Oops... no ND filter

D

DDirector

Veteran
So, today my class was shooting a 5min short film outside on 16mm. Well, I was reading it to like f45, f32. But the people in charge of booking out camera equipment never got the ND filters. Thinking they didn't need it.. Smooth move.

So, not being able to go back and get them, I cut up some ND gel and slid it into the filter tray in the mattebox. I used 3 ND3's, and from what I saw, there wasn't any flaring or anything drastic.
Now, I want to know if what I did was a good thing or a bad thing. Haha. There was no time to get some ND, so this was the only thing I could think of.
 
Totally fine. As long as the ND is clean I don't see why not. I remember hearing a story about people shooting the space shuttle lifting off with huge long lenses. The front elements were so big that they didn't have ND filters big enough to cover the front element. So instead what they did was pull some ND off a roll and stuck it onto the front of the camera.

The other thing you could have done was just used a polarizer with it spun off, so it doesn't give any polarization. Or you could have just pulled the film a few stops if that look is to your liking.
 
We used to do the same thing in film school. Worked fine on the Bolex and Eclair ACR. But those things were little more than bricks with some gears in them
 
I used polarizer recently for an extra stop and screwed directly on lens to avoid half hour of setting up camera with rails, matte box and ND 4x4 glass filters. Yes lazy I know.
 
The risk is that the ND gel may not be perfectly optically clear and so distorts the image slightly - after all, it's not designed to be shot through. Other than that, sounds a good workaround.
 
Rear lens filtration using gel's used to be semi-common with film cameras, but if I remember correctly they were always optical grade rear lens gel filtration... not the type you put in front of lights or tint windows with.

Great work around for being in a pinch and well, having to do it. Likely not the best idea in the real world, where running a PA to the rental house would have been a must. It's also good to hear you are in school because you really only can take this as a learning experience

I guarantee by using lighting gel there was a sharpness reduction of likely a decent amount. Maybe one piece of brand new virgin gel can go unnoticed, it depends on final format and some other variables, but considering you used three pieces of ND3 versus one piece of ND9, that will make a difference. That said, you will get a picture and it will likely seem alright in the sense you can see what is going on and etc. It's also likely you won't tell just how much resolution you lost since you likely don't have anything to compare to, however you've done quite the job of reducing your film's ability to resolve detail.

Also, what was your lens stop, after all said and done? I'm assuming you used three pieces of ND gel to get the exposure just barely to the maximum closed aperture your lens offered. You said it was as high as a F/45? So three stops down, you're sitting pretty at a F/16... which depending on the lens could also be an issue. You should also know that almost all lenses loose sharpness at their full closed apertures (maybe even a couple stops before), because of lens diffraction. It really depends on many factors, but many lenses can suffer from this. The HVX200 did quite a bit past F/11 and even cinema glass does past certain T-stops.


So likely your image has suffered from three layers of lighting gel, but from lens diffraction too. It's a catch 22, because you could add more gel and open the lens up or take gel away and theoretically stop down. :/


On the bright side, this is the type of film education that really sticks and better in school than on the job. ;) School is where you should make mistakes and learn from them you will. If you just HAD to get something onto the celluloid (I know it's not celluloid) I think you did a good job of finding a way to get an image, despite how less sharp and clear it is compared to what a good IR-ND1.2 or IR-ND1.5 filter would have done... maybe even a linear pola depending on what you were shooting.
 
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RyanT said:
I remember hearing a story about people shooting the space shuttle lifting off with huge long lenses. The front elements were so big that they didn't have ND filters big enough to cover the front element. So instead what they did was pull some ND off a roll and stuck it onto the front of the camera.
Click to expand...

Every long lens I have seen has a rear drop in filter slot. Just saying....
 
If you have concerns about the quality if the ND, drop it behind the lens so that the focal plane is not a problem. That is what the Bolex system has.
 
With the Bolex, though, you're supposed to be using optical-grade gelatin filters in that slide behind the lens, which can go in the image path without issues. They're many times more transparent, free of contaminants, and lower in dispersion and distortion than the mylar or acetate filters used over lights or windows.

I used to help maintain a clutch of Bolexes for a college film department, and have spent more hours than you would believe cutting up little pieces of 85B and various neutral density gelatin filters to fit in those things ...

- Greg
 
In the end I was shooting at around f/11. If I had a singe piece of ND9, I would have used that, but using 3 small pieces of ND3, was my only option. Usually there is any type you want, but I didn't see anything over 3. I could possibly get 1 or two more ND3s, but I was worried about major quality loss as I've never heard this done before.

With the gel, more light was refracted and more noticable flaring problems. So, flagging with the mattebox was required. I personally didn't notice much sharpness loss. Maybe in the final product we will see something.
 
So, I heard from others that our teacher (who wfind to be a bit crazy) drove to Toronto to drop off the film himself.. 2hrs away because he was flipping that what I did will apparently ruin the shoot.
 
Hahahaha, over-reaction for a student film.

What does dropping off the film personally do?

Like i said, film school is a time to experiment and learn. Now you'll know what 3 ND.3 lighting gels looks like in a mattebox! :P
 
For rear of lens applications, a gel swatch book is handy to keep in your camera case. I've done it before to get a magenta minus green, but that was in the sd 16mm days when nobody knew what resolution was.
 
Ryan Patrick O'Hara said:
Hahahaha, over-reaction for a student film.

What does dropping off the film personally do?

Like i said, film school is a time to experiment and learn. Now you'll know what 3 ND.3 lighting gels looks like in a mattebox! :P
Click to expand...

Obviously I don't know this fellow's reasons... but when the Wife was active in the wedding biz, I would personally drop off the film, so the only way the
film could be damaged was either my stupidity, or the lab's... but not an intermediary such as Fed Ex... who doesn't pay for anything other than perhaps
replacement film... one needs additional insurance to pay for collecting the principles back and getting something of the required coverage...

I'm sure movie productions have similar insurance...

As for 'ruining' the shot with non-optical materials... No exposure is more of a disaster than a 'soft' exposure... unless one has insurance to pay for
a reshoot...
 
When I shoot fashion stills, I'll use a gel for mild diffusion if the gel color is what I'm looking for and I want that strange sort of plastic-ey diffusion. It's always given me a unique sort of look. Gel material isn't made to be optically neutral like CC gel filters are, it would worry me if I wanted a sharp image.

In the film days I shot a lot of 4x5 and always had those clear plastic sheet film sleeves. Similar diffuse look in front of the lens - I'd rub the stuff in a straight line across my forehead to pick up skin oil - but sweeping it straight made a cool sort of "long & stretched" diffusion, where highlights spread in a linear way, sort of like anamorphic flares.
 
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