I guess this has probably been discussed, but sometimes things don’t make perfect sense until you play them out in your own situation… I have discovered that, against natural lighting work in the field, studio work with a 4x5 is a whole new animal.

I own four low-ish powered strobes at 200w/s each. At first I was very intimidated by using multiple pops to fulfill the smaller working apertures on my 4x5 lenses, especially on slow films such as RVP 50. However, I spent the day figuring out a system and I was hoping some of you could help me verify or tune what I’ve come up with.

I use an L-358 light meter and I have decided to work with 1/10 stops. Here is my workflow:

Say I am using a 210mm lens with an aperture range of 64 to 5.6. I setup my scene and perform a focus analysis using my camera’s DOF calculator (on the fine focus knob). I determine that the largest applicable aperture for the DOF range that I want is f/32. I back focus from the nearest point by half and lock the focus down.

I then use my QuickDisc, or I do an extension calculation, and determine that my bellows factor is 6/10 of a stop.

I then take a meter reading (incident) and my meter returns an aperture of f/16 and 8/10 for an ISO 50 film. Because this is too large of an aperture for my intended DOF, I need to scale this figure and use multiple hits of my strobes. Here is what I am doing:

First I subtract my bellows factor from my initial meter reading to get an adjusted value of f/16 and 2/10, this is my target exposure. My working aperture is, again, f/32, so I adjust this to f/32 and 2/10 with the error on the side of greater DOF, which is safe. My target exposure of f/16 and 2/10 is, then, exactly two stops brighter than my adjusted working aperture of f/32 and 2/10.

The reason I am adjusting the working aperture to be a multiple of the target exposure is because I don’t want to change my strobe powers, I want to figure whole hits of my strobes as they stand.

So, given the adjustment, I will need (2 stops = 4) four hits of my strobes to meet my target exposure with my aperture set to approx f/32 and 2/10 (physically, slightly below the f/32 and 1/3 mark on my lens scale).

I have now verified my math by doing a multi-reading with my flash meter and setting the exposure compensation to -0.6. The result of four hits on my meter is f/32 and 3/10. Just 1/10 of a stop off from my calculations, which is finer in resolution than I can probably set my lens aperture, heh. That is hugely satisfying, I am so proud of myself right now, lol. I know that I could just rely on my meter, but I’d rather get used to doing the calculations myself because this will make me universally more prepared to handle any situation in any studio.

Is this a sound method? It seems that it would be adaptable to just about any situation and any factor can be adjusted to fit the scene, which is just great. I have just exposed two sheets of 4x5 Velvia 50 using this method, one on my 210mm and one on my 180mm (both Nikkor-W’s) so I guess I will see some hard proof as soon as I get them processed. But if anyone would care to chime in and suggest any adjustment to this method, from math knowhow or experience, I am all ears!