Adapted lens and crop factor of camera

andy_jansen

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Hi,

I'm sure it is asked before, but i really cant't find it.

I have a couple of Olympus OM & Minolta M lenses.
If the lens says that it is a 50mm. Should it give the same magnification as my Panasonic 45-200 on 100mm??
Or will it still be 50mm when mounted on my E-PL1?
 

andy_jansen

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So the Minolta 73-300 my father in law gave me, is actually a 600mm superzoom lens on my E-PL1???

Haven't had the change to test it, ordered the adapter yesterday on eBay, so will be in next week
 

PeteMarshall

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The focal length of a lens has nothing to do with the crop of the sensor or film. If it says 50mm it will be 50mm, irrespective of the camera it is attached to.
 

Krang

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The focal length of a lens has nothing to do with the crop of the sensor or film. If it says 50mm it will be 50mm, irrespective of the camera it is attached to.
Excuse me but this seems like a pointless and brash comment to me.

You should have at least clarified you comment a bit. Of course the focal length does not change, but what we see in the image is equivalent to a lens double the focal length in 35mm film/sensor. Hence the terminology mistake is more or less irrelevant.
 

andy_jansen

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So to conclude.

Off course the focal length of the lens doesn't change (maybe I phrased it incorrect).
But a 20mm lens on my E-PL1 gives the same image as a 40mm on a full frame?

But will a 300mm lens on a fullframe give a 600mm image on a u4/3? Or will it be 150?
I'm confused :S
 

grebeman

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The "effective focal length" on a :43: camera is double what it would be on a full frame 35mm camera, so your 20mm lens is "effectively" a 40mm lens in 35mm film terms, your 300mm is "effectively" a 600mm lens in 35mm terms.
I have written before about this constant reference to 35mm cameras, it would be different for every different film format.
I believe we should get used to what the effect of a particular lens is on our chosen format, thinking in terms of the actual focal length of the lens against the diagonal dimension of the sensor will enable a quick and ready comparison of one lens against another.

Barrie
 

Krang

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I believe we should get used to what the effect of a particular lens is on our chosen format, thinking in terms of the actual focal length of the lens against the diagonal dimension of the sensor will enable a quick and ready comparison of one lens against another.

Barrie
I think this will happen naturally. But it will take each person a while to get used to the new crop factors, and for that period you need a point of reference. Hence the comparison to the 35mm format. And I think this camera format also lures a lot of film shooters to digital.

And to andy_jansen: I have gone from 35mm -> medium format -> large format -> m4/3 and dabbled with Polaroids at the same time. The focal length confusion will fade eventually :)
 

deirdre

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A 20mm lens on the E-PL1 is 40mm effective, so equivalent to a 40mm on full frame.

A 300mm lens on full frame gives a 600m image on :43:.

Focal length * crop factor. Crop factor for full frame is 1, :43: is 2.
 

grebeman

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I think this will happen naturally. But it will take each person a while to get used to the new crop factors, and for that period you need a point of reference. Hence the comparison to the 35mm format. And I think this camera format also lures a lot of film shooters to digital.

And to andy_jansen: I have gone from 35mm -> medium format -> large format -> m4/3 and dabbled with Polaroids at the same time. The focal length confusion will fade eventually :)
Krang,
I've done the same, so a standard lens on 2 1/4" square is 80mm, on 6x9 it's 105mm, on 4x5 it's 150mm (all ball park figures), the constant is the focal length of the lens divided by the diagonal of the film negative (or now the sensor), again all ball park figures. All the above lenses giving roughly the same perspective as one another on their respective formats.

Barrie
 

andy_jansen

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The reason I asked for this is because I have a Minolta 75-300.
When the effective focal length would decrease to 150, the lens would be useless for me, since I also have the Panasonic 45-200.

If I understand correctly, a u4/3 lens with FL300 is machnically the same as a full frame 300mm lens.
But because of the cropfactor of the sensor a lens with 300mm will give the same effect as a 600mm on a full frame.
 

grebeman

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A lens with a focal length of 300mm will always have a focal length of 300mm.

When you use that lens on a :43: camera it will produce an image with the same perspective as a 600mm focal length lens would on a full frame 35mm camera.

Barrie
 

Brianetta

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It'd be simpler if people stopped using focal length to describe field of view. Of course, they won't, because on any given camera system that's the only variable.
 

Narnian

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Grebeman uses a better term - perspective. When we talk focal lengths we really need to think perspective. I believe that is what Krang was trying to point out as well.

As an old medium and large format user as well it took me a while to shift seamlessly between formats and when I tried to think more in terms of "angle of view" it made it easier to change between formats. Brian has it spot on.
 

pdh

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yep that's how I've been trying to think about it too, and it's helpful ... the important thing is to remember that you aren't getting greater magnification, which is possibly what some get confused about ... can't get something for nothing ...
 

grebeman

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Grebeman uses a better term - perspective. When we talk focal lengths we really need to think perspective. I believe that is what Krang was trying to point out as well.

As an old medium and large format user as well it took me a while to shift seamlessly between formats and when I tried to think more in terms of "angle of view" it made it easier to change between formats. Brian has it spot on.
Yes, a point I made in another thread recently. I started off with a 120 roll film camera taking 8 on 120, thus 6x9 negatives, negative diagonal 105mm, focal length of fixed lens, 105mm, ratio 1. With my Mamiya Press on the same format 90mm lens, ratio close to 1, Mamiya C330 12 on 120 roll film, standard lens 80mm, negative diagonal 79 mm, ratio all but 1, think in those terms and don't continually compare :43: to another format. When 35mm was introduced did they continually refer back to some other format to understand the perspective obtained by a particular lens on that "new" format or did they perhaps compare the ratio of the negative diagonal to the focal length of the lens and then past experience with other formats, whatever they were made it all clear.

Barrie
 

gcogger

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Hi,

I'm sure it is asked before, but i really cant't find it.

I have a couple of Olympus OM & Minolta M lenses.
If the lens says that it is a 50mm. Should it give the same magnification as my Panasonic 45-200 on 100mm??
Or will it still be 50mm when mounted on my E-PL1?
No wanting to get into the whole debate, but no-one has directly answered the original question :) So, to avoid confusion, your Olympus/Minolta 50mm lens will look the same as your 45-200 set to 50mm (not 100mm). If you want to think in terms of focal length multipliers, then the same multiplier applies to both lenses.
 

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