Effective apertures.

[scrichton]

Anyone got a simple formula for this. As the 1.4 I have in 35mm is not as dreamy as a 2.5 in 4x5. However a noctilux would be a different matter. Plus I would proabably have money oozing from my pores

[Walter Calahan]

A Noctilux is overrated. Grin.

A Kodak Aero-Ektar is another matter. HA!

http://www.walterpcalahan.com/Cheers...1BFD94960.html

I just happen to write about one today!

[Dan Fromm]

Huh? What is y'r question? Effective aperture matters only when shooting at magnifications > 1:10. At lower magnifications, aperture set is more than close enough to effective aperture.

Are you thinking about depth of field? If so, please ask again and explain better what you're after.

[scrichton]

Sorry yes I am talking about depth of field in comparison of the formats.

As in f5.6 on 16mm film appears to have a large DOF coverage, whereas 5x4 shallow DOF.

How are these equated between the formats? As the aero ektar looks very shallow in comparison to a 2.5 75mm on my 35mm bessa. Also just to clarify 35mm to 5x4 lens length is roughly a divide LF by 3 for equivical focal length.

[scrichton]

Ok so once again my work time learning has me thinking the effective depth of field at 2.5 on a 5x4 camera with a 2.5 lens will be just slightly less than an f1 (so probably about 0.95 of the old canon dream) At the focal length 60mm in terms of 35mm.

Is this a good or a bad assumption. This is taken from the wikipeadia Depth of Field Article. In the section concerning DOf over format size.

35 mm camera required f/11, a 4×5 camera would require f/45 to give the same DOF

[Nick_3536]

What's the print size? Circle of confusion?

Why do I think we don't want to go down this road -)

[Dan Fromm]

scrichton, wikipedia is like everything else on the 'web, including posts here. Riddled with errors.

Why don't you buy a good book -- I'm tempted to suggest A. A. Blaker's Applied Depth of Field, but it is likely too expensive and suffers from having been written before desktop computers were available -- on basic photography instead of looking for wisdom on the 'web? Blaker's Field Photography might be about right for you.

Short answer to your poorly posed question is that DoF given the size of the tolerable circle of confusion is controlled by magnification and relative aperture. Ain't no simple rule of thumb for comparing situations across formats. Double negative and substandard usage for emphasis.

[scrichton]

Sorry for causing so much pain by asking a question on an observation made by myself and researched with what I have.

Why do I think we don't want to go down this road -)

Nick gets it. A person asks a question that does not meet technical minded people's criteria, then they rip them to shreds over the information being discussed.

Why don't you buy a good book -- I'm tempted to suggest A. A. Blaker's Applied Depth of Field, but it is likely too expensive and suffers from having been written before desktop computers were available -- on basic photography instead of looking for wisdom on the 'web? Blaker's Field Photography might be about right for you.

Said with the subtlety of a bull in a china shop. Thanks next time I'll ask does any know a good book on ..... ?

[Ole Tjugen]

http://www.trenholm.org/hmmerk/

Harold Merklinger adresses an astonishing number of points about focus, DoF, LF cameras and LF camera movements.

[Dan Fromm]

scrichton, I have no opinion about your good qualities or lack thereof. At even odds, you're a wonderful person.

But you're asking questions that suggest you're a beginner and somewhat confused. Your questions are short ones, but they require long answers. That you think a short answer will do suggests you don't understand enough about what you want to learn.

And that's why I suggested that you might want to buy a good book on the basics. You'll learn more than way, and more quickly, than by looking around on the 'web.

I for one am not up to transcribing what's been written better -- more clearly and in greater depth -- than I can write it myself. Why should I type what's been typed already? Wonderful person though you no doubt are, I can't see the point of working that hard to help you. Would you do for me what you want me to do for you? Of course you wouldn't.

Good luck, have fun,

Dan

Oh, and by the way. When you post questions on the 'web, you should be prepared to receive some responses that don't please immediately.