some time ago I started with analog photography. I have a manual Olympus OM camera.
I mostly photograph landscapes with wide angle lenses.
In the beginning I used the split image indicator to focus to infinity. According to that, the photos were sharp if I turned the focusing ring to the very end. However, when I developed and digitized the photos, the sharpness was not optimal. I suspect that I turned the focusing ring a bit too far - I know from digital photography that infinity is actually 1 or 2mm before the endpoint. At the very end, the image gets less sharp again.
Then I did this: I mounted the lens with an adapter to my digital camera and checked where infinity is with the help of live view. Turns out, on this 21mm lens, infinity is right before the infinity sign, exactly at the 3m mark which is the last distance mark before the infinity sign.
However, if I now mount the lens on the analog camera and turn the focusing ring to 3m, the split image indicator indicates that the picture is not sharp at 3m and that I need to turn the ring a bit farther.
I have not yet had the possibility to test this with developed film. Is the split image indicator right or wrong?
So far I had a macro shooting at a butterfly house where I used exclusively the split image indicator and the pictures were very sharp.
There are separate issues here, the film body and the digital body with an adapter, and the lens itself.
You don’t say what lens you’re using. I would expect that an Olympus lens would focus almost perfectly at infinity on the film body. However, third party lenses may not be calibrated as well for focus at infinity at the end of the focus throw. If it’s an autofocus lens (not likely for an OM mount lens), those all focus past infinity in order for autofocus to find a ‘solution’ for focusing.
When using an adapter to put a vintage lens on a digital body, those are often not calibrated exactly for infinity at the end of the focus throw. Adapters often focus past infinity in order to assure infinity focus. That’s considered ‘better’ than focusing closer than infinity at the end of the focus throw. So testing on the digital body is no indicator of how the lens focuses on the film body.
You might be able to shim the adapter if you want to try that.
The split image rangefinder in the OM body is likely to be very accurate unless something has damaged the mirror, the pentaprism, or the correct seating of the ground glass focusing screen.
It’s also possible that some repair or wear on an OM lens has offset the focusing scale, but the split image focusing will compensate for that and remain the best indicator of focus if the mirror and focusing screen haven’t been somehow offset from factory specs.
Hello, the only way to test the quality of the split image indicator is to test! So load a film, shoot at infinity and at 3 meter and (after developing and scanning) your answer is there.
It can be the lens though, as you said your butterfly shots were sharp and I suppose you don’t shoot macros with a 21mm lens.
On the other hand, if you focus on infinity and stop down to f11 you have a great depth of field which will mask/eliminate the unsharpness.
Well, I have to add, the landscapes that were unsharp were shot with a 28mm f/3.5 OM Zuiko lens. I have to emphasize once again: according to the split image indicator they were sharp, but they were not!
I have not yet had the opportunity to test the 21mm thoroughly.
So you all are saying that if the split image indicator says that the image is sharp it is sharp?
The butterfly macros were taken with a 50mm f/3.5 macro lens.
The adapter is too thin, so it focuses past infinity.
Cheap, low-tolerance adapters do this to avoid complaints from people that they can’t focus to infinity.
For my Contax lenses adapted to Canon, I have two-piece adapters that I have shimmed to the perfect thickness so the hard stop is perfectly at infinity.
