ND filter to reduce shutter time?

[bosscock]

hello,

I just been given a Kodak Specialist No3 with a rollerblind shutter and a 1900's barrel lens.

I had some good results using paper negs with 20 second exposures. I would like to shoot some film negative, however I cannot trust the rollerblind shutter and the higher iso of the film means I cannot 'remove and replace' the lens cap (my 'shutter) quick enough for the metered exposure.

Would it be possible to use a ND filter to reduce the shutter speeds to say 1-3 seconds and use the lens cap as the shutter? would this affect the quality of the image.

thanks in advance for any help or suggestions..

Neill

[Sevo]

You would want to increase rather than reduce. And yes, that is the main purpose of ND filters.

[Larry H-L]

Yes. ND filters are marked by density rather than stops. A 0.3 ND filter will require one more stop of light, it will double the exposure time.

A 0.6 is 2stops, and will increase exposure by 4 times, a 0.9 is 3 stops and will increase required exposure by 8x.

A 1.2 ND is 16x, etc.

[bosscock]

Thanks for the quick replies.

much appreciated, this will really open up the where and when I can shoot.

Neill

[Daniel Stone]

I use nd(both graduated 4x6 and solid 4x4) in the field, sometimes combined with each other. Sometimes, when I want to photograph flowing water(such as in a stream or river, or the ocean), and I want it smooth and velvety, I put a 2 or 3 stop ND filter on the lens. I don't like to stop down more than I absolutely have too, and with 4x5 or 8x10 this usually means no more far down than F/22 or 32, sometimes more... 1/15 can show too much texture sometimes FOR ME, so I put a filter on it to take it down to 1/4 sec, or 1/2 second, which smooths out the water.

Testing out filters on a DSLR before implementing them in the field with film can help you understand their actual trasmissive change(how much light they actually take out), and allow you to "experiment" w/o having to commit film to a shot, and it can help you learn faster that way.

happy shooting!

-Dan

[bosscock]

Thanks for the advice Dan, I've got a canon400d so I'll have a play with that.

Am I Ok to focus without the nd filter on and then attach when I'm fitting the film holder..

Neill

[Daniel Stone]

Neill,

You'll want to make sure that you ND filter(s) doesn't cause any focus shift. Good filters SHOULD NOT, so you can focus, then install the filter on the lens before photographing. If it causes focus shift, you'll need to focus with the filter in place, this can be a pain with heavy ND filters(especially a 3 stop or more)

-Dan

[bobwysiwyg]

Dan,

How does adding an ND filter alter the point of focus?

Just curious.

[Daniel Stone]

Dan,

How does adding an ND filter alter the point of focus?

Just curious.

If you add a poor/lower quality filter after manually focusing you effectively change the focal distance of the lens. I can't really explain it in "technical" terms, just what I've experienced w/ poor quality filters. Good quality filters SHOULD NOT affect focal distance. I've just made it a habit after shooting 5 negs w/ a chinese yellow filter(ebay "freebie"), only to find that the filter caused focus shift. I now only use a high quality(B+W) polarizer and occasionally a GND filter kit, and final focus WITH the filters IN PLACE.

-Dan

[BrianShaw]

I sincerely believe that image quality degradation was noticed when using a lower quality filter, but I doubt it was a noticable focus shift.

[Heroique]

Watch out for color shifts too.

Here’s an example:

— The first shot is w/o filtration, Astia-100F, 1/30th @ f/22.
— The second shot is also Astia-100F, w/ B+W’s 10-stop ND filter, 34 seconds @ f/22. This was taken moments later in the same light.

Based on my experience w/ Astia-100F w/o filtration, this color change is not caused by the film’s reciprocity failure. The B+W filter is responsible for it.

I’m amused that B+W would call this a “neutral” filter. Be this as it may, an 80d (blue) filter “corrects” its color influence to my satisfaction.

Tachi 4x5
Schneider XL 110mm/5.6
Astia-100F (both shots)
Epson 4990/Epson Scan

[Preston]

I have shot a lot of Astia 100F and can confirm that the color shift is not due to reciprocity failure. it is surprising that a B&W filter, that is purported to be neutral, would induce such a color shift.

--P

[Sevo]

I’m amused that B+W would call this a “neutral” filter.

B+W (and Heliopan) explicitly warn that any glass ND filter past three stop has colour shift. And while high density gelatin filters had better properties to start with, they aged rapidly - IIRC the ten stop Tiffen had a shelf life of something like two years, and was to be used within very limited humidity range.

[Heroique]

That’s interesting – I bet B+W decided that “neutral” should, nonetheless, stay in the filter’s title for marketing purposes.

I remember investigating this filter’s color shift in an earlier thread, and sharing some of the revealing data.

Down at my local Glazer’s shop, we used a sophisticated Sekonic color meter, and the B+W 10-stop filter caused a 970° K drop in temperature (more red, just as the photo shows). This was even more than I (and the Glazer’s experts) suspected – I’d even call it significantly un-neutral. A handy chart equated this change w/ a +40 nm shift.

For comparison, we also had a Nikon 2-stop and Tiffen 3-stop ND filter, and we measured these, too. The Nikon produced a 160° K rise in temperature (more blue). The Tiffen produced a 340° K rise (also more blue). These smaller changes, of course, would not be as noticeable to the naked eye (if at all). Much more “neutral,” especially the Nikon.