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The same issue. (solved)
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All Ex



Joined: 20 Jul 2015
Posts: 246
Location: Greece Thessaloniki

PostPosted: Mon Apr 24, 2017 12:11 pm    Post subject: The same issue. (solved) Reply with quote

I`m always getting that strange "mist":



I`m shooting with that rig:



I have a D800 2X SB800 and in that photo I used a Nikon EPlan with NA 0.1, for tube I used a self-made one based on a Rodenstock Apo Gerogon 150mm with distance sensor to lens element 150mm. I dressed the inside of the tube lens with flocking paper to avoid any light leaks.

In the front of my 2 SB800 I placed common plastic diffusers in which I replaced the front plastic layer with 3 layers of semitransparent tape (the one is used not to appear in the photocopies) and one layer of printing paper).

To avoid that phenomenon to happen I`m thinking to place black tape in the side of the objective (in the head of the speedlights).

Forgot to tell you that I am using a black carton cylinder on my objectives that extend so as to block that rays (that are somehow manage to hit the frond of the objective).

Also set my flashes to focus in 105mm instead of 24 mm that I am having them now.

Any suggestions?
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Last edited by All Ex on Sun Apr 30, 2017 6:30 am; edited 1 time in total
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Charles Krebs



Joined: 01 Aug 2006
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PostPosted: Mon Apr 24, 2017 12:51 pm    Post subject: Reply with quote

It really appears to be caused by flare (non-imaging light bouncing around somewhere and reaching sensor.) It sounds like you have taken precautions to avoid it but I think you must have missed something.

I have used a 150 Apo-Gerogon as a tube lens and it worked fine. So I don't suspect that too much. The first (and most obvious) thing to check are the interior surfaces of your optics. Check for some type of haze or smudge on element surfaces. But I would imagine that you have already done so.

Have you blackened or covered the rear ring of the objective? See 2nd and 3rd images here:
http://www.photomacrography.net/forum/viewtopic.php?t=9758

Sometimes, even if you are pretty careful about shading the front of the objective from direct light, a very bright diffusing surface or reflective surface behind the subject (just outside of your field-of-view) can cause this. You set-up picture is pretty small, but I wonder about the white hemispherical object I can see on your subject stage. It seems close enough to the axis of your lens to cause problems. (A larger, more detailed shot of the actual set-up used (where this flare occurred) might be helpful).

Do you by any chance happen to have an older Nikon film body. A very good way to track down problems like this is to look through the optics from the back while looking for anything that shows undesired light bouncing off of a mechanical or optical surface. Since (from the pictures) it appears you are using a lens attached to the camera body, and older film body set to "B" would allow you to view through the system and likely find the problem.
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JH



Joined: 09 Mar 2013
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PostPosted: Mon Apr 24, 2017 1:25 pm    Post subject: Reply with quote

Hi
It sounds like You have tried a lot of things to get rid of stray light.
I do not know if You already have tried Charles suggestion or if You have had the chanse to test with another lens.

Anyway my suggestion is to try something like this.



Try to have the light sources behind the lens.

If it works You can try to possition the flashes the same way.

Regards Jörgen
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All Ex



Joined: 20 Jul 2015
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Location: Greece Thessaloniki

PostPosted: Mon Apr 24, 2017 2:45 pm    Post subject: Reply with quote

I'll stick straight to the point :
The first thing you propose Charles is taken care since I flocked all my objectives leaving anflocked only the hole of the ojective.
This is an older photo of my rig, the half of tthe ping-pong ball is now a black surfase to "hold" the pin with the insect.
Tomorow I'll get a frech picture.

Jörgen as I'll so tomorow I'm trying to do just this that you suggest, that`s the reason I propose to change the focus of the flashes, as well as tape the edge of their head.

unfortunately Charles I don`t have an old nikon body.
And Jörgen this thing apears to all my objectives.

For today goodnight...


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JH



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PostPosted: Mon Apr 24, 2017 3:39 pm    Post subject: Reply with quote

Another thought - based on my own experience.
Use manual flash settings and make sure that none of the colour channels are close to or overexposed. For stacking I try to have an extra marginal.

Good luck!

Best regards Jörgen
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All Ex



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PostPosted: Tue Apr 25, 2017 1:11 am    Post subject: Reply with quote

Here are the prooves of flocking every of my objectives:



The same configuration goes to the BD Nikon 20X that it is sowing here.
In that photo:



you can see that the mount of the speedlight is flexible to bend in the needed angle.

In my 3rd photo you can see the adjastment that I`ve made to avoid the wite half of ping pong ball that might have caused the problem:



(I frequently brash the all flocking paper because it colects dust)
I always use manual setings Jorgen, your other suggestion is indeed something I`ll see right away.
On staking I use the formula that I took from enother Jorgen and I always use marginal.
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ChrisR
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PostPosted: Tue Apr 25, 2017 4:30 am    Post subject: Reply with quote

Is it possible light is still going in through the "BD" light path?




Suggestion:
remove the assembly from the camera, (perhaps add another extension tube),

put it to your eye
use a bright small light like a mobile/cell phone
and try to see reflections or "unwanted" light inside.

Suggestion 2 -unlikely to be a problem...
Cover the viewfinder on your camera in case it's "leaking". Stranger things have happened!
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All Ex



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PostPosted: Tue Apr 25, 2017 5:22 am    Post subject: Reply with quote

If I understood wright in the first answer you are refering to the Nikon BD 20X ELWD.
I use it all stript from its outside coverage as sown here:



I must confess that I keep on forgeting to close the door in the viewfinder. I have to remind that all the inside of the tube is covered with flocking paper, your suggestion to check for any light leakage is something that nevertheless I`ll check.
This tube has a focusing helicoid, would you sagest to extend it a bit more (in its spining part I placed black tape, in the outside, in case there is a lite likage here)
I`ll pray for your second sugestion.

Brick wall
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ChrisR
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PostPosted: Tue Apr 25, 2017 7:03 am    Post subject: Reply with quote

I can't think what else to suggest.
Maybe put a strong light INSIDE the assembly (without the camera ) and see if any light comes out of the wrong place Smile
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lonepal



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PostPosted: Tue Apr 25, 2017 7:52 am    Post subject: Reply with quote

You also have dust on your sensor Laughing
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All Ex



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PostPosted: Tue Apr 25, 2017 7:57 am    Post subject: Reply with quote

Forgot to tell Jorgen, I looked all the chanels and the histogram sows that the exposure in every one of them is in the midle of the spectrum.

Once I took this:




I don`t remember the setting.
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All Ex



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PostPosted: Tue Apr 25, 2017 8:00 am    Post subject: Reply with quote

I didn`t bother for the dust since my problem was obviously allswere.
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JH



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PostPosted: Tue Apr 25, 2017 8:45 am    Post subject: Reply with quote

For me this is a true mystery. I have almost not used flocking at al. I realy hope that you figure it out. Hopefully it is a simple problem that is easy to handle when you figure it out.

The last picture looks OK to me Very Happy


Regards Jörgen
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All Ex



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PostPosted: Tue Apr 25, 2017 8:54 am    Post subject: Reply with quote

Isn`t it looks like a mistery.
It would drive me insane.


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johan



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PostPosted: Tue Apr 25, 2017 9:23 am    Post subject: Reply with quote

Well the only reason this happens is if light is getting in there from somewhere, so you have to find what that light is. Consider using progressive elimination testing to find the answer.

Ie first take a shot that gets you this result, then take the same shot but wrap the lens and objective in cloth (so it can't be that), then take the same shot with say 1 flash instead of 2, then take the same shot with the other flash. Keep changing all variables until you get some that seem to work and some that don't.

One thing to ask - you are just using flash right, and not some longer exposure setting that lets in light through the viewfinder?
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