If you have Canon MR-14EX ring flash, Do you have the same problem. Here is the problem statement:
I attached the flash to my 30d and 100mm f2.8 macro lens and mounted the camera on a tripod and put a piece of paper in front it and keep the camera and the paper static during the test. The camera was set to manual exposure (1/250s and f22) and manual focus. Then I started my test by setting the manual power output of the flash from 1/64 all the way up to 1/1 and get 7 images. The intensity of the 7 images should monotonically increase.
But the 1/16 image turns out to be brighter than 1/8 image. it's as bright as 1/4 image. That's 2 stops brighter than it should be. I have tried different objects and get the same problem. The problem is not always at the
1/16 output. The effect of 2 stops brighter has occurred for 1/64,1/32, 1/8. In one word, I can't get the desired power output all the time. The problem doesn't happen all the time. It happens once out of 5 shots on average.
I have tested it with both eos 30d and 40d. Both have the same problem.
When I found this problem within the first flash Adorama sent to me, I thought it might be a deficient one. So I asked for an exchange. Then Adorama sent me a second one. The disappointing thing is the second one also has the same problem. I think that's an inherent problem of the MR-14EX Ring flash.
