Which is the largest format size a lens with a focus ring can cover

awty · Feb 18, 2020

My 14x17 camera is just a box inside a box. The inside box slides in and out to the dedired focal length. It was first just a pinhole, now have converted to take a lens. I just use a 8x10 ground glass to mark infinity for the desired lens and can focus closer with ground glass. F32 helps with not having perfect focus, or f125 and everything is in focus.

Bob S · Feb 18, 2020

F125 and everything is also in diffraction!

Dan Fromm · Feb 18, 2020

Bob S said:
F125 and everything is also in diffraction!

Still good enough for contact printing.

Laci Toth · Feb 19, 2020

So as this Goerz Celor 1B, 180mm is on the way, my plan is to calculate the right distance between the film/paper negative plane and the lens’ iris when it's focused to infinity, I'm not sure if that's the right solution though. So I assume that I‘ll start with 180mm unless someone won't come up with a better idea which I of course will consider as I’m far not an expert on the field. It’s all about fun that's the reason it's so simple. The box, paper negative in, the lens, the front cap as the shutter. Case closed, end up story, dot. I‘ll stick a white label on the focus ring and mark it with a pen so I know the yards. I might use a different colour for the in-between distances. 5x7 RC paper negatives are cheap 25p for each and I’ll halve them so I’ll use even less paper while I'm checking the accuracy. It doesn't have to be tack sharp though it's obviously an advantage but I'll make contact prints then on a fibre based paper which I then lith so the look of the final outcome is more like a painting rather than a photo.

Laci Toth · Feb 22, 2020

NedL said:
I really think you should consider a sliding box camera like Dan suggested or like the one I linked to. It can be a simple as two boxes made out of black foamcore, and you can build a working prototype in an hour or two. A lot of fun and great for big paper negatives! I've built a couple of them, but as I mentioned, even when the two boxes are fully nested, FL is not as close as I like for pinhole... I too was originally thinking of a camera to swap lens/pinhole, but without a bellows it's not very practical ( at least if you like WA pinhole like I do )...

So I made a slide box out of cardboard used a 3 pass black out material to cover it and also my head. I had a small glass and taped it at the back. I focused at infinity and opened up the lens. f4.8 was great till f16 after that it was so dim that I couldn’t see anything.
On the ground glass there was no image at all.
My other problem was that when I slided the box my eyes also started to focus so I couldn’t determine the sharpness. So I moved the camera until I saw the image on its wall. The f numbers didn’t seem to matter in terms of depth of field. The subject was about 50 yards away. That shallow field was about 10mm or a bit less or more. So I assume if the film plane would be there it’d be right. I measured the distance and it was approx. 190mm from where the lens was mounted on the cardboard.
I also used the lens focusing ability and the image apperared 15mm closer to the lens.
I don’t know. It’s a bit like nowhere.
I feel that it’s not beyond my comprehension, but for me it’s getting way too complicated even with a slide box. =D

Dan Fromm · Feb 22, 2020

Oh, dear. Perhaps you should look for a beat-up old press or view camera. Ian Grant, who posts here, may be able to direct you to a usable inexpensive Speed Graphic. PM him. The last time I checked, but in the US, not the UK going on little England, Cambo SCs and a variety of Sinars weren't too costly.

Interesting that you got no image at all on the GG. Please tell us more about things like the range of extensions you tried. Also, not to be insulting, but did you cut a hole in the back of the box and put the GG on it so that you could see them image the lens put on the GG?

Keep on tinkering, you'll get there.

Laci Toth · Feb 22, 2020

Dan Fromm said:
Oh, dear. Perhaps you should look for a beat-up old press or view camera. Ian Grant, who posts here, may be able to direct you to a usable inexpensive Speed Graphic. PM him. The last time I checked, but in the US, not the UK going on little England, Cambo SCs and a variety of Sinars weren't too costly.

Interesting that you got no image at all on the GG. Please tell us more about things like the range of extensions you tried. Also, not to be insulting, but did you cut a hole in the back of the box and put the GG on it so that you could see them image the lens put on the GG?

Keep on tinkering, you'll get there.

Dan Fromm · Feb 22, 2020

Thanks for the photos. How deep is the box when the inner box is as far in as possible. Why is the GG solid black? And what does photo 140SFCD-... show?

Laci Toth · Feb 22, 2020

Dan Fromm said:
Thanks for the photos. How deep is the box when the inner box is as far in as possible. Why is the GG solid black? And what does photo 140SFCD-... show?

46cm is the longest distance from the lens till the gg.
The gg is not solid black is just the reflection and on the other photo it’s just facing the table. It’s just a plain glass, I followed NedL’s advice.
140 sfcd shows the lines where the image is sharp, what I could see on the box’s wall. The first line from the us is when the lens is focused to infinity and the second is when it’s focusing approx. 1 yard.

Dan Fromm · Feb 22, 2020

You need a piece of ground glass. Plain glass won't do. Waxed paper has been used as a temporary substitute.

Laci Toth · Feb 22, 2020

Dan Fromm said:
You need a piece of ground glass. Plain glass won't do. Waxed paper has been used as a temporary substitute.

Okay, thanks!

Ron (Netherlands) · Feb 25, 2020

Guess you were asking for LF lenses in a barrel with a helical, perhaps like this one:

Here's a picture of how they used these lenses on a camera:

Which is the largest format size a lens with a focus ring can cover

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