How do you correctly expose?

[the lemming]

This may sound like a daft question, but it has me stumped.

During the day, taking shots I have various tools at my disposal, histogram, zebras and waveform.

But at night, what should I be doing to get good exposure?

Should I consider something like Expose To The Right?

I only have one more good night of my holidays and I want to learn as much as I can before going home.

 

Cheers

[MarkAR]

I think with astrophotography you will always be to the left of the histogram. I think a lot depends on your target, what ISO you choose and what camera you have. 

You want to expose as long as you can without causing too much noise from your sensor and without blowing out the image. 

Try ISO 800 to 1600, 2min exposures, 2.5 mins and 3 mins and maybe up to 5 minutes if you can guide/track accurately enough.

[the lemming]

While randomly wantering through Youtubes of editing astrophotography, I just heard about ISO Invarience. I've never heard of this before.

Of those that have heard of this, and understand it, does ISO Invarience do what it says on the tin?

Can I shoot ISO 650 and then bump up to ISO 2000 in post production without suffering a noise penalty?

[wxsatuser]

The easiest way, ISO 800 for dim targets ISO 400 bright targets, shoot so the camera luminance histogram peak is approx 20>25% from the left.

25% will get the RAW histogram off the lefthandside.