p.5 #2 · So I destroyed my first camera (40D) the other day...(FINAL UPDATE)
gfiksel wrote:
Correct. I was talking about depth of focus. Depth of focus is the distance behind the lens within which the image remains sharply in focus. It is proportional to the focal length.
In any case, the tolerance for image that is 100% pixel focus is very small (less than a millimeter). But, the Sun is not a pinpoint subject, so it should not produce a pinpoint result, either. And in any case, the long focal length lens has such a high light collection ability that the resulting lightbeam will be very not, even when not in perfect focus. That is the reason why this accident will happen with long focal length lenses but not with wide angle lenses.
p.5 #3 · So I destroyed my first camera (40D) the other day...(FINAL UPDATE)
astrolucida wrote:
Actually, it seems to be proportional only to the focal ratio. See http://starizona.com/acb/ccd/advtheoryfoc.aspx (and scroll until you see a table based on focal ratios).
In any case, the tolerance for image that is 100% pixel focus is very small (less than a millimeter). But, the Sun is not a pinpoint subject, so it should not produce a pinpoint result, either. And in any case, the long focal length lens has such a high light collection ability that the resulting lightbeam will be very not, even when not in perfect focus. That is the reason why this accident will happen with long focal length lenses but not with wide angle lenses.
It's only so for diffraction limited images (point objects, like stars). Image of the Sun is about 5mm for 500mm lens - far grater than the Airy disk.
Focusing, is somewhat critical. The total amount of solar energy collected by a 100mm diameter lens is only about 10 Watts. If spread over a large area it should not cause a serious damage. However, if focused into a small spot, it's a different matter.
BTW, for non-aberration optics the temperature of the image would not depend on the focal length, only on the f-ratio. Yes, the collected energy would be smaller for a shorter lens, but the image size would be smaller by the same factor. So, at least, if only radiation cooling is dominant, this would be a wash. Just an academic point, no relation to real life
p.5 #6 · So I destroyed my first camera (40D) the other day...(FINAL UPDATE)
Bad thing sometimes happen, even though you are careful. The day I came home with my first dslr, a 10d with a 70-200 sigma attached. I took it out for a few shots and slung it over my shoulder to take it into the house for the first time to show my wife. Something fell off the camera (lens cap or the like) and I bent over while closing the door. The shoulder strap caught the doornob and ripped the camera off my shoulder and flung it through the air and onto the floor. I almost cried. Fortunatly no damage, but it goes to show you strange things happen.
p.5 #9 · So I destroyed my first camera (40D) the other day...(FINAL UPDATE)
Wow .. I would never considered that in a 100 years. But I live in Newfoundland where the sun shines about once every 100 years
So should we be careful when shooting into the sun with normal lenses as well? .. I like shooting with the sun in the frame and had never considered it a potential problem until reading this.
p.5 #15 · So I destroyed my first camera (40D) the other day...(FINAL UPDATE)
twistedlim wrote:
Bad thing sometimes happen, even though you are careful. The day I came home with my first dslr, a 10d with a 70-200 sigma attached. I took it out for a few shots and slung it over my shoulder to take it into the house for the first time to show my wife. Something fell off the camera (lens cap or the like) and I bent over while closing the door. The shoulder strap caught the doornob and ripped the camera off my shoulder and flung it through the air and onto the floor. I almost cried. Fortunatly no damage, but it goes to show you strange things happen....Show more →
Indeed. I stood around like a goof for a while just looking completely perplexed.
p.5 #17 · So I destroyed my first camera (40D) the other day...(FINAL UPDATE)
Just have to share the story - my stupidity has hit a new low. How is that possible you ask? Read on.
About a week ago, I was doing some AI Servo testing with my 40D. It was a nice, bright, sunny day around here - which doesn't happen all that often in Feb. Oh, I was in a good mood. So I mounted my 40D on my biggest lens, and that was in turn mounted on my tripod. I wanted to make a couple of test images from my back deck. So far, so good. Then, wanting to try another lens, I was about to remove my camera from the first lens. But wait, I need to get a cap for the body. You see, I'm a bit of a dust freak. No problem, cap is ohhhhhh, 20 feet away. Right, I'll just scoot over and get it.
Within 10-15 seconds, I'm back to the camera. As I remove it from the lens, SMOKE COMES POURING OUT! What the heck A short circuit? Ummmm, no. Just before getting the cap, I had tilted my setup upwards.....and....are you ready for this....pointed the lens RIGHT INTO THE SUN. Yup, that's right. Big lenses are like a magnifying glass. And I had managed to guide those bright rays of light straight through the lens and into the camera. Result you wonder? Well, there's the mirror - burnt. Then there is the mirror box - burnt. Then there is the shutter curtain - burnt. Behind the shutter curtain, there is that sensor thingy............ you can figure out the rest.
My camera is now in the Canon hospital. I found out today that a repair MAY be possible but let's just say my 40D is on life support.
The moral of the story is that....well, this is where you get to add your theory and comments. And please keep in my that my ego is already bruised.
UPDATE:
Well, the patient could unfortunately not be saved. After heroic attempts, the plug was pulled. BUT in the end, Canon took very good care of me. I now have a new 40D at the repair charge. Thank you Canon for great service - it made the pain and ego bruising pass a little more easily. And thanks to all of you FM members who offered comments - even the funny ones.
Moral of the story is not to point your camera at the sun with a long lens attached.
p.5 #18 · So I destroyed my first camera (40D) the other day...(FINAL UPDATE)
I'm glad to hear Canon took care of you. They're good people.
BTW, did you get the old 40D back? I'd give it a viking funeral. little raft, set it on fire, kick it off into the ocean. I plan to do that with about 2 or 3 of my cameras.
p.5 #19 · So I destroyed my first camera (40D) the other day...(FINAL UPDATE)
pranic wrote:
Good thing this was a 40D. If it had been a 1DmkIII, people would be complaining about it smoking and overheating on warm sunny days and looking for a permanent fix from Canon.
or perhaps it could have fixed the focusing issues
p.5 #20 · So I destroyed my first camera (40D) the other day...(FINAL UPDATE)
PShizzy wrote:
I'm glad to hear Canon took care of you. They're good people.
BTW, did you get the old 40D back? I'd give it a viking funeral. little raft, set it on fire, kick it off into the ocean. I plan to do that with about 2 or 3 of my cameras.
Max
Brilliant idea! Just like the old, old, old days. Unfortunately, the body remained with Canon. They did, however, send me back the extra battery with the new body. I thought that was a nice added touch.
at least you have good humor in posting your story. Hope your day goes better 
A short circuit? Ummmm, no. Just before getting the cap, I had tilted my setup upwards.....and....are you ready for this....pointed the lens RIGHT INTO THE SUN. Yup, that's right. Big lenses are like a magnifying glass. And I had managed to guide those bright rays of light straight through the lens and into the camera. Result you wonder? Well, there's the mirror - burnt. Then there is the mirror box - burnt. Then there is the shutter curtain - burnt. Behind the shutter curtain, there is that sensor thingy............ you can figure out the rest.