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Old Jan 5, 2004, 10:51 PM   #1
hst
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Default Does memory card brand make a difference in picture quality

I have two different brands of 256K memory CF cards. One seems to record better images with less noise. Is that possible? or just coincidence. I don't see how it would matter but it does seem to. Both cards have been formated by the same camera.
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Old Jan 6, 2004, 11:41 AM   #2
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No, the quality of the card should not effect picture quality.

But it will effect write times, which could mean the difference between getting the picture and not.

Eric
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Old Jan 6, 2004, 3:40 PM   #3
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The card brand/quality will not cause image noise. If the data is getting corrupted on the card - the image wouldn't be readable by your camera or PC.
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Old Jan 6, 2004, 4:41 PM   #4
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Curiously I read somewhere, that if you've got a cam like mine where they put the battery pack right next to the media, then the media can get quite hot. But data is data and I can see no reason why what's written assuming error free, is no different to what's read back.

These cards all have cpu's in them, so unless the camera is picking up clock noise interference via the ccd sensor circuits and modifying the data before it gets stored or they have a high pulse load and again could be causing power line interference in the camera - I'm afraid that's my only guess. Put a 'scope across the batt. terminals and compare writes for 2 cards and see what's lurking about. Perhaps cheap cards miss out a bit of filtering and decoupling! VOX
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Old Jan 7, 2004, 8:39 AM   #5
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Vox,
Huh?
First off, there is no CPU in a CF card. It is simply nonvolatite memory.
Second, I find it hard to believe heat from a battery could cause any sort of problem. Most CF cards have a VERY large operating temperature - and vendors typically run environmental tests within these ranges. CF cards are used in equipment which gets MUCH MUCH hotter than a digicam. The ranges vary greatly (in fact in industrial CF, used in products such as data networking equipment, the range is -40 C to +85 C) - you can check a manufacturers web-site for their range. I've seen fan failures in commercial data comm equipment to the point where FPGA's and CPU's burn out, then pull out the CF and find it still works somewhere else.
Also, I find it hard to believe if you had power-line interference it would cause a series of bit-flips only enough to see some noise on the image - my guess is you wouldn't get a valid write to the card (and therefore - would be unable to read the image back).
Lastly, by the time the data is moved down to the CF A-D conversion has already taken place - so power line interface wouldn't cause an analog signal to be misread and misinterpret a bit.
I find it most difficult to believe this problem is the media.
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Old Jan 7, 2004, 9:09 AM   #6
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I just took a quick read through the CF standards. The standard includes a 32 bit polynomial Error Correcting Code capable of correcting mulitple random bit errors furthering my belief that this can't be the media.
hst - Are you sure there isn't another explanation for what you are seeing? Are you sure you are using the same level (or lack of) JPEG compression when using both cards? Are you shooting under similar conditions with all the same user settings on your camera when using both cards?
If you still think it may be the cards - the only other thing I would think to check is to see if the manufacturers post their bit-error rates on their sites (or query the manafacturers for their specifications). What are the manufacturer's and part numbers/names?
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Old Jan 7, 2004, 5:53 PM   #7
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.......First off, there is no CPU in a CF card. It is simply nonvolatite memory............

csd - sorry but you need to do a bit of reading!. Now Smartmedia IS just non-volatile memory which is why it's so compatible in all respects and has no speed compatibility issues.

CompactFlash on the other hand, is nearly as complex processing wise as your hard drive - or did you think that was just a bunch of media coated platters! The CF host controller even has embedded software and some processor has to run it and execute instructions, so two cards from different manufacturers might have performance differences, whilst still adhering to the CF spec. I'd expect the pinouts to be the same though!

http://www.analog.com/library/analog...act_flash.html

It's hard to think of bit errors as responsible for a jpeg quality problem unless we're talking of failure to store data in the midle of the JPEG file data block. I've seen this happen with a correct file crc and black lumps missing from the pic. Encoding errors are more likely coming off the camera before hitting storage. If you are really keen try shooting two identical pics of something artificial and simple in Black & White using manual camera settings. Convert both pics to bitmaps. If you are lucky bitmap data may align reasonably well so you can look up the Windows bitmap file spec and peek around bytes near the same obvious picture transitions with an editor. If you see vast differences in the data level values between two different cards stoing the same image data, I'd be most surprised.
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Old Jan 7, 2004, 6:27 PM   #8
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The flash controller and buffering do not have embedded software. These are not considered CPU's by any means.
Processing is external to the card.

Two compact flash cards definitely could have performance differences - what we were talking about was whether or not they could create image noise. The ECC algorithm employed is standard and all AD is done before reaching the CF - so it is very unlikely they would make a difference.
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Old Jan 7, 2004, 8:22 PM   #9
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vox - let me add that I wasn't trying to flame you - although re-reading my original post it did sound that way. I was just sceptical of your suggestions. Sorry if I came off sounding harsh.

And although I don't necessarily feel this is the place to debate the difference between transistor-logic circuits versus embedded software running on PU's - I always seem to have trouble listening to terminology snafu's. I guess I'm anal in that regard. (As I said - I wouldn't consider a ECC chip/buffering CPUs - these are transistor logic circuits - not embedded software - there are no instructions and no processors for them to run on - whoops - sorry I'm doing it again).

okay - so lets put our BSEE/MSEE/PhD degrees aside and get back to photography.....
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Old Jan 7, 2004, 9:11 PM   #10
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Default Thanks for the replies

I tried shooting both RAW and in several JPG modes. The card that appeared to have the best picture was a Simpletech. The other card I won't mention the name because I don't want to be critical when it just may have been me. The other card seemed to right files faster and I could shoot faster sequences. It actually appeared to be a better performing card. But when I went to put them on the screen, the images just didn't look as good. I don't have the one that didn't appear as clear or I would do some testing with identical situations which I didn't do. I'm getting ready to buy another card and just wanted to know if the type made a difference in image quality. Thanks for all the input!
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