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Neutral Density vs Aperture f-stop

Changing my aperture from 10 to 11, 13, 14, 16, 18, 20, 22 is eight f-stops
No, changing your f-number by a factor of sqrt(2) equals one stop of light. So going from f10 to f14 is about one stop. f10 to f22 is just over 2 stops, not near 8.

Though an ND256 filter is 8 stops because 2^8 = 256
 

sfoster

Staff Member
Moderator
No, changing your f-number by a factor of sqrt(2) equals one stop of light. So going from f10 to f14 is about one stop. f10 to f22 is just over 2 stops, not near 8.

Though an ND256 filter is 8 stops because 2^8 = 256

Ah, I've now looked up that the standard f-stop scale is
f/1, f/1.4, f/2, f/2.8, f/4, f/5.6, f/8, f/11, f/16, f/22, f/32, f/45, f/64, f/90, f/128

Instead of the 1/3 f-stops that my camera makes.
I'm glad I asked the question I would've got an ND filter way too strong.

Thanks!
 

sfoster

Staff Member
Moderator
Do you guys think I should use a polarizing filter for this location or a graduated ND filter?

I've never used a polarizing one before but searching around about graduated ND filters some websites have suggested it.

https://www.youtube.com/watch?v=zKkc-HYiGwM
 
I know nothing. Just taking a shot at it. Given what you've got in that shot, a graduated ND filter might be the way to go.

https://www.youtube.com/watch?v=Z0rubRtnavY
 
All graduated NDs I've seen are horizontal, which might look odd since you have a V-shaped sky in your shot. Can you wait for golden hour so you can properly expose both the sky and the ground together? Or find an angle where the sky is actually horizontal to match the filter?
 

sfoster

Staff Member
Moderator
All graduated NDs I've seen are horizontal, which might look odd since you have a V-shaped sky in your shot. Can you wait for golden hour so you can properly expose both the sky and the ground together? Or find an angle where the sky is actually horizontal to match the filter?

I doubt I can find a horizontal angle. A forest glade with power lines is always going to have the middle part lower than the trees.

Golden hour maybe.. I'd have to talk to my actress and see if she is willing to come out multiple days for that since one hour isn't enough time.
 
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I doubt I can find a horizontal angle.

Golden hour maybe.. I'd have to talk to my actress and see if she is willing to come out multiple days for that since one hour isn't enough time.

I would think you can still use a graduated filter, even with the V-shaped hole through the trees, and then just use a power window in DaVinci to brighten up the trees again so that they aren't too dark due to the filter. Your problem area is the sky, much less the trees.
 
Grads might also be a problem if you have any foreground action in the scene. If you have people in this shot, you wouldn't want them crossing in to the denser area of the filter. Also, a pola mlight not bring down the levels enough to get a lot of detail in the sky (though this would depend on the day and time of course). Looking at the sky and lack of shadow on the grass in the clip above, it probably would do very little as they aren't as dramatic on overcast days.
 

sfoster

Staff Member
Moderator
I know nothing. Just taking a shot at it. Given what you've got in that shot, a graduated ND filter might be the way to go.

https://www.youtube.com/watch?v=Z0rubRtnavY

I haven't seen one of those square holders before, that's pretty cool!

I would think you can still use a graduated filter, even with the V-shaped hole through the trees, and then just use a power window in DaVinci to brighten up the trees again so that they aren't too dark due to the filter. Your problem area is the sky, much less the trees.

My computer is the bane of my film making existence. I spent $3,000 on this POS mac because everyone talks about how good macs are for editing. And it can't run davinci. It doesn't even have an audio input jack for Foley.

Grads might also be a problem if you have any foreground action in the scene. If you have people in this shot, you wouldn't want them crossing in to the denser area of the filter. Also, a pola mlight not bring down the levels enough to get a lot of detail in the sky (though this would depend on the day and time of course). Looking at the sky and lack of shadow on the grass in the clip above, it probably would do very little as they aren't as dramatic on overcast days.

Ah crap I didn't even think about peoples heads getting stuck inside the darker portion.

Wow graduated NDs are even more of a PITA than I thought!
I bought some permethrin spray and I'm going back there today with a camping chair to test out the magic hour.

I haven't tried filming anything during magic hour before.
 
My computer is the bane of my film making existence. I spent $3,000 on this POS mac because everyone talks about how good macs are for editing. And it can't run davinci. It doesn't even have an audio input jack for Foley.

how old is this mac? i'm on the market for a new machine and want to avoid face value bullshit (pardon my bluntness)
 

sfoster

Staff Member
Moderator
Bad news guys - Magic Hour does not solve my dynamic range problem.

I just spent an hour on location doing test shots every 10 minutes.
I'll upload some footage soon.

During the down time I opened "Rebel without a crew" never read it before. But the very first page said I can learn all the technical aspects of film making in 10 minutes.

What a load of shit, I can't even get this one shot with power lines in it.

Any other ideas? Test shots coming soon.
 

sfoster

Staff Member
Moderator
Magic Hour Test Shots

https://www.youtube.com/watch?v=DF6JieTtOck

This time I tucked my pants into my socks and coated my clothes with permethrin. If you want to see what my foot looks like right now here it is covered in tick bites :no:
 
Hmm, that's annoying. Have you tried exposing somewhere in the middle and adjusting your Luma curve? You might be able to salvage something. Or can you use HDR photography and composite actors in from a green screen? Or use an HDR photo for an establishing shot, and then cut to closeups that don't include the sky? Or, last resort, just make the actors silhouettes and call it art?
 

sfoster

Staff Member
Moderator
Hmm, that's annoying. Have you tried exposing somewhere in the middle and adjusting your Luma curve? You might be able to salvage something. Or can you use HDR photography and composite actors in from a green screen? Or use an HDR photo for an establishing shot, and then cut to closeups that don't include the sky? Or, last resort, just make the actors silhouettes and call it art?

The one advantage that I have is that it's a dream sequence shot at this location. So I could get away with a little more than usual.

I have magic lantern on my t2i so I could try HDR video although it's a funky effect with people moving. It could work - Or like you say just don't include the sky in the other shots. The power lines are supposed to be a part of the dreamy atmosphere so ideally I'd have them but nothing about this is ideal.

I haven't tried modifying the luma curve, I wish I had a prores camera instead of h264. and I wish I could use da vinci. I'm pretty handicapped in the area of colorization but I'll give that a shot this weekend with one of my test frames and FCP.

What really sucks is that I HAVE to get this in before the leaves start changing color.. so like.. the 5th in 8 days.
 
Or, forgive me, I don't know how green screening or special effects software work really (haven't done my duty watching nearly enough Film Riot or Indy Mogul :P). But instead of using HDR or trying to composite actors into the shot, couldn't you use some sort of a mask, or whatever they use, for the sky, or cut the over exposed sky out somehow(?) and composite in a shot of a properly exposed sky and power lines? Or is that asking too much of what can be done by do-it-yourselfers? I have no experience with Photoshop or After Effects or the rest. I suppose you'd have to cut around all those jaggedy edges of trees etc? Or is the idea that you can do that sort of thing only fantasy on my part?

Yikes! Is that what tick bites look like? Make sure you and your crew keep an eye out for bulls-eye-shaped tick bite swellings.
 

sfoster

Staff Member
Moderator
Or, forgive me, I don't know how green screening or special effects software work really (haven't done my duty watching nearly enough Film Riot or Indy Mogul :P). But instead of using HDR or trying to composite actors into the shot, couldn't you use some sort of a mask, or whatever they use, for the sky, or cut the over exposed sky out somehow(?) and composite in a shot of a properly exposed sky and power lines? Or is that asking too much of what can be done by do-it-yourselfers? I have no experience with Photoshop or After Effects or the rest. I suppose you'd have to cut around all those jaggedy edges of trees etc? Or is the idea that you can do that sort of thing only fantasy on my part?

Yikes! Is that what tick bites look like? Make sure you and your crew keep an eye out for bulls-eye-shaped tick bite swellings.

Yeah tick bites after I got the suckers out. I didn't get any ticks this time though since I came prepared with permethrin. Kills them on contact and stays on your clothes and gear. I went to 3 stores before I found it. It's not much help when girls are going to be in their underwear though, so I'm going to spray down the whole area beforehand. I feel kind of bad about killing the ants and stuff, but I am willing to kill for my film and to protect my cast.

As far as cutting out the sky, the problem is that I need the power lines.
If it were just a plain sky or clouds I wouldn't care much if it were overexposed. But you can't hardly see those power lines at all.

HDR test coming tomorrow, as well as knightly suggestion of adjusting the luma curve on a mid-range shot.
 
I spent $3,000 on this POS mac because everyone talks about how good macs are for editing. And it can't run davinci. It doesn't even have an audio input jack for Foley.

A bit off topic but as you bought it up:

1. Back in the day, Apple was largely saved by the Picture Editing and Audio Pro guys. The Mac Pro was well built, reliable, had a far more stable OS, for this reason many software creators preferred it and for all these reasons pros wanted it. Whilst the reliability and stability is still there, out and out performance can usually be matched by PCs at a lower cost and in many cases the reliability/stability gap is smaller than it once was. A lot of pros still prefer macs though as ultimate reliability/stability is usually the primary concern.

2. No audio pro or even serious amateur would ever record into the input jack of any computer. Decent audio input requires relatively expensive components and it simply wouldn't be worth significantly raising the cost of computers for everyone just for the benefit of the tiny number of consumers who require decent audio input. Anyone after decent audio input always buys some sort of audio interface. Apple therefore took a fairly logical decision to save the cost of a poor quality audio input and spend it on features more appropriate for their customers would actually use.

3. As virtually always, any advice or even collective knowledge, needs to be taken in context, rather than applied out of context.

G
 
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