Accuracy of depth-of-field scale of lenses on M8

[AGeoJO]

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I am gearing myself mentally up for an extended trip where I will be using my M8 gear (body plus 5 lenses) as my my main camera setup. How accurate is the depth-of-field scale of Leica lenses on the M8? Is the scale on the lenses as accurate as on film M bodies? Any feedback is appreciated.

[jaapv]

Due to the crop and a more defined DOF because of the difference between film and a sensor, you should take the DOF markings one stop narrower. Of course these markings are just a guideline and you may want to interpret DOF differently depending on the intended enlargement and subject matter.

 

The standard Circle of Confusion as taken on a 1.33 sensor is 0.023 mm, as opposed to 0.03 on 24x36.

[AGeoJO]

Jaap,

Thank you very much for your fast response. In my film MF days, I used to close the aperture one extra stop or to set the focusing ring that way to cover a narrower range. Now, probably I need to do some more than I used to. I am planning of using hyperfocal focusing method for landscape shots only. But due to diffraction issues, I don't want to stop down the aperture too much either. Again, thanks.

[stunsworth]

Joshua, I'd consider 2 stops rather than 1. But that is based on viewing on screen and zooming in rather than a print.

[AGeoJO]

Steve,

Thank you for your input. It will be an interesting trip since the last time I used MF exclusively on a serious trip dated back some 20 years ago and that wasn't on a RF system.

[sean_reid]

Depth of field scales are a very rough approximation even when the lenses are used on film cameras, there are multiple factors that a formula cannot always take into consideration. I'd recommend doing some tests yourself to see how the DOF shakes out with your lenses. That's the only way to get a reliable sense of what's happening.

 

Cheers,

 

Sean

[wparsonsgisnet]

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Generally speaking, and benefiting from the fact that the DOF is greater on the M8 compared to film-M's, if you are trying to decide where to set the infinity mark, if you're inside the aperture mark, you can't miss.

[jaapv]

Sorry, Bill. DOF is more shallow on the M8:

 

All at 3 m 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 the M8 at 0.023 mm and the film at 0.03 mm.

Unless I have been clicking very stupidly,(not impossible at all) or DofMaster is totally out (rather more unlikely), the DOF on the M8 will be more shallow than film at the same focal length, not too much out when "jumping" one focal length.

[martinb]

Sorry, Bill. DOF is more shallow on the M8:.

 

I think he's meaning when comparing lenses on film and M8 equivalents..

[jaapv]

But then the DOF markings don't match, which was the original question. On the same lens it is more shallow. But yes, as I said in my previous post, on the next shorter length it is more wide (about half a stop) but given the different rendering of a sensor as opposed to film, I would judge it to be the same. And as I indicated and Sean pointed out quite clearly, DOF is not an absolute value, but dependent on many variables, not the least of which is the judgement of the photographer. I've said it before and I say it again: DOF is in the eye of the beholder.

[tashley]

My experience with no math whatsoever is that you need two stops. But actually, this varies from lens to lens and with distance to subject - and so you need to shoot a lot of frames, not switch glass too promiscuously, and learn what works. If you do that , you'll have that magic that really good photographers have, which is the ability to second-guess the result.

 

Of course you could chimp every shot - but a whole lot of shots only happen once!

 

Best

 

T

[sean_reid]

How much macro-contrast does the lens show? At which apertures?

How much micro-contrast does it show? At which apertures?

Does it shift focus? If so, to what extent?

Where (within the frame) does the object (that one wants to appear "sharp") appear? - (Lenses vary in how their resolution is distributed across the frame.)

Will the file be sharpened? If so, how much and by what method?

Will the file see tonal manipulations? Will the contrast change?

How large a print will be made from the file?

How far are viewers expected to be from the print when viewing it?

What constitutes "acceptably sharp" for you, the individual photographer?

 

This list is just the tip of the iceberg. I again recommend forgetting the formulas and, instead, spending a day doing some real world tests with one's lenses at different apertures.

 

Cheers,

 

Sean

[AGeoJO]

Again, I really appreciate all the input, guys. Sean, you are right, I need to "play" more with my lenses, which I started to after the hardware fix, new firmware, 6-bit coding, availability of IR cut filters, etc. Finally, I am enjoying my M8 and feeling good about making that the main camera .

[lars_bergquist]

This is an embarrassing subject. Leitz should have changed their tables and scales more than seventy years ago.

 

The rationale behind the 1/30th of a millimeter circle of confusion (c.o.c) was the following, back in the 1920's: A print, to appear sharp at normal viewing/reading distance (abt. 30 cm or 12 inches) must have a maximum c.o.c. of 1/10th of a mm. The competition was a contact print from a 6x9 cm roll film negative. In order to beat that, the 35 mm neg must be enlarged 3x. So, 1/10 ÷ 3 = 1/30 maximum c.o.c in the negative. And we have lived with that since then; Leitz obviously felt that if they changed to a more realistic value, customers would complain that the re-scaled lenses had deteriorated, because depth of field had shrunk! (Early Retina cameras used a c.o.c. of 1/20, actually).

 

Today a c.o.c of 1/60th would be realistic, in the M8. That would give us a reasonably good 18x24 cm or 8x10" or A4 print. You get that c.o.c. simply by reading d.o.f at 4 for an actual aperture of 8, and so forth, doubling the numbers. This of course means that you can forget about calculated d.o.f. when using anything longer than 35 mm. From 50 mm on, you just point-focus. Of course d.o.f. exists, but it is too shallow to be used in a premeditated way.

 

I agree with Sean of course that circumstances and subjects and intentions are important. I don't agree however that anything but aperture and reproduction ratio (a combined product of focal length and subject distance) decides d.o.f. For the same c.o.c. criteria, any 35 mm lens whatever at, say ten meters, will produce the same d.o.f. I could go even further: Any lens, irrespective of focal length, and at a given aperture and ratio of reproduction on the sensor, will produce the same d.o.f.

 

The old man from the Age of Tape Measure Focusing

[jaapv]

I could not agree more, Lars, but I would like to add: Each lens will produce the same DOF,that is correct, but incomplete. The rendering of that DOF, i.e. the perception of the viewer, is dependent on the resolution of the human retina. That being a constant, albeit slightly variable from one person to another, perceived DOF is ruled by the enlargement of the original subject, as determined by the distance to the camera, the focal length, the sensor/film size , the resolution of said sensor/film, the capture process (film? sensor? AAfilter?), the enlargement of the final print and the viewing distance.

Having said that, Seans factors obviously influence that same perception, making DOF indeed a matter of experience- and taste.

[tom0511]

Jaap,

I think the thing is that you would shoot the 135mm from a closer distance when using film in order to get the same crop.

So comparing just the numbers at the same distance does not give the real picture.

Also I think itscommen sense that the thickness of the media (film thicker than the sensor-surface) has an influence which so far seems not to be integrated in the formula.

Overall the smaller the sensor the more DOF at same F-Stop when shooting the same subject from same distance (meaning to use different focal length) should be true?

cheers, Tom

 

 

Sorry, Bill. DOF is more shallow on the M8:

 

All at 3 m 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 the M8 at 0.023 mm and the film at 0.03 mm.

Unless I have been clicking very stupidly,(not impossible at all) or DofMaster is totally out (rather more unlikely), the DOF on the M8 will be more shallow than film at the same focal length, not too much out when "jumping" one focal length.

[jaapv]

That is all correct, Tom. I pointed out the difference between film and sensor several times in this thread. Changing distances - yes that will make a difference. You change the perspective then, so you change the DOF. If you keep the distance the same and change the focal length accordingly to maintain enlargement it is different again.But if you change distances, you change everything. I must shamefully admit that I have not worked that one out. Personally, my taste is for going to both extremes. Maximum DOF for some subjects, minimum for others and very little in between. I am not a hyperfocal shooter, I like to position my plane of focus exactly and forget about the numbers.

[wparsonsgisnet]

... Sorry, Bill. DOF is more shallow on the M8 ....

 

OK, got it. I was thinking of all the DOF on the D2 compared to my film M's, but of course, that's a 7mm to something zoom.

 

Given the 1.33 of the M, all my lenses are longer -- and therefore have narrower DOF's. Thanks for the hit upside the head. It shook all the sleepy gray cells loose.

 

Back to my specific recommendation -- is the infinity mark on the lens still correct? If so, why wouldn't the hyperfocal distance be correct when getting inside the corresponding aperture mark? That is, if I'm shooting at f8 and I set the infinity mark to 5.6, won't I have everything in focus from infinity to somewhere about the distance on the lens at the other 5.6 mark?

 

Per Sean's prescription, I will test this hypothesis. It's supposed to rain this weekend, anyway.

[lars_bergquist]

-------------

Back to my specific recommendation -- is the infinity mark on the lens still correct? If so, why wouldn't the hyperfocal distance be correct when getting inside the corresponding aperture mark? That is, if I'm shooting at f8 and I set the infinity mark to 5.6, won't I have everything in focus from infinity to somewhere about the distance on the lens at the other 5.6 mark?

 

Per Sean's prescription, I will test this hypothesis. It's supposed to rain this weekend, anyway.

 

Bill, no matter what, the lens will have its plane of best focus where it is set, as long as sensor-lens alignment is correct. And, disregarding some of the more peculiar opinions expressed in this forum, I do think Leica does get this right. So infinity is infinity, i.e. somewhere beyond the Kuiper Belt …

 

Now if you set your aperture to 8 and the infinity mark opposite the far f:4 mark on the d.o.f. scale, then you will have everything in focus down to the distance opposite the near f:4 mark – that's what 'hyperfocal' means – as long as you do not insist on an even smaller circle of confusion than .015 mm. But as I have written before, the practical criterion is what it takes to produce a visually sharp A4 or 8x10" or 18x24 cm print. This is all you can take in at 30 cm. Anything larger will be viewed at a correspondingly larger distance, which will permit a larger print c.o.c. A 16x20" for instance cannot be comfortably viewed closer than 60 cm so the permissible print c.o.c. will be 1/5th of a mm!

 

There are of course cranks who will procure a two by three foot enlargement and use a 10x magnifier to search for the unsharpness or grain or whatever that their hearts crave. It goes without saying that they will always find it. But these people are not into photography but into fault-finding, and they could just as well have searched for their faults in musical recordings, or pole vaulting, or whatever.

 

Another reservation: An optical system which exhibits really low definition all over, will of course lack a discernible depth of field. The prime example is the pinhole camera. Here, the distinction between sharp and unsharp is meaningless. Even in a glass lens, low resolution and contrast may mean that the transition from (not very) sharp to unsharp seems smoother and maybe more pleasant than in a crisper lens, where it will be seen as more abrupt. This may bear on Sean's argument. Soft focus lenses or 'soft filters' (diffusers) may subjectively seem to create more depth of field, for this reason. But d.o.f. is a physical quantity that can be measured and computed, and the arguments above hold, as long as you can at all discern where the plane of best focus lies!

 

The old man from the Age of the Rodenstock Imagon.

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Hallo,

Look here: Leica M

[steve_l]

Things I've read:

-Sensors exhibit sharper transitions from in focus to out of focus than film, so DOF is more discerible - with film, the eye doesn't notice as much as the image gradually goes out, which adds to perceived DOF.

-Leica lenses uniquely (maybe ASPH only, I forget) exhibit (acc. to Erwin Putts, I think) a characteristic of infinity not being truly in focus unless the lens focus is set on infinity.

 

Anybody know if those are true or not? They would certainly affect using hyperfocal distance...

 

I did my own hyperfocal tests (always do) with a forested mountain in the background and marks in the foreground at 1-yard intervals....and it seemed that for M8 with 24mm lens, print size of 16x24 (actual size, on the screen), one stop more than marked was pretty good for most practical situations (where the far point in the image isn't really infinity), but two stops were needed for really crisp true infinity focus at hyperfocal settings.