Focus and RF adjustment - revisited [Lynx 14]

[btgc]

Hello fellows,
after some time I'm able to sit back at '14 to make it user. I adjusted focus at 1m distance - for my eyes it's easier to see details at this distance than distant objects. And I'd prefer exact focus at distances up to 10m rather than infinity. Isn true that once it's set at 1m it's correct for 2m, 5m and OO too ? Usually, though, people start from OO and rely that close distances are focused well. Judging by eye, it's now sharp at OO too.

Next....when focus ring is set at 1m, RF doesn't align up. When RF were adjusted for OO focus setting, at 1m (and other intermediate distances) RF didn't matched. When adjusted for 1m, RF were off for OO.

So I touched linearity screw - with bigger head in upper triangle of VF section, near to semi-silvered glass; screw with smaller head just fixes RF module to body.

Basically I want to know if there's method for two-phase adjustment (infinity & linearity). I somehow managed to get things at approximate match, though not perfect.

From Winfried's older posts at KYphoto boards I got confirmation that RF doesn't perfectly compensate "real focus distance" to double picture coincidence and one has to choose in which range - close or distant - distance and RF match. Do I understand this correctly ?

If true, I'll prefer closer range to match, because of wide open shots.

Another question - do numbers on distance scale of lens ALL exactly match real distance? I wonder which part of number should line up to red mark - first number has red mark on left side, though infinity symbol has red mark right at middle. Where it should line up for intermediate distances - on left side or at middle ?

If someone has good advice, my mind is open. Thanks!

 

[FallisPhoto]

"Isn true that once it's set at 1m it's correct for 2m, 5m and OO too ? Usually, though, people start from OO and rely that close distances are focused well."

No, you calibrate lenses and rangefinders differently. For lenses, you start at infinity. For rangefinders you start at 10 feet. It would be nice if you could do them the same, but unfortunately, it doesn't work that way. If the focus of your lens looks good at 10 feet, it can be wildly off at 50 and infinity. If it is calibrated correctly for infinity, then it should be good for 10 and 20 feet. The double check for 10 and 20 feet is to check that the infinity adjustment was accurate. A lens requires the finest adjustments at long ranges -- just the opposite of how a rangefinder works. The checking at 10 feet and 20 feet is because many people can't see well enough to adjust it for infinity and will have to readjust it a few times to get it correct. Personally, I use a piece of frosted glass and a loupe.

With rangefinders you do just the opposite. You start at 10 feet and then go to longer ranges for fine tuning. This is because, given the way a coincident rangefinder works, it is going to be much more accurate, and require finer adjustments, at close ranges.

I'd suggest that you first calibrate the lens and then adjust the rangefinder to match it.

The numbers on the distance scale are supposed to exactly match the distance, particularly at close ranges. This is because, with both the scale focusing versions and rangefinder versions of each model, studio portrait photographers used to use tape measures to set up distance marks and their models stood on those marks. For portraits, pro photographers most often used wide open apertures and very precise focusing was critical. Have you ever been into an old time portrait studio and seen all the bits of tape stuck to the floor? Well, that's what it is for.

 

[btgc]

Thanks Fallis for exploded replay.

>No, you calibrate lenses and rangefinders differently.

This I figured out from many common adjustment descriptions.

> If the focus of your lens looks good at 10 feet, it can be wildly off at 50 and infinity.

Thanks, this is something new to me. Yeah, reason is same you mentioned - I used 50mm lens instead of 15x loupe and details at 1m meter are easier to see.

Seems I may have additional labor. This time it should go faster.

Note on portrait studios is very interesting. I don't remember that times, though I have used metal ruler to focus scale focus camera, so tape marks on floor is very logical solution.


Btw, I found that rangefinder patch coincidence with main picture depends on angle one looks into (this were known to me) as well as where object is located - on axis of VF or RF window. Keeping in mind no one follows exact placement of camera relative to subject while focusing I assumed there's some error and results depends on how one uses to know own camera.