Ektachrome 16mm and ND filters

Hi everyone

I'm just looking for some advice having had little experience with using ND filters in the past. I'm looking to shoot some Ektachrome 100D with my Cine Kodak Model K over the summer. I haven't used any colour stock in years and when it was last available I could buy it in 25iso so there was no need for using ND filters.

As Ektachrome stock is much more sensitive at 100iso I'll need to use an ND filter to reduce the light. The model K runs at 16fps so approx 1/32 shutter speed.

I've been doing some research and found an article stating ND4 as an equivalent to an increase in 2 stops. If I'm right this should effectively bring the sensitivity of the film down to 25iso.

If any of the experts can just re-assure me or tell me I'm completely wrong then that would be great. I don't want to go through the expense of shooting on colour stock after so long to find I've made a silly error.

You are correct, an ND4 filter slows by 2 stops so you can treat 100 as 25 ISO. An ND8 would slow by 3 stops, ND16 for 4 stops, and so on.

Even at ISO 25 you're looking at an aperture of ~f/16 in full sun -- still plenty of speed. When shooting b&w film I'll usually opt for an orange filter rather than an ND but that obviously doesn't apply to ektachrome.

Is the Model K a magazine style camera or does it accept daylight spools? Double-perf only?

Thanks for confirming. It did seem pretty straight forward but with my lack of experience of ND filters I wanted to be sure first, especially with how expensive cine is nowadays.

The model K is a daylight spool type with a double perf claw and sprocket. It's a bit more fiddly though as the full reel sits under a door which the take-up reel sits on top of, making a rather unusual twisty film path. It's quite a good low-cost 16mm camera and the results I've had from it so far have been very good.

The FPP sells Ektachrome as double perf 16mm so I'll be buying it from there. They also stock double 8mm which I shoot. For around $10 more on the price of 50ft double 8 I get 100ft of 16mm so it seems more economical to go down the 16mm route.

Going 16mm also avoids the perilous step of slitting the Double8 and splicing to a full 100' for actual projection. I process cine film myself, so that is the biggest blocker around 'real' double8 for me.

If you are a fan of 16mm cine I'd suggest checking out subminiature still cameras (the Minolta 16 series being my favorite) if you haven't already. They use the same 16mm cine film and are a nice adjunct bit of kit to carry along in a shirt pocket. You can snap 14x10mm or 17x12mm stills if you think enlargements from the 10x8mm cine footage won't suffice

I don't process my own cine so slitting 8mm has always been the labs problem! Still though, I'm somewhat surprised that 25ft of Ektachrome doesn't really save you anything in comparison to 100ft on 16mm. That said I won't turn this into a discussion on pricing and it's likely that having to cut and re-perforate for Double 8 adds to the costs.

I haven't looked much into sub-miniature cameras. The only 16mm one that I recall is the Coronet Midget though this was on a unperforated roll film. I'll have a look at the Minolta series, they sound interesting!

Regarding ND filters: I find having ND filters of different densities offers a wider choice of Fstops. I shoot BW reversal and usually, but not always, process film myself.

Not sure how you are calculating cost, but any length of dual 8 runs four times longer on the projector than the same length of 16mm film. If one is shooting the dual 8 at 18fps and the 16mm at 24fps, the difference is even more dramatic.

I have collected a bunch of nice ND filters to fit my Switar lenses, for use outdoors. Especially with dual-8 where I don't want to stop down past f8. I use the 0.9 filters (3 stops) in 'series' sizes that fit between the lens and the lenshood.

Thanks for all of the helpful tips and replies everyone. ic-racer, I actually hadn't considered costs in that way and I was just looking at raw stock cost but still, for the sake of cost I'd be happier with 100ft of 16mm than a 25ft roll of double 8. I do have a soft spot for double 8 though, it's the format that I started shooting with when I inherited a Lumicon III which was used by my grandfather throughout the 70s, 80s and early 90s.

Finding a filter to fit my Kodak K hasn't exactly been easy. I did eventually manage to source a 28mm ND4 filter which I'm able to do something with. When I bought the camera it came with an old Kodachrome haze filter, the lens of which had degraded and separated somewhat. This is essentially a lens holder with three thumb screws to mount to the model K lens. I managed to remove the original lens and found the new 28mm ND filter fits perfectly.

I will source a few different ND filters to use if it is beneficial to have a wider range of F stops, I may look for more of these old kodachrome filters to modify as it'll be very fiddly to replace the lens within the single holder by having to unscrew the fine retaining ring every time.

I've just ordered some Ektachrome stock so I look forward to shooting some colour for the first time almost 10 years!