Digital Rebel xt - faulty CF card?

arroyoshark

Picked up a new 2GB Sandisk Ultra II CF card. Formatted it and stuck it in the Rebel and went out to shoot test images with a Sigma lens at various aperatures and settings. I was floored when I got back and uploaded images to PC. All of the images were seemed a bit out of focus. I was shooting RAW.

Camera settings were Aperature Priority, ISO 100, RAW, one shot autofocus, lens AF switch on. Conditions were clear, sunny, contrasty lighting.

I took some more photos yesterday, just out side the house, with both the Sigma lens and the kit lens, and the results were the same - blurred. I noticed when I uploaded the shots from the kit lens, I could not see the metadata in Bridge or a thumbnail, but could bring the image into ACR . I removed and re-installed the battery and tried some more shots, no change. I then tried an old CF card in camera and took some more shots with the Sigma. The images were sharp again.

I am beginning to conclude that the new CF card is bad. Have never experienced this phenomena before. I tried this new CF card in a Canon A80 and took some jpeg shots out doors. Same thing, images did not appear sharp.

Is it possible the new CF card is faulty?

Has anyone had a a similar experience with memory cards?

:dunno

ziggy53

I have never even heard of this happening before. It seems a little bizarre.

I believe that you are experiencing something, you just have to figure out what that might be.

I strongly suggest a controlled test, tripod, controlled lighting, fixed subject at fixed distance, ... Try to make the different CF cards the only change. If this confirms a problem, please let us see hires JPGs of the problem.

Possible problems, (thinking "waaaay outside the box") only two possibilities come to mind.

1) EMF interference. I suppose it's possible that something is "contaminating" the image in an electro-magnetic fashion. The imaging chip is an array of solid-state junctions, and strong radio type interference could possibly affect the signals coming from the chip. Very strange if that's what's happening.

Compact Flash uses a variation of the PCMCIA interface and PCMCIA can be influenced by EMF Interference. Doubtful.

2) Unusual current draw. Digital cameras do all sorts of wierd things when current is diverted or sumped at too rapid a rate. I suppose that an improperly manufactured (defective) CF card could cause that to happen. Usually, the failure is more catastrophic in nature; the card just stops working or the whole camera shuts down or fails to recognize the card. Doubtful.

Anyway, concentrate on proving the problem exists in a controlled test, and you will have an easier time getting remediation from the card manufacturer or vendor.

Best,

ziggy53

wxwax

You say you formatted the card and then put it in the camera?

Have you tried formatting it in camera?

arroyoshark

wxwax wrote:

You say you formatted the card and then put it in the camera?

Have you tried formatting it in camera?

Thanks, ziggy and waxy. I will rerun some more tests in morning. Yeah, I always format the card in the camera, tho my words would indicate otherwise. I had initially formatted it in camera then removed and placed in case for later use. Perhaps I should reformat it again. It does seem like unlikely scenario to me, but when I got pretty much the same result in my P&S, it made me more skeptical about the CF card.

I was trying many settings originally with the camera and lens. I had set it up on my tripod to do this, in the field. Ambient temps were in low 90's when I did this, with direct NM sun. I realized later that I had not covered the eyepiece when using tripod...so initially thought this may be affecting things. The camera manual warns that it could affect exposure. My Tuesday tests at home were done with my eye up to the camera.

I will post some sample pics tomorrow.

Richard

If I am reading your post correctly, you have got the following data points:

1. New card in Rebel -> Blurry
2. Old card in Rebel -> Sharp
3. New card in A80 -> Blurry

You didn't mention old card in A80. Assuming this comes out sharp, that would pretty much be conclusive evidence that the card is causing the problem. "When you see hoof prints, look for a horse, not a zebra," and all that. I have never had a problem with any CF card, but in this case I think I would just return the card and get a replacement.

Regards,

jimf

arroyoshark wrote:

Is it possible the new CF card is faulty?

I doubt that the card is the problem but let's consider a couple of possibilities.

It might be an energy budget issue (ie a flaw in the card causes it to pull too much energy, leaving the camera with too little to properly run the focus electronics -- remember, those are amongst the camera's most energy-hungry parts). It's certainly possible that there is a short in the card and that could have all kinds of odd effects.

But I'm really dubious about this, there's almost no way you'd get the same response out of two different camera models and a short is far more likely to cause complete camera failure (up to and including failure of the camera to even turn on).

Regarding the possibility that it's an EM interference issue ... I'm likewise dubious that you'd get similar behavior from two different cameras, even if EMI were likely to cause an out-of-focus type of error rather than random noise. EMI could, I suppose, interfere with the communication between camera and lens, but again two different lenses and cameras with totally different lens management systems make this highly unlikely. Or interfere with the focus detection system, but two different cameras and the probability that something like that would simply cause loss of focus lock....

Generally speaking what you describe contradicts the way the devices operate. Unlike film the storage system is rather dissociated from the image capture system. It doesn't come into play until after focus, capture, and even manipulation has already been performed. There are some common elements -- ground plane in particular -- where one bad element could cause a remarkable number of issues but by and large if such a basic interconnect were causing you issues it's unlikely the camera would operate at all, and almost impossible that you'd get the same behavior from two differently designed sets of electronics.

Almost everything a bad card is likely to do would result in data loss or corruption or, in the case of a short, perhaps complete failure of the camera. Out-of-focus results are really, really unlikely. So: I think it's something else.

Has anyone had a a similar experience with memory cards?

Nope, never heard of anything like this. I might take it to a shop (if you bought it retail I would certainly do this) and try it on a couple of different cameras of different makes to see what the behavior is like. But again, I think it's probably circumstantial -- that something else is causing the problem and you just didn't figure it out, although admittedly it appears you've ruled out everything I would have considered if by no other means than trying it with a much more automated camera.

Having said all of this, if you're in the Boston area I wouldn't mind looking at the card. I have some card test software and a bunch of different cameras, card readers, etc to try stuff like this in. And if you ever do figure out what it is (card or otherwise) I'd love to hear about it.

ziggy53

arroyoshark wrote:

... I will post some sample pics tomorrow.

Did I miss it? Find anything?

ziggy53

arroyoshark

ziggy53 wrote:

Did I miss it? Find anything?

ziggy53

No, Ziggy, ya didn't miss much. I decided to reformat the new cf card 3 times in a row then reshoot some test images, to see if it made any difference. Then I got real busy and did not have time to get them into pc and convert to web files. I will post some before, during and after shots for comparison in next day.

Oh, BTW, JIMf, that was a pretty indepth discussion...and I agree with you about the card being disassociated from image processing. That's why I did try card in different camera that I had. I was fearing it had something to do with canon camera body and Sigma lens. I got similar results with the kit lens, but then the kit lens isn't great to begin with. It would be great to connect, as you seem most knowledgeable, but I live in the southwest.

Thanks for your interest.