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marcel_fiala

GH5s color depth vs FPS considerations

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I was considering underwater photography / videography for a long time, but now I am ready to take the plunge as I found a really nice niche - underwater fluorography:


For those unfimilar, here are some examples:




As you guys a light year ahead of me, I am turning to you with some questions. Please consider following while writing answers:


- I've made the decision to buy Panasonic GH5s with Ikelite housing.

- I want to shoot at 10bit so I have more leeway for color correcting.

- I do not budget for an underwater recorder that would allow me to shoot 60fps at C4K 10bit 4:2:2

- I am shooting in cold (and later in the year greenish) water in DK, only at night and with no natural light.

- I will be shooting macro/semi macro without a tripod most of the time.



1) Does it make sense to shoot Vlog to get the most leeway for color correction, presumably needed for this kind of project?


2) How much leeway and dynamic range I'd lose by switching C4K 4:2:2 10bit to C4K 4:2:0 8bit to get the option to shoot 60fps for cinematic slow-mo? Is not 60 fps full HD with preserving 4:2:2 10bit be a better idea?


3) How far can I get only with Oly 60mm macro lens? How far and large objects I will be able to shoot with it?



Your answers and any suggestions/remarks that come to mind are most welcome :)

Edited by marcel_fiala

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Posted (edited)

I was asking myself the exact same question the first trip so i decided to test all of it out.

1) Vlog is only good for 10bit in 8bit the footage suffer a lot from color banding, also i find that if you white balance correctly there is no need for massive color correction.
2) I guess you have to prioritize what you want, for me i think 4k is the way to go so about 8bit and 10bit is FPS right here i find that 60fps have more room for editing as i did not find much use of the 10bit file.
3) For oly 60mm macro lens you can go as far as you want but you will lose color and have to deal with stabilization of the footage as distance increase.

This is my personal opinion i am not sure if i answered all of your question.

Edited by supawoot.t

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Posted (edited)

My question would be what are you correcting your footage to? You're recording the florescence from sea creatures which is going to be monochromatic light and correcting it is more a matter of ensuring that you don't drown out those colours rather than correcting to a white balance. What I mean to sya it's not your classic colour correction you would have in a daylight image. The other consideration as I understand it is that the glow is quite faint so you are using high ISO which means noise problems - in general stretching images tends to be more problematic with noisy images.

 

I recall someone expressing to me that video is not a RAW file and the ability to correct it is rather limited compared to what can be achieved on a still Raw image. It sounds like a rather challenging field and if it were me I would try to find settings that get you close to what you want first up and getting into the details of video codecs and bit depth as you gain experience.

 

The other thing I note is that the blocking filter means that backscatter while illuminated by your blue light is not seen because of the blocking filter. This gives you increased freedom to position your lights in close to your subject, without worrying about preventing backscatter so much

 

On the 60mm macro it can be challenging as you need to back off quite a bit for larger subjects with the concern being more water with particles between you and the subject, while the blocking filter takes care of the backscatter, the water will potentially be absorbing the light emitted by the subject, so anything fluorescing red will be lost or diluted rather quickly. The fact you are shooting in green water makes me think getting close will be very important. Whether the 60mm is a problem really depends on the size of your subjects, you are nicely placed using it for example on 30-40mm nudis and smaller. I have started using the little Panasonic 30mm macro quite a bit for regular still photography and find it is good for about half life size at max, but better for larger subjects like medium size fish than the 60mm. Without knowing your subjects it's hard to be more specific.

Edited by ChrisRoss

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It will be very interesting to see which creatures fluoresce in temperate waters. Not all do, and most fluorescence imagery has been done in warm coral reef type environments.

 

Using the fluorescence filters dramatically reduces the available light. With stills, this can be somewhat compensated for in post, but with video, your options are much more limited. If I was to choose a camera to do this with, I would look for one with RAW output (Blackmagic Design or Nikon Z with the Ninja V) that would give more post-capture options.

 

I would be unwilling to lose any color information. I think your overall exposure issues will mean that you definitely want to have as much information as possible.

 

The limit in terms of subject position and size will be determined more by available light than focal length. Fluorescence imagery is pretty much limited to macro subjects. The challenge will be to keep the camera steady enough. Some kind of support would be a good idea.

 

Adam

 

Adam

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- I do not budget for an underwater recorder that would allow me to shoot 60fps at C4K 10bit 4:2:2 --> this is not supported anyway




1) Does it make sense to shoot Vlog to get the most leeway for color correction, presumably needed for this kind of project?


It probably makes more sense to shoot 50p 8 bits 150 mbps you will need the ability to slow down if you hand hold


2) How much leeway and dynamic range I'd lose by switching C4K 4:2:2 10bit to C4K 4:2:0 8bit to get the option to shoot 60fps for cinematic slow-mo? Is not 60 fps full HD with preserving 4:2:2 10bit be a better idea?


Dynamic range is not going to be important if you shoot with artificial lights to be honest


3) How far can I get only with Oly 60mm macro lens? How far and large objects I will be able to shoot with it?


I would recommend a stabilised lens like the 14-42 MKII and diopters instead of the 60mm that will require a tripod



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On 3/12/2019 at 2:59 PM, Interceptor121 said:

Dynamic range is not going to be important if you shoot with artificial lights to be honest

Agree with that, I almost stopped to use 10bit, does not make any sense to me, it will not fix white balance and does not give much advantages for color correction.

8bit 60p gives me more freedom and ability to work with smooth footages than 10 bit 30p.

So it does not make any sense to use FHD, because 4K is a huge quality improvement.

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