Oh no! What is this?

[charles_clark1]

<p>I own a 5D. I routinely shoot in the dark. On Friday night, I shot a series of night shots at a couple different sites. When I loaded the RAW files into Lightroom 3, I noted a red streak on each photo. I have not seen this before. I have posted a jpeg of the photo and will follow up this post with a closeup of the red streaks.<br>

Has anyone else seen this? Is my beloved 5D about to die?</p><div></div>

[charles_clark1]

<p>Here is the closeup.</p><div></div>

[craigd]

<p>That doesn't look like a "camera about to die" sort of thing to me. It looks more like an internal lens reflection, but of what, I couldn't say. The scene doesn't give any (other) suggestion of a light source outside the frame.</p>

<p>I suppose it's also possible that there really was some dull, faintly glowing streak in the sky that your long exposure picked up even though it wasn't visible to you. But I kind of doubt that, partly because the streak looks to me to be a short arc of a circle concentric with the image circle itself, which is suggestive of a lens reflection.</p>

[alan_bryant1]

<p>Was there a light somewhere in front of the lens but not in the frame? That might have caused a reflection.</p>

<p>It doesn't look like a there's anything wrong with the sensor. I'd guess the sensor was recording real light, either from a reflection in the lens, or maybe it really was there in the sky - perhaps contrails from a passing jet. It might have been to faint to see. Is it in more than one image?</p>

[charles_clark1]

<p>I had the same streak in the photos from two different sites miles apart. I hang a flashing red light from my tripod but I haven't seen a problem before. I will experiment some more.</p>

[divo]

<p>Once a poor USB connection introduced atrifacts into an entire series of my shots. It looked quite different, but you may want to check just to rule that out. I also thought my camera was about to die at the time.</p>

[alan_bryant1]

<p>I have heard of, and occasionally encountered, an artifact on my 5D mk I during long exposures. It appears as a circle of reddish light on one end of the frame - seen here as a reddish artifact over on the right edge -</p>

<p><img src="http://img.photobucket.com/albums/v490/alanpix/IMG_8738M.jpg" alt="" /></p>

<p>I've seen a few reports from other people of the same thing. The best explanation I've heard is that it's something near the sensor that gets hot during long exposures. The heating of the sensor causes the noise level to rise. Your streaks are much smaller and I have no idea if they're related.</p>

[JDMvW]

<p>Another possibility might be a variant on the technological factors behind the "rod" phenomenon in video (<a href="http://en.wikipedia.org/wiki/Rod_%28optics%29">link</a>), that it that it is something ordinary that shows up peculiarly under the circumstances of long exposure and different distances from the lens.</p>

[charles_clark1]

<p>All,<br>

Thanks for your help so far. I will do some more experimentation to see if I can isolate the cause. More to come...</p>

[scott_ferris]

<p>Err,</p>

<p>I have a red streak in my pictures.... I mount a red light on my tripod. Occam's Razor anybody?</p>

[catchlight]

<p>Charles, pardon my low-tech question if it's too simplistic, but were you using a lens hood?</p>

[redphoto]

<p>It could be some flare caused by long exposure or just a noise artifact from your sensor. The 5D was not the best with noise and long exposures.</p>

[William Michael]

<p>+1 on Scott Ferris’ comment.</p>

<p>Additional to that – it was the 24 to 105 at FL=24mm - a typical scenario for Internal Reflections and or Ghost Images.</p>

<p>Add a filter on that lens, and you have an even better recipe.</p>

<p>WW </p>

[john_r._fulton_jr.]

<p>Please eliminate the flashing red light when you do your test to see if eliminating the flashing red light eliminates the red streak in your photographs. It's where I would start. BTW, it use to be that with long exposures light could sneak in the viewfinder window during exposure and effect the exposure. I'm not sure if that's a problem anymore. The point is all kinds of stuff happens during long exposures. The last thing you need while doing them is a flashing red light nearby.</p>

[tallplumphotography]

<p>Also try an equivalent exposure with the lens cap on. If you get the same red patch, you'll know the problem is inside the camera. Does using long exposure NR affect it?</p>

[charles_clark1]

<p>All, thanks for the continued input. To answer a couple questions, yes I use the lens hood, yes the blinking light could be the problem but I have been doing it form more than a year with no impact, yes, it could be a feature of the 24-105 when shot at 24 but I have been using that lens for more than a year without the red streaks. </p>

<p>I did do something different on this session than I normally do. I shot with a filter on the lens. That was unintentional and not what I normally do. </p>

<p>So, I plan to scrap the use of the flashing red light. Regardless of how the reflection might have occured, it was the only thing out there that was red. </p>

<p>Again, thanks for your insights.</p>

[William Michael]

<p>Assuming it was the Red Flashing Light (or a reflection from it) which was the source problem; it could be just co-incidence that all the elements merely fitted together on these few occasions and “Luck" was why it never happened before.

 

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This does not mean you should never use the lens at 24mm. <br>

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But I suggest it does mean you limit as many un-necessary elements as possible and I agree to cease using the red light - but I would remove the filter also - which I think is your intention – but I just mention it anyway as you didn't actually state that you would.</p>

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<p>WW

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[charles_clark1]

<p>William, I normally shoot at night without a filter. This was a one-time (hopefully) mistake.</p>

<p>None of you asked why I had the red light. It's purpose is so I can find my camera in the dark. Since I program my intervalometer to shoot sets of photos that I then stack, and a set of photos could be more than an hour in duration, I often hang out in my car or fidget doing something else away from the camera. Early on, I found that my camera and tripod were not necessarily easy to locate in the dark. The light helped me locate it. </p>

[William Michael]

<p>. . . But I knew (humbly) it was for location, that's why I didn't ask.<br />I have a friend who shoots long exposure and interval timing using the TC-80 . . . and it is very cold where he works. But he sets it at the rear of the camera about three feet away and it is a flashing beam straight out pointed at his car.</p>

<p>Maybe you could modify your light so it flashes only at a view of about 120 degrees - paint the rear of the plastic dome black - i.e. so there is no light flashing forward where the camera is facing - assuming it is a dome beacon or such, like we use here for emergency breakdowns on the road.</p>

<p>WW</p>

[charles_clark1]

<p>William, I like the idea of setting up the beacon so that it is pointed at the car/trail/wherever I am waiting. Thanks.</p>

[William Michael]

<p>... he's got a torch (US = FLASHLIGHT) and it has a "flashing" function. It is normal sized torch two or three D cell batteries the face is about 4 inches across - he actually uses an amber gel across the torch's lens glass (ie not red – but dark orange) he has a clamp and clamps it to a stake behind the tripod set up facing away . . . does that description make sense?</p>

 

[charles_clark1]

<p>Yes it does. Pretty clever. I have a pen light size "battery powered chemical light." I like your friend's idea better.</p>

[William Michael]

<p>... I was thinking about this as I was driving into work this morning. (Pouring rain here and a lot of time to think on the road which became a car park) –</p>

<p>Anyway I have a little "book light" it is not expensive and it has its own clip fitting and a long gooseneck. Very bright white LEDs - I don't use it for reading books, but keep it in the car for maps and passengers reading and etc, so they do not disturb me / driver with the cabin light turned on.</p>

<p>I was thinking that this would be ideal - it costs about $15 - the batteries seem to last forever - it is a bright, reasonably focussed beam and it all folds up to the <strong>size of a normal business card </strong>and is as <strong>thick as a mobile phone</strong> - the gooseneck wraps around the body. It <strong>does not flash</strong>, however - but this little book light might be ideal for your purpose as it has its <strong>own clamp </strong>and it is so <strong>lightweight and small </strong>- and the <strong>gooseneck</strong> could be useful ? ? ?</p>

<p>I think my mate uses the torch, simply because he always has. . . anyway I was thinking about this… listening to the radio… going nowhere and my it little book-light was in the centre tray next to me – thought I would share the idea.</p>

<p>WW</p>