Jump to content

Shooting 4K for 2K on the Panasonic GH4 plus pre-review short film


Andrew Reid
 Share

Recommended Posts

Indeed, Andrew you make this camera singing (outcome counts, not a set of limitations) and who is used to defend you outside being proud now to see that's not in vain

 

; )

 

It is a truly professional amateur cinema camera, I've always believed in both talents! (E :-)

Link to comment
Share on other sites

EOSHD Pro Color 5 for Sony cameras EOSHD Z LOG for Nikon CamerasEOSHD C-LOG and Film Profiles for All Canon DSLRs

I'm of two minds about this, as least as it pertains to the review of the GH4. On the one hand, it's a beautiful piece, and really showcases the potential of the camera. On the other, you contrast it with some of the garbage being shot on the GH4 (

>ahem), and it makes you realize that ultimately it comes down not to the quality of the lens or sensor but the talent of the person behind it.

Link to comment
Share on other sites

It ends up being a 0.9x crop with BMCC Speed Booster if you compare it to the typical Super 35mm sensor size. I.e. it goes larger than Super 35mm, but still a 1.4x crop over photographic full frame.

 

Thanks for the quick response! Ok, it's starting to make sense now. But would using a normal M43 Speedbooster with a .71 reducer give almost an exact 1x crop to Super 35? I just find it easier to think in Super 35 focal lengths, which is why I'm asking  :P

 

Aside from the cropping/math question, I noticed in the post Daniel Peters' test with just a generic focal reducer looked great! Is the Metabones Speedbooster the only way to go or would something like a Mitakon Lens Turbo do the trick as well and not mess up the IQ too much?

Link to comment
Share on other sites

My full review of the Panasonic GH4 (final retail unit) is coming next week. Until then I am enjoying Philip Bloom's views on the camera here!
 

 

Re: the video - I'm noticing blown-out highlights in some scenes (hair of the actress), and underexposure in others. Unless this was an artistic choice, could it be possible that the video was shot in full 0-255 range but edited in 16-235 broadcast range without lifting shadows and bringing down highlights? Or is Stu Maschwitz right with his claim that the GH4 lacks dynamic range? 

Link to comment
Share on other sites

Guest Ebrahim Saadawi

I am sorry Andrew but I truly, truly, didn't like this short. It's exactly the look I've been trying to avoid for years during my entire filmmaking career. The edits, the exposure, the music, the mood, the acting, the movement, even the colors hit me in the face.

That's a personal preference of course, not facts. If we all agreed upon one style of films we would all be out of business.

Thank you for taking the time to share your work and to provide this awesome content everyday, I know it aint easy!

Link to comment
Share on other sites

I'm hoping Rarevision develop something as user-friendly as 5DtoRGB, which I use everyday.  I'm sure if they can develop a nice user interface, they have a winner in terms of sales.

Totally agree. 

Link to comment
Share on other sites

  • Administrators

Re: the video - I'm noticing blown-out highlights in some scenes (hair of the actress), and underexposure in others. Unless this was an artistic choice, could it be possible that the video was shot in full 0-255 range but edited in 16-235 broadcast range without lifting shadows and bringing down highlights? Or is Stu Maschwitz right with his claim that the GH4 lacks dynamic range? 

 

The only time the blown-out hair happens is on the slow-mo footage, not the 4K. And it was a challenging shot because of extremely bright direct sunlight on Susanna's hair. She was backlit by it and I was exposed for her face. An Alexa would have struggled with that.

 

I didn't grade for maximum dynamic range and one of the 4K shots was a bit hot, a bit over exposed.

 

I am fine with the dynamic range from the 4K files so far. Seems similar to what I am able to get with 5D Mark III raw. The GH4's sensor is rated for nearly 12 stops, same as the 5D Mark III's sensor. Packing that into a JPEG, which is effectively what the 4K video is but more compressed, well... you be the judge. Possible or not? Think about stills. I'd say yes it is possible.

Link to comment
Share on other sites

Another method to shoot 4K for 2K is to have the camera downcovert the signal over HDMI. It seems the HDMI scaling algorithm is way better than the line skipping algorithm they use on sensor. As such you get a sharper 1080p 10-bit 4:2:2 straight out of camera if you use 4K downcovert over HDMI. Downsides are the 2.3x crop and the 30fps limit, plus you lose the ability to possibly punch-in in post. Upsides are the noticeably increased sharpness and less noticeable noise pattern. And this way you skip having to downconvert it in post, which can help a lot with storage (4K 10-bit 4:2:2 files gobble up a lot of space, especially if you intend to output to 1080 anyways).

Link to comment
Share on other sites

Another method to shoot 4K for 2K is to have the camera downcovert the signal over HDMI. It seems the HDMI scaling algorithm is way better than the line skipping algorithm they use on sensor. As such you get a sharper 1080p 10-bit 4:2:2 straight out of camera if you use 4K downcovert over HDMI. Downsides are the 2.3x crop and the 30fps limit, plus you lose the ability to possibly punch-in in post. Upsides are the noticeably increased sharpness and less noticeable noise pattern. And this way you skip having to downconvert it in post, which can help a lot with storage (4K 10-bit 4:2:2 files gobble up a lot of space, especially if you intend to output to 1080 anyways).

Thanks for the hint, have a Ninja2 so will try that route too.

Link to comment
Share on other sites

Hey, I have got an important question. Will the Sigma 18-35 Work on the BMCC Speed Booster in all Modes (4k, FHD).

The Sigma 18-35 is only for APS-C, but FHD + BMCC Speed Booster is larger than APS-C. Is there any kind of vignette or something?

Link to comment
Share on other sites

The crop factor calculations for the GH4 in this topic are completely wrong.

Crop factors must be calculated using the diagonal of the sensor.

 

The full frame film camera sensor is 36x24mm and has a diagonal of 43,26mm

It uses all the image circle from the full frame lenses.

 

The GH2 multi aspect sensor for 16:9 video is 18.8x10.6mm and has a diagonal of 21.6mm wich is half diagonal of full frame film cameras

So the GH2 crop factor for video is 2x and not 1.86x (43.26 / 21.6)

 

Considering the GH3 and GH4 uses all the horizontal pixels of the sensor to capture 1080p video:

 

The GH3 and GH4 sensor for 16:9 video is 17.3x9.7mm and has a diagonal of 19.85mm

So the GH3 and GH4 in 1080p has a crop factor of 2.18x (43.26 / 19.85)

 

Considering the GH4 sensor is 4608 pixels in horizontal and C4k is 4096 pixels in horizontal and UHD is 3840 pixels in horizontal:

 

The GH4 in C4k mode uses an area of 15.38x8.11mm of the sensor and has a diagonal of 17.39mm

So the GH4 in C4k mode has a crop factor of 2.49x (43.26 / 17.39)

 

The GH4 in UHD mode uses an area of 14.42x8.11mm of the sensor and has a diagonal of 16.54mm

So the GH4 in UHD mode has a crop factor of 2.616x (43.26 / 16.54)

 

This is all without focal reducer.

Link to comment
Share on other sites

The crop factor calculations for the GH4 in this topic are completely wrong.

Crop factors must be calculated using the diagonal of the sensor.

 

The full frame film camera sensor is 36x24mm and has a diagonal of 43,26mm

It uses all the image circle from the full frame lenses.

 

Since you use such strong language: your calculations are completely wrong because you're comparing apples to oranges - namely 16:9 video on MFT to 3:2 stills on full frame. The only meaningful comparison is 16:9 MFT video to 16:9 video on full frame (on a Canon 5D, Nikon D800 or Sony A7) - which is cropped from 3:2, and thus has a smaller diagonal.

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Restore formatting

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

 Share

  • EOSHD Pro Color 5 for All Sony cameras
    EOSHD C-LOG and Film Profiles for All Canon DSLRs
    EOSHD Dynamic Range Enhancer for H.264/H.265
×
×
  • Create New...