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04-12-2012, 01:04 PM   #1
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Really strange flare - any idea what caused it?

At least, I *think* its flare. Its in the lower right corner of this shot. Surrounding shots didn't show this circular... whatever it was. Camera was my K-x, lens the 18-55 kit.

It obviously isn't a major flaw or anything (as I haven't seen it repeated anywhere else), but it just struck me as extremely odd when noticed it while going through some of my old images.

Clicking through to flickr will let you see the thing in all its unprocessed full size wonkiness.




04-12-2012, 01:18 PM   #2
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although I cant see any exif data it looks like you were stopped down, with the sun just out of the field of view in the upper left corner, but because you are not at minimum focal length, the lens hood is worthless, as it only provides full protection for flare when at minimum focal lengtth
04-12-2012, 01:27 PM   #3
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QuoteOriginally posted by Lowell Goudge Quote
although I cant see any exif data it looks like you were stopped down, with the sun just out of the field of view in the upper left corner, but because you are not at minimum focal length, the lens hood is worthless, as it only provides full protection for flare when at minimum focal lengtth
I don't have a hood for my kit lens (probably worthwhile grabbing one some day). I'm assuming I flared, and I know the reasons for flare - but I've never seen flare that looked like this. I'm trying to figure out what on the camera caused this to happen because its just so strange looking. I'm guessing its possibly off the blades (ie, its round, divided in 6 sections) but that just seem kind of odd as well.
04-12-2012, 01:32 PM   #4
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what are the key points for exosure, focal length, & aperture ?

these might be the things to look for,

04-12-2012, 01:35 PM   #5
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It looks odd because you can't quite see the sun in the upper-left corner, but it's definitely being caused by that.

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04-12-2012, 01:43 PM   #6
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QuoteOriginally posted by Lowell Goudge Quote
what are the key points for exosure, focal length, & aperture ?

these might be the things to look for,
Its been a while since I took this shot, but if it was the kit, I assume I had it set to just choose a point for me. The sun definitely was off to my left and in front of me The next shot I took actually included it coming through the trees ahead of me.

What I'm really curious is what made the flens take on that particular shape. When I think 'flare' I tend to think of something quite a bit more solid for a lack of a better word, not a wierd 'frisbee' type situation like this was.

FWIW, this is the very next shot taken after that one, so it was definitely the sun causing the flare itself.


04-12-2012, 02:37 PM   #7
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QuoteOriginally posted by Lowell Goudge Quote
but because you are not at minimum focal length, the lens hood is worthless, as it only provides full protection for flare when at minimum focal lengtth
Is this true?
I thought the whole front element is always used.
04-12-2012, 03:30 PM   #8
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It is certainly true. The whole front element may be used, but the angles are different. For 55mm, a much longer hood would be possible.

04-12-2012, 09:32 PM   #9
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Well yeah but that doesn't make the hood worthless, it would be just as worthless on 18mm as it is at 55mm right (same amount of protection)?

Hood is useful though but just kept the word choice the same
04-12-2012, 10:13 PM   #10
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QuoteOriginally posted by RKKS08 Quote
For 55mm, a much longer hood would be possible.
Yep, but that does not mean that a shorter hood does not do anything with regards to flare ('worthless' was the term that Lowell used); my thought is that it is just less than optimal under certain conditions.
04-12-2012, 11:04 PM   #11
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Flare

The flare is interesting but how could you ignore that weird green and red face near the bottom right corner?

Whazzit?


The flare in picture no. 1 is somewhat similar to the fare in picture no.2 which is less pronounced. No. 2 has a small near vertical shallow orange arc just at the right edge of the flare. No. 1 has the same thing more to the left and considerably larger and fainter.
Could that be a reflection off the metal/plastic rim of the lens?

Mickey

Last edited by mickeyobe; 04-12-2012 at 11:14 PM.
04-13-2012, 03:44 AM   #12
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QuoteOriginally posted by RKKS08 Quote
It is certainly true. The whole front element may be used, but the angles are different. For 55mm, a much longer hood would be possible.
Think about this from the field of view

The FOV is much narrower at 55mm as opposed to 18 mm. Therefore the hood can only cover the shortest focal length to avoid vignetting
04-13-2012, 03:45 AM   #13
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The unique pattern may be more related to the fact that the sun is partially blocked by the trees
04-13-2012, 09:02 AM   #14
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The flare looks like an optical phenomenon I've seen in microscopy (especially electron microscopy) where (as I recall - it was along time ago) a point source at infinity images as a diffraction circle which has distortion features caused by lens aberrations.

But I can't figure out how the sun's reflection in the water would be bright enough to cause that image - the geometry doesn't seem right. Perhaps it is caused by the sun reflecting from the objective lens' front surface.

Here's a similar looking flare caused by a bright light source - imagine what the photo would look like if the bright light source were cropped out of the frame.


There is always a region outside the field of view from which a light source can cause flare; the only time this is not true is when the hood extends all the way to the subject. A bright light in either of the V shaped regions above the hood as shown would strike the lens surface. As the hood gets longer compared to the lens' focal length the region gets smaller but never disappears.


Or maybe it is a USO - an Unidentified Submerged Object?

Last edited by newarts; 04-13-2012 at 10:32 AM.
04-13-2012, 10:31 AM   #15
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Back in the 1960s all lenses would exhibit these types of flare and internal lens reflections (the blob in the lower right), because lenses were only single-coated. Much of learning photography was learning how to manage these by picking a field of view to consider light sources more carefully than is necessary with today's lenses. Now these reflections are so rare that people don't know what they are. I've seen a number of "UFO" pictures that are clearly internal lens reflections.
The reflections depend on lens opening, so they may not be visible in the viewfinder, since lenses are wide-open then. That's one good reason to stop-down using the "Green button" or DOF preview, as that will often show what the flare/reflections will look like.
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