Built In ND Filters

bcheong

bcheong

Well-known member
Been shooting with my new DVX100A camera and find myself a little confused with the built in ND filters. I know the two settings (1/8 and 1/64) equal 3 and 6 stops respectively. Sometimes I've found myself at F5.6 and wanting to shoot a little more open as to get a shallower DOF. By engaging the first ND setting I figure I can open up to F2.0 and it should look relatively the same exposure wise. I'm finding this is not the case and it's actually darker. I ran some quick tests and I've been finding that the 1/8 setting is actually more like 4-4.5 stops. Haven't tested 1/64 setting. This 4-4.5 stops that I've tested at is on the widest end of the lens as well. I know you loose about 1/2-1 stop at the telephoto end so that doesn't seem to explain why it's still more than 3 stops even at the widest angle of the lens.

What gives?
 
Re: Built In ND Filters

I love this kind of post! The hair-trigger reaction is to say "what are you talking about, it says right on it 1/8 and 1/64".

Yeah. And everybody said the DVX was 320ASA also. So I decided to take it out and test.

Initial reactions showed that ND1 was indeed a bit over three stops, and ND2 was four more stops!

So I took the camera into a dark room, used one light, and put that light on a dimmer so I could absolutely dial in exactly the stop I wanted -- so I could get the camera to settle on f/2.0, for example. Then I'd swap to a lesser ND.

Testing shows that on my DVX100, ND1 is over three stops, looks like about 3.5. ND2 is a full four stops, I don't think it's quite four and a half.

Testing conducted at the widest angle of the lens.

So yes, Barry, you're right! The ND filters are stronger than what they say. I don't know why that is, but it is.
 
Re: Built In ND Filters

Thanks Barry! I just tested with some external Cokin ND's that I have. Just to double check I metered the filter...good ole meter never fails! Funny enough they're 2 stop ND is actually 2.5 stops and sure enough the camera metered it the same. Go figure.

Thanks again!
 
Re: Built In ND Filters

So is the overall conclusion that you should have an external ND lens as well?
 
Re: Built In ND Filters

Not neccesarily. It just means if you're calculating exposure you might be in for a surprise if you're expecting exactly 3 or 6 stops and it's not.

It's about knowing what the true stop of the filter is.
 
Re: Built In ND Filters

The immediate bene Im finding in having an External ND is that is a Grad.

Very nice.
 
Re: Built In ND Filters

Have to 3rd that...ND grads are a saviour in the right situation.
 
Re: Built In ND Filters

For the ignorant masses, what is a "grad" ND? (I, ahem, of course know, ahem, I'm just asking you to explain it to all those, ahem other readers who don't . . .)
 
Re: Built In ND Filters

A "grad" is graduated -- i.e., it's not all one uniform density. It's dark on one side, clear on the other, and gradually goes from dark to light across its surface.

Positioned properly, you could put the dark surface across the sky, but have the clear surface exposing for your subject, and thus be able to bring the sky's exposure down a few stops, etc.
 
Re: Built In ND Filters

Exactly! While also NOT having to STEP DOWN on whatever is below the sky. So, your sky can look killer with clouds and blue while still having the proper exposure on, say, the city street.
 
Re: Built In ND Filters

Screw Ons or THREADED would be measured in 'mm' whilst 3 by 3 and 4 by 4's are made for the Mattebox (Filters drop or slide into STAGES; some of which actually ROTATE).
 
Re: Built In ND Filters

I imagine there is probably some use for a screw-in graduated filter, but the whole notion seems silly to me. Grads need to be oversized, slidable, positionable filters. If you're using a 3x3 mattebox, you'd get a 3x4 grad filter, so you can slide it so that the darkening effect (and the transition to clear) are where you want it to be. Same with a 4x4 box -- you'd get a 4x5.65 grad for that.
 
Re: Built In ND Filters

So my matteblox really isn't gonna work for this than.:(
 
Re: Built In ND Filters

No experience with a matteblox, but I don't see how it could support a sliding tray to allow for an oversized filter. Or does it? Someone who knows needs to chime in.
 
Re: Built In ND Filters

well, heres their filter holders available..

http://www.cinetactics.com/mb-fh.php

but since you just velcro them into the hood, you could make a little cloth fliter holder easily , and velcro it in there if you really wanted to. although a 4x4 barely squeezes into the main matteblox hood in the cinetactics 4x4 filter holder so i imagine you would have to velco the larger filters into the inside of one of the hoods. otherwise it wouldnt really support a sliding mechanism unless you taior mad it, but atthat point you should probably get a hard box.
 
Re: Built In ND Filters

I was trying to decide between the Cavision 3x3 or the Matteblox, and I went with the Matteblox. Now I wish I'd gone with the Cavision.:(
 
Re: Built In ND Filters

Well they are both relatively inexpensive (comparing other models). Perhaps you could sell your blox at a discount and then pay 'a lil more' for the Cavision?

Just a thought
 
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