with knurled rubber for ease of grip. It is a good value for the money, and recommend it for anyone getting started with a Celestron SCT. ... show more
Reviewed in the United States on January 9, 2026 by Chuck Chuck
    • Buy this, you need it.
Style: Corrector
A brilliant solution to a problem I didn't know I had. I have been doing a lot of astrophotography with my celestron scope. This is a tremendous help. Before, when trying to get a photo of the entire moon, I was taking maybe 22 photos and stitching them together on the PC for one combined picture. It took a long time to photograph and to stitch. With the reducer, the field of view is wider (but less magnification) and it took just 6 shots to get the entire moon, and I could possibly have done it in 4. With the Deep Sky Imager I am taking much superior shots of the Orion Nebula. It looks far superior with a much wider field of view and it also makes things brighter which eases the exposure problem. The product is easy to install. I can do it as the telescope continues to track. Unscrew the eye piece, screw on the reducer then screw the eyepiece into the reducer and you are ready for your wide angle shots. Summary: it is really improving my photography. ... show more
Reviewed in the United States on January 11, 2017 by M. Wilson
    • Worked well, easy to install
Style: Corrector
I put this on my celestron 8se SC telescope with the goal of increasing the field of view (because I have a zwo asi224mc camera with a relatively small sensor area). It was easy to install and worked quite well. Before buying it, I was worried that the focal plane would shift so much that I would not be able to focus within the limits of my focusing knob. But that worry was unfounded and I got to focus easily. I could fit the Dumbbell nebula with enough contextual background in the field of view of my camera. As far as I could tell, I did not observe significant vignetting. My plan is to leave it in the back of the telescope forever and only take it off when doing planetary observation or imaging (which requires higher magnification). ... show more
Reviewed in the United States on July 30, 2021 by Jahan Dawlaty
    • Does the job, Be sure it's really what you want. Pricey.
Style: Corrector
A focal reducer is pretty much a must have for SCT owners due to the high focal ratios they use to keep the secondary mirror to a reasonable size. This one does what it says it does, just don't expect it to miraculously turn your C5 or C6(what I have) into a dark DSO hunter. After I ought this I discovered that there are reducers on the market that will drop to f/4 or even lower as needed for the large dim deep sky objects. It doesn't distort or diminish light noticeably so I still give it good marks, just know what you're getting..a bit of reduction from a great planetary scope to a more usable near and large object one. It didn't quite get the whole moon on screen with my little homeade logitech webcam at prime focus (about equivalent to an 8mm ep) ... show more
Reviewed in the United States on August 13, 2015 by Rabbit
    • Great Product
Style: Corrector
Great product from Celestron and an imoirtant part of the image train on the Celestron 8SE AVX.
Reviewed in the United States on July 5, 2025 by Robert B.
    • Must have.
Style: Corrector
Excellent optics. Reduces exposure times. Quality manufacturing.
Reviewed in the United States on January 10, 2026 by Yervant Parnagian Jr
    • Valuable accessory for DSO viewing and photography
Style: Corrector
I read about such corrective lenses in a book on astrophotography. The goal of the lense is to effectively decrease the f value of your scope, increasing light gathering ability and the field of view. This lense accomplished both goals for my Celestron NexStar 6SE. It changed the scope from F10 to F6.3 and increased the FOV so that objects that formerly were too big to image "whole" now were imaged completely. The visual brightness of objects was increased and the resulting exposure times decreased. I keep this lense on the scope by default and only remove it (restoring the original F ratio) when intending to view and image planets or split close double stars. I have not noticed any distortion in the images when the lense is in place. I count this purchase as one of my best decisions when acquiring accessories. ... show more
Reviewed in the United States on August 11, 2020 by Lewis Weinstock

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