Dumb question number 786976
Any advantage of one over the other? Either will hold the equivalent of a closet full of 35mm slides, but which is better, and why?
Lyle

It's obviously best to use whichever card(s) is/are supported by your camera(s). ("Captain Obvious" here.)

A major difference between CF and SD, besides the form factor, is that compact flash uses an internal (to the card) controller, while SD cards use a controller in the camera. (i.e., SD cards do not have their own controller.)

A reason this can be significant is that transfer speeds and even transfer stability is often related to signal and stream timings of the controller. By placing the controller in the camera, it's more likely that more cards will be supported or better supported. To some degree that implies a more universal compatibility for SD cards and cameras. (Internal card timings can still mess things up, however.)

CF cards also have a separate "header" to receive the pins of the camera's CF card socket, while SD cards use a much simpler set of contacts. The SD card contacts are easier to clean, and don't seem as mechanically stressed during card insertion. The header/pin system of contacts on CF cards is prone to bending the pins, especially using devices with a short path to the pins.

That said, CF cards have been around longer and tend to have better shielding than SD cards. CF cards present the opportunity for more robust "leveling" by the controller, since the card manufacturer is in a better position to understand the internal needs of the particular memory used in the card. CF cards have a set of grounding pins to make first contact, which tend to dissipate static charges better than SD cards.

For more information regarding CF and SD designs and standards:

http://www.sdcard.org/
http://www.mmca.org/home
http://www.compactflash.org/

Rob Galbraith used to do empirical testing of different cards relative to different cameras. I don't think that he is either testing or updating much these days. (He's teaching now, last I heard.)

http://www.robgalbraith.com/bins/mul...e.asp?cid=6007

Aside from the great info Ziggy gave.....I am wondering if you can explain your question a bit better.....
as your wording left me wondering if you are wanting to store images for a LOOOOOg term on them or
just wondering if one is better than the other....to which I would say and this is without any science
behind it...no, one is not better than the other and my reasoning is that SD card slots are going into PRO
cams now and if there was a major difference that made the SD unreliable or more prone to corruption,
then I doubt they would be placing them into the PRO line of cameras......but as I said there is no science
to this....but for me, I do not want a camera that takes Sd cards...and my reasoning is..I have lot
ever SD card I have ever owned and they totaled over 1K of music CD's on them...for me they are just to
small to handle when I am out shooting wildlife in the dead cold winter or making quick changes when
shooting a wedding... ... ... now when I can no longer purchase a camera that takes CF cards then I will
have have to adapt to the form factor that is available at that time... so to add extra storage to my phone,
I had to buy mini SD cards and just trying to get that danged little thing into the slot was a major B for me....

ziggy has already given you plenty to chew on :)

I use a cam with slots for both types - and prefer changing SD cards to CF ones - especially in the winter (also shoot w/life) because of the elimination (imo) of getting bent pins.
Yes, they're smaller, more fiddly ... but no more so than using some of the (smaller) cam controls anyway.

Using SD cards and therefore removing the (cold weather) tactile 'feel' aspect of inserting a CF card is - for me, anyway - worth it, having once bent pins on a CF socket.

pp