SV193 2-Inch 0.8x Focal Reducer / Flattener for SV503 ED Refractor

SKU: W9152
US$ 135.99

SV193 2" 0.8x focal reducer and field flattener, designed specifically for SV503 70mm, 80mm, and 102mm f/7 ED Refractor telescopes, which can meet the illumination needs of full-frame shooting. The field flattener corrects the inherent spherical aberration of curved lenses which causes distortion at the edges of the field of view. The default back focus is 55mm. 70mm telescope's front end is an M54x0.75 socket to connect to the main lens. With SV193 0.8x focal reducer and field flattener, it can take dazzling celestial photos without worrying about the distortion of the star points on the edge of the photo.

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SV193 2-Inch 0.8x Photo Reducer / Flattener for SV503 ED Refractors

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3-Elements 2-Groups Lens Structure

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Hard Anodize Finished Aluminum Body

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SV193 For SV503 102ED -- Structure

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SV193 For SV503 102ED -- Installation Steps

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SV193 For SV503 70ED -- Connect With Filters

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SV193 For SV503 70ED -- Connect With Cameras

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SV193 For SV503 80ED -- Connect With Filters

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SV193 For SV503 80ED -- Connect With Cameras

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SV193 Photo Reducer / Flattener For Astrophotography

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1 reviews

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Definitely needed for astrophotography

I've got the SV503 70ED and the matching field flattener. Without the field flattener there is quite a bit of distortion outside of the center of the image. With the field flattener the distortion is moved to the very edges of the image and is very minor, leaving most of the image perfect and even if you don't crop the image the distortion is hard to notice unless you're looking for it. Back focus is critical to making this work as intended so get some small spacers to fine tune if you need to. One final note about filters - If you need to you can attach a 2" filter to the end of the field flattener designed for the SV503 70ED. You'll notice female threads on the end that attaches to the focuser and I was pleased to find that they're M48 x 0.75 - just what I needed to attach the SVBONY 2" filters. It screws in fine with the filter installed and doesn't leave you needing to change spacers to maintain proper back focus. I'm very pleased with the results I'm getting from my SV503 70ED and SV193 combo. It gives me the light weight and portable telescope I wanted.


Model SV193
Fit For SV503 70ED F6 SV503 80ED F7 SV503 102ED F7
SKU W9152A W9152B W9152D
Back Focus 55mm 55mm 55mm
Barrel Size M54x0.75 2-inch 2-inch
Threads Standard M48*0.75 M48*0.75 M48*0.75
Lens Structure 3-Elements/2Groups
Lens Coating FMC
Blackened Lens Edges Yes
Net Weight 273g / 9.63oz / 0.6lb 164g / 5.78oz / 0.36lb 177g / 6.24oz / 0.39lb


1. Designed for fixed field astrophotography with the SV503 refractor. While it will also thread through and work with other makes and models of f/6~f/7 refractors that use 2" focusers, its performance with other ranges cannot be well.
2. For faster and wider astro and terrestrial photography. After the focal is reduced, the starry sky can be captured wider, the star points are finer, and the signal-to-noise ratio is better under the same exposure.
3. In addition to shortening the focal length of the telescope for faster photography, the SV193 0.8X focal reducer/field flattener the normal field curvature inherent in all refractors.
4. The 0.8 times defocusing system shortens the exposure. It can meet the needs of astrophotographers who need sufficient exposure in a short time.
5. With SV503 refractor, it can take dazzling celestial photos without worrying about the distortion of the star points on the edge of the photo.
6. The default back-intercept is 55mm. Using the 360° field rotator at the end of the focusing tube (not included), you can meet your composition requirements without turning the main lens, and it can also meet the use of filter wheel/OAG/astronomical camera at the same time.

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