I hadnt realised...

[dannyrich]

I moved from a D40 to a D80 then on to a D90. I kept the D40 because I like it and sometimes use it for ease.

I bought a D40x on behalf of a friend this week and thought I would test it out before I gave him it. Firstly, I prefer my D40 but anyways... whe taking pictures, in A or M as normal I found it difficult to get the correct exposure, to the point where i was quite annoyed with myself.

I thought I was getting better at photography but I think the fact is the D90 is so fool proof and has such good use of auto ISO that I have been thinking im more accomplished than I am. Not to be deterred I have decided to take a host of shots now with my D40 just to make sure I develop.

I was quite shocked although I noticed the same when playing with teh D80 after I got the 90.

Not very interesting but I often need to log this sort of stuff before i push myself to do something about it lol.

Anyway on the plus side I got some good pictures, i use a 18-135 though and that only had a 18-55mm, my goodness did i miss the reach!

[OsmosisStudios]

I would recommend never using Auto ISO. That's one of the biggest image quality changing sides of the exposure triangle that Im usually not willing to mess with.

That being said, the reason for that is that the D90 is newer than both the 80 and 40/x, so it has faster and more pwoerful programming and processing to choose those kinds of things.

[sk66]

I almost always use auto ISO (set to 200 ISO "preferred") and Aperture Mode.

I would guess the biggest issue you are seeing is a difference in metering. I would check you have the D40 set the same as our D90 for metering pattern, or just set it to spot metering...

[dcclark]

There are two different "auto ISO" variants in the D90 -- Nikon's standard Auto ISO, which bumps up your ISO when you go below a certain shutter speed, and the ADR (forget the meaning) which locally increases the ISO to help avoid underexposed portions of the image. The ADR is much more advanced than Auto ISO, and can be adjusted to various levels of strength.

I always have Auto ISO on, unless I'm in a situation where long exposures are just fine -- with a VR lens, I set my minimum shutter speed to about 1/15 and max ISO to about 800 -- which rarely happens in most situations.

[sk66]

ADR is "Adaptive Dynamic Range"....I usually have it set to "normal". In-camera it's called Active D-Lighting.
As I said, I usually have it on, but I also find that it can tend to make some high contrast scenes "flat" so it's not always a good thing. The same results can be achieved in post if you don't want to take the risk.

[dannyrich]

I changed my D90 for some night shots the other day, i then proceeded to take a pile of underexposed rubbish in low light the following day! then it clicked!