Astromania Focal Reducer f/6.3, Fully Multi Coated Focal Reducer Corrector That Reduces Focal Length & Ratio 37% for Telescope Eyepiece Observing, Work for C Series Schmidt-Cassegrain Telescopes

Exactly What I Needed – Huge Improvement in My Views! I purchased this 0.5x focal reducer to use with my telescope for both visual astronomy and astrophotography, and I couldn’t be happier. The build quality is solid, the glass is crystal clear, and it threads easily onto my camera adapter or eyepieces without any issues. The difference is night and day—literally! My field of view is noticeably wider, which makes it so much easier to fit large objects like the Moon, Orion Nebula, and star clusters into one frame. For imaging, it really speeds up exposure times, which helps bring out more detail and color in less time. No noticeable distortion, minimal vignetting, and stars stay sharp across most of the field. For the price, this is an absolute game-changer and a must-have accessory for anyone serious about deep-sky observing or astrophotography. Highly recommend!

It works as intended. While distortion can be seen at the outside of the field, its a lot cheaper than many of its competitors (including the much better Starizona one, its logical upgrade). Something that works is to focus a star mid-way through the image. Make sure you get the distance right (105mm is ideal), and get good flat frames to counter the vignetting you may get with larger sensors.

This is an achromatic (color-corrected) doublet (two lenses glued) that is plano-convex (one flat side, one curved outward). Typically you want to look at (or aim your camera at) the flat side of the lens, yet mine shipped with the curved side facing the male threads/user/camera. I used vernier caliper teeth to gently unscrew the retaining ring and carefully with a cotton pad reversed the lens. After reversing the lens, it went from hazy and distorted to sharp, clear, and color corrected. I'm glad I took a chance on this because it's a great find and an amazing pairing with my sv205 astrophotography camera with it's imx415 sensor (only 6mm diameter, but 4k). This helps 'shrink' the image coming from the telescope down so more of the telescope's image and definition fit on the sensor, making a WORLD of difference. If you're looking at this vs the $10 one - get this. By comparison, the $10 versions: - use a smaller lens, have really bad color fringing, even just for visual use

This is an excellent reducer. I use this with my Celestron CPC 800 (f10) and Nikon D3300 DSLR and calculated that I get about 0.6x reduction based on the field of view. You also need a Celestron T adapter and camera-specific T ring to connect the telescope to your camera. These should give a proper back focus. I’m able to get perfect focus (using Bahtinov mask) and I don’t see any distortions of star shapes. It’s nice to be able to have a wider field of vision and faster light acquisition compared to DSLR without reducer.

As advertised, reduced image so I could capture full moon image with my current imager and configuration.

I have three of these from various makers, and they are coming in handy. When setting up a scope you probably want a very wide field view to find stars for lining up your sight. Pop one of these on your highest number eyepiece. The downside is that these may not give great field flatness, possibly producing strange flare effects. Handy, but no substitute for a really high quality field flattener if you are going for wide angle views.

I got this .5X reducer to use with my Celestron 127 SLT telescope - it is a Maksutov Cassegrain telescope. The problem I was trying to solve for is that without the adapter, the sun and moon fill the screen when my camera is attached, so I am unable to capture the images showing the full moon and sun without them being close to the edge of the photos, and they get cropped in videos. This .5X reducer alone did not work - not a fault of the reducer, it is simply how it works with my telescope. When attached to the camera adapter and inserted into the telescope, the telescope would not focus. I had to additionally purchase an extension adapter to move the camera further away from the telescope to attain focus. This combination worked beautifully. The reducer did indeed widen the field of view as I wanted. I tested during the day and was able to figure out just where my focus ring needed to be adjusted. Then back out at night, everything was set but when it was time to take photos, I could not get rid of the halo around the moon. I tried adjusting the exposure on the camera and nothing worked. I also double checked to be sure that the reducer was clean of fingerprints or any smudges, etc. I'm including photos of the moon with and without the reducer to show the difference.

Works well. Well machined threads. Allows for full view of sun with solar filter or moon with 8” sct.