Something's still wrong with my 35mm Canon

[LaFoto]

Some of you know me well enough to have realised that my trustworthy CanonEOS 500N (SLR) was "sick" and had to go to "camera hospital", right?

Well, as you can tell by my signature, it is back home with me.
The problem it had - felt like "cardiac arrest" to me - is solved and it is back to taking photos. So far so good.

But I am thoroughly unhappy with the outcome of most.
And I realised something.
For certain periods in time, something will happen. How can I describe what exactly that is? Some shutter-click sound can be heard while I am in the process of focussing and in the viewfinder everything becomes considerably much darker than it used to be. At first I did not really notice when and that it happened, only did I find out that the camera suddenly required a lot more light. I had shutter times of 1/15 and less on bright-sun-blue-sky days, without any filters on. At first I thought it was because I used the zoom lens pretty much, extended to the max. But the amount of light required THEN was ridiculous!

While I was in Hamburg taking photos of industrial plants and typical port "sights" (containers, huge cranes, railroads, yes, the occasional ship, too), I felt this wasn't ok. Suddenly I heard a click, and everything went much lighter in the viewfinder. And the camera required the normal amount of light, the amount that I would have expected on a bright sunny day, even with the telephoto lens extended.

Today I was taking "boredom photos" in the railway station of the town where my daughter takes ballet classes (I have to while away an hour of time then), happily snapping away, shhht-click. Viewfinder dark, camera slow.

What is this?
Will I have to wait for the next coincidence for it to click back to normal?
I feel there is nothing much I can do.
OK, I changed lenses from the 70-300mm to the kit lens (28-80mm) and everything looked fine. But then the kit lens is a 1:3,5, though the difference cannot be THAT big.

Anyone familiar with the problem? Any ideas? Should I rattle and shake the telephoto lens? Or rather not?

Help!

 

[Mitica100]

LaFoto, that is not right. I would send the camera back to the repair shop. Simply put, you shouldn't have variations on exposure like the ones you describe. Something got messed up.

Sorry to hear your baby is not cooperating...

 

[AlmightyWa]

Is the click noise like the DOF preview? I don't have a canon, but on my Nikon F80, the DOF preview makes a 'clicking sound' when pressed (the aperture stopping down) and the the view becomes a lot darker (because the aperture's smaller = less light)

Is the aperture stopping down at random intervals?

 

[ksmattfish]

Sounds like the aperture is closing down. Try taking the lens off and putting it back on. Is it possible you are accidentally pressing the DOF preview button?

 

[LaFoto]

Sounds like the aperture is closing down. Try taking the lens off and putting it back on. Is it possible you are accidentally pressing the DOF preview button?

Sounds like it, doesn't it?

Did take the lens off, the other on (ok results, by the look of it), back on, same situation.

No, it is not possible, there IS no DOF preview button.

Usually I don't SEE in the viewfinder what will happen with the photo shutteropening and exposuretimewise. All I see is the sharpening process (either manual or automatic, and when this "darkness"-situation arises - out of the blue! - automatic focussing gets next to impossible for my camera...).

Mitica, erm: "Send it back???"
Dang.
It was so difficult to get it there in the first place...

 

[ksmattfish]

All I see is the sharpening process (either manual or automatic, and when this "darkness"-situation arises - out of the blue! - automatic focussing gets next to impossible for my camera...).

Your aperture is closing down for some reason. If it happens with different lenses it's probably a body problem.

 

[LaFoto]

It never happened before the body got "sick" (I pressed the shutter and the mirror seemed to fall shut and stay shut - the film I exposed for test reasons at the time remained all unexposed, really, apart from the first two photos which had a tiny bit of light). It is something the camera has come back with after the repair.

"Dirty contacts" had been the explanation they gave me as the reason for the camera going wrong in the first place.

 

[PlasticSpanner]

A quick test would be to close down the aperture as far as it will go and see if it still makes the click and if the viewfinder goes as dark!


It can only close the aperture as far as the lens will go can't it?

 

[LaFoto]

Close the aperture? You mean to go down to f22 or so? Does "close the aperture" mean that?

 

[LaFoto]

OK, whether you meant it or not: it did the trick (for the moment): 'things' clicked-jumped back to normal, the little picture I see in the viewfinder went brighter again with this sound and I am back to getting normal exposure times.

When all went all wrong in Hamburg and again yesterday when I took those photos at that railway station there, I suddenly had exposure times of 1/13 in the brightest sunlight. That is NOT normal!

But hey, I put it to f22, had the autofocus zoom in on a random object and --- ssss-T --- it went back to good. Yay!

But no one knows WHAT it is that is (still) affecting my SLR, right?

 

[PlasticSpanner]

I had a problem with one of my 50mm lenses in that when it was put on the camera the aperture lever got stuck. When I reduced the aperture on the lens to F22 it freed up! (signified by a click from the camera)


After a while this seems to have sorted itself out so unfortunately I don't know what caused it of how it was fixed except that it must have been down to use?

 

[PlasticSpanner]

Just another thought but there was something I read about the Practika cameras about setting the exposure to 1/60 sec (or flash sync) when changing a lens.?


Maybe this is more something to do with the camera rather than the lens?

 

[LaFoto]

Well, I still don't quite know.
What I have done yesterday during my second trip into Hamburg for some photos is: I set the aperture to a predetermined f5.6 or so and adjusted the exposure time by a very rough rule of thumb, hoping that everything will turn out all right.
On Wednesday I will know more, when the prints will be back. If most of them go wrong, I have material to send to Canon, should I feel like sending them the camera back...

 

[fightheheathens]

i dont know if this is any help at all, and it seems other people have mentioned the same thing, but i feel compelled to discribe how my SLR works. (im kinda a geek so ive spent hours figuring out how every aspect of my camera works)
this is all on my pentax, but is probably similar on cannons
when the lens is attached, there is a lever in the lens that automatically holds the apature at 1.7 (widest) no matter what i set the f/stop to. so while setting f/stop and adjusting exposure my apature is always opened to f/1.7. when i release the shutter, my camera first releases a trigger causing my apature to close to the set value, then lifts my mirror, then oppens the shutter, then closes the shutter, releases the mirror, and the apature pops back open. when i hit the DOF preview, it releases the apature and thusly makes the image darker and causes my light meter to go all wacky.
This is because my light meter calculates exposer based on light comming in with full open apature and then reads what i have set the apature to and calculate how over or under exposed i am.
So what i think is happening is your apature is closing down, (hence darker) and your light meter thinks it is calculating exposer based on full open apature times apature value when really it is calculating it based on set apature value times set apature value.
this would result in why your exposer times are off.
my camera is completely manual so it could only be a mechanistic problem if mine did this, but im assuming yours has some electronics in it other then a light meter which could be malfunctioning and such.
i would go back to the store and demand they fix it free of charge. they probably bumped something and screwd it up.

 

[ksmattfish]

Try cleaning the contacts on the lens and camera body where they attach to each other. Cleaning the electrical contacts is the first thing I try when I'm having lens or flash malfunctions with a fancy, smancy, electronic SLR. More often than not, it fixes the problem. If that doesn't fix the problem, it probably needs to see a repair tech.

In the mean time, when you have this problem you can get around the exposure issues by calculating correct exposure, and switching to manual mode.

If you have a lens that is f/4 at it's widest, but it's metering with the aperture stuck at f/8, then you need to under expose 2 stops from the meter's recommendation. If you had the f/4 lens set at f/16, and the meter has to read it stopped down then you would under expose 4 stops. Everytime you double the shutter speed it's a 1 stop under exposure.

Aperture in 1 stop increments: 1, 1.4, 2, 2.8, 4, 5.6, 8, 11, 16, 22, 32...