From Peter C.: "I have just started using an Olympus E-PL2 with 14–50mm standard lens. This was taken two days ago in the evening.
"I'm pretty disappointed. I assure you, those red dots were not UFOs in the sky. This seems to me to be internal flare off the sensor itself, since the sensor looks red when you have the lens off. Notice the regular pattern to the dots.
"Hasn't this ever happened to anyone else? I've never seen it mentioned.
"The camera is brand new and the lens is brand-new clean, only six days old. I wasn't using any filter.
"This doesn't turn me right off the camera, but clearly I can't use it for sunset shots. I'll have to try my K-5 in the same situation. Probably will do tonight although the sky is clear blue coudless today (heh heh, in mid-winter).
"This new camera probably qualify in Australia as 'unfit for purpose' or 'clearly faulty,' but I'm not going to return it. Just very surprised, that's all."
Mike replies: That's just lens flare, and a nice example of it. The sun is pretty high in the sky there and hence still plenty bright. Most lenses, especially zooms, will flare in that situation in one way or another. In this picture you are able to see it because the flare is against the dark clouds; if those red "dots" had been against red "sunset" sky, you might not have noticed them. The color of the flare might possibly be different with a different sensor or with film, but this isn't primarily a sensor artifact. It's coming from the lens. My guess is that there's nothing wrong with your camera or lens—you just chanced upon a situation where the lens flared and you were able to see it easily.
Funny, but back when I got into photography, it used to be assumed that pictures with the sun in them would show flare; now, coatings are so good that people can have the opposite assumption.
If I were you I would continue to use your new camera and lens and keep watching your results—you will soon learn when and where you're likely to encounter flare. It can be an interesting investigation, and useful to know. It's all part of getting to know your lens.
The next evening Peter photographed a completely different sunset with his Pentax K-5 and got no flare, but I suggested that that was a bad test—the subject might be nominally the same according to our conceptions (category "sunset") but the conditions in each shot are completely different. To know what's going on, I suggested he photograph each evening's sunset at the same time with both cameras and compare the results. An even better idea would be to make three shots, using two different lenses on the Olympus, since that would indicate the contribution made by his main lens more easily.
Today's lenses let you include bright light sources in the frame with impunity. Half a century ago, it would have been one of those things photographers would have learned to avoid. Here of course the sun is behind some cloud, but it was a lot brighter than the rest of the sky. I've owned lenses in the past that would have done nasty things with an off-axis bright spot like this. (Note that there are some JPEG artifacts around the sun in this little screen JPEG. They aren't there in the original).
There are all sorts of little tricks you can employ to keep flare at bay, for instance putting the sun behind a little feathering of cloud to reduce its intensity. (This picture was taken with the OM-D's standard zoom, yet it's one I probably wouldn't have tried with my Zeiss 50mm ƒ/1.4 of 30 years ago.)
You can also play with flare. There have been times I've actually been a little disappointed with the high flare resistance of today's lenses—older lenses sometimes do things that are funky, surprising and nice with flare; they at least entertain you. The super-competent coatings of today put up an impressive fight against flare of all kinds.
Surprisingly, one of the toughest forms of flare for lenses to deal with, and consequently a great torture-test for lenses when you're learning about their flare characteristics, is bright off-axis window light in interiors. The flare will impinge on masking structures, of course (i.e., the window casing and muntin bars in this shot), but the test is to see how much veiling glare carries over to the rest of the picture. Although this is the zoom again (the OM-D's standard M.Zuiko Digital ED 12–50mm ƒ/3.5–6.3) it recovers nicely from the influence of the flare source, showing good contrast in the bench and wall lamp in the hall.
These four shots are from the reject pile from my recent vacation, all taken with the OM-D E-M5. They're all camera JPEGs save the last one.
(Thanks to Peter)
UPDATE: I see various readers have pointed me to various "known issue" forum threads here and there about the so-called "red dot" issue. Okay. I'm certainly not going to insist I'm right about this, for the simple but very good reason that I might not be. For every camera system, real (as opposed to, say, software-generated) artifacts are a system-dependent result; you can only rule out contributors if you remove them and find that the results persist.
However, flare is the proximate cause here, in my opinion, regardless of how the system manifests it.
I'm sure I've seen "red dot type" flare with film cameras. But then I've seen all kinds of flare artifacts over the years. Some are characteristic (enough so that software can now fake generic effects), and some are truly bizarre (one friend's camera created a small reddish "C" shape in exactly the same place in about one out of every dozen frames, for no apparent reason and without apparent pattern. Numerous experiments couldn't reproduce the cause and numerous attempts at camera repair didn't help). But it's all flare, folks—non-image-forming light getting through the lens and rattling around in the lens-camera system somehow, bouncing off things it's not supposed to be bouncing off of and making gremlins.
So it's flare. Who cares how exactly it manifests itself or exactly what it looks like? You can get flare with any camera and lens if you try. No optical system is devoid of it.
I might also gently point out here that forums aren't the right place to "decide" technical issues, because all they do is create group consensus. Short or long disputations end up with people agreeing to agree, or perhaps continuing to disagree with the majority helping to enforce the group's preferred determination or choosing to support the group's leader or leaders, or perhaps deferring to whomever has the best-sounding explanation (and I've seen examples of conclusions that were extraordinarily well-developed at great length and effort that were utterly, completely wrong) or even whoever's been hanging around the forum the longest (because they can say things like "we've discussed this many times before and here's what we decided"). Forums can often engage in long, fanatically detailed, partially researched, closely reasoned epic arguments that culminate in a strange "folk" conclusion that real experts simply roll their eyes at. (I say that not to claim that I'm a real expert, but because I've known those who are.)
A few examples of weird flare (most on film):
http://www.flickr.com/photos/spinfly/2438532946/ (This is caused by a filter, but it's clever)
Note that this is from a very quick and cursory search. Want more? Seek, and ye shall find.
P.S. Gene Spesard alerts me that Kirk has written about Peter's issue too.
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Original contents copyright 2012 by Michael C. Johnston and/or the bylined author. All Rights Reserved.
Featured Comment by Jeremy Fagan: "Some people pay a fortune for a red dot on their camera. Count yourself lucky to have so many...."
Featured Comment by Tim Parkin: "I'm pretty sure this is a microlens phenomenon.... Yes it's flare but of a particular type to digital cameras. You can even see the variation in brightness across the bayer array. here's a diagram from this page...and here's some great research on it with examples of different focal lengths."