DOF for 90 Summicron

[RobertS]

I love to use my OLD 90'cron. I think it was one of the first 2000 or so made in M mount. It is old (like I said), BIG, and Heavy. It has some chunks inside and even a fingerprint smudge cemented between elements. BUT...but despite all of these drawbacks it is a super lens when you get it focused***

And I DO mean 'when'. Stopped down is easy, and using the 1.25x mag. eyepiece helps alot... but wide open it has a TINY DOF. Cool effects... but only if you have what you were hoping for inside of that sharp area. It is an extreme twister of a lens: very long throw from close to infinity. That is part of the problem, I guess.

QUESTION:

Does someone know of an online source/ chart that helps calculate DOF at various f stops/ distance for 90 mm focal length??? Maybe one of you lens-heads knows offhand what the dof is at f2 HAHA!

I know some folks like the "thin" 90/2.8 better... does it focus with less of a twist??

Comments please!

 

[jlw]

Here's one:

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

And here's another, written in Javascript. The one on the page doesn't include the 90mm focal length -- but it DOES include the source code, so you can easily add it and then run it in a web browser whenever you want to calculate DOF.

http://javascript.internet.com/calculators/field-depth.html

Incidentally, DOF for a 90mm lens on 35mm film at f/2 and a focusing distance of one meter is about +/- 0.01 meter... that means the total depth is less than one inch! So you definitely want to twist focusing ring with care...

 

[Wayne R. Scott]

Here is another site for DOF:

http://bobatkins.com/photography/technical/dofcalc.html#calc

Wayne

 

[Roger Hicks]

The trouble is that DoF isn't an absolute. It depends on how big the final picture is and what you regard as 'acceptable'.

Cheers,

Roger

 

[jlw]

That's the nice thing about the calculators that include source code. You can plug in your own circle-of-confusion value based on your own parameters.

Personally, I hardly ever worry about it. I have to shoot at full aperture almost all the time, so the way I calculate depth of field is that I just assume there ain't any!

 

[VictorM.]

Source code with a 90mm Summicron?!! Better to buy a Leica manual with dof tables at the back.