How the distance for Rollei 35 is calculated?

[bitfeng]

Dear All, I am a new comer and need your kind help
I am confused by how to calculate the "distance" for Rollei 35. From the film plane? Or the front of the lens?
Thank you very much

[jayavant]

I suspect it would be from the film plain.

But how accurate do you have to be?

[bitfeng]

Hi jayavant, thank you very much for your reply. I also suspect it is from the film plane. The distance from the film plane and the front of the lens is about 5cm, or 2 inches. At f2.8 and 0.9m, this 5cm is huge.
I tested three of my rollei 35& 35s at 1m and 1.5m, with the film plane as the start point for the distance, and they all turn out to be near focusing in a silimar way. Therefore I am wondering if it is actually from the film plane.

Originally Posted by jayavant

I suspect it would be from the film plain.

But how accurate do you have to be?

[Vics]

I think that the maker thought you would estimsate the distance in feet (8 feet, 12 feet or infinity). For real focusing accuracy, try a rangefinder camera.

[bitfeng]

Hi Vics, thanks for the reminder. Actually I use both english and metric marks. One on the top and the other on the bottom of the ring.

Originally Posted by Vics

I think that the maker thought you would estimsate the distance in feet (8 feet, 12 feet or infinity). For real focusing accuracy, try a rangefinder camera.

[dct]

Originally Posted by bitfeng

Hi Vics, thanks for the reminder. Actually I use both english and metric marks. One on the top and the other on the bottom of the ring.

Decades ago I also had a B35 as my pocket P&S camera for daily use. I always closed the aperture a little bit to use mostly hyperfocal settings. Never used this camera for close up shots with blurry background at that time.

[bitfeng]

Thank you guys all! I used a OM1 + 50mm/1.8 for infinity collimation test of two of my 35S, then film tested at 1m and 1.5m with tape measure from approx the film plane. One is dead-on at 1m but maybe ~2cm off at 1.5m; another is dead-on at 1.5m but ~2cm off at 1m. Curious why the focus scale is not quite self-consistent. Infinity looks good for both though. Guess I am too obsessed at focusing accuracy -- cannot guestimate better than ~2cm any way. Why bother

Originally Posted by dct

Decades ago I also had a B35 as my pocket P&S camera for daily use. I always closed the aperture a little bit to use mostly hyperfocal settings. Never used this camera for close up shots with blurry background at that time.

[Nomad Z]

I reckon the focus scale is too small for setting distance to tolerances of 2cm. As Vic says, if you want that sort of accuracy, a rangefinder is far more effective. I use my 35S as a point and shoot for general snaps. If I really needed to do a close shot with it at f2.8, I'd maybe bracket the focussing and hope that one comes out okay. Got better things to do than mess around with tape measures.

[bitfeng]

well said. my wife said the same ...

Originally Posted by Nomad Z

I reckon the focus scale is too small for setting distance to tolerances of 2cm. As Vic says, if you want that sort of accuracy, a rangefinder is far more effective. I use my 35S as a point and shoot for general snaps. If I really needed to do a close shot with it at f2.8, I'd maybe bracket the focussing and hope that one comes out okay. Got better things to do than mess around with tape measures.