GH2 DOF calculations for GH2

Craighoit

Craighoit

Active member
Hello everyone

I hope I'm posting this in the right place and if this has been answered before (and I suspect it has, I just couldn't find it) please accept my apologies.

Here's my question:

When you use a standard 35mm lens on a GH2, you double the focal length to get the "correct" field of view for the GH2, right? So a 50mm lens acts like a 100mm lens, a 85mm is 170mm etc.

But, and this is the actual question, does it correspondingly change the hyperfocal distance of the lens and the depth of field?

If you put a 50mm lens on a GH2, and you're looking at a DOF chart, do you look at 50mm or do you look at 100mm?

Thanks!

Craig
 
Wow, that is one of the coolest things I've seen all day. Thank you for sharing. It's no messy charts at all (my eyes aren't that good anymore anyways).
 
The lens remains the same, but the image does not when sensor size is changed. If you are satisfied with the cropped image, then hyperfocal distance and depth of field remains unchanged. However, if you need to change camera distance from the subject to get similar image for smaller sensor size, this will change the hyperfocal distance and depth of field.
 
Craighoit said:
Hello everyone

I hope I'm posting this in the right place and if this has been answered before (and I suspect it has, I just couldn't find it) please accept my apologies.

Here's my question:

When you use a standard 35mm lens on a GH2, you double the focal length to get the "correct" field of view for the GH2, right? So a 50mm lens acts like a 100mm lens, a 85mm is 170mm etc.

But, and this is the actual question, does it correspondingly change the hyperfocal distance of the lens and the depth of field?

If you put a 50mm lens on a GH2, and you're looking at a DOF chart, do you look at 50mm or do you look at 100mm?

Thanks!

Craig
Click to expand...

While using the 'crutch' of 35mm film to GH-1 (or any other sensor sized camera...) is sort of useful initially, I'd recommend looking at the following Apps... if you have an iPhone, or equivalents for other mobile devices...

Toland ASC Digital Assistant

pCAM Film+Digital Calculator

I have the Toland App above, and it cuts through a lot of mental gymnastics to get to 'can I shoot this scene with the lens, and distances that are given?'. It also can be used to estimate what one may need. For example, I thought about shooting surfers from the beach. I wanted the surfer to take up about 2/3's of the frame, and I then 'found' what length lens I needed to do that... about 300mm, which I don't have... nor do I have the $500 for a 1.8 magnification adapter for my 200mm Nikon lens... so, if I want to do this I'd have to rent...
 
@Aki_Hartikainen: That's what I thought - the lens keeps the same optical properties - it's the size of the sensor relative to a bit of 35mm film that creates the different field of view. And of course (this is what I wasn't considering, but it's really a "well, duh" sort of thing) you'll need to change the subject to camera distance to get the same framing, so the other things (like DOF) will change. Mental gymnastics for sure.

@j1clark: Those look like really fantastic apps. Does the Toland one (love the name) have a setting for the GH2 or is it more orientated to film cameras and cameras like the Red and Alexa? For example, will it allow you to do calculations with F stops rather than T stops?
 
Craighoit said:
@Aki_Hartikainen: That's what I thought - the lens keeps the same optical properties - it's the size of the sensor relative to a bit of 35mm film that creates the different field of view. And of course (this is what I wasn't considering, but it's really a "well, duh" sort of thing) you'll need to change the subject to camera distance to get the same framing, so the other things (like DOF) will change. Mental gymnastics for sure.

@j1clark: Those look like really fantastic apps. Does the Toland one (love the name) have a setting for the GH2 or is it more orientated to film cameras and cameras like the Red and Alexa? For example, will it allow you to do calculations with F stops rather than T stops?
Click to expand...

Toland has a gh1/2 configuration. I believe pCam does as well.
 
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