Lefty I am probably getting the TI ADS1115 chip you mentioned but also found a thread here http://www.avrfreaks.net/index.php?name=PNphpBB2&file=printview&t=111569&start=0 where 'oversampling and decimation' was discussed.
Is this worth considering or... From my point of view, I am aware that 2ms delay is suggested between analogue reads and then there is a 100µs or so required for an interrupt and would be grateful if you were able to comment.
Unfortunately I am very aware that the opportunity for oversampling is limited - in an earlier post I suggested that one shot is only possible, but needs must where the devil drives.
Here is the maths assuming a 0.5mm maximum permitted image travel 'window' (it is assumed that the image would not change shape beneath the sensor during this time):
Minimum speed... 20 feet per min = 6096mm per min
Time elapsed for 0.5mm travel... 4.92ms ±
Earlier I indicated that there would be 1mm of 'constant' image available and here I take 0.5mm to be the maximum. Fact is, it is as long as a bit of string in that sometimes 0.5mm might not be available and so I have to play devils advocate.
Another aspect that I am aware of is the permitted frequency of AD reads from this chip and wonder whether, given that there will be an interrupt overhead too (Arduino), and that it will then issue commands over the bus and that the I2C bus is not the fastest (V4 doesn't seem to be available on this chip), will this scupper it?
I am clearly looking at the minutiae, which is not always the best route, but please comment if you have a view.
Thanks again.