Diagnosing strange "missing sunbeam" effect

[Joey Pasco]

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Hi all,

 

I'm hoping to get an explanation as to what could be causing this strange effect I've noticed in some of my shots.

 

These were all taken with two different Leica M6 cameras, so unless the bodies both have the same issue, I'm leaning towards the lens being the culprit, as all of these examples were taken using a 50mm Summicron (type 4) lens.

 

Also, no filter or lens hood was present on the lens for any of these shots.

 

This effect has only occurred in shots that include a sunbeam (or nearly so, in the shot of the Gatsby sign). I have no more examples because frankly I'm not shooting into the sun very often.

 

At the top of the frame, part of the sunbeam is missing:

 

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Here, it's the side of the frame (which would translate to the top of the frame were this a horizontal shot):

 

 

Lastly, and this one is a bit more subtle, but here's the effect on the bottom of the frame:

 

 

Has anyone seen this before? Is this sort of thing to be expected when shooting into the sun in this manner?

 

Thanks in advance!

Joey

[Doc Henry]

Joey, curtain hole ?

Open and look behind and against the light leaving open the diaphragm

Henry

[Joey Pasco]

Just a couple of updates.

 

• I took a bunch of shots in similar conditions with a different 50mm f2 lens in an attempt to determine whether this effect would happen again (which would imply the effect is independent of the lens and is more likely to be a camera issue). I was entirely unable to reproduce this effect when shooting into the sun with the second lens. However, I didn't get a "full" sunbeam on any of these shots either; I was unable to achieve a sunbeam of any sort. Perhaps the conditions weren't correct to produce a sunbeam, or perhaps the sunbeam itself is something unique to the 50mm 'cron.

 

• I also took the camera into a pitch dark closet and shined a bright through it while looking through the back. I was in there for 10 minutes and was unable to identify a light leak of any sort.

 

So I'm still baffled. I have a couple of days to decide which 50mm lens to keep, and while I lean towards keeping the 'cron due to the Leica craftsmanship, I obviously don't want to keep it if it is faulty. (For the curious, the other lens is the Zeiss Planar T* 50mm f2.)

[TomB_tx]

The small gap at the top of the picture is actually at the bottom of the film gate in the camera (image is inverted on the film). This looks like the film gate leaves a shadow, indicating the "beam" is a reflection coming at quite an angle from near the bottom of the body. Perhaps a reflection from the rear edge of the inside of the lens?

[Stealth3kpl]

I've seen something similar in the film "The Omen".

Be careful.

Pete

[pgk]

Has anyone seen this before? Is this sort of thing to be expected when shooting into the sun in this manner?

 

Joey

Yes. Its flare caused by light from a strong source striking the front of the lens. I had a similar effect on an early 35 Summicron. My conjecture is that the flare (created as what appears to be a sunbeam and due to strong light striking the front of the lens at a fairly specific oblique angle) may be being imaged through the rear section of the lens (ie the optics behind the diaphragm) but a part of this flare image nearest the edge is being blocked, either internally in the lens or more probably, by the film gate or edge of the digital frame.

 

I'd say that its an inherent problem with some lenses and whilst difficult to recreate with certainty it might occur unexpectedly when conditions are appropriate. I'm not sure, but I seem to remember that it happened when the light source was at such an angle that the hood didn't actually prevent the strong light falling on the front element, but I may be remembering incorrectly. Its an odd and potentially irritating phenomenon but I personally wouldn't worry overmuch about it unless you shoot frequently in ways that cause it.