Picked up my first medium format camera - equiv. f stop?

Ken Nadvornick · Apr 14, 2016

CropDusterMan said:
...but when I was in high school, my math teacher said "Any good man worth his salt should know how to use a slide rule", and he forbid the use of electronic calculators, so we were all pretty awesome with them.

NASA landed men on the moon with nothing more than 3 significant digits...

Ken

pentaxuser · Apr 14, 2016

Ken Nadvornick said:
NASA landed men on the moon with nothing more than 3 significant digits...

Ken

Winston Churchill managed quite a lot with only two. They were significant when the palm faced outward and inward
pentaxiser

MattKing · Apr 14, 2016

pentaxuser said:
Winston Churchill managed quite a lot with only two. They were significant when the palm faced outward and inward
pentaxiser

I'm not sure that Alan Turing was actually limited to just two significant digits .....

ColColt · Apr 14, 2016

I'm surprised anyone has a slide rule anymore for any reason. I still have my old yellow metal Picket from long ago but cant recall how to do much with it anymore. And, they think records are antiques!

Ken Nadvornick · Apr 14, 2016

MattKing said:
I'm not sure that Alan Turing was actually limited to just two significant digits .....

Ultimately, he WAS limited to only two digits, regardless of any arguments claiming significance. As are we all. We just don't realize it. But the universe does. And he did. There is a reason Yoda said "Either do, or do not. There is no try."

Alan Turing was da' bombe!

But we digress. Severely...

Ken

rayonline_nz · Apr 14, 2016

Thanks ... in the 35mm world I generally use F8 or F11 perhaps at most F16 to shoot landscapes / cityscapes before diffraction sets in, I did that for generally all my lenses from 18mm or 85mm. I was looking for the equivalent under 6x7 ..

Alan Gales · Apr 14, 2016

CropDusterMan said:
View attachment 154568

Lol. I actually have a pretty valuable collection of slide rules I've collected over the years...some of
them are works of art...beautifully made with Bamboo...as smooth today as 60 years ago. By the
mid-1970's, the electronic calculator had all but replaced them, but when I was in high school, my math
teacher said "Any good man worth his salt should know how to use a slide rule", and he forbid the
use of electronic calculators, so we were all pretty awesome with them.

They even have an iPhone app. The one picture above is a Faber Castell 2/83N...goes for big bucks...
the Leica of Slide rules.

That's interesting. I didn't know people collected slide rules. Thanks for the info.

CropDusterMan · Apr 14, 2016

Alan Gales said:
That's interesting. I didn't know people collected slide rules. Thanks for the info.

There are a pretty large group who do, most are members of the Oughtred Society...basically a group of serious collectors,
many of them mathematicians, engineers etc.

Alan Gales · Apr 14, 2016

CropDusterMan said:
There are a pretty large group who do, most are members of the Oughtred Society...basically a group of serious collectors,
many of them mathematicians, engineers etc.

Well, that makes sense. I've heard of doctors and dentists collecting antique medical instruments. I guess slide rules would look cool displayed in a mathematician or engineer's office.

Kawaiithulhu · Apr 15, 2016

After the introduction of electronic calculators there were speed competitions between them and slide rules. For a long while slide rules ruled the roost when used by anyone familiar with them, calculators got results too slowly, but ease of use to newcomers made the limitations moot in the long run.

CropDusterMan · Apr 15, 2016

Darn it...did we answer the OP's question on DOF before I took us off the rails talking about slide rules? lol

The U.S Air Force had these special slide rules for aerial photography...

gone · Apr 15, 2016

The most sensible answer, and the easiest way to do this, is to stop down roughly 2 stops more than you would do w/ 35mm. Diffraction at small apertures won't be much of an issue, as there is a considerable difference between f16 on a MF camera and f16 on a 35mm lens.

It should make for an interesting comparison between the MF camera and your Nikon. I found, assuming that the right films were loaded, that the 35mm gives sharper images but more grain and smaller enlargements if you're looking for low grain prints. So it might depend on whether or not you want to lug that thing around for your print purposes. As much as I liked shooting 6x6, I found that if I shot the right films and developed them well there wasn't enough reason to shoot MF and lose the capability of close ups, grab shots, candids, etc.

RalphLambrecht · Apr 15, 2016

Kawaiithulhu said:
This is European, you'll get used to it.
(a UK example: http://www.ag-photographic.co.uk/kodak-ektar-5x4-10-sheets-1550-p.asp )

I believe it is more British than EuroeanI understand 4 by 5 inches to be 4x5 not 5x4 as the Brits like to call it but what's in a name? It all means the same thing in the end

Alan Gales · Apr 15, 2016

CropDusterMan said:
Darn it...did we answer the OP's question on DOF before I took us off the rails talking about slide rules? lol

The U.S Air Force had these special slide rules for aerial photography...

View attachment 154599

Yeah, the OP's question was answered before we started talking about slide rules.

Slide rules used for aerial photography, huh? Now that's interesting!

BrianShaw · Apr 15, 2016

That's cool! My favorite photogrpahy slide rule (until I saw that one) is the Lawrence Flashrule. I find it an invaluable tool for determining appropriate f/stop when using flash bulbs.

wiltw · Apr 15, 2016

rayonline_nz said:
Thanks ... in the 35mm world I generally use F8 or F11 perhaps at most F16 to shoot landscapes / cityscapes before diffraction sets in, I did that for generally all my lenses from 18mm or 85mm. I was looking for the equivalent under 6x7 ..

Again, things are proportional to the format size...56mm tall frame vs. 24mm tall frame means that 2.33x less magnification of the neg is needed to fill the same 8"x10" print. So you can get away with using a 2.33x smaller aperture with 6x7 and achieve the same level of apparent diffraction as the 135 neg, and at the 2.33x smaller aperture you will also have same DOF as well as same magnitude of background blur.

simply keep in mind the principle of maintaining proportionality...

20mm on 135 = 0.83 * frame height, therefore use 0.83 * 56mm, or 46mm or for same vertical FOV in 6x7
24mm on 135 = 1 * frame height, therefore use 1 * 56mm, or 56mm for same vertical FOV in 6x7
50mm on 135 = 2.1 * frame height, therefore use 2.1 * 56mm, or 116mm or for same vertical FOV in 6x7
100mm on 135 = 4.2 * frame height, therefore use 4.2 * 56mm, or 233mm or for same vertical FOV in 6x7

CropDusterMan · Apr 15, 2016

Alan Gales said:
Yeah, the OP's question was answered before we started talking about slide rules.

Slide rules used for aerial photography, huh? Now that's interesting!

Ya, although I've never seen one, they appear to be about focal length selection, altitude etc...I'm assuming it would have been
for the purpose of optimizing resolution?

wiltw · Apr 15, 2016

CropDusterMan said:
Ya, although I've never seen one, they appear to be about focal length selection, altitude etc...I'm assuming it would have been
for the purpose of optimizing resolution?

Actually a slide rule is far better than calculators (so very much faster than the calculator) in all of the calculations involving proportionality that I did for post 46!

Alan Gales · Apr 15, 2016

CropDusterMan said:
Ya, although I've never seen one, they appear to be about focal length selection, altitude etc...I'm assuming it would have been
for the purpose of optimizing resolution?

I would assume the same.

Denverdad · Apr 15, 2016

piu58 said:
YOu have to add roughly 2 stops to get the same DOF. That means f/4 in 135 means around f/8 in 6x7. The lens should cover the same angle of course.

This is right. For the same FOV (which requires about 2X longer lens) you need to stop down approximately two stops to get back to the same DOF you had in 135 format.

rwreich · Apr 19, 2016

You guys should all get this app for iOS called, "PhotoPills." It was super fast for me to compare the DOF and angle of view to many other cameras, including custom cameras I created for this very purpose. There are lots of other goodies that you'll have to see for yourself, too. As some have implied, the equivalent DOF would be f/2 on 135.

Picked up my first medium format camera - equiv. f stop?

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