Rodenstock Grandagon 90mm 6.8

[Bob Salomon]

The indication by the manufacturer of f-22 has nothing in particular to do with sharpness or a recommended setting. It is the standard at which the angle of coverage is calculated. The lens will cover 4x5 adequately at any aperture unless you are using some extreme movement. In fact, I use mine on the 5x7 occasionally.

f22 is the diffraction limited stop. Beyond that on 45 and smaller you will start to degrade the image from diffraction.

[miesnert]

Thank you all for your answers, you have been very helpful.
I am wondering, why does Rodenstock mean on their website when they state: "working aperture f22-f32" ? If it is not for sharpness (because this is better at larger apertures and not for the image circle which is adequate at larger apertures as well?

[Bob Salomon]

Thank you all for your answers, you have been very helpful.
I am wondering, why does Rodenstock mean on their website when they state: "working aperture f22-f32" ? If it is not for sharpness (because this is better at larger apertures and not for the image circle which is adequate at larger apertures as well?

f22 is the diffraction limited stop. Beyond that on 45 and smaller you will start to degrade the image from diffraction.

[Bernice Loui]

Note what Bob replied regarding f22 and diffraction limit. Beyond this, The image is truly in focus only where the lens is focused, closing down the aperture ("stopping down") results in the other image areas coming into apparent focus.

Using the view camera movements can be used to enhance the areas that are in focus. With a wide angle lens, it does not take much tilt/swing to alter the plane of focus.

It pretty much comes down to what the image maker wants to be in focus in the image.. this is the degree of image focus control easily available on a view camera.

There can also be a significant reduction in exposure times due to reciprocity..

Suggest some experimentation to determine if using significantly larger apertures and reduction in exposure times and film speed results in meeting your image making needs. There are no fixed rules , it depends pretty much on what the image making hardware is capable of -vs- the needs of the image maker to achieve the image in mind.


Bernice

Thank you all for your answers, you have been very helpful.
I am wondering, why does Rodenstock mean on their website when they state: "working aperture f22-f32" ? If it is not for sharpness (because this is better at larger apertures and not for the image circle which is adequate at larger apertures as well?

[8x10 user]

I have actually used a 75mm Grandagon N F4.5 along side the Sironar Digital line with 22 MP phase one back. Both lenses were tack sharp at 100% (note, a higher resolution back would show a difference). The 9um pixel is very close to the grain structure size of slide film. The 9um ccd size roughly equates to a 10x enlargement by drum scan. Like others have said, you should be fine using it up to F/11. In general wider apertures are used with smaller formats and some of the aperture recommendations are based (in part) on the depth of field/coverage in a given format. Some of the longer Rodenstocks have F/33-F/45 down as a recommend aperture. Now is a 360mm Sironar S softer at F/16 then a 150mm? No, it just has lower DOF.

These were done somewhere around F/16, or maybe a little wider.

The first one is the whole image



And these are 100% view crops from the above image.

[8x10 user]

Hmm, I'm looking on Prograf and it looks like they have F/16 down for the F/4.5 version and F/22 for the F/5.6 version. So YMMV from my experiences with the F4.5.

[miesnert]

I have done some tests with the lens at f16 with Portra 400, they look nice and sharp, however the first one does seem to lose a bit off sharpness at the point deepest into the frame. In the second dof would never be a problem anyway.


Wista VX
Horseman 6x9 back
Rodenstock Grandagon 90mm 6.8 MC
f16
Kodak Portra 400


Wista VX
Horseman 6x9 back
Rodenstock Grandagon 90mm 6.8 MC
f16
Kodak Portra 400