I want to experiment taking photos in which the sun appears. I'm afraid of what might happen if I take one with a narrower angle (where sun would be bigger). Can the lens act as a magnifying glass and burn the CCD or CMOS sensor?
Under which circumstances (zoom, exposure, aperture, etc...), can the sensor be damaged by the sun?
Taking direct photos of the sun can destroy your camera, not to mention your eyes. It's exactly as you are afraid, the lens will act as a magnifier and multiply the suns intensity right on your cameras internals. What this effects can vary. Long exposures against the sun can cause permanent damage to your camera's sensor, but besides that, your camera's shutter curtains, and af sensors are also at risk when shooting right at the sun.
Now, taking photos of sunset and sunrises is okay, as is taking photos in direct sunlight (though this does require some finesse to get a good exposure), but pointing your lens right at the sun is not recommended (especially for long exposures).
I would say it really depends on if you have a SLR, DSLR or P&S (Point-and-Shoot) - and maybe even possibly it more (or less) depends if the sensor is CCD or CMOS.
My own experiences says it doesn't occur with P&S cameras - ever. I have 4 cheap P&S (Canon PowerShot) cameras which I have used exclusively over the years for shooting time-lapse series (500 - 100k images per shoot) and all cameras have a minimum of 500k exposures according to Exif data. 2 of 4 have taken between 2 and 3 million images. Many of those sequences were shot during an entire day with complete and direct view into the sun (intentionally). Most of those were shot using a wide-angle or a 180-degree Raynox fish-eye adapter, though I would think that would compound the problem having more lens elements to refract the light?
Oddly enough, all 4 cameras have never exhibited any loss of quality or showed any signs of damage from the sun. However, one with the most exposures has a big purple splotch that sometimes appears in images off to one side, although it seems to be more connected to the LCD screen as when I wiggle the screen it usually goes away (for awhile) - I attribute it to falling off a rock onto other rocks and once falling 2m into the bathtub (which incidentally cracked the fish-eye, so now it rattles when you tip it any direction but amazingly still works fine ;).
I also have a Sony DSC-R1 (a high-end CMOS-based P&S camera) and have accumulated easily over 200k on that one, of which many times I spent very long periods of time shooting directly into the sun in an attempt at making Photoshop-like solar flares ;) Again here I was never able to find any noticeable deterioration or difference between the first images.
Then again, maybe it was all just luck that nothing got burned ;)
At very wide angles the danger is much less and taking photos with the sun in the field of view doesn't normally harm the camera or lens. When the sun is very low on the horizon the energy is also reduced as there is much more of Earth's atmosphere to absorb much of that energy between the sun and an observer on the ground than when the sun is high in the sky.
More importantly, with wider angles of view it probably doesn't do any harm to the photographer's eyesight. Keep in mind, though, that to the best of my knowledge NO manufacturer of cameras or lenses has ever said anything to the effect of, "It's okay to look at the sun through our camera's viewfinder." If in doubt, use Live View or a camera with an Electronic View Finder (EVF). You can replace a camera. You can't replace retinas cooked by the sun's infrared light!
With narrower angles of view provided by longer focal length lenses it's an entirely different story. You can damage your camera in mere seconds. You can also permanently damage your eyes. Your retinas have no pain receptors. Even looking at the unmagnified sun for a relatively short time period with your naked eyes can damage them. Human pupils have a minimum opening of only about 2-4mm when fully constricted. Now take a high powered telephoto lens, such as a 200mm f/2.8 - the entrance pupil is over 70mm wide! The amount of sunlight, including infrared light, striking a circle 70mm wide is 320X as much as the amount striking a 4mm circle, and over 1,200X as that striking a 2 mm wide circle! Multiply that energy times 4 for a 400mm f/2.8 or a 560mm f/4 or an 800mm f/5.6. All of that energy is being refracted and focused into a much smaller area and coming out the back of your optical viewfinder in about a 3mm wide light field which your cornea focuses down to a very small area. You can literally cook your retina in little more than an instant with the infrared light from the sun through such a lens.
For your camera, the worst case scenario would be doing something like using a telephoto lens in Live View. Even though you might take the photo at f/22 to limit the amount of light reaching the sensor, the aperture of your lens is likely wide open until you click the shutter. The energy of the sun is strong enough when focused by your lens to heat the internals of your camera very quickly. If things get hot enough, they will be damaged. Even if the heat doesn't cause damage, the voltages generated in the sensor's electronics may be enough to damage the circuitry.
Thank goodness this camera wasn't in Live View and pointed directly at the sun with the shutter curtains open for the 1 minute it took the sun to do this through a 600mm f/4 lens. It happened during a flare test conducted by Bryan at The-Digital-Picture with the sun just out of the frame but obviously just inside the lens' image circle. If the light that fell on the edge of the light box had been focused on the sensor or shutter curtains (in viewfinder mode) the camera would likely have been rendered unusable.
The warnings almost all camera's manuals have against pointing the lens directly at the sun are there for a reason, and it isn't just so you can't blame the manufacturer when something goes wrong. Especially when the sun is almost directly overhead in a clear sky, the chance of damage is very real. The lower the sun is in the sky, the more clouds there are between the sun and your shooting location, or the more anything else (such as a proper solar filter) is absorbing some of the sun's energy the less likely it is that short periods of pointing your camera at the sun will result in damage. This is why it is fairly safe to take sunrise/sunset photos: due to the sun's angle it is passing through many more miles of the earth's atmosphere than when it is high in the sky.
Be sure to protect your eyesight and do not look directly at the sun through an optical viewfinder at all when it is at or near full brightness high in the sky!
Epilogue:
Lensrentals.com has posted a blog entry in which what happened to some of their rental equipment that were used without proper solar filtering during the recent total eclipse in the United States is shown in photos of the damaged equipment.
Damage to a shutter curtain:
Damage to a sensor:
Damage to the aperture diaphragm of a 600mm f/4 when the user used a rear positioned drop-in solar filter:
Yes, the sun can damage your sensor, as detailed in the previous answer. If it is that strong, compared to your sensor's sensitivity, you won't get a useful exposure in any case.
If you do want to photograph the sun, you can use an ND400 filter. This is the one I use: http://www.bhphotovideo.com/c/product/155266-REG/Hoya_A77ND400_77_mm_Neutral_Density.html
It will reduce the strength of the sun by a factor of 400, making the sun dark enough to not over-expose it and much less likely to damage your sensor, at least for exposures not too long where the sun is not over-exposed.
Remember that with a SLR the mirror is down until immediately before the shutter opens. The mirror would reflect most of the light to the eyepiece and not to the sensor or shutter.
Some of the light would be directed through the mirror to the focus mirror, which is usually behind the main mirror and gets its light through a section of the main mirror that is partially reflective. So, potentially that sensor could get some light hitting it.
Actually hurting the sensor isn't likely though. The light would have to get past the mirror and shutter, or, you'd have to take an extremely long exposure that held the mirror up and shutter open. In that case, odds are really good the photo would over exposed well beyond recovering.
And, in any case where damage did occur, it would be pretty obvious to Nikon or Canon's repair shop what had happened because they've seen it all, resulting in a voided warranty.
There was a known problem with cloth shutter-curtain Leica's having holes burned in them.
If you take a very quick picture of the Sun, it won't kill your camera, but don't point it in the general direction of the Sun at all for very long. Remember that exposure won't last for very long at all. Your CCD probably won't be damaged, but the lens might heat up enough to cause some damage.
I been trying sunrise timelapses with my Canon S95, and on one where I intentionally tried to end in overexposure, with camera running at ISO 80, 1/160 sec, F8.0. Towards the end, the camera defocused itself, whilst running on manual infinity focus. I think the CCD might have over heated, as it is the only logical reason why. Have seen no signs of any damage since, thankfully. You can see the result here: http://www.youtube.com/watch?v=xr5LjRzIUWs
I am not sure if this has been mentioned before, but last Fall, when I was shooting into the Sun with my T2i, the camera simply shut down during one of the shots (I was lazy and using one of the auto modes). It took about a minute, and it was back up taking pictures.
I trained my film camera at the sun, composing the same shot, and as always, had no issues. I have frequently shot with my film camera - at bright, mid-day sun sometimes, to get lens flares and such and I have had no issues.
Even in full manual mode, the DSLR is unable to expose the Sun without trying to mangle the Sun, except at dawn or dusk under manual mode (some of that might be my lack of knowledge owing to a recent, partial transition to digital). Just yesterday, it was tough to expose the Sun as a disk even when it was behind clouds. For all such uses, I would recommend going on with Film, especially as someone alluded, for peace of mind.
