relationship between 54 lenses and a 6 x 7 rollfil back?

[joshdaskew]

Hi, I was hoping that someone could help me with this. I currently own a
Chamonix 45N-1 and have a 65mm, 90mm, 135mm, 150mm, 210mm and a 300mm lens. I was just wondering what the relationship is between using these lenses with a 67 rollfilm back and then what focal length these lenses effectively become?

Also, was just wondering what the relationship is between these same 54 lenses and a 6x4.5 back (or digital sensor)?

Also, was just wondering if the current line of Schneider or Rodenstock digital lenses can be used with a film back and if so, whether they will cover 6x7 (without movements)?

Ok, thanks for all your help. Best Regards Josh.

[John Schneider]

See p. 232 for the format conversions:
http://www.bhphotovideo.com/FrameWork/Product_Resources/SourceBookProPhoto/Section04LgFormatLenses.pdf

[joshdaskew]

Hi, I am not quite sure if I worded my question properly. I am looking to use a rollfilm back on my 5 x 4 which I thought would make all my lenses effectively a "longer" focal length? For example, I thought a standard lens on 5x4 would become a 210mm or so? From what I understand of that table it is showing the relationship "between" formats ie standard focal lengths across the various formats. Ok, thanks so much again for all your help. Best Regards Josh

[dave_whatever]

Your 65mm on 6x7 acts as a fairly wide angle (similar to a 110mm on 4x5").
Your 90mm is a normal lens on 6x7 (similar to a 150mm on 4x5).
Your 135mm is a short-long lens on 6x7 (similar to a 240mm on 4x5).
And so and and so on.....

Basically multiply your focal length by about 1.7 to give you a 6x7-to-4x5 equivalent (i.e. 65mm x 1.7 is about 112mm).

[cjbroadbent]

You might find it easy to think of it this way:
A short lens is as long as the short side of the film. A normal lens as long as the long side of the film. A 'portrait' lens as long as the short side plus the long side.
Some will object that a normal lens is as long as the diagonal of the film; that's Leica lore and good for taking slices of life out of their surroundings. I you tend leave some breathing space for your subject, stick to the easy way of thinking.

[domaz]

Lens that cover a wider field of view are not as sharp in lines/mm as those that cover smaller formats, that is also something to consider, does it really make sense to use conventional LF lenses on a 6x4.5 back?

[Jack Dahlgren]

Lens that cover a wider field of view are not as sharp in lines/mm as those that cover smaller formats, that is also something to consider, does it really make sense to use conventional LF lenses on a 6x4.5 back?

Sure, why not? You can also use lenses from 2x3 or 3x4 cameras. If you want you can probably figure out a way to mount lenses from medium format cameras as well. Some of the new digital lenses are optimized for smaller backs and to deliver more parallel light to the sensor, but they give up coverage in return.

If your goal is higher amounts of detail on film you are going to do better with larger film so slap some 4x5 film in there or step up to 5x7, 8x10, ...

If you have a necessity for roll-film, then consider a camera dedicated to rollfilm. Mamiya 7 is very sharp for 6x7cm.

I think using 120 roll-film on a 4x5 is a compromise at best. It makes more sense on something like a 2x3 graflex. But it is up to you.

[Vaughn]

Lens that cover a wider field of view are not as sharp in lines/mm as those that cover smaller formats, that is also something to consider, does it really make sense to use conventional LF lenses on a 6x4.5 back?

Definitely -- especially if one wants to take advantage of the movements of a view camera. LF lenses are, generally, sharp enough...especially if one uses the middle f/stops. All depends on the size of the final print.

I have only used a 6x7 rollback on my 4x5 using a 150mm lens. I was a little disappointed with a B&W 16x20 print (I did not use the best f/stop), but color images up to 11x14 were fine.

Vaughn

[dave_whatever]

Definitely -- especially if one wants to take advantage of the movements of a view camera. LF lenses are, generally, sharp enough...especially if one uses the middle f/stops. All depends on the size of the final print.
Vaughn

Especially if you're in need of tilt to get a lot of depth of field. If you're stuck shooting at f/22 with a fixed-geometry medium format camera then shooting with large format lenses on a 6x7 back will likely give you the same sharpeness (almost all lenses operate at diffraction limits by f/22, its a great leveller!) but with the advantage of tilt and shift.

[joshdaskew]

Sorry about the late reply, have been without internet access for a bit.. Thanjs everyone who helped me out and answered, much appreciated!! Am basically just trying to het a bit of a travel kit together so it as much about trying to cut down on weight and bulk etc etc as well as having some movements.. Thanks again, much appreciated!! Best Regards Josh:)