DS1052E controls question

[i_like_sparks]

Hello,

excuse a probably stupid question from a beginner.

Let's say I'd like to use my new shiny DS1052E to measure the ripple/noise on a +12V signal. I know it's at 12V and want to zoom in to the 20mV level centered around +12V. If I first set the vertical scale to 20mV it takes ages spinning the vertical position knob to get up to 12V. Hmm... Ok, next time I set the vertical position to 12V first at the, say, 10V level, and THEN try to zoom in to 20mV. BUT this changes the vertical position as well, and it is now at 24mV, so I'm wheeling the vertical position knob again to get up to 12V...   

This is incredibly annoying. I must be missing something obvious. Can anyone enlighten me?

[AG6QR]

If you want to look at the ripple, switch to AC coupling.  Now the signal is centered around the origin.  This also improves the resolution of the samples.

[Psi]

Use AC coupling mode to measure noise.

Since you're not concerned about the actual voltage, you just want to see how much its moving up and down by. Which is AC

AC mode doesn't move when you adjust the vertical scale.

[i_like_sparks]

Ah, that's very useful.

Still, I think this is not a good design. If the display is centered around 12V and I'm switching vertical scale it should be obvious that I'd still like to have it centered around 12V and not, say, 6 or 3 instead.

[sync]

This is how analog scopes works. But you can change it:
Utility -> Preferences -> Expand Refer. -> Center

[i_like_sparks]

Thank you so much, that's exactly what I was looking for. Hadn't found that menu yet. 

[Psi]

lol, i didnt know about that setting.

Thanks

[rdl]

omg! That has been bugging me ever since I got this scope. Thanks for the tip. Maybe I should read the manual some time.

[Mechatrommer]

yeah its usefull when the dc level is not changed.

Still, I think this is not a good design.

what do you expect from a $300 scope?