Mounting a LF lens on a focusing ring

[CHELLM]

Hullo everyone !
Say I have a LF lens that - once mounted on a flat board - from nodal plane / point to film plane needs 7 cm and from last lens to film plane needs 2 cm. If I need / want to mount this lens on a focusing ring large - say 4 cm - the distances of nodal point and last lens to film plane will be moved 4 cm forward the front of the camera or not ? Will the build of focusing ring make the difference or not ? Schneider - say - focusing ring will keep the same distances from film plane and "commercial" focusing ring will not ?

Say that all distances when lens is mounted on focusing ring are moved forward - what will be the solution to regain the original focusing distances ? Maybe a recessed board ?

Thank you for any answer - clue - documantation link..

Bye

[Bob Salomon]

Helical focusing mounts from lens makers for lf all maintain the flange focal length of the lens. What you apparently need is a top hat board or a set of extension tubes for a lens board like the Wista ones.

[Pere Casals]

Adding to what Bob said...

The recessed board would be a solution, but perhaps it has to be a DIY one because the 40mm deep, at least in CAMBO the common one is 30mm.

I guess you are speaking about something like this:

175944

Another solution is an adapter ring having a lens in it, like the nikon FX to canon FD adapters.

That intermediate lens that increases the flange to film distance has to be well calculated to not lose a lot of optical performance.


So the best solution is a focusing ring that can put the lens in the right place, and if not using a recessed board, DIY probably because the depth you may need.

[Dan Fromm]

Hullo everyone !
Say I have a LF lens that - once mounted on a flat board - from nodal plane / point to film plane needs 7 cm and from last lens to film plane needs 2 cm. If I need / want to mount this lens on a focusing ring large - say 4 cm - the distances of nodal point and last lens to film plane will be moved 4 cm forward the front of the camera or not ?

Correct. And then the lens won't focus to infinity.


Will the build of focusing ring make the difference or not ? Schneider - say - focusing ring will keep the same distances from film plane and "commercial" focusing ring will not ?

The only difference that may matter is the helicoid's length.


Say that all distances when lens is mounted on focusing ring are moved forward - what will be the solution to regain the original focusing distances ? Maybe a recessed board ?

The best solution is to use the lens on a short view camera. If you need movements, a short view camera with a bag bellows. Otherwise, if 4x5 then a Pacemaker Crown Graphic should do just fine. Minimum extension 52.4 mm. This assuming that y'r rear node to film distance >= flange to film distance. If 2x3 without movements, a Century Graphic or a 2x3 Crown Graphic.

[CHELLM]

Ok, Bob, I know what you mean - just skip the helical ring alternative and go to top hat board. I will highly consider your advice

Grazie..

PS
just 2 years ago I went to Linhof, München to have my Family Technica restored.. Christopher - the 34 yo tech - did a superb job, it's just like new..

[CHELLM]

Yes, Pere Casals, one of the point is the recessing depth requested .
Sincerely, I will pass over the adapter with a lens in it as quality of lens would be "unknown"

Grazie..

[CHELLM]

Hullo, Dan..
Downsizing / scaling the film format could be a solution to all - but you know photographers - never happy with the easiest way and with small film size.. I try hard to find a less width focusing ring and do new calculations about rear nod distance >= flange to film plane..

Grazie..

[Dan Fromm]

I must not have been clear. Most modern w/a lenses that cover 4x5 will work on a 4x5 Pacemaker Crown Graphic. One of the Pacemaker Graphics' strong points is that the inner (in the box) and outer (on the front door) bed rails are linked. This makes focusing lenses that make infinity with the front standard on the inner rail easy.

A top hat board adds extension. You don't want that. If you are going to use a helical to focus (why? And what is the lens?) then you'll need a deep recessed board. Wide, too, to let you reach the helical to focus.

[Pere Casals]

Pacemaker Crown Graphic.

And this includes a fine rangefinder... allowing for hand held or monopod shots

Also an SW light saber may come included !

[CHELLM]

Hullo, Dan (& all)..
Sorry for delayed reply but had a Pc RAM crash..
Yes, you are right, I need less extension - not to add. I'm trying / studying to adapt a wood pinhole 4x5 camera to a Wide Angle (from now WA) Camera. Today wood carpentry can be precise to 1/16 of inch - and even less. As I was adding to pinhole camera a lens board I didn't want to renounce to focusing possibilities - as pinhole cameras have any. The process would be:
1- making a larger hole out of original pin hole
2- adding a lens board with helical ring and the lens of my choice
Doing like this I will move forward the focusing plane of the lens.
I considered 2 Schneider lenses: the 58mm XL f.5,6 or the 72mm XL f. 5,6. In the following chart (that I'm sure all you know)
https://www.schneideroptics.com/pdfs/photo/LensCharts.pdf ( Flange focal distance - column S' A infinity ) the distance from flange to film plane is given of respectively 70 mm and 82,2 mm. Therefore from last lens to film plane there would be respectively a distance of *about* 30 mm and 40 mm. But adding a focusing ring will move forward the film plane and impeding to focus at infinity and making my set to need a recessed board
I took the advice of a top hat board in this way: I wil ask to cut part of the wood pinhole camera box and making a new wood front standard for the WA Camera. Then mounting a top hat lens board precise to the need of chosen lens and focusing then with the hyperfocal distance - i.e. f. 32 in focus from - say - 6 meters to infinity ; f. 45 in focus from 4,5 meters to Infinity and so on..

Hopefully at the end the result should be close to this
https://www.ebay.it/itm/K-B-CANHAM-4x10-CAMERA-LIMITED-WALNUT-with-90mm-Schneider-XL-Large-Format/372245954344?hash=item56ab967f28:g:sdAAAOSwX7BaaATR
[ when you get the above page scroll down to see the camera taken as prototype)

but at a very lower money.. ;-)
Best

Mauro

[Dan Fromm]

Mauro, how thick -- front of front panel to film plane -- is the wooden pinhole camera?

[CHELLM]

This is another pinhole camera to adapt for Schneider 58mm XL and 72mm XL - both f. 5,6

https://www.ebay.it/itm/Karlos-136-4x5-pinhole-camera-with-75mm-focal-length/123014653709?hash=item1ca43ea70d:g:BgkAAOSw6ctapYzD

Mauro

[CHELLM]

Hullo, Dan..
for some reason I don't see a much more extended reply.. Anyway the distance from front standard to film plane is about 75mm - I say about as the front standard may have different tickness over the surface itself..
We are trying to adapt a very inexpensive pinhole camera before trying to adapt instead one of these:

http://www.zeroimage.com/

or any other of the like..

Bye

Mauro

[Dan Fromm]

A pinhole's focal length is the flange-to-film distance. So the ebay camera's body is 75 mm +/- a little thick.

If you're going to use a box camera a Schneider -XL lens' coverage and, therefore, expense, will be wasted.

If you want to experience the joy of tinkering, by all means adapt a pinhole camera - why not a cigar box? - to take a lens on focusing helical and have fun. But if your goal is to shoot wide angle lenses on 4x5 getting a 4x5 Crown Graphic and lenses that cover little more than 4x5 is probably the better approach.

[Dan Fromm]

This https://web.archive.org/web/20180319151513/https://www.ebay.com/itm/Rare-Burke-James-Orbitar-4x5-Wide-Angle-Handheld-Camera-65mm-Schneider-Lens/222885215844?hash=item33e4fe7e64:g:bR4AAOSw9Cpaq4hK is approximately what you want to make. The box is very thin.

[CHELLM]

Hullo, Dan..
Beautiful camera - very tempted ! Yes more or less is what I aim to..
Certain China or Hong Kong wood pin hole camera makers sell their 8x10 for around 500 USD - beautifully finished ..

http://www.zeroimage.com/

Best

Mauro