DOF Question

[mikemgb]

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Serious question ....Isn't perceived sharpness what Noctilux is all about?

The reality is at 3' f/.95  DOF is 7" ........the rest is "perceived sharpness".

 

I thought it was about that very narrow band of sharpness, I always assumed most people buying these lenses do so to highlight their subject and throw everything else out of focus.

[adan]

Shutter speed has absolutely nil effect on DOF.

 

Absolutely correct - with focal-plane shutters (which means, any Leica M).

 

Not quite so correct with leaf shutters. Because a leaf shutter "irises out" from the center of the lens as it opens and closes, with a high shutter speed and wide aperture setting, one actually gets an "overlay" of exposures (and a "continuum" of DOFs) at every f-stop from f/∞ to the nominal set aperture, as the rapidly-changing shutter opening itself also acts as an f/stop. An in-camera analog of "focus-stacking," in a way.

 

http://www.kern-photo.com/wp-content/uploads/2013/01/wpid-leaf-shutter-lens-images-04-2013-01-9-00-55.jpg

 

Of course, the effect diminishes substantially as one moves to longer speeds and smaller apertures - the changing DOF part of the exposure makes up a tinier and tinier proportion of the total exposure. And will not occur with fast strobes synced to only fire at the instant the shutter is fully open.

 

(The same effect can lead to over-exposure when using the smallest apertures, since the aperture is "uncovered completely" for a longer part of the total exposure duration, while the shutter completes its own motion to wide-open, and then closes down again.)

 

Just one of those little-known oddities of photography.

Edited December 3, 2017 by adan

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[SrMi]

There is only one 'relation' between ND-filters and DOF that I can think of, and that is when you want to reduce the DOF. If the light is too bright you may not be able to open the aperture enough as you are hitting the maximum shutter speed. In that case, you need to use an ND filter in order to be able to open the aperture fully.

[michaelwj]

But what does all this mean if I'm shooting an M8 compared to an M10?

 

 

(No internet discussion of DOF is complete without an additional side argument (I mean discussion) on the effect of crop factor)

 

Edit: Spelling

Edited December 3, 2017 by michaelwj

[jaapv]

Serious question ....Isn't perceived sharpness what Noctilux is all about?

The reality is at 3' f/.95  DOF is 7" ........the rest is "perceived sharpness".

That is another thing.

DOF is not really an absolute 7". The distance at which things are less unsharp enough to be seen as "sharp" starts at (disregarding the 1/3rd 2/3rd rule which would be in play at this distance) 3.5" before your focus distance, rises gradually to the plane of focus  @ 3' and maximum sharpness  and diminishes again gradually to unacceptable unsharpness at 3.5" behind that plane.

The only place where your photograph is sharp is in the plane of focus.

 

DOF is not a block of sharpness floating in a sea of bokeh, but two points on the curve of gradual transition.

[Exodies]

Motion blur - camera shake and subject movement can affect the perception of dof.

[jaapv]

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But what does all this mean if I'm shooting an M8 compared to an M10?

 

 

(No internet discussion of DOF is complete without an additional side argument (I mean discussion) on the effect of crop factor)

 

Edit: Spelling

  Sure, sensor size, subject distance, perspective, the works...  

 

There is one interesting thing though: In the past I noticed that, using M8 and M9 side by side, the difference in DOF was not as pronounced as one would expect. I suspect that the reason lies in the design of the lens. It will retain most of  its OOF characteristic during a moderate change in format. We'll see more of this when we get more CL images in.

[pico]

[... snip material we might wish to revisit ...]

Just one of those little-known oddities of photography.

 

So, using a center-filter with leaf shutter should have some significant effects upon DOF, no?