ND Filter + Red Filter

[jjstafford]

Final note: TEST! Nobody can assure you with adequate results. You have to make the effort to make some test images and decide for yourself. Is that so much of a worry to do?

[Donald Qualls]

I might mention here that Efke 25 requires a much larger filter factor for a red than normal film -- it has a relatively low red sensitivity compared to common panchro materials and will probably lost at least one more stop with a red, perhaps as much as a stop and a half. If you haven't shot Efke with a red before, I suspect you'll be in for a surprise, and not an altogether pleasant one; at the very least, bracket to +2 over what you think you'll need.