For a long time I have owned and used sev­eral Singh-Ray Vari-ND (vari­able neu­tral den­sity) fil­ters, each of which allows me to dial in from 2 to 8 stops of den­sity as needed. Recently, I acquired a Singh-Ray Mor-Slo ND, a rel­a­tively thin 5-stop neu­tral den­sity fil­ter which I can mount on my vari­able ND to give me up to a total of 13 stops of neu­tral den­sity. Now I can set slow (very slow) shut­ter speeds even when the ambi­ent light is quite bright. Which is what I did in this photograph.

The trick, of course, is not to try and com­pose and/or focus the image with the ND fil­ter at the required strength. Fire up 13 stops of neu­tral den­sity and you can’t see a thing (well, I can’t see a thing) through the viewfinder, even in good light. I either com­pose and focus with no ND fil­ter attached, or dial my vari­able ND down to its min­i­mum den­sity (2 f-stops by itself, 7 f-stops if paired with the 5-stop fil­ter) and crank it back up when I’m ready to shoot. On a tri­pod, of course.

The other require­ment for an image like this, need­less to say, is that some­thing in the scene needs to be mov­ing. On this day, clouds and mist and bits of blue sky were whip­ping by sur­pris­ingly fast along the rim of Yosemite Val­ley. So fast that, with a 30 sec­ond expo­sure, you couldn’t really pre­dict what the end result might be. So the final require­ment for shots like these, as with most mov­ing sub­jects, is to take lots of expo­sures. Or, if your expo­sures are really lengthy, as many as is prac­ti­cal. In this case, I didn’t have a lot of time, so I man­aged to take maybe two dozen shots. In this one, a rather clas­sic Halloween-style “spirit” some­how mate­ri­al­ized from the mist. Con­verted to black-and-white, it is both play­fully spooky and won­der­fully ethe­real at the same time. In the com­ing weeks and months, I’ll be adding more images like this one to my long-exposure pho­to­graph Still gallery.

Tech­ni­cal Data:
Body: Canon EOS 7D
Lens: Canon EF 70-200mm f/4 L USM at 70mm
Expo­sure: ISO 100, f/19, 30 seconds