macro question

[tonyz]

Hi there

Help needed here please

I keep trying to take a picture of this small circuit board (PRam I think) with my canon 5d3 and 100L and get a flare in the middle of the board but for the life of me cant figure out how/why.

I did have the 21 and 31mm tubes attached too and its on a tripod with remote and the lens hood so not too sure how this could appear? there were no windows close byfor sunlight and i tried to shield the circuit when i took the pictures but this still appeared in the centre?

Am I missing something obvious here?

Many thanks

Tony

 

[mackguyver]

Hi there

Help needed here please

I keep trying to take a picture of this small circuit board (PRam I think) with my canon 5d3 and 100L and get a flare in the middle of the board but for the life of me cant figure out how/why.

I did have the 21 and 31mm tubes attached too and its on a tripod with remote and the lens hood so not too sure how this could appear? there were no windows close byfor sunlight and i tried to shield the circuit when i took the pictures but this still appeared in the centre?

Am I missing something obvious here?

Many thanks

Tony

What are you using for lighting and where is the lighting in relation to the circuit board?

 

[tonyz]

It was just natural light - long exposure around 6 seconds but just a window on the far side of the room but i was standing in between to ensure no flare when I saw this.

I also tried removing the uv filter too just in case and it didnt make any difference?

 

[Jim Saunders]

Nothing wrong there a radial filter in LR couldn't fix.

Jim

 

[tonyz]

do you mean a radial blur?

I'm just not sure why it appeared though - amy ideas?

 

[Jim Saunders]

do you mean a radial blur?

I'm just not sure why it appeared though - amy ideas?

No, LR5 has radial filters. They work the same as a grad but in a circle. Put one in the middle, stretch it out to fit, adjust exposure to suit. The cause of your hot spot there I don't know.

Jim

 

[mackguyver]

Hmm, if it's flare, it would have to be from a reflection off the transistors, but I think what you're seeing isn't flare. I think it's vignetting caused by the extension tubes and what you're seeing in the middle is the un-vignetted part. I bet you would see less and less vignetting as you stop down, so you could give that a try, but Jim's recommendation would be the easiest way to fix it.

 

[tolusina]

I've sure no definitive answer, several possibilities do come to mind, all may be hooey.

I'm liking mackguyver's suggestion that it might be vignetting, I think that would be easy to test.
With the same set up, change out the circuit board as subject with plain paper as subject, if lens/extension tube vignetting is the issue it should be readily apparent.

I'm thinking this one is way off the wall, but I'm thinking it anyway.
Wondering if light is reflecting off the solder pads, maybe bouncing around between the pads and the lens.
Try shifting the part that now shows brighter off to one side of the frame. If that part remains brighter, it's a light distribution issue, see Jim Saunders' radial filter in LR suggested fix.

Is it possible in your set up that light is coming through from the other side of the circuit board? If so, that should be easy to block. The central, green part of the board might well be able to pass light that would be blocked by the adjacent IC chips.

And, it's quite possible that the answer you seek is something else entirely, I freely admit I'm only guessing.



.