Proper ND filter for daylight video?

[Pekka Virtanen]

Hi,

 

I have had trouble on exposure with Sony A7SII at cloudless daylight videos and I am looking for proper strength ND filter for the purpose. I take film at 25fps 1/50 with SLog3/S-Gamut3.Cine with ISO1800-3600 at f3.5-7.1(preferably) at +1EV and during daylight testing I found out that I had to stretch the aperture up to 20-22 in order to have somewhat decent exposure.

 

I got a Chinese Fotga variable ND filter for free from a friend but the vignetting is noticeable even at lower stops and at higher end it is useless.

 

It appears to me that I would need something in the range of ND10000 to coop with the excess light.

 

On the other hand, someone suggested switching to Cine.4 from SLog3 at daylight shots to bring down the iso, thus balance the light. Should this adversely affect the video quality?

 

I'm not a pro so pardon me if there if I've tripped in a few pits on my way at this matter.

[cws]

Hi Pekka.  
Wondering why you are using ISO 1800-3600 in daytime?  If you drop from 1800 ISO to 100 ISO that's around 4 stops of light you've allowed for right there.  Could even go to 50 ISO, so 5 stops down already.  Shouldn't need a heavy ND unless you want to shoot wide open (f2.8 - f4) for depth of focus reasons.
And what is the end result you are shooting for?  Mentioning you are "not a pro" makes me think you should stay away from the s-Log settings for the time-being... ( I think min ISO for s-log is 800 ISO?) until you've got a better handle on the camera, and what s-Log is meant for.
Try using one of the rec.709 profiles, PP4 to start with.
Some good comments on this page about video settings on the A7R2... https://www.erwinvandijck.com/nieuws/optimized-video-settings-sony-a7r2

 

PS...  ALWAYS have your exposure graph visible when shooting video... then you'll know if you are in the ballpark making the most of your sensor or not.

 

good luck!

[Pekka Virtanen]

Hi,

 

I switched to Cine1 + S-Gamut3.Cine for ISO100 and it appears that with my adjustable filter I get good results at f.7.1 with 7 stops added with variable filter. I consider f3.5 - f7.1 a good range of aperture for my needs(I've got the 2870 kit lens btw). I actually abandoned the S-Log for now because it appears that Cine1 and Cine4 will do better job for me.

 

I also got the ND1000 but there appears to be a significant amount of degradation of detail and vignetting and hence it does not work for video.

[michandr]

Hi !

 

For me ND16-ND64 filters works well, however I don't use S-log much, mostly Cine profiles, while S-log2/3 mostly for situations with high contrast, like filming with direct sun, night scenes etc. 

Btw ND64 is reducing light by 6 full stops which equivalent going from f22 to f2.8

 

Best Regards,

Andrey

[JCC]

Variable ND filters are all garbage, including the very expensive ones.  This is most obvious at the darkest settings.

 

Even a cheap fixed ND filter will give better results.

 

JCC

[MikeOfBonsall]

I stopped using ND filters and now shoot at higher shutter speed. I have never found a problem doing this despite what some purists say. Put the camera (without ND filter) in full auto mode and see what it does. Settings close to what the camera does adjusted for DOF gives me excellent results. Sometimes we make things more complicated than they are. This camera is great in auto mode; try shooting in aperture priority - it's easy - and in most non studio environments will give perfect results.