Monday, May 26, 2008

Proof of the Pudding: Guide Numbers 101

This set of photos was done to test my previous article about using Guide Numbers to get a first shot pretty close to the correct exposure. The main aim below was to show you a series of shots I did using the guide number sheet posted in the above mentioned article.

I post the mistakes as well as the good shots below to show you what I went through and that I am human after all :-) The mistakes I made were all due to using the wrong chart to begin with. In light of this I am thinking of redesigning the print out to make it simpler to use.

Please remember that the aim of the guide numbers is to get as close as possible to getting the right exposure form the first shot. I had previously written about the vast amount of test shots I was taking to get a close shot. Once you get close, it's up to you to tweak them :-)

Anyway here are the shots:


Shot 1a
This shot was taken with a single strobe camera left, using a reflective umbrella @1/8 power and @50mm zoom. I read the wrong number for the wrong chart (2*580 GN number) which means it was shot at -1 stop.

Shot 1b
This is the same shot from Shot 1a, but I have increased the exposure by 1 stop in Adobe Lightroom. I feel that this would have been a good starting point for a shoot.

Shot 2a
This shot was taken with a single strobe camera left, using a reflective umbrella @1/8 power and @50mm zoom. This time I read the right chart and you can see that the exposure is similar tot he adjusted Shot 1b

Shot 3a
This shot was taken with a single strobe camera left, using a reflective umbrella @1/8 power and @50mm zoom. I read the wrong number for the wrong chart (2*580 GN number) which means it was shot at -1 stop.

Shot 3b
This is the same shot from Shot 3a, but I have increased the exposure by 1 stop in Adobe Lightroom. I feel that this would have been a good starting point for a shoot.

Shot 4a
This shot was taken with a single strobe camera left, using a reflective umbrella @1/8 power and @50mm zoom and ISO200.

I calculated the guide number to be -3 stops and it should have been -2 stops.

I used the wrong calculation and over exposed by 1 Stop

Shot 4b
This is the same shot from Shot 4a, but I have decreased the exposure by 1 stop in Adobe Lightroom. I feel that this would have been a good starting point for a shoot

Shot 5a
This shot was taken with a single strobe camera left, using a reflective umbrella @1/8 power and @50mm zoom.

I calculated the guide number to be -2.5 stops and I feel that this would have been a good starting point for a shoot

Shot 6a
This shot was taken with a single strobe camera right, using a reflective umbrella @1/8 power and @50mm zoom.

I calculated the guide number to be -2.5 stops and I feel that this would have been a good starting point for a shoot

For a really good starting point I would have changed the model (me) :-)

Shot 7a
This shot was taken with a two strobes:
1) camera right, using a reflective umbrella @1/8 power and @50mm zoom.
2) camera left, bare light @1/64 and @24mm zoom.

Although this wasn't too bad as a starting point I felt the the left strobe was too bright and I would have stopped in down 1 stop.

Shot 7b
This is the same shot as 7a but the left strobe was decreased by 1 stop and re-shot:
1) camera right, using a reflective umbrella @1/8 power and @50mm zoom.
2) camera left, bare light @1/128 and @24mm zoom.

I feel that this would be a good starting point for a shoot.

Shot 7c
This is the same shot as 7b but the I changed the settings on the left strobe but still aimed to get the same amount of light:
1) camera right, using a reflective umbrella @1/8 power and @50mm zoom.
2) camera left, bare light @1/32 and @14mm zoom.

You can see that the background is more lit than 7b, due to the wider angle of light, but I am lit pretty much the same as in 7b.

I feel that this would be a good starting point for a shoot.

Shot 7d
This is the same shot as 7c but the I added an 8" Honl Snoot without changing any settings to test the theory that a snoot won't change the amount of light just the coverage:
1) camera right, using a reflective umbrella @1/8 power and @50mm zoom.
2) camera left, bare light @1/32 and @14mm zoom with an 8" Honl Snoot.

You can see that the background is much darker than 7c, due to the snoot and the narrower angle of light, but I am lit pretty much the same as in 7c.

I feel that this would be a good starting point for a shoot.

Shot 7e
This is the same shot as 7d but changed the snoot to a Stofen diffuser and recalculated the settings:
1) camera right, using a reflective umbrella @1/8 power and @50mm zoom.
2) camera left, bare light @1/64 and @70mm zoom with a Stofen diffuser.

You can see that I am lit pretty much the same as in 7d.

I feel that this would be a good starting point for a shoot.

Shot 7f
This is the same shot as 7e but I added a pink filter to the Stofen diffuser and recalculated the settings:
1) camera right, using a reflective umbrella @1/8 power and @50mm zoom.
2) camera left, bare light @1/16 and @28mm zoom with a Stofen diffuser.

You can see that I am lit pretty much the same as in 7e.

I feel that this would be a good starting point for a shoot.

Please feel free to leave comments or questions below or email them to me.

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