GH2-to-APSC Crop factor

[M. Gilden]

The two widget apps I have both have FoV calculators for given cameras and lens focal lengths and subject distance combinations. The only time I've needed to 'compare' is when there's the potential, or actuality, of using two cameras which are not identical, to match up.

I bought the pCam app, mainly for it's 'match' function, since over the last few months, the 'groups' I've been to get some sort of film projects going, have had members with a variety of cameras, and it was too 'burdensome' to hand calculate comparable focal lengths 'on the fly'... for some reason everyone in these groups... except me... was dead set on using 'their' camera... so... ok... go with the flow for group cohesiveness...but still I like to have known alternatives should someone not show up to these 'all volunteer' deals...

Sounds useful, but I personally wouldn't buy an app for something I can throw together in an excel sheet in about 5 min.
Yes, I have excel on my non-iphone.

But this isn't really the topic...

[David W. Jones]

But then again pCam offers so much more than just field of view calculations. It's well worth the money.

[janusz]

Sorry for the confusion. Both images were recorded on the same GH2 body, locked-off; 14mm on the Panny zoom, 10mm on the Canon. That sentence would have negated the need for everyone to re-explain how FOV works.

Still though, I got the answer to the only question I asked, and the is 1.18x. Thanks everyone

[janusz]

Thanks Barry.

It's not nearly 1.4. It's 22.3mm / 18.9mm, for a direct crop of 1.18.

[janusz]

Sorry, Gilden. I wasn't confused as to how FOV and focal distances work. I confused you all by unfortunately failing to state that both lens were on my GH2.

The point is, I think the OP was confused as to how FOV and lens focal distances work. Any lens at a particular focal distance as measured in mm, not matter what camera it was designed for, should render identical FOV.

The whole "35mm equivalent" thing is just there for folks who have a background in still photography and are having trouble understanding what is considered wide/medium/telephoto on these newer crop sensors. If you come from the world of cinematography, where APS-C is about the same FOV as s35 film, this whole translation into equivalents is nonsense. Just stick to what mm size you need on your particular sensor size and forget about what the equivalent size on a full frame is (unless you are also shooting with a full frame camera or something).

As far as translating APS-C to Micro 4/3, I get that- m43 is slightly less than APS-C, so even coming from cinematography worlds there is a bit of crop going on. But its not much, and it seems backwards to what the op was trying to do. You need to go a few mm wider on the GH2 to match the FOV of your APS-C cam. But that's assuming your APS-C lens is mounted on an APS-C sized sensor, otherwise you are just changing FOV.

[janusz]

Thanks Dingo.

Canon APS-C Lens / 1.18 = GH2 Lens

Canon 17mm Lens on APS-C Body = 14.4mm Lens on GH2 Body

[M. Gilden]

Still though, I got the answer to the only question I asked, and the is 1.18x. Thanks everyone

No problem. Its why we're here!

Sorry for the confusion. Both images were recorded on the same GH2 body, locked-off; 14mm on the Panny zoom, 10mm on the Canon. That sentence would have negated the need for everyone to re-explain how FOV works.

Actually, on the contrary- it just reaffirms my theory that you've got the whole FOV thing mixed up!

Your original post implied that you were under the impression that a lens from an APS-C camera would somehow have a difference FOV than one made for m4/3. If you had tested it on an APS-C body, that would be different (but still backwards, I would think the 14mm on the APS-C and 10mm on the m43 would have a better chance of matching). But adding that sentence just reinforces our need to explain FOV!

Bottom line: 10mm will always be wider than 14mm, regardless of lens mount! If you are using two different camera bodies, that would be a different story. Hope that helps clear things up!

[janusz]

If I put an APSC 10mm on my GH2 body and a M43 10mm on my GH2 body I would get two images with different FOVs, wouldn't I? Because that 10mm APSC lens is directly based on the diagonal dimension of the APSC sensor which of course is a wider FOV than a M43 senor. So in order for my GH2 to see as wide as the 10mm APSC lens on an APSC body, the GH2 needs a M43 lens that is 1.18x wider. 10mm in APSC sees approx. what a 8.47mm sees in M43.

[janusz]

And so, I think, that what that 10mm APSC lens is showing me on my GH2 body is the equivalent of a 11.8mm M43 lens on my GH2 body.

[j1clark@ucsd.edu]

And so, I think, that what that 10mm APSC lens is showing me on my GH2 body is the equivalent of a 11.8mm M43 lens on my GH2 body.

That definitely is 'confused'... there is no 10 mm APSC 'lens'(*)... there is just a 10mm lens... how the 10mm lens affects the Field of View, is related to how large the sensor is. I don't have experience with the APS-C sensor... but I do know it is not the same size as the GH-1 micro-4/3's size.

Hence these sensors will have different Fields of View for the SAME LENS FOCAL LENGTH.

*It may happen that the 10 mm lens is a Canon lens and usually mounted on a Canon APS-C sensored camera... but that does not 'tie' it to the APS-C sensor size, at least in terms of focal length... mounting hardware is what makes it a Canon lens...

The Nikon lenses I have were all designed for a full frame 35mm still negative, but when I put the 28mm Nikon lens on the GH-1... it has an Angle of View of about 37 degrees, that is contrast to the SAME LENS on a 35mm still Nikon, which has a Angle of View of about 65 degrees. As a note, a 25mm lens has an Angle of View about 40 degrees on a GH-1, so 25mm is considered 'normal'...

A 50mm lens on a 'full frame still' has an Angle of View about 40 degrees... but on my GH-1... it's about 20 degrees... giving a 'telephoto' look.

A lens is a lens... it is the sensor size that sets these parameters.