james2

Thanks for the reply, Roy! Vandalism isn't an issue - although temperature resistance is - these boxes (really fiber drums of varying heights) are being fed to an incinerator and we need to read a label on the one closest to the feed door. We may put the camera in an open-bottom enclosure and have a flow of compressed air through the enclosure to protect it from the occasional gust of hot air from the feed door. Your comments on glare were intereresting - I hadn't really considered that as an issue. We can add lights without too much trouble - would glare be less of a problem if we added two - one to the left and one to the right and aimed them at an angle? That would seem to reduce the amount of light that bounces directly back toward the camera. Also, we can move the camera a bit farther back than 2 feet from the top of the highest box - which also might get us back to the 4 - 10 mm lens. From some experience with an old Pentax K1000 35 mm SLR, I remember that depth of field drops off pretty dramatically as the f-stop decreases - what are the typical f-stops for these lenses? Also, you mentioned Auto Iris - is that a self-contained feature of the lens or does the camera send a signal to the lens to close the iris? The old K1000 was manual everything, so some of this is new to me! The labels are black letters on white glossy paper, so a B&W camera will be best, I guess. I had found a reference to the Sony SPTM320, a B&W camera that claims 570 horizontal lines. (Anyone have any experience with that camera?) I tried a bit of math: the area where the label could be is 28 x 28 inches. Dividing 570 lines by 28 gave about 20 lines per inch which means that in a 3/4 inch high letter there would be about 15 lines. Since I can't control the orientation of the labels, if the letter was sideways (and is 7/16 inches) that would mean that about 9 lines would span a character. That seems sort of on the low side, but might be OK. Of course, this sort of analysis may be totally out in left field - any comments would be welcome! Again, thanks for the feedback - hoping to get more. James Cox

This may be a bit out-of-place here, but this seems to be the place with the most knowledge on applied use of cctv, so here goes. We need to mount a b&w camera about 2 - 5 feet away from the top of boxes. The height of the boxes varies by about 15 inches. We are trying to read text (characters 3/4 inches high, 7/16 inches wide) that can be anywhere on the box tops. This gives requirements of having a camera / lens system that has enough resolution to cleanly show 3/4 by 5/16 letters which can be anywhere in a 28 by 28 inch region - and the depth of field needs to be 15 inches. Is this going to be a big challenge or is this a piece-of-cake camera / lens application? Do we need to be looking for a high resolution camera (if so, how many lines vertical lines)? Are we going to have problems getting the combination of close-focus and depth of field - and what sort of lenses should we be considering? Thanks for any and all help on this! James Cox