Depth of field on M8 vs MP... Sorry for being thick!

[Leicaliker]

Guys

Sorry if I should know this... :bang: but I am new to digital and the smaller format of M8 vs 35mm MP. I have shot 35mm film for 25 years so it's a bit like being a kid again!

If I use my 35mm Summicon I get 47mm-ish field of view equivalent on the M8. Right? So does the DoF change from that indicated on the lens barrel or can I still use the markings for hyperfocal and so on. Does the DoF REDUCE as the effective focal INCREASES?

Many thanks for your help and support.

Andrew

 

[ampguy]

The lens is the same. Leica says the DOF markings are still fine for the M8.

The images you take are the same as with the MP, just cropped a bit.

Experiment with some side by side prints and decide for yourself. I find that even for film I like a bit narrower settings than what is on the barrel of the lens.

Remember, there is only one true point of sharp focus.

 

[Finder]

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.

 

[Frankie]

Try this:

http://www.dofmaster.com/dofjs.html

Select Leica M8/8.2 and lens focal length...

 

[aizan]

circles of confusion are confusing, aren't they?

 

[ferider]

Finder (post #3) said it better than I could. It's a good question and people get confused easily, mainly because 2 scenarios are mixed:

.) if you use the same lens (same physical focal length) and the same subject distance, DOF decreases with increasing crop factor.
.) if you use the same effective FOV, DOF increases with increasing crop factor.

Roland.

 

[arturo]

The issue is indeed confusing. I believe both Finder and ferider are correct above, but my experience de facto is the opposite of Finder: when using crop factor cameras the DOF increases. If you compare a MP with a 50mm lens and a M8 with a 40mm and you shoot the same subject with the same frame, DOF is bigger with the M8. If you shoot with a MP and a 50mm lens and you repeat the shot with a M8 and a 50mm lens, walking one step back to keep the same frame, the result is the same: DOF is bigger with the M8.
In digital, if you want swallow DOF you need a full-frame camera.

 

[splitimageview]

The bigger the film/sensor, the shallower the DOF, all other things being equal. The M8 will have slightly more DOF than the MP with identical lenses.

 

[ferider]

The bigger the film/sensor, the shallower the DOF, all other things being equal. The M8 will have slightly more DOF than the MP with identical lenses.

It is exactly statements like this that fuel the confusion, because they are meaningless.

"All other things begin equal" meaning what ? Focus distance ? Image coverage ? At the same focusing distance the statement is wrong. With identical image coverage and different focus distance the statement is correct.

A Hasselblad with an 80mm has less DOF than a Leica with a 50. But try the Hasselblad lens on the Leica.

 

[ampguy]

It's not confusing at all.

With an M8, you can immediately see the results, but I recommend spending a few dollars to do this test:

1. Use what Leica recommends, the DOF scales on your Leica lens.

2. The metaphysical square root of 2 method as proposed by Finder

3. Using both methods above, focus at your favorite subject distance and exposure settings, with objects placed at noted distances in front of and in back of what you focus on.

4. Go make prints at Walgreens at Costco, in the print sizes you usually print at.

5. Analyze who is right, Leica, or the Internet??

To understand the real science that Leica, Canon, Zeiss and Nikon base their DOF on, the best site I've found is here:

http://dpanswers.com/content/tech_crop.php#dof

Forget about dofmaster.com for a bit, and study the link above.

 

[ferider]

Can we see the Leica quote, Ted ?

It's very simple really:

1) take a "bokeh shot" with background lights on film; scan in; print it on 5x7.
2) take the scan into Photoshop; crop it by factor 1.3; enlarge it and print it out on 5x7.

The OOF circles of 2) will be 1.3x larger than 1). Less DOF in the cropped picture.

2) is equivalent to taking the same picture as 1) on the M8, at the same focus distance.. Ergo, the DOF marks on the lens mean something different for MP vs. M8.

DOF is defined for fixed print size and viewing distance.

Here is a longer explanation (scroll towards the end):

http://www.luminous-landscape.com/essays/Leica-M8-Perspective.shtml

Roland.

 

[ampguy]

Arturo

Arturo

When comparing crop factors, I think it is best to use digital in both cases, i.e. M8/M8.2 and M9 rather than M8 and MP (film).

However, I do agree with your results from both studying the physics involved, and looking at my results.

DOF does not increase when using a crop factor with the same lens. You are simply getting a smaller area than what a full frame sensor would capture. Depending on what sizes you print or view these at, you may get more, or less subjective DOF.

re:

... DOF is bigger with the M8. If you shoot with a MP and a 50mm lens and you repeat the shot with a M8 and a 50mm lens, walking one step back to keep the same frame, the result is the same: DOF is bigger with the M8. In digital, if you want swallow DOF you need a full-frame camera.

I do not have that experience with an M6 and an M8. My M8 DOF corresponds exactly to the FF specs in the PDF 75/1.4 lux brochure for DOF for each aperture for my 75/1.4 lux on-screen, in 4x6 prints, and in 8x10 prints. These scales and the brochure are from before the M8 was developed, and they use the math and calculations that are consistent with the link above.

 

[ampguy]

Roland

Roland

I got this from an inquiry sent from an l-camera forum user about his M8, DOF and older Leica FF lenses.

You can get the same reply, just send your inquiry to:

whatstherealdealwithdofandcropsensors@leica.com



With Photoshop, you can selectively blur wherever and however much you like. Try a test without using photoshop.

Can we see the Leica quote, Ted ?

It's very simple really:

1) take a "bokeh shot" with background lights on film; scan in; print it on 5x7.
2) take the scan into Photoshop; crop it by factor 1.3; enlarge it and print it out on 5x7.

The OOF circles of 2) will be 1.3x larger than 1). Less DOF in the cropped picture.

2) is equivalent to taking the same picture as 1) on the M8, at the same focus distance.. Ergo, the DOF marks on the lens mean something different for MP vs. M8.

DOF is defined for fixed print size and viewing distance.

Here is a longer explanation (scroll towards the end):

http://www.luminous-landscape.com/essays/Leica-M8-Perspective.shtml

Roland.

 

[Finder]

2. The metaphysical square root of 2 method as proposed by Finder

I guess you don't understand the significance of the square root of 2 and how it would relate to depth of field. It is hardly metaphysics. But that is not an excuse to give a snotty answer. I can understand your confusion, most amateurs have a tough time with simple photographic relationships--so much easier to simply believe what corporations tell us. And as we know, Leica could never be wrong...

 

[Finder]

The bigger the film/sensor, the shallower the DOF, all other things being equal. The M8 will have slightly more DOF than the MP with identical lenses.

Not with the same lens. Angles of view would not be equal and the M8 would lose DoF as it would have to enlarge the circles of confusion more to reach the same display size.

Just as you lose DoF field when you crop an image and enlarge it to the original display size.

 

[ampguy]

well

well

not only is it metaphysical, it is completely irrational

I guess you don't understand the significance of the square root of 2 and how it would relate to depth of field. It is hardly metaphysics. But that is not an excuse to give a snotty answer. I can understand your confusion, most amateurs have a tough time with simple photographic relationships--so much easier to simply believe what corporations tell us. And as we know, Leica could never be wrong...

 

[Finder]

The issue is indeed confusing. I believe both Finder and ferider are correct above, but my experience de facto is the opposite of Finder: when using crop factor cameras the DOF increases. If you compare a MP with a 50mm lens and a M8 with a 40mm and you shoot the same subject with the same frame, DOF is bigger with the M8. If you shoot with a MP and a 50mm lens and you repeat the shot with a M8 and a 50mm lens, walking one step back to keep the same frame, the result is the same: DOF is bigger with the M8.
In digital, if you want swallow DOF you need a full-frame camera.

Right, but you are changing things like focal length and object distance which will impact DoF. The OP wants to know what to do with the lens's DoF scale which is calculated for a 35mm format. And in that case, the one stop (or almost one stop) compensation on the scale will be valid at any object distance.

 

[Andy Kibber]

I was wandering in the darkness on this subject until I recently saw the light. Ferider says it right in post #6.

If you don't believe that a 50mm lens at f/2 focused at 1 meter has different DOF on an M9 vs. M8 vs. EP-1, just trot over to http://www.dofmaster.com/dofjs.html, input the data and see for yourself.

 

[splitimageview]

It is exactly statements like this that fuel the confusion, because they are meaningless.

"All other things begin equal" meaning what ? Focus distance ? Image coverage ? At the same focusing distance the statement is wrong. With identical image coverage and different focus distance the statement is correct.

A Hasselblad with an 80mm has less DOF than a Leica with a 50. But try the Hasselblad lens on the Leica.

Yes, I should have been more clear. Thanks for your post Roland.

 

[ampguy]

ok

ok

Just went there and compared the M8 to M9 with 75/1.4 @ 1m.

It shows the proper results, per my previous posts, and is in agreement with Leica, God, and Einstein.

I was wandering in the darkness on this subject until I recently saw the light. Ferider says it right in post #6.

If you don't believe that a 50mm lens at f/2 focused at 1 meter has different DOF on an M9 vs. M8 vs. EP-1, just trot over to http://www.dofmaster.com/dofjs.html, input the data and see for yourself.