The Folly Of The JML 21mm f/3.5

THIRTYFIVEMILL

THIRTYFIVEMILL

Messages
4,611
Name
Duncan
Edit My Images
No
It doesn't like artificial lighting! I made a hood for this lens but it hasn't worked and will tomorrow purchase a ping pong ball and try again. If you get the lighting just slightly wrong you'll get the result below, which is a 30 image stack. I'd have been fairly happy with this stack had it not been for that problem. Sigh..:( Anyone with stacking experience see anything else I'm doing wrong?

STACK.png
 
Are you sure this is light leaking in from front I have many a time had this issue with reversing old lens and cheap adapters which the light leaks through.
 
WingTsun said:
Possibly. When you say "light leaking in from the front", how do you mean. Where would it leak in?
Click to expand...

I mean glare... light entering directly from flash or reflective surface directly into lens.

Leaking I was really referring to joints inbetween.
 
Tintin124 said:
I mean glare... light entering directly from flash or reflective surface directly into lens.

Leaking I was really referring to joints inbetween.
Click to expand...

Not sure. There was no lighting in front of the lens but I do know that many have struggled with glare with this lens so I need to sit and study it a bit and see where I can cancel it. Darned annoying as I didn't notice it during the stack as I was concentrating on getting the instructions right. :D
 
I get a similar effect with my tamron adaptall 90mm f2.5 macro, obviously a very different beast, but I understand it's due to the rear element being flat. A lens hood sorts it out, but I wonder if you are experiencing something similar, along with a similar issue I observed with using extension tubes on certain lenses.

I think Bryn is right and you are getting light bounced directly back into the lens (as I understand it it's the sensor itself that is being reflected back, which is why it appears purple), maybe bouncing back from your reflective subject. I would suggest the following:

  • It looks like you are using a twin flash (MT24?) Can these be angled more to try to prevent light bouncing directly back?
  • Make a small lens hood of some kind (rolled up bit of card should do it) - if the light is being reflected directly back through the lens, I don't understand how this works; but it works for me, so worth a shot!

The ping pong ball is a good idea anyway, I've seen excellent results with that as the diffuser (even if it does look a bit fiddly).

Good luck! It seems like you are going to get some amazing results once you've overcome this little obstacle.
 
TimmyG said:
I get a similar effect with my tamron adaptall 90mm f2.5 macro, obviously a very different beast, but I understand it's due to the rear element being flat. A lens hood sorts it out, but I wonder if you are experiencing something similar, along with a similar issue I observed with using extension tubes on certain lenses.

I think Bryn is right and you are getting light bounced directly back into the lens (as I understand it it's the sensor itself that is being reflected back, which is why it appears purple), maybe bouncing back from your reflective subject. I would suggest the following:

  • It looks like you are using a twin flash (MT24?) Can these be angled more to try to prevent light bouncing directly back?
  • Make a small lens hood of some kind (rolled up bit of card should do it) - if the light is being reflected directly back through the lens, I don't understand how this works; but it works for me, so worth a shot!

The ping pong ball is a good idea anyway, I've seen excellent results with that as the diffuser (even if it does look a bit fiddly).

Good luck! It seems like you are going to get some amazing results once you've overcome this little obstacle.
Click to expand...

Thanks Tim! I'm going to play around later today using only natural light. That might help determine what's happening. The shot above was using several studio lights so I'm guess light was leaching somewhere.
 
•


Great iridescence and cool colours…
too bad for the glare!

As for the stacking, the usual mistake:
the last point should be behind the subject!
The background is not what you wanted for
sure, Duncan!
 
Kodiak Qc said:
•


Great iridescence and cool colours…
too bad for the glare!

As for the stacking, the usual mistake:
the last point should be behind the subject!
The background is not what you wanted for
sure, Duncan!
Click to expand...

No, I kind ignored the background, TBH. I just wanted to see how to do it and how CS4 fared. I'm thinking about getting stacking software but first wanted to just get a grasp of what I was doing.
 
I use a black party popper for a hood - it's severe but does stop this sort of issue. I also wrap the whole lens - bellows train with a thin black metal sheet material I bought a few years ago (sorry can't remember name) to cut out light entering from any other gaps... seems to work for me
 
nass said:
I use a black party popper for a hood - it's severe but does stop this sort of issue. I also wrap the whole lens - bellows train with a thin black metal sheet material I bought a few years ago (sorry can't remember name) to cut out light entering from any other gaps... seems to work for me
Click to expand...

Thanks Johan. Good ideas which I'll use! The problem appears to have been a few factors. I was using it in my light-box which does create a lot of diffused light from all directions. This little critter is very reflective, too! The main problem, however, appears to have been light from beneath the subject. I had it positioned on an acrylic stand within the lightbox. When I placed my dark iPad cover underneath, instead, the problem all but vanished. I then used one of my pizza pack reflectors over the bug to add some more diffusion and that seemed to take care of most of the problems that were left. The addition of a small paper hood helped, too. Here's a single image from the side now. Glare is pretty much gone. Guess I'm going to always have to be very careful setting up shots with this one. The JML 20X is far more forgiving than this 21mm, it would seem.

SINGLE.png
 
Looking better but still looks a bit grey to me in the centre... but it looks like you're on the right path! Fwiw, I've never used a "complete surround " softbox for this myself, I usually have flashes perpendicular and almost behind the lens with a cone diffuser expanding in front of and the lens and a hood inside that. Good luck!
 
You must log in or register to reply here.
Back
Top