GH4 GH4 cropping in different formats

Elmer_Lang

Elmer_Lang

Well-known member
Hi
Just got GH4, seems like I heard something about the picture 'cropping' from 4096 to 3840 dependent on format choices, but this still seems a bit odd.

I shot a little using Lumix 20mm, f1.7, first in NTSC with 4K (3840) and 1080p, then in Cinema with C4K (4096), 1080p and 4K.

With NTSC the 4K was zoomed in a little bit while the 1080p had the framing I expected from my Lumix lens.
In Cinema, again the 4K was zoomed, the C4K a tad wider (the extra pixels, I assume) and the 1080p as expected.

Is that what I can expect from the GH4 and C4K and 4K? It would be disappointing if so, why use a wide lens when you get a narrow picture.

The only wild card—no pun intended—I can see is that, with B&H closed till Tues. the only cards I have are the SanDisk Extreme 45MB/s Class 10 / UHS-I / U-1 so maybe the slower card is having an effect, but still...

best
elmer
 
Yes, 4k is cropped more than 1080p, and 3840 UHD cropped more than 4k. The reason is that the camera extracts the 4k and UHD from the middle of the sensor in a 1:1 ratio. This eliminates aliasing and results in a better picture. 1080p uses the whole sensor and gets 1080p by pixel binning (throwing away lines), which is why 1080p aliases a lot more. There is a 1080p zoom mode (ETC), which crops way more than even UHD that eliminates aliasing. It's useful if you want to increase the zoom range of your lens. Crop factors are roughly 2.0 for 1080p, 2.25 for 4k, and 2.4 for UHD. Chart--

GH4+video+recording+area+4k+1080p.png
 
Thanks, Batutta, for the reply and the great graphic! That says it all.

Wow, seeing it was a bit of a shock, but my bad for not being more up on that.

I certainly see lots of wonderful pictures being shot with it, maybe I'll get used to it, I guess I've got 30 days to return it if I don't.

Maybe that's why the anamorphic lens update is so popular.

best
elmer

ps Yes, I recall that ETC from maybe my early GH2 days, it's an option for certain things I'll have to put in my basket of tricks. Thanks for that, too.
 
One reason I pulled the trigger on the GH4 now instead of waiting was hoping to use it finishing up on a project that is exclusively GH2 footage.

Just curiously, how well do the 2 cut together, are they easily color matchable? I was thinking so, maybe I should get the final word from someone.

best

elmer
 
elmerlang said:
Maybe that's why the anamorphic lens update is so popular.
Click to expand...

Yes, that's one of the reasons. I don't know your budget but if you want wider on the GH4 in 4K, I strongly recommend the SLR Magic 10mm CINE T2.0 (that's similar in speed to your 20mm but no autofocus). It produces a full frame FOV equivalent to a 24mm in 4K and for me it's a perfect pairing. The IQ ain't too shabby either (read that as very good!).
 
Thanks for the reply. Great lens. Not as good but still a nice lens, I also have the Olympus 12-50mm. Made some tests. Much better frame size.

Will examine shots. Looking up. Doable for my uses, I think.

I appreciate the posts!
 
The Metabones Speedbooster really makes a difference if you're thinking about sensor size. In 4K mode with the speedbooster, you're getting really close to Super 35/APS-C sizes, and in 1080p, it's basically identical. I have been able to do a lot of work with the GH4 and Zeiss CP2s speedboosted, and they really are amazing together. Which I guess they should be, since the lens kit is like 10 times the cost of the camera body.

I've had the GH4 on set with GH2s and matching wasn't exactly easy. But we hadn't experimented with picture profiles first and just tried to shoot "flat" with both cameras.
 
A quick note that has been made a thousand times before - that if one wants the same framing in 4K as in 1080p, then one can record 4K and downscale it to 1080p in editing (thereby getting a better looking 1080p anyway).
 
I don't see this as a problem in that you do see the "framing" in the EVF or on the LCD. Yes, the difference in crop is noticeable but you can still "frame" as you wish in the viewfinder. If the field of view is not as "wide" as you want and increasing camera to subject distance doesn't give you the composition you want, you may need to get a "wider" lens.

I have the Olympus m.Zuiko 9-18mm f4.0 to f5.6 zoom (18-36mm full frame equiv) which will get me into the 22mm to 24mm (equiv) ballpark. For marginal lighting environments there is either the Olympus m.Zuiko 12mm f2.0 or the Rokinon 12mm f2.0 which at 2.4 crop factor (Cine 4K setting) results in a 28.8mm equiv. For a long time I considered the 28mm a very good "workhorse" wide angle.
 
stoneinapond said:
How can you get back framing that has already been cropped?
Click to expand...
No, you shoot in 4K for a 2.3 crop, rather than to a 2.0 1080p crop. But, if you want your shots to match, you can shoot everything in 4K and then render it down to 1080p in editing.
 
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