Non-FF lenses on GH1 [Crop Factor]

[reaktor]

I was wondering if the 2x crop factor that results from adapting Canon and Nikon lenses to the GH1 would be lesser, if Nikon DX or the respectable Canon style lenses were used?

The grounds for my theory come from the fact that FF lenses have a 1.5x crop on non-FF sensors.

Can anyone clear this up for me?

[upshot]

Focal length is focal length. There is no difference between say a 24mm FF and 24mm DX except the diameter of the image circle. In both cases the image circle is overkill (super overkill with FF) to cover the fourthirds sensor. Here is a chart of a few different sensor and film sizes with various smaller image circles overlaid: As you can see a fourthirds lens would vignette like crazy on a DX sensor (that is IF you could mount it... not):
http://spreadsheets.google.com/pub?key=p9kkgjwEQQQ-HJwvNDobeEw&oid=1&output=image

[reaktor]

So no?

[hish]

Every lens ever made will have a 2x crop factor as referenced to a FF sensor. EVERY LENS.

[Steve Castle]

So no?

So I think your question is if using a DX/EF-S lens on a GH1 will have a 2X crop factor or not. Which is, yes, you will. Focal length is focal length. This is a common misunderstanding.

Keep in mind a Nikon DX lens is 1.5x crop and an Canon EF-S is 1.6x crop. Your 50mm lens on a D90 is 75mm and a 50mm lens on a Rebel is 80mm (on a GH1 it will be a 100mm). People think that a 50mm DX lens is 50mm on a DX sensor, as if the lens is compensated for relative to the sensor size- but its not. The only think that changes is the size of the image circle.

[Martti Ekstrand]

135mm still photography is not the one and single norm. Just stop thinking with the marketing term 'crop factor'. It's easy:

On GH1 a 25mm lens give the field of view regarded as 'normal' - anything shorter than that is wide, anything longer is tele.

Upshot's diagram is not fully correct - GH1 in 16:9 mode uses the full image circle on a slightly larger sensor than G1 so 16:9 is wider than the 4:3 blue frame. Click on '16:9' on the diagram here to see.
http://panasonic.net/avc/lumix/systemcamera/gms/gh1/high_image.html

[upshot]

Just stop thinking with the marketing term 'crop factor'

Exactly! Think:
mFT = 25mm
APS-c = 33mm (ish)
FF = 50mm

These are just different sensor plate sizes with different 'baselines' and Image circle needs.


Upshot's diagram is not fully correct - GH1 in 16:9 mode uses the full image circle on a slightly larger sensor than G1 so 16:9 is wider than the 4:3 blue frame.

interesting. Guess that means the vignetting will increase with exotic lenses. What's the actual sensor plate dimensions on the GH1?

[Martti Ekstrand]

You forgot:
35mm cinematography ≈ 28mm

I think it's the same but as stated using more of the width for 16:9, click the Specifications tab on the link I posted.

[Steve Castle]

Exactly! Think:
mFT = 25mm
APS-c = 40mm (ish)
FF = 50mm


More like...

mFT = 25mm
APS-C (Canon 1.6x)= 31mm
APS-C (Nikon 1.5x)= 33 mm
FF = 50mm