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View Full Version : larger format lenses(8x10) on smaller(4x5) format system?



buggz
19-Apr-2012, 17:36
Hello,
I have a 4x5 Sinar f2
I was thinking, that the "effects" from 4x5 petzvals and soft focus type lenses would work better on a 4x5 system,
rather than using a lens that is for 8x10.
I am mistaken on this?
Though, the longer focal lengths would make for a nice perspective difference...

STILL learning lens designs, etc.

Leigh
19-Apr-2012, 18:02
A lens designed for an 8x10 camera will give a reduced image on 4x5.

Shoot the lens on an 8x10 camera.

Take that negative and a pair of scissors.
Cut out any 4x5 section of that negative.
That's exactly what you'll get with that lens on a 4x5 camera.

Nothing more, nothing less.

Remember...
A lens throws an image circle at the plane of focus.
It knows nothing about what film, if any, is at that plane.

- Leigh

genotypewriter
22-Apr-2012, 22:06
I was thinking, that the "effects" from 4x5 petzvals and soft focus type lenses would work better on a 4x5 system, rather than using a lens that is for 8x10.

Three things pop to mind here...

1. If the lens design is the same, a lens that covers 8x10 and a lens that covers 4x5 will produce identical (temporarily ignoring DOF) images, but the 8x10 image will just be larger. However, the "look" (whatever that may be to you) that lenses produce typically vary across the image circle radius.

So if you put a 8x10 lens on a 4x5, your image is going to consist of the "look" that particular lens design produces in the middle of the image circle. When you put a 4x5 lens on 4x5 of the same design, you're looking at pretty much the whole image circle.


2. When speaking about lens designs, a lens can be made to different focal lengths but the f number stays the same. So if using a 8x10 on 4x5, the 8x10 lens will be longer than a 4x5 lens of the same design. If we're comparing the same lens design on 8x10 vs. a 4x5, with different focal lengths to get the same image, the DOF will be different between the two.


3. If the lens design is the same, a version that covers only 4x5 will be sharper than one that covers up to 8x10 because the larger image circle means the aberrations are also magnified, at least in theory. However, since you will only be looking at the center of the image circle with a 8x10 lens on 4x5 and the whole image circle with a 4x5 lens, it's not going to be a straight forward comparison.


Of course... the more variables you change, the more stuff we can say.

rdenney
23-Apr-2012, 05:15
Hello,
I have a 4x5 Sinar f2
I was thinking, that the "effects" from 4x5 petzvals and soft focus type lenses would work better on a 4x5 system,
rather than using a lens that is for 8x10.
I am mistaken on this?
Though, the longer focal lengths would make for a nice perspective difference...

STILL learning lens designs, etc.

Lenses like these are often used with formats larger than they were original designed for in order to get more pronounced pictorial effects around the edges. If you take a smaller format bite out of the middle of the lens's field, you will lose some of those effects.

So, if those effects are important to you, then you will probably want to stick with the shorter focal lengths. Those shorter focal lengths were probably intended for smaller formats (e.g., quarter plate, 2x3), because their original designers would have been seeking a sharp image across the frame.

Other than that, people use lenses with coverage for 8x10 on 4x5 cameras all the time to get the longer focal length. The 12" lens I use on 4x5 was definitely intended to be a "normal" lens on an 8x10 camera, and the 8-1/2" lens I play with on my Speed Graphic was definitely intended to be used as a "normal" lens on a 5x7 camera.

Rick "generally preferring sharp images across the entire focus plane" Denney

buggz
23-Apr-2012, 09:12
Bummer, it is as I feared.
Thanks for the information.
Sigh, this is getting rather expen$ive now, contemplating an 8x10 format kit for my Sinar f2...

Old-N-Feeble
23-Apr-2012, 10:35
*never mind* query already addressed.