Tiffen Variable ND Filters, any experience?

bozcrags · Jun 5, 2016

I would like to have the flexibility to log in some ultra long exposures, and was looking for some 77mm ND filters for both a Sigma 10-22, and a Canon 17-40L (thankfully both 77mm). I stumbled across this variable one, but it seems like it has some issues. Can't accept a lens cap?! That sounds annoying. Does anyone have any experience with this set up?

Thanks for any info!!!!

Boz

petrochemist · Jun 7, 2016

Variable ND filters don't work well with ultra wide-angle lenses.
AFAIK all variable NDs are made using crossed polarizers, and often give a dark X in the sky with wide shots. My variables take lens caps with no problem though they're cheaper models than the Tiffen.

bozcrags · Jun 7, 2016

This is on a 1.6x crop factor, do you think it would be an issue on 16mm equivalence and up? Which models do you have, and have you used them @20-30mm (equivalent)?

petrochemist · Jun 8, 2016

I've not personally had issues, but when going wider than the kit zoom I've only really got Fisheye lenses & I don't use variable NDs much anyway. The Siggy 10-20 on crop bodies is probably responsible for many of the examples I've seen.

astroNikon · Jun 8, 2016

I looked into Variables. But the good ones are very expensive.
I just stack an ND if I have to, or even put a CPL on an ND too, or GNDs.

Ido · Jun 8, 2016

Variable ND filters can be useful tools, at least in the lower densities. They are especially useful for a video shooter who is forced to use a certain shutter speed, or someone who shoots with fast lenses wide-open in daylight. In stronger densities, however, they can get nasty; search on Google for "variable ND filter X pattern" and you'll see one issue. If your budget is somewhat tight, it will also most likely have a bad color cast. I'm sorry to generalize here, but it does hold true almost all the time.

For long exposures, it's a lot better to have a solid ND filter. Just find out what density you need. This guide can help: 2015 ND Buying Guide. It is clearly an advertisement to a certain (up and coming) filter manufacturer, but it actually contains very useful information.
I like a more personal approach, though. Go out to a place nearby—could even be your street—at a time of day you're likely to want to shoot a long exposure image. Use Aperture Priority mode, set the aperture around f/8–f/16 and the ISO to the base setting. Use exposure compensation if needed, and take note of the shutter speed the camera picked. (You can go back home at this point :~) .) Now think about the shutter speed you actually want for the image; how long an exposure do you want? Seconds? Dozens of seconds? Minutes? Calculate how many stops it takes to get from the shutter speed that got you a good exposure without a filter, to the shutter speed you want to use. Then buy a filter that blocks at least close to as many stops as you calculated.
Friendly reminder: Doubling or halving the shutter speed accounts for one stop. For example, it takes stop to go from 1/60 s. to 1/30 s., or 3 stops to go from 1/60 to 1/8, or 6 stops to go from 1/60 to 1 full second, or 10 stops to go from 1/60 to 15 seconds. There is some rounding going on here; if you don't know/remember the numbers, put your camera into Manual mode and spin the dial that controls the shutter speed (by default, most cameras change in 1/3-stop increments, so three clicks of the dial get you one stop lower/higher).