My GF1 & some M39 Canon lenses

[Armoured]

DOF should remain unchanged

DOF should remain unchanged

My bokeh, or OOF areas are as evident as they are when I use the lens on my OM-1 body and film. DOF seems to be, again in reality, not much changed. Furthermore, a cursory look at exposures seems to yield very similar exposure settings on film, as well as the digital.

DoF should remain unchanged with the same lens/lens length (measured in absolute terms). Where depth of field will change is when the same angle of view is preserved for a different sized sensor (chunk of film). In other words, if you use a 50mm _equivalent_ (which is what, 25mm?) on a micro 4/3, the DoF will be deeper than with the 50mm lens used on your OM1, even though the 'picture' (field of view) is the same.

How I think of this (and this may not help): imagine taking a picture of, say, a long tunnel or hallway with the same 50mm lens on your OM1 and your 4/3. Crop the OM1 picture so that you get the same picture - DoF should be identical (arbitrarily, let's say covering 10 meters to infinity). For the 4/3, this might be effectively be the entire frame (and the entire frame of our cropped OM1 picture). DoF is unchanged because the same lens length is being used.

Now, go back to your full-frame OM1 picture ('decrop'): you've just added a big chunk of area around the edges - corresponding, in this case, to the closer parts of the tunnel/hallway. Now imagine the area that you've just added is out of the DoF of the 4/3 picture, say, you're catching walls from two metres to ten metres distant - instead of everything looking in focus, you've now got a foreground (around the edges of the expanded frame) that is out of focus.

The bottom line? You have the same _technical_ DoF, ten metres to infinity. But if you're comparing the full OM1 picture to the 4/3 picture, the former has a larger area out of focus. Does it have shallower depth of field? No.

Do you perceive the larger format to have shallower depth of field? Possibly, depending on the subject matter, because now you may be seeing things out of focus that weren't out of focus - because they weren't _in_ the other picture.

All things being equal, DoF for an 80mm lens will be the same on any format - but the usage and subject matter are not always equal.

I don't know if this helps, and terminology may be wrong or confusing, but it's how I think of it when comparing different formats. Comments welcome. Thinking is hard.

 

[Finder]

DoF should remain unchanged with the same lens/lens length (measured in absolute terms). Where depth of field will change is when the same angle of view is preserved for a different sized sensor (chunk of film). In other words, if you use a 50mm _equivalent_ (which is what, 25mm?) on a micro 4/3, the DoF will be deeper than with the 50mm lens used on your OM1, even though the 'picture' (field of view) is the same.

How I think of this (and this may not help): imagine taking a picture of, say, a long tunnel or hallway with the same 50mm lens on your OM1 and your 4/3. Crop the OM1 picture so that you get the same picture - DoF should be identical (arbitrarily, let's say covering 10 meters to infinity). For the 4/3, this might be effectively be the entire frame (and the entire frame of our cropped OM1 picture). DoF is unchanged because the same lens length is being used.

Now, go back to your full-frame OM1 picture ('decrop'): you've just added a big chunk of area around the edges - corresponding, in this case, to the closer parts of the tunnel/hallway. Now imagine the area that you've just added is out of the DoF of the 4/3 picture, say, you're catching walls from two metres to ten metres distant - instead of everything looking in focus, you've now got a foreground (around the edges of the expanded frame) that is out of focus.

The bottom line? You have the same _technical_ DoF, ten metres to infinity. But if you're comparing the full OM1 picture to the 4/3 picture, the former has a larger area out of focus. Does it have shallower depth of field? No.

Do you perceive the larger format to have shallower depth of field? Possibly, depending on the subject matter, because now you may be seeing things out of focus that weren't out of focus - because they weren't _in_ the other picture.

All things being equal, DoF for an 80mm lens will be the same on any format - but the usage and subject matter are not always equal.

I don't know if this helps, and terminology may be wrong or confusing, but it's how I think of it when comparing different formats. Comments welcome. Thinking is hard.

Sorry, with a given focal length, the DoF is less with the smaller sensor. This is why you use the f/4 DoF scales on a 35mm lens when the lens is set to f/8 on a m4/3. DoF is less simply because the circles of confusion have to be smaller to be equally sharp to the larger format--m4/3 image are enlarge twice as much to an equivalent display size to 35mm.

And the "theory" holds up in practice. I zone focus with 35mm lenses on my E-P1. Not that that should be a surprize.

 

[Armoured]

Sorry, with a given focal length, the DoF is less with the smaller sensor. This is why you use the f/4 DoF scales on a 35mm lens when the lens is set to f/8 on a m4/3. DoF is less simply because the circles of confusion have to be smaller to be equally sharp to the larger format--m4/3 image are enlarge twice as much to an equivalent display size to 35mm.

:bang:You're right of course; thanks for catching that. This approach is still correct _for an enlargement of the same portion of the original neg/sensor_ (or to keep/use only the same segment of the picture covered by the smaller sensor). So the example above (tunnel/hallway) is still correct, but limited in application.

Which is a big enough qualification that this way of thinking about it may not be that useful.

 

[wakarimasen]

Hello Folks,
Sorry for the newbie question, but how does the GF1 meter with legacy lenses - i.e. old LTM etc? If the camera does not 'know' which aperture is set, how does it meter? Is it just metering the light at the (unknown) aperture and providing the corresponding shutter speed?
Can't help thinking this is a daft question, but I don't know the answer...
Best regards,
RoyM

 

[Finder]

Hello Folks,
Sorry for the newbie question, but how does the GF1 meter with legacy lenses - i.e. old LTM etc? If the camera does not 'know' which aperture is set, how does it meter? Is it just metering the light at the (unknown) aperture and providing the correcponding shutter speed?
Can't help thinking this is a daft question, but I don,t know the answer...
Best regards,
RoyM

In aperture priority, the camera determines the correct exposure simply by the amount of light falling on the sensor. Unlike a (D)SLR which opens the aperture for viewing, the aperture on legacy lenses is already stopped down and so the camera does not need any aperture coupling.

 

[srtiwari]

How about somepictures BY it, rather than just OF it ?

(I own a G1, and pictures taken with M39 lenses- including Leica and Zeiss glass- are never nearly as good as the M4/3 lenses)

 

[ampguy]

Very nice kit!

Very nice kit!

but missing the all important 28/2.8 😉

.
So do you like my kit then? :bang:



😀
.

 

[wakarimasen]

In aperture priority, the camera determines the correct exposure simply by the amount of light falling on the sensor. Unlike a (D)SLR which opens the aperture for viewing, the aperture on legacy lenses is already stopped down and so the camera does not need any aperture coupling.

Aha - thanks for the explanation. I guess that shutter priority is not possible with such a lens then - only aperture priority and manual exposure?
Best regards,
RoyM

 

[ampguy]

interesting

interesting

I know the wides have in-camera corrections for the native 4/3 lenses, but I guess one could apply some of that later with a 3rd party lens.

I recall a year ago or so with that several folks thought their native M lens performed similar to the native 4/3 lens, but never could say if the 4/3 lens was really good, or if their M lens were just ok. In any case, many of those folks now own M8s and RD1s 😉

The 2x crop of 4/3, is like having your digicam on 100% digital zoom, a bit much for me personally, though 50% and 33% are just fine 😉

How about somepictures BY it, rather than just OF it ?

(I own a G1, and pictures taken with M39 lenses- including Leica and Zeiss glass- are never nearly as good as the M4/3 lenses)

 

[maxpiz]

Forgive the naive question, but the M39 mount is the same as M39 Leica?
Thank You!

 

[Finder]

Both my cv 12mm and 21mm are equal to or better than the m4/3 Olympus 17mm.

 

[Coco]

Forgive the naive question, but the M39 mount is the same as M39 Leica?
Thank You!

Yes its the same mount.. M39 LTM 😉

 

[Jim-st]

Aha - thanks for the explanation. I guess that shutter priority is not possible with such a lens then - only aperture priority and manual exposure?
Best regards,
RoyM

Is this correct (that shutter priority is not possible on GF1 with legacy lenses)?

I'm having an issue with the "S" setting on mine: whichever way I turn the wheel, the shutter speed gets slower and slower until it reaches 60", where it jams until I move out of the S setting.

I was thinking I had a firmware issue with my camera, but maybe not... I only have my CV lenses to try it with at present - no M43 lens to see if that would make the difference.

Can anyone spell this out for me? I've seen other posts in this forum suggesting "S" should work with legacy lenses

TIA

 

[illuminati_02]

The Olympus 17mm is not all that great, and I wouldn't doubt there are some better alternatives. The Panasonic 20mm is absolutely stunning, and I am amazed everytime I use it. I highly doubt I could ever find an equal to it, especially in the size and speed. (20/1.7) I am, however, enamored with trying various 'legacy' lenses on the GF1, to the point of buying a complete Contax G kit, and a Hexanon kit. You have to approach using legacy lenses as trying to adapt their unique signatures to digital format, rather than top some of the already excellent native lenses, IMO.

Back to the original topic, very nice looking kit, and I would love to see some images from them as well.

Both my cv 12mm and 21mm are equal to or better than the m4/3 Olympus 17mm.