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

[Laci Toth]

I am after a lens with a focus ring which can cover the largest frame size or a camera which has the largest frame size and has a lens with a focus ring.
If it's a lens I would mount it on a lens board and clamp it on a box I build around it, if it's a camera I would use it straight away. I am only interested in large format sizes, 4x5 or larger. It doesn't matter if the film negative is not produced anymore as I am using paper negatives so I could cut them to custom sizes.

 

[DMS206]

There are several Goerz Dogmar lenses in a focusing mount on *bay, 165mm and 180mm, either would cover 4x5. 180mm should cover 5x7.

 

[bdial]

There is no real limitation, aside from the diameter that a focus mount could accommodate. There is no real relationship between the physical size of the lens and the format it can cover. I have a 180mm lens in a focus mount that covers 8x10 and it's only about 40mm or so in diameter including the mount.

 

[Ian Grant]

I could mount many my LF lenses in a focussing helical, definitely my 300mm Nikkor M so covering 10x8.

Ian

 

[BradS]

Fotoman make an 8x10 point and shoot... (the site is very slow to load)
http://www.fotoman.cc/showPro.asp?id=35

As others have implied, it is possible to purchase a focusing helical independent of the lens...but, I do not know where. Perhaps others can suggest a good supplier.

 

[Laci Toth]

Thanks everyone for your thoughts! I really appreciate it! My question wasn’t properly composed, I’m sorry about that!
So I would like to mount this lens on a pinhole camera box so I can use the pinhole and after changing the board the lens itself. But because it’ll lack of bellows I need a lens which can focus and it’s able to show me the distance in meter or feet. So I’m looking for a similar lens what is used on a 35mm camera but a large format version.
I’ve checked on the helical focusing mounts but as far as I could see they don’t show the distance and probably just for small adjustments rather than long distances.

 

[BradS]

I'm not entirely clear on your goal but, it might be simpler/more economical to get a camera that has a bellows and a lens and then fashion a pinhole to substitute for the lens. So for examples, a Mamiya RB67 - remove the lens and make a pinhole lens out of a body cap or some such...likewise, a crown graphic with a pinhole lensboard.

 

[Dan Fromm]

Laci, thanks for sort-of explaining what you want to do. Please give us more hints. In particular, what format are you shooting, how deep is the box, and which focal lengths do you want to use?

 

[Laci Toth]

I'm not entirely clear on your goal but, it might be simpler/more economical to get a camera that has a bellows and a lens and then fashion a pinhole to substitute for the lens. So for examples, a Mamiya RB67 - remove the lens and make a pinhole lens out of a body cap or some such...likewise, a crown graphic with a pinhole lensboard.

I’d like to build a very simple and lightweight design, without even a sheet holder, similar to Ilford Obscura but a larger size 5x7, 8x10. I’d mainly will use it as a pinhole or entirely if I won’t find a solution.
The main reason I started thinking about it is because I’d like to decrase the extra long exposure times I sometimes might face with as I won’t use sheet film rather photographic papers as negatives and then make contact prints, so medium format is way too small for this.
I’ll measure the distance with a rangefinder but then I need to focus with the lens because a fixed focus distance won’t work in a lot of situations.
As I use Ilford RC papers and they have an ISO around 3-6 a lens could decrease the exposure times significantly in certain situations.

 

[Bob S]

Thanks everyone for your thoughts! I really appreciate it! My question wasn’t properly composed, I’m sorry about that!
So I would like to mount this lens on a pinhole camera box so I can use the pinhole and after changing the board the lens itself. But because it’ll lack of bellows I need a lens which can focus and it’s able to show me the distance in meter or feet. So I’m looking for a similar lens what is used on a 35mm camera but a large format version.
I’ve checked on the helical focusing mounts but as far as I could see they don’t show the distance and probably just for small adjustments rather than long distances.

Both Rodenstock and Schneider made two types of helical mounts. One for large format taking lenses in a 0 shutter. These were specific to the actual focal length by lens model. They have both distance and DOF scales on them that are only accurate for that specific lens.
The other type are for using enlarging lenses for macro work. These have no scales.

 

[BradS]

I’d like to build a very simple and lightweight design, without even a sheet holder, similar to Ilford Obscura but a larger size 5x7, 8x10. I’d mainly will use it as a pinhole or entirely if I won’t find a solution.
The main reason I started thinking about it is because I’d like to decrase the extra long exposure times I sometimes might face with as I won’t use sheet film rather photographic papers as negatives and then make contact prints, so medium format is way too small for this.
I’ll measure the distance with a rangefinder but then I need to focus with the lens because a fixed focus distance won’t work in a lot of situations.
As I use Ilford RC papers and they have an ISO around 3-6 a lens could decrease the exposure times significantly in certain situations.

I see. It seems kinda tricky - unless you are careful about the designed focal length of your box....

One way to eliminate the need to focus is to choose a very short focal length lens, like 65mm (on 4x5) and build your box so that the film to flange distance of the box is the hyperfocal distance for some f/stop (like f/16 or f/22). If you use fast film, like HP5+ this is a very simple and workable solution that avoids the costs and complexities associated with trying to focus (you'll need a ground glass or calibrated focus scale).

Or, you might also think about a simple overlapping box kind of setup?

 

[BradS]

OK...that was a bit sloppy. I'll try to be a little more clear with a concrete example.
Let's suppose that you acquire a 65mm lens that will cover 4x5 (like a Schneider Super-Angulon or Rodenstock APO-Grandagon)
and suppose (I'm just making these number up, you'll have to get the actual values), suppose that the flange focal length of your chosen lens is 65mm
and suppose that at f/16 , if the distance from flange to film is 68mm (made up number) then everything from (again, numbers out of the blue here) 3meters to infinity is acceptably focused (this is the hyperfocal length of the lens at f/16)

then you could construct your box so that the lens mounting flange, the rear surface of the shutter, is 68mm from the film plane....and when the lens is mounted and set to f/16 you would know that everything from 3meters to infinity is acceptably in focus by design...make sense?

Otherwise you have to add some means to verify that what you wanted to focus on is in focus - which gets more difficult.

Adding a helical gives the ability to focus at an arbitrary distance but also necessitates some means of knowing that it is set so your desired subject is in focus...

 

[reddesert]

As Bob S alluded to, focusing scales are specific to the exact focal length of the lens (not the labeled focal length, as two different models of "150mm" lens could differ by a few percent).

Probably the best way to do this is to calibrate your own focusing scale. This could be done either by: using film holders and building your camera to take a ground glass back at the proper rear spacing to match the holders; or by taking test shots of a target oblique to the camera (like a fence running diagonally) with the lens focused at various settings, so you empirically calibrate the focus scale.

 

[Bob S]

As Bob S alluded to, focusing scales are specific to the exact focal length of the lens (not the labeled focal length, as two different models of "150mm" lens could differ by a few percent).

Probably the best way to do this is to calibrate your own focusing scale. This could be done either by: using film holders and building your camera to take a ground glass back at the proper rear spacing to match the holders; or by taking test shots of a target oblique to the camera (like a fence running diagonally) with the lens focused at various settings, so you empirically calibrate the focus scale.

See this:

http://www.rodenstock-photo.com/Archiv/e_Rodenstock_Analog_Lenses_27-42__8226.pdf

 

[Laci Toth]

See this:

http://www.rodenstock-photo.com/Archiv/e_Rodenstock_Analog_Lenses_27-42__8226.pdf

Thank you for the info! I appreciate it!

 

[Bob S]

Thank you for the info! I appreciate it!

Here are more:

http://www.rodenstock-photo.com/Archiv/Objektive_digitiale_Fotografie_d_10469.pdf

 

[Laci Toth]

OK...that was a bit sloppy. I'll try to be a little more clear with a concrete example.
Let's suppose that you acquire a 65mm lens that will cover 4x5 (like a Schneider Super-Angulon or Rodenstock APO-Grandagon)
and suppose (I'm just making these number up, you'll have to get the actual values), suppose that the flange focal length of your chosen lens is 65mm
and suppose that at f/16 , if the distance from flange to film is 68mm (made up number) then everything from (again, numbers out of the blue here) 3meters to infinity is acceptably focused (this is the hyperfocal length of the lens at f/16)

then you could construct your box so that the lens mounting flange, the rear surface of the shutter, is 68mm from the film plane....and when the lens is mounted and set to f/16 you would know that everything from 3meters to infinity is acceptably in focus by design...make sense?

Otherwise you have to add some means to verify that what you wanted to focus on is in focus - which gets more difficult.

Adding a helical gives the ability to focus at an arbitrary distance but also necessitates some means of knowing that it is set so your desired subject is in focus...

Thanks! Sounds interesting! Could you recommend me a good source from where I can get further infos in case I’d use a different set up as I’m looking forward how to calculate.

 

[Laci Toth]

As Bob S alluded to, focusing scales are specific to the exact focal length of the lens (not the labeled focal length, as two different models of "150mm" lens could differ by a few percent).

Probably the best way to do this is to calibrate your own focusing scale. This could be done either by: using film holders and building your camera to take a ground glass back at the proper rear spacing to match the holders; or by taking test shots of a target oblique to the camera (like a fence running diagonally) with the lens focused at various settings, so you empirically calibrate the focus scale.

Thanks for the idea!

 

[BradS]

Thanks! Sounds interesting! Could you recommend me a good source from where I can get further infos in case I’d use a different set up as I’m looking forward how to calculate.

I don’t know your background so please forgive me if you are already aware of these things.


First start with “online DoF calculator” and “online DoF table” tools on....
http://dofmaster.com

Think about what focal length you want to use. Shop for large format lenses - to get an idea for prices, etc.

...and dig up data sheets for large format lenses. The single most important piece of info for now is the flange focal length. This is the focal length you will put into the tools mentioned above.

I’ll come back later and continue when I’m on a real computer- am on the iPhone right now.

 

[Laci Toth]

I don’t know your background so please forgive me if you are already aware of these things.


First start with “online DoF calculator” and “online DoF table” tools on....
http://dofmaster.com

Think about what focal length you want to use. Shop for large format lenses - to get an idea for prices, etc.

...and dig up data sheets for large format lenses. The single most important piece of info for now is the flange focal length. This is the focal length you will put into the tools mentioned above.

I’ll come back later and continue when I’m on a real computer- am on the iPhone right now.

No worries it’s better to build it up from the basic.
So you mean the real focal length is measured from the place where the rear of the shutter meets with the lens board?

 

[BradS]

The flange focal length is tangible and relevant to actual camera (in this case your box ) design.

The actual focal length is a lens design parameter- not really a camera design parameter. For most large format lenses, the difference between two numbers is usually quite small.

edit: focal length is defined as the distance from the lens to the film plane when the lens is focused at infinity. The question then is from what point in the lens do we measure? Lens designers use the rear nodal point of the lens...which isn’t generally something that is physically tangible. When dealing with a physical lens, instead of a theoretical lens design on paper, we can the rear surface of the the shutter, where it comes in contact with the lens board it is mounted to, is physically tangible and real.
Thus if you make your box so that the lens flange surface is exactly one flange focal length from the film surface, the lens will project an image of a subject at infinity onto the film.

 

[NedL]

have a look at this

often, LF pinhole images are better with a wider field of view than you would normally use with a lens.... I've built a few fixed-focus lensed cameras, and was never satisfied when I tried them with a pinhole because the "focal length" was longer than I like for pinhole.... have fun!

scotch tape on cheap framing glass works okay for a makeshift GG.

 

[Laci Toth]

Laci, thanks for sort-of explaining what you want to do. Please give us more hints. In particular, what format are you shooting, how deep is the box, and which focal lengths do you want to use?

Hi Dan,

Would be nice to shoot 8x10. So I need a wide angle lens which I can mount on a box as deep as the lens needs to cover the negative size. There would be no bellows so the lens should be able to focus from short to long distances similarly to 35mm format or some medium format lenses. It’d be an advantage if it would have a focal scale but if not I can mark its focus ring.

 

[Laci Toth]

have a look at this

often, LF pinhole images are better with a wider field of view than you would normally use with a lens.... I've built a few fixed-focus lensed cameras, and was never satisfied when I tried them with a pinhole because the "focal length" was longer than I like for pinhole.... have fun!

scotch tape on cheap framing glass works okay for a makeshift GG.

I already have a pinhole and would like to make another one but as sometimes I face with extra long exposure times as I use paper negatives I’d like to try it with a lens and also for the experiment.

 

[Dan Fromm]

Hi Dan,

Would be nice to shoot 8x10. So I need a wide angle lens which I can mount on a box as deep as the lens needs to cover the negative size. There would be no bellows so the lens should be able to focus from short to long distances similarly to 35mm format or some medium format lenses. It’d be an advantage if it would have a focal scale but if not I can mark its focus ring.

Wide angle lens to cover 8x10? £££ - ££££, depending on which you get. Your answer raises more questions.

First key fact. Your camera will have no movements so the lens will have to cover 8x10 and no more. 300 mm circle will do it.

How wide do you want? Understand that because 8x10's and 24x36's aspect ratios differ there's no easy comparison. 24x36's normal focal length is 43 mm and 8x10's is ~ 300 mm. So, very roughly, half focal lengths are, respectively 22 mm and 150 mm. 24 mm on 24x36 corresponds to 170 mm, 28 to 200, 35 mm to 240 mm, all very approximate. You have to decide that before you can go shopping. 150 mm lenses that cover 8x10 exist, are dear. 180 mm lenses ... also exist and are more common, less expensive. 210 and 240, likewise.

Focusing travel. How close do you want to focus? The farther away, the less focusing travel you need given focal length. The lens' rear node (for most LF lenses, including w/a, this is approximately at the diaphragm) has to be one (1.0) focal length from the film when focused at infinity. That gives you approximately the box's depth.

There are formulas for calculating focusing travel from the infinity position given focal length and focused distance, whatever that means. In 35 mm land, focused distance usually means film plane-to-subject. I usually think in terms of magnification instead of distance, the magic formula I use is: rear node-to-film distance = focal length * (magnification + 1). You can see that focusing travel from the infinity position is just focal length * magnification. Magnification of 0.5 (1:2) will require 75 mm travel with a 150 mm lens and so on.

You might want to consider making a sliding box camera.