We're all familiar with the idea that with fast movement, shutter speed is a priority, if depth of field is critical, aperture is a priority, and if neither of those are critical, keeping noise low (i.e. low ISO) is a priority. When it comes to choosing camera settings in those situations, our priorities are clear.

But what about the most demanding situations where we can be pressurised from all three directions and our choice of shutter speed, aperture and ISO could all end up being less than ideal? What are our priorities then?

In that sort of situation, instead of thinking about what our priorities are we need to think about what the most compromisable variables are. To answer that question we need to ask what has the most potential to negatively impact the quality of a shot, perhaps to the point of spoiling it altogether.

Everybody will have their own take on that subject depending on what area of photography they operate in. There are various ways in which a shot can be degraded or spoiled (for example over- or under-exposure), and it will very often be caused by user error. However, degradation can also be caused by unavoidable compromise. Looking at the latter situation, and looking at it from a very general point of view, my suggestion for what the worst shot spoilers are (in order of significance) would be:-

1) Motion blur / camera shake (i.e. a shutter speed issue).

2) Excessive loss of sharpness and/or detail due to insufficient depth of field (i.e. an aperture issue).

3) Excessive noise, possibly accompanied by a loss of sharpness, contrast and colour accuracy (i.e. an ISO issue).

Still speaking in very general terms I would say the main implication of the above list is that the most compromisable variable is ISO, followed by aperture and leaving shutter speed as the least compromisable variable.

Still speaking in very general terms, another implication is that if you had to choose one variable to float, ISO would be the best choice, since it is the most compromisable variable (this is especially true of the most recent cameras, some of which have exceptional high ISO performance).

Feel free to agree or disagree with any of the above and feel free to share your own take on the subject.

Wow! It looks like you have some serious networking going on there. You may be the best person to answer a question for me. I recently purchased a high end router to replace the one furnished by the cable company we use. Their's is about 4 years old and rather than continue to pay the 16.00 a month rental, decided to buy this unit. The problem is that it needs the cable connector box which I don't have. I see them on line for anywhere from 40.00 to 150.00. Is this device only a pass-through enabling the cable to connect to the router? If so, what advantage would a higher priced unit give me? Thanks in advance for your help.

Just got my new camera last week and slogging thru the 274 page user manual. Moving from a cell phone to a SX70 is proving a rougher road than I expected. Took it out yesterday to take a photo of a rainbow, clicked the shutter and then asked to see my picture - i saw the house and tree but no rainbow, gosh the sky is very white. Oh I had the camera on manual from the day before when I was trying different shutter speeds resulting in washing out the sky. Ok - lesson learned check the settings before rushing to take a picture.

Later that evening my wife says take a picture of the "pink" moon as it reflects off the bay. Ok, I check the settings and take the rookie way out and set the camera to auto- I get the focus i want, then go to press the shutter, all sorts of things are blinking at me in the eye piece and the shutter won't work. Some sort of red camera icon in on the bottom left side of the screen. No joy, haven't found out that symbol in the manual yet.
Oh well, there is nothing on TV tonight so i will read the manual some more...