M8 and DoF

[Bob Ross]

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Here is a DOF comparison that I did for a friend a few years back. The wheels are from DOF Master, FLs are 50mm eqivs. and COC based on an 8" X 10" print. Subject distance 7ft for the same field size.

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[rosuna]

Well, statistics are not lies.

In muy opinion, the reality has a uncomfortable stochastic component. It is difficult to take account of it, in addition to many unknown variables (ommitted from our understanding of things) and many variables of which we have partial information. We have fear to recognize the truth: our understanding of the 'reality' is very limited.

We want to think and speak in terms of 'plain facts', a few words for the essence of the things... we think in deterministic and very simple terms. Variable A must to be explained mathematically by a few well-defined variables, from which we are obliged to select one main determinant, relegating the others to secondary explicative variables. This is a wrong approach. Too simple.

In statistics terms, we tend to think in means, but means are not all the story. If the variance is big the mean 'means' nothing.

All the really interesting models (approaches to reality) are stochastic. The reality is 'stochastic'.

I agree, there are statisctics (means) that are like lies, but only because we are unable to accept the truth. We want a simple mean.

[sean_reid]

Sean, but the question I would have is -- separate and apart from the technical specs, and without violating your embargo agreement with Leica -- is it reasonable to assume that the glorious bokeh one gets using fast Leica lenses will make the transition from the analog Ms to the M8? If an advantage of rangefinders over SLRs is, as you have stated, that you have to imagine the blur behind what is viewed in the viewfinder as being in focus, does it in fact blur with the M8?

 

Yes, certainly. It's already true of the R-D1. Depth of field knows no brand so a given sensor sizer with a given lens focused at a given distance on a subject at a given distance will show the same (theoretical) DOF no matter what the camera is. So, to get a feel for this, look at pictures made with the DMR (which has a sensor that's just a bit smaller than the one in the M8). To be sure, the DMR can deliver shallow depth of field if desired.

 

Cheers,

 

Sean

[sean_reid]

Well, statistics are not lies.

In muy opinion, the reality has a uncomfortable stochastic component. It is difficult to take account of it, in addition to many unknown variables (ommitted from our understanding of things) and many variables of which we have partial information. We have fear to recognize the truth: our understanding of the 'reality' is very limited.

We want to think and speak in terms of 'plain facts', a few words for the essence of the things... we think in deterministic and very simple terms. Variable A must to be explained mathematically by a few well-defined variables, from which we are obliged to select one main determinant, relegating the others to secondary explicative variables. This is a wrong approach. Too simple.

In statistics terms, we tend to think in means, but means are not all the story. If the variance is big the mean 'means' nothing.

All the really interesting models (approaches to reality) are stochastic. The reality is 'stochastic'.

I agree, there are statisctics (means) that are like lies, but only because we are unable to accept the truth. We want a simple mean.

 

Hi Ruben,

 

Well, as I'm sure you know, Twain was prone to exaggerate in order to make his point. But his point of course, which you know very well as an economics professor, is that people should often be skeptical of statistics and be aware of how they can be manipulated.

 

I agree with your point but would again suggest that the real mathematical models for this are so complex that a photographer, as opposed to a mathematician, might do better to find these things out empirically - from the pictures themselves. An afternoon doing experiments with a given camera and set of lenses can be an extremely educational.

 

Cheers,

 

Sean

[ho_co]

On the D2X you will only be getting the angle of view of a 43mm (ie x1.54, which Thom Hogan says is the more exact Nikon crop factor).

Tim--

Nikon and other users of so-called APS-C sized sensors are not always consistent about actual sensor size among various camera models, and sensor size information isn't always readily available.

 

However, Nikon lists sensor size of D2X and D2Xs as 23.7 x 15.7 mm, yielding a diagonal of 28.43 mm. Assuming a 36 x 24 mm image as 'standard 35 mm format' gives a diagonal of 43.27 mm. Ratio between the two is 1.52.

 

D200 has a slightly different sensor size, viz 23.60 x 15.8 mm, with a diagonal of 28.40 mm. But comparing this to our standard of 24 x 36 mm, the crop factor to two decimal places is still 1.52.

 

--HC

[TimF]

Howard,

Thanks for that. Are your figures for the actual physical chip size, or only for that part which contributes to the picture? As everyone here will be aware, there is a difference between the total number of pixels on a chip and the effective pixel number.

[reddawn]

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Hi

 

all this technical talk is confusing me. That's why we need full frame sensors! I don't hear 5D users discussing DOF

[frc]

I'm with you Reddawn.

This circle of confusionism becomes dazzling.

Let the engineers and statistics figure it out.

My DoF becomes more limited by the minute.

On sensorsize: have to get used to the 1.33 crop.

It's what Leica brought us.

Happy anyway to be able to use my M-lenses digital.

[doubice]

Sean is (of course) correct in his explanation. The depth of field of a given lens is the same, no matter what camera, crop factor or sensor size is used. The only variable is the field of view.

 

Using a 150mm Symmar on a 4x5 Linhof will give you the same depth of field as if you mount the same lens on a Leica with a bunch of adapters and a Visoflex. The only difference is that on the Linhof the 150mm lens gives you a view of roughly a 50mm lens on a Leica, while on the Leica it is a telephoto lens. The depth of field, as stated above, stays the same.

 

Kind of a simple explanation, but I hope it makes sense.....

 

All the best,

 

Jan

[ho_co]

Are your figures for the actual physical chip size, or only for that part which contributes to the picture? As everyone here will be aware, there is a difference between the total number of pixels on a chip and the effective pixel number.

Tim--You've caught me! I'm unfamiliar with Thom Hogan and was wondering how he had come up with his 1.54x crop factor.

 

You are quite correct of course, and I hadn't taken the effective pixel count into account.

 

I was using the rule LFI mentioned a few months back and comparing the physical dimensions. Nikon does 'waste' a lot more of its edge pixels than some Canons or the DMR or the Digilux 2, for example.

 

But since in all these cases the initially 'unused' edge pixels can be uncovered and used as part of the image with DNG Recover Edges, shouldn't we be talking about the actual chip dimensions? That way we're on the same footing with all camera models, it seems to me.

 

--HC

[ho_co]

All this technical talk is confusing me. That's why we need full frame sensors! I don't hear 5D users discussing DOF

David--

Good point! But I bet you don't see many users of smaller-sensor Canons discussing the matter either!

 

I don't know about all, but with many current AF lenses, the DoF scale is missing anyway.

 

Some of us older critters still want to set up some shots by considering hyperfocal distance, and our manual lenses (Zeiss, Leica, Canon, Nikon etc) will let us do that.

 

--HC