35mm adapter "ghosting" problem (help?)

adventusfilms

adventusfilms

Active member
I'm basically finished with a homemade adapter but the only real problem left is this ghosting (slight double images) towards the edge of the frame

I thought at first it might be aberration, but the macro is a 2-element and I don't see anything like that shooting with just the macro. I can only see it at certain focal lengths. I don't know if this is a common problem, but if anyone knows where it stems from, maybe I can work on fixing it. Thanks
 
Ghosting is usually due to the GG element not diffusing enough, but is usually constant across the frame. Maybe if you could post some grabs or video of the problem we could help more.
 
It may even be the way your GG diffuses. I know if you use a heavy grit, then a fine grit, it can cause some weird effects.
 
Sounds like your getting a reflective image. Are all you optical surfaces anti reflective coated? And are they all paralle to each other? The optical alignment of the various componets is critical.
 
I've experienced an odd occurence of that nature before. It was the same as
what you've described; only toward the edges.

What I found, in my case, was a camera focus error. My zoom setting was 72
and the focus was 14. A simple adjusting of the focus cleared the problem right
up.

Can you describe your setup and maybe a few grabs of the problem?



DVX_focus_error.jpg
 
Thanks for the help. Does everything have to be purchased with coating or can it be done after the fact? My GG is encased in two UV filters, so I'm thinking that's where the problem might be. I honestly don't think its a camera focus error because I've been messing with it all day and monitoring it on a 19" screen and the problem is there no matter what. One thing I do notice is when I zoom into the GG, it isn't centered, but it's the camera, not the tube. My step down ring by itself on the camera isn't even centered and there really isn't anything I can do about that. I will post some images on Friday.....thanks again.
 
Right, I had that feeling too, but I need to pinpoint it exactly so I can work on fixing it. Here's the grabs:

soldier2copy.jpg


soldiercopy.jpg
 
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It's hard to make a qualitative judgement of optical problems when viewing live action footage. I would set up a registration target, (cross hatch) set up square to the film plane and lit at a 45 degree angle from both sides. Like you would do on a copy stand.
Have either a very large target or be able to move it or the camera while maintaing squarness so that it always fills the frame no matter what focal length your testing at.
This should tell you alot about the alignment and the quality of the optical path.
I for one would be interested in seeing such a test and also some photos, (top and side views) of your actual rig.
Do you have a real name you go by? I would feel kinda silly addressing you as "Dear adventusfilms" LOL

Chuck
 
I may be wrong, but i have a strong feeling its to do with the achromat or macro optic you are using. Try not using the macro and try zooming in as much as you can with your camcorder and see if the ghosting disappear. If it does, then confirm its the macro. Else, something else. Process of elimination.
 
How about reflection from inside the adaptor? Coat your inside with matt black paint. That should get rid of the reflection. Just a thought.
 
Alex0607 said:
I may be wrong, but i have a strong feeling its to do with the achromat or macro optic you are using. Try not using the macro and try zooming in as much as you can with your camcorder and see if the ghosting disappear. If it does, then confirm its the macro. Else, something else. Process of elimination.
Click to expand...

I do not believe this is an issue due to a lens, but rather the recording nature of the camera.

was this shot at 1/48th shutter? If so, remember that its not a mechanical shutter, and the camera with its electronic shutter may create this kind of effect. Raise itto 1/60th or higher.
 
adventusfilms said:
soldiercopy.jpg
Click to expand...

It looks like you have the same problem that I had. Humor me for a bit.

Point your adapter at a dark object against a bright bg... like a light pole
or something like that. You can also stand a pen up against a bright
white wall.

Position the pole screen left/right and play with the focus. Check to
see if the 'ghosting' goes away.

If not, one could suspect the macro is the problem.

Try to post pics of your setup too!
 
By the looks of it, you have a wide angle lens on the image converter which could contribute or... most likely, your GG is too close to the camcorder's lens. Try a 50 see if the result is the same and then (if is not) try to increase the distance and zoom-in a touch more. Post the grabs.
Best,
Dan
 
Actually, that is a 50, but it does it with my 24 and 85 as well. Alright....I'm gonna see if I can knock out the macro theory and move on from there.

Thank you for all the help

One other thing I want to point out real quick...you notice the closer the subject, the more distorted the ghosting gets?
 
If that's a 50, then try and increase the distance camera/macro to adapter (and zoom-in) It should work.
Best,
Dan
 
Well, I still can't seem to get rid of it. I don't know if it would matter, but I took everything off the camera except for the macro and I don't get any ghosting.

One additional thing to mention, when I zoom out of the GG, the ghosting remains in the same spot on the same objects(if an image is ghosting, it fades the closer it gets to the center by panning). Gonna keep doing tests to see if it'll decrease
 
By the way, the setup goes as follows:

camera-->step down-->Hoya macro-->52mm lens tube[UV filter-->GG-->UV filter]
-->lens mount-->lens
 
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