Depth of Field markings on old M lenses with new M8 camera

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Topdog1

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If I use an older Leica M lens on the new M8 with a 1.33 crop factor, are the depth of field markings on the lens still correct?


Thanks,
Ira
 
My experience with my Canon 20D (1.6x crop factor) is that my 50mm Takumar gets the same DOF as on my friend's 5D ( we checked very carefully with bowling pins at various distances along an alley--he owns a bowling alley) even though on the 20D the fov is actually more like an 80mm. So in short I still use the DOF markings on each lens and find them the same as they were on my Pentax film camera. In practice though I usually choose the markings for one stop wider than I'm actually shooting, because it tightens the tolerances up in case I need to crop.

I find it useful on the 20D for many shots that the lens I use for a 50mm angle has the extended DOF of a 35mm lens (which in fact is what it is), but when using the 50mm as an 80mm sometimes I'm frustrated by that longer DOF because more of the background is recognizable than I'd like.
 
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ferider said:
Like Jaap once said, DOF is in the eye of the beholder :)

It depends on enlargement and viewing distance. If you enlarge to the
same print size the DOF will change.

In practice different lenses have different DOF scales, compare for instance
a Jupiter 3 to a fast older Leica or Canon lens.

Similar to what is said above, I usually use at least one less stop for DOF estimation which
puts me on the conservative side, even with Russian lenses.

Roland.
Click to expand...
I am really thinking about this in terms of using the DOF scale on the lens for setting a hyperfocal distance at a particular F-stop for the purpose of obviating focusing, something I believe is commonly done with rangefinders. Are the lens markings reliable for that when the lens is on an M8?

Regards,
Ira
 
It is not generally known that it is easier to judge DOF in a RF viewfinder than in a SLR :eek: :eek:
With a SLR one pushes the preview button and everything goes black, removing all information about DOF and all else.
A rangefinder shows double contours in the RF patch and the distance between these contours is an exact indication of the relevant DOF. It needs some trial and error and practice but once one has mastered this it is nearly intuitive.
The Leica M3 and M2 used to have markings in the RF patch, the small one indicating f 16, the big one f 5.6 at 50 mm.

Just for Ira ;) I will repeat my DOF comparison chart:



All values at 3m distance:

135-2.8
08 cm film
06 cm M8
05 cm RD1

90-2.0
13 cm film
10 cm M8
09 cm RD1

90-2.8
18 cm film
14 cm M8
12 cm RD1

75 - 1.4
13 cm film
10 cm M8
9 cm RD1

75-2.0
27 cm film
20 cm M8
18 cm RD1

50-1.0
21 cm film
16 cm M8
14 cm RD1

50 -1.4
30 cm film
23 cm M8
20 cm RD1

50-2.0
43 cm film
33 cm M8
28 cm RD1

35-1.4
62 cm film
48 cm M8
41 CM RD1

35-2.0
89 cm film
60 cm M8
59 cm RD1

24-2.8
326 mm film
227 mm M8
192 mm RD1

I used DofMaster, calculated M8 at a COC of 0.023 mm, the RD1 at 0.020 mm and the film at 0.030 mm.Those are the accepted average values for those formats.



Btw. thanks for the quote, Roland :) I DID apologize for the remark :D
 
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This is all nice mathematics ....... but for all practicle purposes just use the current dof-markings as guidelines and your pictures will turn out fine 99,9% of the cases.
For dof .. yes it is different from full frame but you will addapt .... if you want to blow a background out of focus for instance... by lens/ aperture use and your distance to the subject ... this goes also automatic after a short period of use....
 
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Let's not stretch the laws of physics again. DOF for a lens will stay FIXED. If you stand with a cropped OR a FF camera at a certain distance from the target, the DOF is same, that is, what;s IN focus and OUT of focus will not change.

Enlarging will NOT change DOF.
 
DOF is a subjective measure based on circle of confusion, so laws of physics (aside from cognitive properties of human brain, which are statistical) do not play decisive role here.
 
just my observation, made with 21mm elmarit on RD-1.

setting to hyperfocal distance using the DOF marks on the distance scale works, but only if you use the DOF marks for 2 aperture values smaller than actually used.

example:
actual aperture F/8
set the infinite scale mark to the DOF field mark for F/4 will result in sharp rendering of far away objects (more than 50 meters).

sharpness evaluated at 100% on my computer screen, so the 2 aperture values difference may be more than actually necessary for smaller sizes.

insofar, i can back by experience tha values jaapv has given. looks reasonable to me.

regards,
sebastian
 
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Size certainly does matter...circle of confusion is a dimension that enlarges with print size.

FYI, Standard DOF marks are calculated to work at 8x10 print size. I got this from a technical guy at Canon when I asked him about the mode setting they used to have on the Pro SLRs that would automatically set aperture to keep two objects at different distances in focus.
 
and by the way, if you assume that viewing distance increases with print size, then size doesn't matter - because standing further away shrinks the apparent circle of confusion.

If you have ever made small and large copies of a print the relationship between size and focus becomes very obvious....
 
Steve L said:
FYI, Standard DOF marks are calculated to work at 8x10 print size.
Click to expand...
Old Zeiss lenses (and derivative Soviet designs) had DOF marks to provide satisfactory 13x18cm prints.
 
gogopix said:
Let's not stretch the laws of physics again. DOF for a lens will stay FIXED. If you stand with a cropped OR a FF camera at a certain distance from the target, the DOF is same, that is, what;s IN focus and OUT of focus will not change.

Enlarging will NOT change DOF.
Click to expand...
You should look at it this way:
I once said DOF is in the eye of the beholder and though it sounds facetious, that is the essential point. As photographers we start our attempt at understanding at the wrong end, at the lens, making for no end of confusion.

Start at the human eye, which is not able to distinguish between two seperate points if they are too close together.That is all DOF is. As soon as that happens we perceive an unsharp photograph as sharp.
So,when we walk the chain backwards:

1. It depends on the viewing distance. Close up, you'll see more detail and less DOF
2. It depends on the size of the print, the enlargment: Smaller, points closer together, more DOF
3. It depends on the film or sensor format. Smaller sensor, more enlargement on the print, shallower DOF
4. It depends on the lens. A tele enlarges more, points further from one another, shallower DOF
5. It depends on the subject distance. Closer up, points more apart, shallower DOF.
6. It depends on aperture. Smaller aperture=smaller point with better separation=more DOF

So there you are: Sensor size matters according to point 3.
 
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Of course, Mango, so everybody has to strike his own balance. But this subject distance is automatically considered in the COC, so that can be kept as a constant. As it is the difference in DOF between M8 and film is equivalent to less than one stop on the same lens. So it is rather theoretical anyway. The quality of the eyes of the viewer is the decisive factor on the other side.
 
jaapv said:
3. It depends on the film or sensor format. Smaller sensor, more enlargement on the print, shallower DOF
Click to expand...

I took my wife's tiny-sensor Canon S80 with 76-degree FOV lens, my APS-C sensor 20D with 76-degree FOV lens, and my friend's full-frame 5D with 76-degree (28mm) lens to his bowling alley with pins placed down the alley, and we shot the same shot with all 3 focused on the same pin and set to the widest common aperture. We made 8x12 prints of all 3 shots. The S80 (smallest sensor) had the obviously deepest DOF, the 5D (largest sensor) the obviously shallowest DOF, and the 20D in the middle somewhere. So in practical photography (the only place I care about the issue) the smaller sensor, deeper the DOF.

Perhaps your assertion is correct if the actual rather than the effective focal length (FOV) is the constant, but I can't really see the value of that.
 
ferider said:
Like Jaap once said, DOF is in the eye of the beholder :)

It depends on enlargement and viewing distance. If you enlarge to the
same print size the DOF will change.

In practice different lenses have different DOF scales, compare for instance
a Jupiter 3 to a fast older Leica or Canon lens.

Similar to what is said above, I usually use at least one less stop for DOF estimation which
puts me on the conservative side, even with Russian lenses.

Roland.
Click to expand...


I R Stoopiid. How does changing the print size change the depth of field. I mean, once the image is recorded there is no resolving anything that is not already there.... Right? Maybe I'm just having problems wrapping my brain around that concept.
 
Technically, the DOF markings are already too conservative for modern emulsions. the perceived DOF is narrower when using film with very fine grain, and some even recommend that you should carry over the markings one stop (i.e., the DOF for f/4 is really for f/2, etc.) when examining large prints.

Given camera shake, the DOF markings are still rather useful.

But to many, I may be blowing smoke. Grab a bottle of Scotch and a book on optics for photography; it's a long road.
 
Ben Z said:
I took my wife's tiny-sensor Canon S80 with 76-degree FOV lens, my APS-C sensor 20D with 76-degree FOV lens, and my friend's full-frame 5D with 76-degree (28mm) lens to his bowling alley with pins placed down the alley, and we shot the same shot with all 3 focused on the same pin and set to the widest common aperture. We made 8x12 prints of all 3 shots. The S80 (smallest sensor) had the obviously deepest DOF, the 5D (largest sensor) the obviously shallowest DOF, and the 20D in the middle somewhere. So in practical photography (the only place I care about the issue) the smaller sensor, deeper the DOF.

Perhaps your assertion is correct if the actual rather than the effective focal length (FOV) is the constant, but I can't really see the value of that.
Click to expand...

You changed two parameters, sensor size and focal length. The relationship is not linear.
 
DOF is NOT related to resolution - the ability to distingush between two points. DOF is related to the circle of confusion - the size of each point. When the circle appears too large, the human visual system thinks it is out of focus. Since the DOF scales are calulated based on a 35mm frame, they will not be "correct" for the smaller sensor. Whether they are accurate enough depends on the photographer as DOF is a subjective number based on viewing a standard size print at a relative viewing distance. DOF is always in relation to the human visual system and is not an absolute physical property.

The interesting thing that no one has talked about is as the sensor size decreases, the affects of diffraction increase. So a minimum aperture that is acceptable with a 35mm frame, may be too small for the smaller format. While small apertures increase the DOF, they also increase diffraction (the size of the Airy disk) which could mean the difference between a sharp looking image and one that looks soft.
 
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