Carl Zeiss on EOS 5D with CY mount adaptor issue

I got a CZ 35mm/2.8 len mounted on the my Canon 5D. So far all my shots are sharp and contrasty, except those taken using scale focusing (hyperfocusing). Has anyone tried scale focusing on mounted len?

Thank you.

Do you have some example shots with the CZ lens?

I've tested hyperfocal focusing vs. infinity on a landscape with 35mm and 50mm lenses and found focusing on infinity to be far better. The theory with hyperfocal focusing is that the DOF should extend out from 1/2 the indicated distance on the lens to infinity but I found distant objects to be unacceptably blurred.

foxbat wrote in post #2092925
I've tested hyperfocal focusing vs. infinity on a landscape with 35mm and 50mm lenses and found focusing on infinity to be far better. The theory with hyperfocal focusing is that the DOF should extend out from 1/2 the indicated distance on the lens to infinity but I found distant objects to be unacceptably blurred.

I second that !!

I have just recently purchased a CZ Distagon T* 18 mm f/4 with an incredible distance scale, and trying to use it at hyperfocal, the far distances objects are blurred. I have to scale down to half scale distance (from the theoretical hyperfocal) to get the infinity clear.

Anyway I have ordered a better C/Y adapter to check if it´s a problem or not with the adapter (although the first one I did ordered said no issues with infinitum).

The distance scale was made for the lens mounted on a Contax type camera. The adapter lets you use it on the Canon and allow infinity focus. However, you will need to re-calibrate the scale before you can rely on it and this will differ from adapter to adapter (with differing thicknesses it's like having different settings on the scale)

AJSJones wrote in post #2093119
The distance scale was made for the lens mounted on a Contax type camera. The adapter lets you use it on the Canon and allow infinity focus. However, you will need to re-calibrate the scale before you can rely on it and this will differ from adapter to adapter (with differing thicknesses it's like having different settings on the scale)

Thanks for the info.
That´s I suspect (it sounds logical), for that reason I did ordered a new adapter from a different source to check it.

Thanks for all the info.

How do we know what to look for when buying another adaptor. I don't think any adaptor resellers mention about scale focusing in their marketing.

markloy wrote in post #2094779
Thanks for all the info.

How do we know what to look for when buying another adaptor. I don't think any adaptor resellers mention about scale focusing in their marketing.

Yeah, problem is the thickness of the adaptor. The C/Y lens goes stright on coupled to the body of the camera. When you put an adaptor, you put a tinny or a thicker piece of metal in between, so focal distance change slightly.

The only way is to search in the adaptor´s specs if there is something about o just look in the forums for other´s experience to see which one is the recomended.

The register - front of lens mount to film plane/sensor - on a Canon EOS is 44mm.
Therefore any lens made for a camera with a greater register - C/Y is 45.5mm - should be able to give infinity focus on an EOS body.

If the lens + adapter focuses at infinity when viewed through the finder then all the other distance scale markings should be accurate.
If the distance scaleis not accurate then infinity focus is likely to occur before the infinity mark on the lens; the thickness of the adapter could account for this as fitting the diameter of the C/Y bayonet inside the EOS mount may mean that a certain amount of mis-registration has to be accepted.
The only way to know is to measure the thickness of the adapter - which in the case of C/Y to EOS body should be 1.5mm

Any example images to share? I've often considered going this path.

I have posted some photos (those I focused at infinity or at certain objects). I did not post those I used scale focusing because none of them came out sharp. All photos did not go through post processing.

Len used: Contax distagon 35/2.8 with CY EOS adaptor on Canon 5D.
Aperture used: f5.6, f8.0, f11.0
Speed: around 1/125 - 1/250

The Link is : http://public.fotki.co​m/markloy/shanghai_200​6/

PaulB wrote in post #2095863
The register - front of lens mount to film plane/sensor - on a Canon EOS is 44mm.
Therefore any lens made for a camera with a greater register - C/Y is 45.5mm - should be able to give infinity focus on an EOS body.

If the lens + adapter focuses at infinity when viewed through the finder then all the other distance scale markings should be accurate.
If the distance scaleis not accurate then infinity focus is likely to occur before the infinity mark on the lens; the thickness of the adapter could account for this as fitting the diameter of the C/Y bayonet inside the EOS mount may mean that a certain amount of mis-registration has to be accepted.
The only way to know is to measure the thickness of the adapter - which in the case of C/Y to EOS body should be 1.5mm

That´s correct, but we are going beyond ....

I can shoot correctly to infinitum when I put the middle mark of the scale to infinitum, no problem,

But we are trying to use the hyperfocal and shooting in that conditions, LEt´s say with my 18 mm f/4 lens: I select f/11 for the diaphragm and adjusting the scale dial if I put the infinitum over the right mark of the f/11, I can go through 0.4 mt´s with the left mark of the f/11.
Then I shoot --->> It should be clear between 0,4 mts & Infinitum. But not, in my case the far objects are blurred. But if I adjust the infinitum of the scale to the right mark of the f/8 instead or a little bit less, shooting with the f/11 set, then the far objects are clear. It means there is a decalage or offset to be accurate using the full scale.

About DoF with digital camera's and an article advising not to use hyperfocal distance

Several points:

1. If the adaptor places the lens such that when the scale reads infinity, infinity is in focus, then there is NO difference between the Canon and the original Contax cameras in function. The scales for both distance and aperture mean exactly the same thing in both applications.

2. Depth of field does not mean sharp focus. Depth of field means acceptable sharpness even though not in focus. For something to be acceptable, it must exceed a standard of quality. The standard of quality is the issue here. I'm not talking about lens quality, but rather image quality for things almost but not quite in sharp focus. No matter what your aperture, only the plane of sharp focus is sharply focused. At small apertures, items in front of and behind the plane of sharp focus may be acceptably sharp, but they are not sharply focused.

3. "Acceptably sharp" means that the details resolved outside the plane of sharp focus appear to be sharp in the final print.

4. Depth-of-field scales on lenses make assumptions about what is acceptable. They assume a print size and viewing distance in determining acceptability. If you enlarge the print more, or if you view the print more closely, or if you have higher standards than they assume, the result will not be acceptable sharpness.

5. "Hyperfocal distance" means that distance which, when sharply focused, just permits infinity to be within the depth of field, as defined above.

6. If your standard of acceptable sharpness exceeds that which is the basis for a depth-of-field or hyperfocal distance scale or table, you will find the results unacceptable. Your alternatives are to derive your own table, which will direct you to use a smaller aperture or a longer hyperfocal distance, or determine those smaller apertures through experimentation.

7. When using the hyperfocal distance, you will never see the same sharpness at infinity as at the plane of sharp focus when viewing the image in actual pixels on your computer monitor. That corresponds to a print far larger than was the basis for any reasonably depth-of-field calculation. Before rejecting it, make a print of the target size and evaluate it from normal viewing distance.

8. The size of the fuzzy spot made by a sharp point that is slightly out of focus is called the circle of confusion. That's the measure of the precision in a depth of field table.

9. You can, always, just experiment to determine what works. I have some lenses that I can count on for the work that I do if I stop down two stops below their scale. In other words, the f/5.6 part of the depth of field scale is reasonably accurate when I stop down to f/11. I arrived at that through experimentation, not calculation.

Rick "offering some basic depth of field truths" Denney

Rick's explanation is an excellent one.
The problem isn't helped by the fact that the distance/DoF scales on lenses are not always accurate either - even on expensive lenses - and this is compounded by the ability we have to see sharpness from a digita limage on a monitor at magnifications which would rarely have been possible, or even deemed necessary or disirable, by the manufacturer of lenses when film was the only recording medium.
Moral - don't trust lens markings for DoF .