Noise, Open?

mattmatheson

mattmatheson

Well-known member
I here that noise is more noticeable when shooting with an open iris but I shoot with it wide open for more dof but how would an open iris, which is letting more light in, ad more noise, which noise is caused for lack of light? It's been on my mind lately so I thought I'd ask.
 
the pixels of the ram of the ignition can occur more than 5.6 times so u can interlace the null layer, and adjust it to its axis on the adjustment parented null object. You then duplicate it, and add a twween to prevent the axis of RAMS speed occuring with the connecion of the lithium needs

kidding..


ya ive always wanted to no to...
 
i get a lot of noise, core is at +7, detail level is at -3, cineleke v, cinne gama, 0 pretty much for everything, 24pA, y am i getting noisE?
 
Noise has nothing to do with the iris setting. But you'll see more noise in underexposed situations, and if you're underexposing you'll probably have the iris wide open, so this sounds like more of a "cart before the horse" kind of thing. As in, it's not the iris being wide open that's causing it, it's that they're underexposing the image, and that causes noise, but the shooter is drawing a connection because they notice the noise and they also notice that the iris is wide open, so they think that's the cause. It's not, it's underexposure that's the cause.
 
TheComo said:
so if u r nd filter is at 1/8, and ur iris is open, and ur exposed perfecty, no noise?
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There is always noise with a DVX camera. There's always grain with 35mm film. It comes with the territory, either way. What are you expecting, all fixed pixels like a still camera?
 
well... what you may have heard about is when you use the iris wide open, the image quality suffers...

but thats due to the nature of optics, and not digital noise. The lens is not the sharpest at its outer extreme aperture settings (highest and lowest f/stops)
 
Don't use cinelike for the "matrix" setting. I take it the 85b didn't work? It should help, but nothing will get rid of noise totally. Also, expose as far as you can to the right without blowing out, and bring things down in post if you need to.
 
TheComo said:
i get a lot of noise, core is at +7, detail level is at -3, cineleke v, cinne gama, 0 pretty much for everything, 24pA, y am i getting noisE?
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Thats cause you got no light!!!!!!!!

Iris open + not enough light = noise
Iris open + enough light = better picture/lesser noise

some noise is a fact of life!
 
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TheComo said:
but that gives the film look
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It's a trade off, but it really doesn't make much difference--it just changes a few colors a bit, but it also adds a lot of noise in blues and reds. I'm pretty sure these were shot with the matrix on "normal" but with cinegamma and the grain is there but it's finer:

1.jpg


2.jpg


Also, I'll try out the 85B filter tomorrow and see if it really works that well or maybe I was fooling myself. You do have to open up the iris when you use it a bit since it eats up a half a stop or so.
 
I believe the 85b filter is for outdoor 5600k shooting because 5600k produuces dvx-noise as well. The DVX, as noted in early posts, is a 4:3 3200k camera. The 85b is used in conjunction with the DVX's 3200k wb preset, then shot outside in extreme sunlight. You then adjust in post. I think one of the reasons for this type of "fix" is color fringing at the contrast borders between light and shade. To see more you need to do an extensive search, but there is a lot of info on this!
 
bwest said:
I believe the 85b filter is for outdoor 5600k shooting because 5600k produuces dvx-noise as well. The DVX, as noted in early posts, is a 4:3 3200k camera. The 85b is used in conjunction with the DVX's 3200k wb preset, then shot outside in extreme sunlight. You then adjust in post. I think one of the reasons for this type of "fix" is color fringing at the contrast borders between light and shade. To see more you need to do an extensive search, but there is a lot of info on this!
Click to expand...

I didn't know the DVX had a natively tungsten-corrected sensor but it makes sense. And, yeah, that's what I meant by using an 85b filter outdoors, but footage shot that way shouldn't need any more correction than footage shot normally. What do you do in Cambridge with a dvx, btw? I'm just outside Boston...
 
well up till 5 mins ago I was going to shoot with the 85b experimental, but now I see the rain moving in. Im a hobbiest, waiting for my 35mm adapter!
 
TheComo,

Hi, sorry to get back to you so late with these tests. I'm DPing a movie next month and have been stressed to all hell trying to get everything ready for it and another shoot so I have been busy and distracted lately.

Anyhow, here they are. Sorry I don't have anything in motion; I don't have enough web space for that right now. Also, it appears that my 85b filter isn't perfect because it casts a minor purple hue but I decided not to correct for it. I made sure to set my matrix to cinelike to emulate your settings, even though I recommend shooting with the normal matrix, but everyone has his or her own style. I used the spot meter to make sure the exposure compensation was correct, though.

Anyhow, here is a correctly exposed frame (I used lots of blue because I think the dvx renders the most grain in blue) shot at the 5600K white balance setting:

native.png


Here it is shot at 3200K with an 85B filter:

85b.png


To me, the grain looks very similar and quite acceptable, although still more than a PD170 or something. I don't know why the latter image is softer; it's either the cheap filter or the more open lens.

However, I tried underexposing and using +9db of gain to see what else was revealed....

Here is underexposed with gain and the 5600K white balance:

9dbgain.png


Here is underexposed with gain and the 85b filter:

85b9dbgain.png


To me, it looks noticeably less grainy. In motion, I'm sure it would be a bigger difference. Also, I shot these with 6000K high CRI flo's so I think the color rendition should be fine.

Anyhow, I hope that's helpful. Once I get some more free time I can run some more tests if you would like, though.
 
Also, I've heard others who have doubted the dvx's f-stop settings. (It seems to have a lower ISO when wide open; why is that?) So I tested your theory about wide open adding more noise.

My results were, unfortunately, inconclusive, but I think it seems like you get more noise wide open because everything is softer and the depth of focus is shallower so...the lack of high frequency detail fails to mask any noise. But I'm not sure. I may do more tests when I get the chance.
 
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