A question about the dials and numbers on old lenses

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mumrar

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Matt
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Hello all, I'm still looking in to the purchase of some good quality old prime lenses in M42 mount to fit (via adapter) to my EOS 450D. There is a question about the old lenses (and it's going to seem ridiculous I don't know to older world photographers). Normally abetween the focus ring and aperture ring is a printed display that appears like below
/ | | | | | | | | \
2216852.85816 22
The middle row of numbers in this image
347465773_tp.jpg

Is this showing, against the distances on the focus ring (usually above) how much of the scene will been 'in focus' at the indicated aperture? It's a question that has bugged me, and sorry if I seem like a real child, but I never got to use much pre-AF and pre-digital kit.
 
You've got it in one Matt. :thumbs:

A simple Depth of Field scale like that is something I really miss in my more modern lenses.
 
Yes, you are absolutely correct. It is in effect showing you the depth of field against the distance scale at the various apertures, so you can see at a glance the largest depth of field is at f/22.

It is a very good visual way of showing depth of field on a lens and how it varies with aperture.

Paul
 
Yes, it can be used to set the lens at the hyperfocal distance.

Say you are shooting at f/16 and want everything from infinity to as close to the camera as you can in focus, you would focus the lens so the infinity symbol on the focus scale is at f/16, and then whatever distance corresponds with f/16 on the other side of the focus scale (say its 1.5mtr) tells you that everything from 1.5 mtr to infinity is in focus.

Hope that makes sense!
 
The red dot to the right of the red line is the offset for Infrared photography - i.e. manually focus in visible light and move the focus ring so the bit that lined up with the red line lines up with the dot.

An old Praktica lens, by the looks of it!
 
mumrar said:
Is this showing, against the distances on the focus ring (usually above) how much of the scene will been 'in focus' at the indicated aperture? It's a question that has bugged me, and sorry if I seem like a real child, but I never got to use much pre-AF and pre-digital kit.
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thats about it..........the only other thing worth remembering is that if you are shooting with a crop format DSLR these won't be accurate - they are calibrated for DOF on 35mm cameras
 
boyfalldown said:
thats about it..........the only other thing worth remembering is that if you are shooting with a crop format DSLR these won't be accurate - they are calibrated for DOF on 35mm cameras
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The lens doesn't know what's behind it and it doesn't matter. The DoF scale will be the same either way.

You can argue that differing pixel pitch will have a say in the amount of DoF you get but so does the amount of enlargement you use to make the print and so on and so forth.

The size of the film or sensor doesn't change the physical properties of a lens.

Of course, there really isn't any such thing as DoF anyway. Just one plane of focus and an object is either on it or not. ;)
 
dazzajl said:
The lens doesn't know what's behind it and it doesn't matter. The DoF scale will be the same either way.

You can argue that differing pixel pitch will have a say in the amount of DoF you get but so does the amount of enlargement you use to make the print and so on and so forth.

The size of the film or sensor doesn't change the physical properties of a lens.
Click to expand...

I was just 'bout to say.

I am in the same situation as Matt as well, planning to get some M42 -> EOS adapters soon. Can't wait to use these old babies.
 
Thanks for all the responses. Talk about robbing us of something useful for no reason. I thought progress was meant to be for the good. How can that be if I'm stood with a calculator trying to work out the same things shown here?
 
I've heard a rumour that Oly may be looking into an adapter with a sort of inverse teleconverter so you can mount old 35mm film lenses on microfourthirds and still have the same effective field of view (and DOF) as the original film lens had - that'd be useful...

Andy
 
dazzajl said:
The lens doesn't know what's behind it and it doesn't matter. The DoF scale will be the same either way.

You can argue that differing pixel pitch will have a say in the amount of DoF you get but so does the amount of enlargement you use to make the print and so on and so forth.

The size of the film or sensor doesn't change the physical properties of a lens.

Of course, there really isn't any such thing as DoF anyway. Just one plane of focus and an object is either on it or not. ;)
Click to expand...

The size of the sensor changes everything, including depth of field. It requires a different degree of enlargement and a smaller circle of confusion. Pixel pitch isn't relevant in practise. The result is f/number x crop factor, which means that crop format Nikon/Canon delivers about one and a quarter stops more DoF than a similarly framed image on full frame.

Input the details here www.dofmaster.com

mumrar said:
Thanks for all the responses. Talk about robbing us of something useful for no reason. I thought progress was meant to be for the good. How can that be if I'm stood with a calculator trying to work out the same things shown here?
Click to expand...

Plenty of modern prime lenses still have DoF scales. They are not included on zoom lenses because every focal length needs a different scale and there just isn't room for them. Plus the problem of full frame lenses being used on crop format cameras requiring a different scale again.

You can print out a customised rotary DoF calculator directly from the DoFmaster site linked above, which is better than anything ever engraved on a lens. Any focal length, any format, any scale or range - v good :thumbs:
 
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