GH4 Crop Factor Comparison: GH4, GH3, and GH2

B

Benjobe

Well-known member
Here's a crop factor comparison I made of the GH4, GH3, and GH2. I shot the GH4 in both 4K mode and 1080 mode. The crop factor isn't the same for those two modes. The 4K mode has a larger crop factor. Does anyone know why that's the case?

Incidentally, the GH4 1080 crop factor looks the same as the GH3, which is a relief since I'll be using those two cameras together a lot. And of course, I think we all knew that the GH2 has a smaller crop factor than the GH3.

The testing parameters are explained in the video description on the Vimeo page.

My apologies for the bump between GH4 and GH3 shots. The head just panned a smidge to the right. And I usually shoot the GH3 with a less contrasty, less saturated Picture Profile, but yesterday I was shooting for a certain client who likes the image punchy and I forgot to reset the profile today.


 
Thanks Benjobe. The crop factor of 4K is higher because 4K uses a "pixel on the sesor" = "pixer on frame". 1080P uses some sort of binning from a bigger surface.
 
In order to get full 4k res, does it have to be in 24p, not 23.976? and how does it work for web viewing? do you have to convert it to 23.976 how does that work? Otherwise isn't uhd a bit lower res?
 
maranfilms said:
In order to get full 4k res, does it have to be in 24p, not 23.976? and how does it work for web viewing? do you have to convert it to 23.976 how does that work? Otherwise isn't uhd a bit lower res?
Click to expand...

All the clips where acquired in 23.976p. I shorthanded it to 24p. I apologize for the confusion.

AFAIK the GH4 only shoots 23.976p, 29.97p, and 59.94p.
 
The Gh4 also shoots true 24p when set to 24Hz. In that case, the aspect ratio becomes 1.85:1 and it shoots 4096x2160, so we see a bit more on the sides than the UHD version of 4k that it shoots otherwise.
 
Gh4 shoots 24p, 23.97p, 59.94p, 50p. It has a Cinema 4k setting at 24p 4096x2160 and 3840x2160 24p and a 4k setting at 23.98p, 29.97p at 3840x2160
 
@Mico, If you want the true 4k res (not uhd) it only does it 24p, not 23.976? Is it an issue for web upload to use 24p, or is it advised to use 23.976. If it is an issue is it possible to convert 24p to 23.976? and lastly does it matter.
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dvbrother said:
The Gh4 also shoots true 24p when set to 24Hz. In that case, the aspect ratio becomes 1.85:1 and it shoots 4096x2160, so we see a bit more on the sides than the UHD version of 4k that it shoots otherwise.
Click to expand...

mico said:
Gh4 shoots 24p, 23.97p, 59.94p, 50p. It has a Cinema 4k setting at 24p 4096x2160 and 3840x2160 24p and a 4k setting at 23.98p, 29.97p at 3840x2160
Click to expand...

Thanks for the new information. I had forgotten about the 4096x2160 mode. It took a while to find it in the menu. I had to consult the user manual. Good to know now, although I don't expect that I'll be using it much. Most of my material ends up on TV, Blu-ray, DVD, or the internet.
 
maranfilms said:
@Mico, If you want the true 4k res (not uhd) it only does it 24p, not 23.976? Is it an issue for web upload to use 24p, or is it advised to use 23.976. If it is an issue is it possible to convert 24p to 23.976? and lastly does it matter.
.
Click to expand...

When I ingest into Premiere, I can choose the Interpret Footage menu option to get it to 23.976. So, editing and export normally afterwards.
 
maranfilms said:
@Mico, If you want the true 4k res (not uhd) it only does it 24p, not 23.976? Is it an issue for web upload to use 24p, or is it advised to use 23.976. If it is an issue is it possible to convert 24p to 23.976? and lastly does it matter.
.
Click to expand...


Cinema 4K on the GH4 is panasonic implementing the DCI (Digital Cinema Initiative) 4k standard of 4096x2160. On the camera it is only 24p . There is no 23.98 in DCI 4K

24p can be conformed to 23.98 with pulldown methods in certain programs. NTSC video equipment needs 23.98.

For web uploads its the sites criteria. For instance vimeo accepts 24p and 23.98, as well as others.

http://vimeo.com/help/compression
 
No problem. Just to let you know I have taken DCI 4K 24p mov. footage from the gH4 and converted it to 23.98 prores using the 5DtoRGB app. Quick and easy if you're looking for a standalone program.
 
Awesome lead thanks, Whats the advantage of converting to prores? is it for your editing program? I'm using cs5.5 on a pc, but also have it on a mac. Just curious as I hear a lot about prores, If I correctly recall isn't it apple codec?
 
Yes its an Apple codec and I like working in prores HQ. I have a bunch of blackmagic cameras and I'm trying to get everything to one editing standard which for me is prores 1080p. I should also add that Apples Compressor program can downconvert the 4k 24p footage to 1080p 23.98 footage. Which from what I have read a lot of people are doing, shoot 4k down convert to 1080.
 
I have struggled with Compressor at 4k 30p. It can't seem to read the file. Anyone else have luck with this?

Ended up using Mpeg steamclip to 1080 which seems to have a nice effect of slightly upping the dark shadows and lowing the high highs, revealing data in the highlights I couldn't see with quicktime and the original file. I'm capturing everything at 4k 30p and 0-255, btw.
 
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