Douglas Underdahl from Long Valley Equipment has come up with the ND Slide, a built in ND filter system for your RED Scarlet, Epic, Dragon, and Weapon cameras.
It has two filter stages, each loaded with a different ND value, giving four settings:
1) no filter – no light reduction to the OLPF and sensor;
2) slide one engaged: ND .6 (two stops) light reduction:
3) slide two engaged: ND .9 (three stops) light reduction;
4) sildes one AND two engaged, giving a light reduction of ND 1.5, or 5 stops.
It is shown in bare aluminum but please know that finished version will be black anodized.
Filters used will have both ND and IR reduction. 3 stops, 6 stops, and the combo would yield 9 total stops along with IR attenuation. Or more?
Slides can be engaged and disengaged instantly.
LENS MOUNTS – right now, I’m using this prototype with our Long Valley Equipment Posi Lock Nikon mount for Epic/Scarlet/Dragon/Weapon. This mount uses the Red One Nikon locking system and is very robust. The chassis is CNC machined from a single billet of 6061 aluminum. It offers manual iris control for G series Nikon lenses and other lenses that have no iris control ring. It does not have any electrical contact with the camera and offers no electronic iris or focus control from the camera – a “dumb” mount. I’ve tried about 10 different Nikon mounted lenses, old and new, and none of them protrude into the lens mount enough to contact the ND Slide.
I am sure that there will be interest in this built in filter system for use with other lens mounts such as the Red Digital Cine’s DSMC Nikon, Canon, and PL mounts, but at this point, I’m not sure how compatible it will be. It should be clear that a slot needs to be cut into the top of the mount and I don’t know if this will or won’t be possible with these mounts.
FOCUS – It was Richter who said that anything placed between the lens and focal plane will shift the flange focus distance (some say backfocus) by about one third it’s thickness. So there will be a focus shift when one engages the filters. This is not a problem for the vast majority of users who focus their cameras by eye; that is, viewing the subject on the monitor and turning the focus ring on the lens until sharp focus is achieved. For those who use a tape measure and set focus using the witness mark and focus distances on the lens, it should be noted that the focus marks will not be accurate when one or both filter slides are engaged. They will all be shifted slightly.
SHARPNESS – I’ve been doing some tests with my Epic at 5K, and I’m actually having trouble figuring out which image is with the built in ND and which is without. There is some reduction in quality but it is very slight and probably similar to using ND filters in front of the lens.
RUN AND GUN – Well, you know what this device means for run and gun – and other work. You can instantly switch on ND filters in the camera, so you can react to wildly changing light values without stopping to pull out an ND and place it over the lens. In many cases, this can mean the difference between getting the shot or losing it forever. Even for scripted narrative work, the ND Slide can speed up production and will prove invaluable, as built in ND filters have in other cameras.
CUSTOM FILTERS – not sure what other filters might find their way into the ND Slide, but if you have ideas for effects filters, etc, just let me know. I can imagine nets, UV, IR Pass, fog, double fog, low con, etc etc.