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Forum: Photographic Technique
02-16-2019, 01:52 PM
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I suggested your camera be set to 1/3 steps so that it matches your flash. If you can set both to 1/2 steps, that's fine too. The most important thing for this thread is that they match.
Grids, snoots, flags, etc., if you can get the subject and background lights completely independent of one another and minimize the spill, it can make relative adjustments easier.
You're happy diving in to photoshop, so another possibility you might consider is combing the lighting in post. In your can photo, take a shot with only the front light on, then take another with the backlight how you like it but the front light off. Combine in post. I have an example of this sort of thing in the first post here, where I move a single light around and then blend the results: Lighting for wide angle close-ups - PentaxForums.com. My use was to be lazy and only pack one light, but this has legitimate studio use. That said, it's almost always more satisfying to get the physical setup 'right' and do it in one shot and generally necessary if your subject is alive and possibly moving:).
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Forum: Photographic Technique
02-15-2019, 07:04 AM
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What flashes do you have? I'm assuming that the first number in your power readings are 1, 2, 4, 8, 16, 32, 64, 128, 256? These are reciprocals, 1 is full power, 2 is 1/2 power, 4 is 1/4 power etc. From here it's exactly as Steve said, each step in flash power will double or halve the light and will compensate for opening or closing the aperture one full f- stop.
For example, if you are happy with the camera at f/2 and your key light at 4 (or 1/4 power) and you background light at 8 (or 1/8 power), then the following would give equal exposures:
f/1.4 key 8 background 16
f/2 key 4 background 8
f/2.8 key 2 background 4
It's exactly the same as manual mode with ambient light. If you open the aperture one f-stop (doubling the amount of light you let in) but wanted to keep the exposure the same, you need to halve the shutter speed to compensate (halving the amount of light you let in).
For the "+3" and "+7", these will be adding finer units of 1/3 EV control of the flash power. If it isn't already, I advise you to set your camera to 1/3 EV steps as well (the other option is 1/2 EV). This way, one click on the flash power will match one click on the cameras aperture wheel. Using the above example as a starting point, the following would give the same exposure:
f/2 key 4 background 8
f/2.2 key 4+3 background 8+3
f/2.5 key 4+7 background 8+7
f/2.8 key 2 background 4
It's just a matter of counting 'clicks'.
NOTE: I've written flash powers like "4+3" to match how you expressed it in your first post. I'm not sure how yours actually displays it, but this notation is pretty confusing. My Nikon flashes would write 1/4 + 0.3 with an extra box to separate the "+0.3" to reinforce the mixed notations. The most confusing thing with my Nikons is how the 0.3 and 0.7 units work as either add ons or subrtract ons (that's a new term I think). 1/4 + 0.3 would be the same power as 1/2 - 0.7, which version gets displayed depends on how you get there (ie start at 1/4 power and increase it one press or start at 1/2 and decrease it two presses).
---------- Post added 02-15-19 at 09:19 AM ----------
I'm not sure I understand this, but I think you're saying the softbox isn't lit uniformly and further back you see closer to the edge of the surface which is darker? You might have an easier time with uniformity using a white or neutral grey backdrop and aim your gelled flash directly at it (I 've only skimmed this article, but it shows many examples Creating Perfect Gelled Backgrounds for Portraits).
Or use double diffusion- use big fat diffusion panel as your backdrop and put your flash/softbox behind it.
Not as flexible, but you can also just use actual coloured backgrounds. For small products, a collection of different colours won't be too pricey or hard to manage space wise.
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