My M8/M6 DOF comparison test results

[ampguy]

First photo is with my M6, 2nd two photos are with M8. Both are using the same 35/1.4 pre-asph lux at f8, and both are at 1/30th. Both are on the stationary tripod (note that the M8 has tripod threads under the center, M6 has tripod mount on side).

Focus for the first two images is on the "Scotch" tape wording on the tape on the white comforter, 6 feet away.

Focus for the 3rd image, or 2nd M8 image, focus barrel was moved exactly 1 stop on the DOF markings towards wider open, further focus of about 7 ft.

This author found no improved benefits for the DOF barrel move, to match the DOF of the film image.

Conclusion? Internet Myth Busted. Leica is correct in that no lens adjustment is needed with 35mm M-mount lens on the M8, in order to equal DOF of M FF systems.


Results are here

 

[jaapv]

I'm not disputing the conclusions you draw, but I must confess that I cannot see any significant DOF at all in that image. Maybe some more informative shots, please. And given the basic differences between the way DOF is rendered on film and on a sensor, a comparison between an M8 and an M9 would be more meaningful imo.

 

[Finder]

Thanks. The f/8 FF and M8 images show a change in DoF. As you would expect. I don't get the third image.

I guess I win again.

 

[ampguy]

Thanks

Thanks

Agree that the film, especially the 800 is grainy, and do wish I had an M9 to compare with the M8.

But the OP in the original thread had an MP and was moving to M8 so since I have an M6 and M8, I thought I'd show what I already knew was scientifically and mathematically correct.

I'll think about doing another comparison with some finer grained film and outdoors, but I'm really happy with the M8, and with the settings on the lens without any hocus pocus lens barrel tweaks for DOF that have no scientific bearing.

I'm not disputing the conclusions you draw, but I must confess that I cannot see any significant DOF at all in that image. Maybe some more informative shots, please. And given the basic differences between the way DOF is rendered on film and on a sensor, a comparison between an M8 and an M9 would be more meaningful imo.

 

[ampguy]

explanation

explanation

The 3rd image is with the lens barrel moved open 1 stop on the DOF scale. According to your posts, this is needed to provide equivalent DOF on an M8 to an MP. Reread your posts.

OK, you win if you say so. We have two winners here on RFF, Nick Trop, and you! Congratulations!!

Thanks. The f/8 FF and M8 images show a change in DoF. As you would expect. I don't get the third image.

I guess I win again.

 

[Finder]

The 3rd image is with the lens barrel moved open 1 stop on the DOF scale. According to your posts, this is needed to provide equivalent DOF on an M8 to an MP. Reread your posts.

OK, you win if you say so. We have two winners here on RFF, Nick Trop, and you! Congratulations!!

I did not say to move the lens barrel. I said you use the scales for one aperture stop greater. And your picture show beautifully that the depth of field did decrease when shot at the same f-number. Had you stopped down one stop on the M8, they would have been much closer.

You don't think doF changed? Just look at the remote on the right.

Perhaps you should go reread all my posts.

 

[ampguy]

here is what you said:

here is what you said:

Wow, go back and read your post #3, you are more wishy washy than George W.

I did not say to move the lens barrel. I said you use the scales for one aperture stop greater. And your picture show beautifully that the depth of field did decrease when shot at the same f-number. Had you stopped down one stop on the M8, they would have been much closer.

You don't think doF changed? Just look at the remote on the right.

Perhaps you should go reread all my posts.

 

[Finder]

This is my post:

DoF will decease as the sensor size decreases from a format designed for a specific lens. There is a relationship to the crop factor. A crop factor of 1.4 means the DoF field decreases by one stop (1.4 is the square root of 2)--if the lens is set to f/8, use the f/5.6 DoF marks on the lens (the difference between 8 and 5.6 is a factor of 1.4 or the square root of two). If the crop factor is 2, then use the f/4 DoF marks if the lens is set to f/8. So with the M8 with a 1.33 crop factor, I would use the lens DoF marks for the next larger aperture.

DoF decreases because magnification to a final display size increases.

I clearly say you use a different set of DoF scale marks. I do not say you move the lens barrel of refocus.

Go back and reread my posts.

 

[ampguy]

I did what you said

I did what you said

In M8 photo 1, I used the same DoF scale marks as when lens was on M6 at same position.

In M8 photo 2. I moved the lens barrel to "use one stop closer on the set of DoF scale marks"

This is my post:



I clearly say you use a different set of DoF scale marks. I do not say you move the lens barrel of refocus.

Go back and reread my posts.