Ghosting on 500L?

Luis Villablanca wrote:

Last week I bought a used copy of the 500L at KEH (LN- condition) .

Most shots I've taken are fine, but today while processing some shots I noticed some strange ghosting effect.

Does anyone know if this is normal? or is this a defective copy?
I am trying to decide if I should return it.

Thanks,
--
Luis

cool effect, that's one for the Parapsychologists, those that believe in auras, orbs etc.

I agree this does not look at all like a problem of the lens, it looks like a different shot.

But - while memory cards can go bad, it seems very unlikely that you have an "analog effect" with a digital card, you cannot write a byte of data, and mix it with an existing old byte of data on the card.

The most likely effect seems to be something that looks like "burn in", i.e. when you look at something bright, and you close your eyes, you see inverted ghosts of what you looked at. Likewise, if you have CRT screens, and image can burn in, or linger even after it has been turned off.

A possibility i could imagine is that the sensor of the camera had some residual faint image data (which are analog after all) still on the chip, while acquiring the new image. I suspect the image is part of a series of fast, consecutive shots. i.e. like 5 fps, and the image data is not 100% completely flushed/cleared of the chip before the next exposure.

I have more problem seeing how this could be caused by the shutter, it would have to open partially prior to the real shot - perhaps not totally impossible again with high frame rates. (some "bouncing" due to fast fps??)

Since the bird is moving forward here, it's more likely the camera hasn't finished writing data to the buffer before the next frame started to appear.

This could be what Canon has hoped no one will find out

photonius wrote:

The most likely effect seems to be something that looks like "burn in", i.e. when you look at something bright, and you close your eyes, you see inverted ghosts of what you looked at. Likewise, if you have CRT screens, and image can burn in, or linger even after it has been turned off.

photonius wrote:

... The most likely effect seems to be something that looks like "burn in", i.e. when you look at something bright, and you close your eyes, you see inverted ghosts of what you looked at. Likewise, if you have CRT screens, and image can burn in, or linger even after it has been turned off.

A possibility i could imagine is that the sensor of the camera had some residual faint image data (which are analog after all) still on the chip, while acquiring the new image. I suspect the image is part of a series of fast, consecutive shots. i.e. like 5 fps, and the image data is not 100% completely flushed/cleared of the chip before the next exposure. ...

Is this something that has been encountered by others before? Say with the high rate of the 1D bodies?

Perhaps a crippled HD video recording mode is leaking out !!

Canon won't admit to anything. Good thing your 7D is under warranty. Otherwise, they'd charge you to tell you nothing was wrong.

This looks sad for the latest version of the digic processing engine. Thanks for finding and pointing this out Luis. Although it is essentially imperceptible on my monitor in the first shot, it's not desirable. Another plus in the 1D column on my next camera list.

Luis Villablanca wrote:

I don't have the previous frame because I erased it during my first review of the pictures, but I have the next one and the burned-in ghost of this frame is still there.
So much for fast fps, huh?

Now the question is, could it be a defective unit or a bug in 7D?
I'll contact Canon and see what happens...

Thanks a lot guys!
--
Luis

thien nguyen wrote:

Since the bird is moving forward here, it's more likely the camera hasn't finished writing data to the buffer before the next frame started to appear.

unlikely, it's read in rows/columns so you'd get some kind of stripe/band appearing at one edge.

This could be what Canon has hoped no one will find out

photonius wrote:

The most likely effect seems to be something that looks like "burn in", i.e. when you look at something bright, and you close your eyes, you see inverted ghosts of what you looked at. Likewise, if you have CRT screens, and image can burn in, or linger even after it has been turned off.

-- hide signature --

Thien

Luis Villablanca wrote:

I don't have the previous frame because I erased it during my first review of the pictures, but I have the next one and the burned-in ghost of this frame is still there.
So much for fast fps, huh?

Now the question is, could it be a defective unit or a bug in 7D?

probably not a bug, it's probably due to the fast frame rate (8) they try to squeeze out of the 7D. As suggested, it's probably in the CCD (the CMOS).

a pixel is a "bin" that gets charged as light hits. To read it out, the charge is read and converted to digital, as that happens the charge goes down to baseline, but that is probably an exponential process, like with a capacitor.

I don't know if they do something to clear any tiny remaining charge, but obviously here, with the fast frame rate, it's not sufficient to remove the charge completely.

Might happen with other fast cameras too, but perhaps nobody noticed.

Or Canon, when testing, missed this, and would now need to do something to ensure complete clearing. (apply some strong drain, after the read out? lower the frame rate).

I'll contact Canon and see what happens...

Thanks a lot guys!
--
Luis

What is your Canon employee number? giggle snicker

I shoot with Canon as well. Just tools.

My 40D shutter failed at 12K actuations, and this issue that Luis discovered is a real issue regardless of how perceptible it is. There is nothing unique about shooting at the fastest frames per second setting that a camera can shoot at. It is a typical use of a camera for sports as well as birding. The xxD series has been off my first choice list for a while.

I am very picky, but that has nothing to do with any specific camera brand.

I know Luis. I've been out shooting with him. My comments were directed at him.

The CCD and Digic are very tightly linked. One does nothing without the other. I pretty sure it has a lot to do with software at the machine level in the camera. The CCD is probably not being refreshed properly. Digic is also the camera OS.

tko wrote:

Umm, if this is true, then it has nothing whatsoever to do w/digic or processing, this would be an interesting issue buried inside the CCD.

I'm sure an imperceptible problem in a unique situation is a good reason to stay away from a camera. You did note how far the image had to be pushed to see the ghost?

But I guess Konica user's are very picky : )

Schwany wrote:

Canon won't admit to anything. Good thing your 7D is under warranty. Otherwise, they'd charge you to tell you nothing was wrong.

This looks sad for the latest version of the digic processing engine. Thanks for finding and pointing this out Luis. Although it is essentially imperceptible on my monitor in the first shot, it's not desirable. Another plus in the 1D column on my next camera list.

Luis Villablanca wrote:

I don't have the previous frame because I erased it during my first review of the pictures, but I have the next one and the burned-in ghost of this frame is still there.
So much for fast fps, huh?

Now the question is, could it be a defective unit or a bug in 7D?
I'll contact Canon and see what happens...

Thanks a lot guys!
--
Luis

Luis Villablanca wrote:

Does anyone know if this is normal? or is this a defective copy?
I am trying to decide if I should return it.

Any reply from Canon?

Also, how did you postprocess to see the ghost?

There are pictures posted in the 7D forum, some of them of BIF, so I thought one could try your enhancement on these shots as well - but one would have to ask if they were done at a fast frame rate.

Thanks,
--
Luis

I'm not fretting about the issue Luis brought up at all. I did find it interesting without a doubt. Luis is a very mellow guy. Last guy to make a wild accusation or stir the pot. He was just looking to see if this has happened to anyone else while using a 500f4. I wouldn't have purchased a 7D as my next camera anyway. It looks like a fine camera with many useful features, but I need a couple of old low performance technology features only the 1D series provides.

Your third Paragraph ends with essentially what I was saying. I just skipped all the techno speak, since I had already started happy hour.

As exciting as it sounds, I think I'll skip your "try this" suggestion.

I believe I've designed as many CCD systems as the average poster at DPReview, possibly a few more. I lost count somewhere in the late 1990's. Thanks for asking..

tko wrote:
Look it up : )

The point is, if you magnify and process enough you can always find a flaw. If it's not visible in real life, then why is it a problem? And even if it is a slight problem, I'd still buy the camera w/minor problems that can't be seen 99.99% of the time over one w/lower performance.

Try this. Take any camera is the world, take a blank shot, and use the PS equalize function, and the resulting image will look terrible, showing all types of sensor gunk and other things. Not a real world problem, why fret over it?

CCD are automatically refreshed when the signal is read out. As long as you pumping the signal out they're getting refreshed. There is no way to "partially" read them out, or partially reset them. There isn't an in between, it's the way they work. At the digital control level it's all one's and zero's. If the sensor wasn't getting the right refresh signals there would be a major problem, not something like this. If it means anything, it means the sensor isn't capable of being refreshed fully at this particular FPS and shutter speed, at least not down to the 14 bit level.

How many CCD systems have you designed?