50mm f1.8 killed my DRebel????

[hiaw]

I do not know what happened to my DRebel today. I chuck on the 50mm f1.8 to take pictures. Put it in Av mode, set up on a tripod and press the button.

Result? Horribily overexposed photos!!!! I think it must be 3 stop over exposed. :shock:

So logically, I put on the kit lens and shot in the same mode and check that the exposure is exactly the same. and the photo turns out perfectly exposed..... :shock: :?

Something very weird is happening and I could not understand why. I thought the lens is just letting the light in and the camera take the metering reading and the CMOS record the image. Why is that with the same exposure setting, the 50mm give me 3 stop overexposure, whereas the kit lens is perfectly exposed? :?:

Did anyone have similar experience? This really feel metaphysical to me. I think I should call the Voodoo master at Canon New Zealand on monday to find a cure for it. :evil:

[maderito]

Try this supernatural trick:

Address the camera properly.
Slap on the 50/1.8
While in Av mode, dial in an aperture of 8.0 (it's probably 1.8 now).
Pray.
Snap your picture.
Report back.

[RichardtheSane]

Is the 50mm F1.8 stopping down correctly when you actually take the shot?

It could be that the lens aperture is not working correctly so all the shots are being taken at F1.8 regardless of what the camera tell it....

Experiment with that idea, it seems most likely at the moment...

[BDM]

As someone else has already suggested, it sound like the lens may not be stopping down correctly . . possibly remaining wide open. Try this. Look into the lens and release the shutter in bright surroundings. You may be able to notice whether the iris closes down. You could also set it on manual, pick a shutter speed and adjust the aperature until correct exposure is indicated. Take a shot. If it is over exposed, run the shutter up one click in speed. Take another shot. If the exposure is still over, do it again at another, higher click in shutter speed. At some point, you should achieve correct exposure. How far up you had to adjust the shutter speed from the indicated, correct exposure should give you an idea as to how far off the lens may be. Each higher click on the shutter speed represents one a one stop adjustment.

If the above shows a malfunction, it's time to send it in for service.

Bruce

[Andy_T]

So the Canon 1.8/50 'killed' your DRebel, right? :roll:

From another thread...Read that before you post a question on this here or any forum

How to ask questions the helpful way, by ESR:

http://www.catb.org/~esr/faqs/smart-questions.html

If there were a drivers license for the internet, this would be required reading. =)

Kad

nothing more to add...

Best regards,
Andy

PS: BTW, welcome to the forum! 8)

[CyberDyneSystems]

So the Canon 1.8/50 'killed' your DRebel, right? :roll:

From another thread...Read that before you post a question on this here or any forum

How to ask questions the helpful way, by ESR:

http://www.catb.org/~esr/faqs/smart-questions.html

If there were a drivers license for the internet, this would be required reading. =)

Kad



nothing more to add...

Best regards,
Andy

PS: BTW, welcome to the forum! 8)

Um... I don't see who in there right mind expects anyone to read a 6 billion word diatribe on how to ask a question ? :?

The original post in this thread seems descriptive enough. And it also seems that the answer was provided quickly enough (at least the likely cause)

Again. the actual rule that applies to use of THIS forum is simple.

If you don't feel like taking the tme to help.. don't post.

Thanks.

[Andy_T]

Um... I don't see who in there right mind expects anyone to read a 6 billion word diatribe on how to ask a question ? :?


Hmmm. I did. But then, I might not fit into the group you mentioned :lol:


Again. the actual rule that applies to use of THIS forum is simple.

If you don't feel like taking the tme to help.. don't post.

Thanks.

The point that occured to me is that there *will* be people who read the thread (or maybe don't bother to read it) that will actually believe that the lens 'killed' the camera.

Maybe I overreacted ... so Hiaw, I'd like to apologize if I insulted you ... that was not my intention.

As redemption :twisted: ... a possible logical explanation would be that the settings you used (e.g. f/1.8 on a sunny day with high ISO value) resulted in a shutter speed that's too fast for the DRebel (e.g. 1/8000). (Happened to me sometimes on my G2 after setting the ISO to 400 and forgetting to set it back)

The picture would come out overdeveloped on the 1.8/50, but not on the kit lens.

But to judge that you would have to post the shot and the EXIF information.

Best regards,
Andy

[robertwgross]

As someone else has already suggested, it sound like the lens may not be stopping down correctly . . possibly remaining wide open. Try this. Look into the lens and release the shutter in bright surroundings. You may be able to notice whether the iris closes down.


You could do this by pushing the depth of field preview button.

---Bob Gross---

[CyberDyneSystems]

:lol: :lol:

O-kay.. now that I have reprimanded poor andy.. :P

The shoe is definately on the other foot!

All theories above are plausible.. but Andy's is "the best" in a way because it would mean there is nothing wrong with any of the hardware...

So.. the shoe is on the other foot.. for us to help any further.. we do need the exif info at least.. and the image itself would be helpfull as well..

I'm guesing that if I had read the other 5,999,999,823 words in that link Andy provided.. it may have mentioned the need for the exif.... :roll: :oops:

[BDM]

As someone else has already suggested, it sound like the lens may not be stopping down correctly . . possibly remaining wide open. Try this. Look into the lens and release the shutter in bright surroundings. You may be able to notice whether the iris closes down.


You could do this by pushing the depth of field preview button.

---Bob Gross---

Bob, I thought of that but I have had instances where the depth of field button does cause the lens to stop down but when it is used for an actual exposure it does not stop down fast enough and over exposure results. That has generally happened with older lenses whose lubricants have thickened but because of that experience I thought it best to recommend a test "at speed" so to speak. Of course, if the iris doesn't close even with the depth of field button there is a very obvious problem.

Bruce

[jyrgen]

No wonder. After all, as many have reported, it's a killer lens :D

[robertwgross]

Bob, I thought of that but I have had instances where the depth of field button does cause the lens to stop down but when it is used for an actual exposure it does not stop down fast enough and over exposure results. That has generally happened with older lenses whose lubricants have thickened but because of that experience I thought it best to recommend a test "at speed" so to speak. Of course, if the iris doesn't close even with the depth of field button there is a very obvious problem.


In my experience, about the only time that the depth of field preview button doesn't do anything is if my exposure solution dictates the lens to be wide open.

If you think that the iris is "sluggish" due to too much or too little lubricant, then I guess you don't have much choice except to have the lens serviced. I've only seen that sluggishness on a very old lens at very cold tempertures.

---Bob Gross---

[IndyJeff]

Hiaw just out of curiosity what ISO were you shooting?

[ijohnson]

I read a post somewhere else that especially in good sunlight, the 1.x's can be unuseable wide open (esp the 1.0). Wait till the sun goes down and try again or, as mentioned, try f8.

[Tom W]

I read a post somewhere else that especially in good sunlight, the 1.x's can be unuseable wide open (esp the 1.0). Wait till the sun goes down and try again or, as mentioned, try f8.

Well, you can reach a point where you cannot achieve a fast-enough shutter to expose properly with such a large aperture. Its not a problem with the lens - its a problem with too much light to get good exposure at f/1.4 or 1.8.

If you're seeking to use wide apertures for the background blur effect, you may have to use a neutral density filter to cut down the amount of light entering the camera. These filters are effective in reducing light without adding any color cast to the image. I'm getting one soon for just that purpose.