Snap into focus

dabsond · Joined: 22 Jan 2015 Posts: 37

Just putting this out there. I have been shooting some manual lenses for a while on my Canon T3. Not the best focusing platform out there. Small viewfinder and no chance of economically changing the focusing screen. I have tried quite a few manual focus lenses. My favorites being a Rikenon 135 f2.8, Super Takumar 50mm f1.4 and a Hoya 25-42mm f3.5. What I notice about these lenses is they seem to snap into focus much more noticeably than others. Not sure if it is the wider aperture or just the quality of lenses. My background is astronomy and I have quite a collection of scopes and eyepieces. Telescope eyepieces exhibit the same attributes I have mentioned. The ones I keep are the eyepieces that seem to snap into focus. What other manual M42 lenses do others use that exhibit these characteristics?

visualopsins · Expire: 2025-04-11

Those lenses snap into focus easier because the apertures are near the optimal f/3.5 "sweet spot" of the stock focus screen in your camera. However, getting a sharp photo at faster apertures with faster f/1.4 lens using that focus screen must be difficult to impossible.

I will wild guess the telescope eyepieces you like best have better correction for chromatic aberrations, and if wide field, the spherical corrections are better.