Metering long exposures

<p>Hello all.....<br>

Ill cut to the chase. I shoot film. I use a Sekonic meter. Usually i'm using Kodak Ektar 100. I shoot long exposures at pre-sunrise. (moving clouds...smooth water....you know the drill.) to account for reciprocity fail I usually overexpose by one stop. If I set my meter at asa 50 as opposed to 100 would I be safe? My shots are usually in the 2-4min range. On occasion i'm adding ND filters to the mix.<br>

So whats the best way to do what I want to do with what i've got. For what its worth i'm using a Nikon f3 and a 20mm lens set at F/22.<br>

Thanks in advance for you thoughts.<br>

Dave</p>

<p>Setting your meter for ISO 50 instead of 100 is one stop, but correcting for reciprocity failure is not one stop across the board. Different films require different levels of adjustment and for any individual film the amount of correction requires increases as the length of exposure increases.<br>

http://home.earthlink.net/~kitathome/LunarLight/moonlight_gallery/technique/reciprocity.htm</p>

<p>Henry Posner<br /><strong>B&H Photo-Video</strong></p>

<p>I have an app for figuring out reciprocity failure - one of my favorite apps. For Ektar 100, if the metered exposure is 2 minutes, then you need just over 6 minutes. For a 4 minute metered, you need 14 1/2 minutes. I didn't do the math to know how to come up with numbers for other meter readings, but those might help (or go find the app "reciprocity timer", I think). The app has a place to add filters as well as info for large format cameras like which lens and bellows extension. Anything you're not using, you just leave at 0.</p>

<p>For me with my fav film like Velvia 50 RVP I have this in my head re: reprocity. I also carry a laminted card that tells me. Adjusting the ISO will work but for me I find it easier to adjust the longer time. I am used to using Velvia at any time at ISO 50. I also don't finish a entire roll in each shoot probably more like 8 shots each time. </p>

<p>Here is reciprocity failure on a Nikon F3HP and Fuji Velvia over about a 5 minute period (see the star trails). </p>

<p>I like the night-like look of reciprocity failure.</p>

<p><img src="http://d6d2h4gfvy8t8.cloudfront.net/9198812-md.jpg" alt="" width="679" height="1006" /></p>

<p>Same camera, same film, about 2-3 minutes. Both of these shots I just set the F3HP to Auto, and let the meter take over.</p>

<p><img src="http://d6d2h4gfvy8t8.cloudfront.net/6730758-md.jpg" alt="" width="679" height="1019" /></p>

Wow. Terrific shots.

 

My take on long exposures with film was to do a (rather extreme) bracketing.

 

For the Velvia fans out there (I am one too), the "newer" (introduced 10 years ago or so) RVP50 is said to correct most of

the reciprocity issues of the original RVP. Although to be honest, I cannot really tell, I have no experience with RVP50, I

am still shooting my remaining stock of original RVP I filled my freezer with when I was regularly flying to Japan for work

in 2005-2007.

 

Etienne

<p>Les: I made no adjustment for reciprocity failure. I just allowed the F3 to use its on-board meter in the normal fashion, and these are the results. </p>

<p>Happily, I used a big honkin' Manfrotto 055 XPROB, well anchored. And, I shielded the front of the lens with my hand when cars passed by, minimizing random light inputs.</p>

<p>Les, that is a 7-hour shot, wow!!! How come it is not completely overexposed?? <br>

One could think that after a certain point, the film will simply not take any more light...</p>

<p>Thanks for the info :-)</p>

<p>Les: Not strictly true as Olympus' SLRs also used off-the-film metering and would measure exposure during the exposure. I have an OM-4 which does this.</p>

<p>OP: Use the reciprocity chart for the film to make your exposure compensations for the reciprocity failure associated it.</p>

<p>My Nikon FE bodies also do very long exposures in aperture priority mode. I've gotten some nice snaps on Velvia 50 in this fashion. I dial in +1 or 2 exposure compensation, hit the shutter then enjoy the view and a beer or two.</p>