Nikolai
Jun-19-2008, 08:06 PM
There is a lot of talk about different flash diffusers. Some of them true, some are pure BS. This week you're going to put all this talks to the test and come out with your own opinion based on your own facts..
You would need a dedicated flash unit
To do this we going to build a set of very simplistic diffusers and then use some simplistic targets at different distances from the said diffusers. Naturally there will be a difference in luminosity (and probably noise), but we are not going to be concerned about it and will simply bring every test image to the approximately same general level of luminosity.
Here's just ONE possible suggestion how to do this testing. However you can go your own merry ways as long as the results are comparable.
Get 2 white foam boards (the ones that can stand by themselves) and 2 dark paper poster board.
Get camera on a tripod and a couple of chairs
Wait until it gets dark
Cut one dark poster board in half length-wise, another width-wise. Using scotch tape or some clamps attach both boards to one of the white ones in a way that there is a rectangular opening somewhere in the middle.
Using something like unbent large paper clips (and a scotch tape if you need it) attach a small opaque target (a business card or an index card) to the second foam board in a way that there is about 2-3 inches between the card and the board.
Put the chairs close to each other, put the foam board on them facing each other. Make sure there is no light-colored wall close to the back of the "aperture" board.
Put the flash close to the aperture board, its working surface facing the board (and away from the target)
Adjust your rectangular "poster aperture" that it only opens a white rectangular white space similar in size to the flash surface itself.
Focus your camera on the target in a way it can "see" the shadow that is created by the light reflected
Start taking pictures of the target and increasing the "reflector aperture" (don't forget to take notes). It can also be a good idea to take a picture of each aperture and then a picture of the target, thus making the whole thing self-documented. OR replace the targets (index/business cards) each time and write the conditions directly on them, this would be even better. Don't forget the notes of the flash intensity and ISO level - you would need to adjust those to keep with the distance...
Increase the distance between the boards twice. Repeat step 10.
Repeat step 11 until you're out of the room space.
Download the results to your computer and analyze the sizes of the shadows created.
Create a composite image by putting all your results in a matrix form (reflector opening size vs distance to target)
Make a post here with the said composite shot, few shots of the setup, project description and your thoughts of how the reflector size REALLY affects the shadow sharpness.
For the extra points make a few portraits of the same person at some limited selected number of "reflector size vs distance" combinations.Clear as mud? :wink
Anyway: let's put those diffuser size myths to the test!
You would need a dedicated flash unit
To do this we going to build a set of very simplistic diffusers and then use some simplistic targets at different distances from the said diffusers. Naturally there will be a difference in luminosity (and probably noise), but we are not going to be concerned about it and will simply bring every test image to the approximately same general level of luminosity.
Here's just ONE possible suggestion how to do this testing. However you can go your own merry ways as long as the results are comparable.
Get 2 white foam boards (the ones that can stand by themselves) and 2 dark paper poster board.
Get camera on a tripod and a couple of chairs
Wait until it gets dark
Cut one dark poster board in half length-wise, another width-wise. Using scotch tape or some clamps attach both boards to one of the white ones in a way that there is a rectangular opening somewhere in the middle.
Using something like unbent large paper clips (and a scotch tape if you need it) attach a small opaque target (a business card or an index card) to the second foam board in a way that there is about 2-3 inches between the card and the board.
Put the chairs close to each other, put the foam board on them facing each other. Make sure there is no light-colored wall close to the back of the "aperture" board.
Put the flash close to the aperture board, its working surface facing the board (and away from the target)
Adjust your rectangular "poster aperture" that it only opens a white rectangular white space similar in size to the flash surface itself.
Focus your camera on the target in a way it can "see" the shadow that is created by the light reflected
Start taking pictures of the target and increasing the "reflector aperture" (don't forget to take notes). It can also be a good idea to take a picture of each aperture and then a picture of the target, thus making the whole thing self-documented. OR replace the targets (index/business cards) each time and write the conditions directly on them, this would be even better. Don't forget the notes of the flash intensity and ISO level - you would need to adjust those to keep with the distance...
Increase the distance between the boards twice. Repeat step 10.
Repeat step 11 until you're out of the room space.
Download the results to your computer and analyze the sizes of the shadows created.
Create a composite image by putting all your results in a matrix form (reflector opening size vs distance to target)
Make a post here with the said composite shot, few shots of the setup, project description and your thoughts of how the reflector size REALLY affects the shadow sharpness.
For the extra points make a few portraits of the same person at some limited selected number of "reflector size vs distance" combinations.Clear as mud? :wink
Anyway: let's put those diffuser size myths to the test!