FS7: Higher HFR rates and image degradation.

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surinder

Well-known member
A few questions about HFR or frame rates above 60fps in particular.

Has anyone tested aliasing and moire in HFR 1080p footage yet on the FS7?
I'm not sure if the FS7 behaves in the same way as its older siblings the F5 and F55. Similarly Is there some sort of pixel binning or line skipping going on to achieve a full sensor scan? I can definitely see some increased noise and aliasing going on in my own 150fps tests. I was wondering if there is less degradation if shooting 100fps or 75fps instead.

I've also heard that F5 and F55 users can optionally fit an OLPF that is tailored towards 2k. The results I've seen look impressive. Also F5 and F55 users can do a centre crop which I don't believe the FS7 will do currently.

Is there any filter that could go in front of the lens to lessen HFR artefacts?

Finally is there less aliasing and moire when shooting RAW with the FS7, F5,F55 or FS700?

Surinder.
 
I noticed a definite softening of the image at 180 fps in 1080 30P, and in grading if pushed hard image breaks pretty fast. Much faster than 30 fps at 300mbs. You actually start to see macro blocking, this is only when grading heavily in resolve using the tortures curves adjustments possible there.

That said the quality is really very good. I think I will often shoot 120 fps and then use optical flow to slow further. IMHO the images are better than the ones from my FS700 at 240. Much more testing will be done soon. If you use a Promist filter it will often help an image, but these days I tend to apply softening in post.
 
olof said:
I noticed a definite softening of the image at 180 fps in 1080 30P, and in grading if pushed hard image breaks pretty fast. Much faster than 30 fps at 300mbs. You actually start to see macro blocking, this is only when grading heavily in resolve using the tortures curves adjustments possible there.

That said the quality is really very good. I think I will often shoot 120 fps and then use optical flow to slow further. IMHO the images are better than the ones from my FS700 at 240. Much more testing will be done soon. If you use a Promist filter it will often help an image, but these days I tend to apply softening in post.
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Can we conclude that shooting the slower HFR rates 75,100,120fps will have less artefacts than shooting flat out 180fps?
 
Not according to Adam Wilt. The sensor enters line skip mode a 72 FPS.

(although lower FPS = Lower ISO) which might be cleaner.

S
 
It's pixel binning (4 pixels grouped / combined to make one) not line skipping.

This results in an increase in overall light sensitivity which is also needed for very high frame rates... however it also results in aliasing.

On F5/55 it's resolved by replaceable OLPF meant for 2K - which makes sense because the camera has a 4K OLPF by default as does the FS7.

You won't see aliasing on absolute everything, especially after recompression, etc.. but yes it's there. I got the 2K OLPF for my camera and prefer it for greater than 60fps shooting. I haven't tried anything in front of the lens.
 
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Doug Jensen said:
I don't even understand what that means. ISO has nothing whatsoever to do with FPS.
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Man you need to think two steps. Do I have to spoon feed you like a toddler or do you just have a personal desire to try and make me look silly by contradicting my every post?

For a fixed light level and Tstop if you double the frame rate and sustain the shutter angle you will need to add an extra stop of ISO to sustain the light level. FPS and ISO are therefore connected in real world use. I thought the readers of this board would all find that obvious.

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Is the OLPF replacable on FS7?

If Sony don't offer one may be other 3rd party vendor may offer a solution like the one that was released for the 5dmk2.

I think the FS7 is going to be a popular camera and it may be viable for someone to offer a 2k OLPF solution if Sony don't offer one for the FS7.

Pure speculation here but keeping my fingers crossed :)
 
morgan_moore said:
Man you need to think two steps. Do I have to spoon feed you like a toddler or do you just have a personal desire to try and make me look silly by contradicting my every post?

For a fixed light level and Tstop if you double the frame rate and sustain the shutter angle you will need to add an extra stop of ISO to sustain the light level. FPS and ISO are therefore connected in real world use. I thought the readers of this board would all find that obvious.

S
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That is a crazy **ucked way to look at it, man. I don't know where you get this stuff it so off the wall. No professional I know changes the ISO like that. None.
 
OLPF is not replaceable on FS-7. That is an area where there is a major difference between FS-7 and F5/55. It is worth testing to determine whether in-camera HFR is as effective for your particular shot as speed changes using optical flow.

Ned
 
morgan_moore said:
Man you need to think two steps. Do I have to spoon feed you like a toddler or do you just have a personal desire to try and make me look silly by contradicting my every post?

For a fixed light level and Tstop if you double the frame rate and sustain the shutter angle you will need to add an extra stop of ISO to sustain the light level. FPS and ISO are therefore connected in real world use. I thought the readers of this board would all find that obvious.

S
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I often shoot a slightly faster shutter to reduce motion blur. In that case my choices are add more light to the scene, bump up the ISO a little or open up the iris a little.

I've only tested 150fps in indoors and I had to bump my ISO a little that would explain the increase in noise I'm seeing but that is to be expected. HFR certainly will need more light to be noise free.
 
nsoltz said:
OLPF is not replaceable on FS-7. That is an area where there is a major difference between FS-7 and F5/55. It is worth testing to determine whether in-camera HFR is as effective for your particular speed changes using optical flow.

Ned
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Ned I've not had good luck with optical flow in the past. But may be shooting at 60fps in 4k will yield a little more temporal and pixel info to get it to work better. If I could get pristine 4k 100fps I'd be a very happy bunny ;)
 
Most us have bought the camera now.

I knew the HFR was a bit crap on the FS700 but also totally blows a certain client base who completely love it.

I am therefore entirely happy with the HFR for the right clients.

For 'serious' jobs I will shoot 4k (even if delivering HD) and stick to 60p, for the pop crowd Ill shoot 1080 who care about nothing but content.

Most importantly I was kind of evaluating FS7 vs the Cion and that, while probably having a better image (proRes) just doesnt have any HFR above 60 without a very expensive box on the back.

For £6g I feel very good 4k and wooly HFR make for a saleable package..

S
 
As far as I've concluded for high frame rate shooting on the FS7 you need to feed the sensor much more light to get a good looking image. I think that when you enter high frame rate mode on the FS7 the sensor have to work faster and in the process becomes much noisier. Add to that the binning of lines and you'll get aliasing and moire, sometimes it's just to much.

If it's usable or not depends. Fine lined objects and micro details like facial hair can be problematic but faces and softer shapes works fine in general. As long as you get a decent exposure noise is not an issue but aliasing and moire can be. To me a RED Epic makes much better high frame rate recording. On paper the specs for HFR on the FS7 looks great but in reality it's crippled.

I would use HFR with caution because it wont work for everything.
 
morgan_moore said:
Man you need to think two steps. Do I have to spoon feed you like a toddler or do you just have a personal desire to try and make me look silly by contradicting my every post?

For a fixed light level and Tstop if you double the frame rate and sustain the shutter angle you will need to add an extra stop of ISO to sustain the light level. FPS and ISO are therefore connected in real world use. I thought the readers of this board would all find that obvious.

S
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Yes Sam, I thought the connection was pretty obvious too!

Steve
 
I guess the NFL just has loads of light unlike Exeter, St James park, Coventry City,Sheffield United and the other the dumps I learned my trade... builds a different mind set.
 
I don't think the HFR stuff looks too bad from the FS7, but I'm still working on making it look better. This high school football game was all shot at 180 fps -- ungraded.

https://vimeo.com/114608622

I've also got 30 minutes of really nice S-LOG3 60-120 fps footage I shot at an NFL game as a test for the NY Giants that I would love to share the link . . . but don't have permission.
 
Ben Scott said:
In fairness mate... Sheffield? ;)
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V long time ago - maybe it was City used to do both no idea - or the Steelers or Rugby leauge - never had too much light - manual focus 300/2.8

--

Doug it looks excellent - and good shots- just the footy may not sit to well next to 4k originated material IMO

S
 
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