Categorizing DS images by exposure time

[RobertI]

Following Stevie P's excellent "30 minute challenge post " I wondered if it would abe helpful for beginners if deep sky objects were categorised by exposure time. Eg: M31 is a 10 minutes object, M51 a 30 minute object, etc.

I know it would be a massive simplification and dependent on equipment, conditions, etc, but I've never seen a simple imaging categorisation that could help a newbie imager in this way.

I'm possibly displaying my ignorance here but does this idea have legs?

[baggywrinkle]

What about ISO levels , they have to be considered...mount type...alignment....

[RobertI]

What about ISO levels , they have to be considered...mount type...alignment....

You're right of course. Perhaps the categorization could be for a typical exposure (say 800), with a typical short focal length refractor (say 500mm), regardless of whether one long exposure or lots of smaller ones. Just to give a 'typical' figure.

Possibly a can of worms......

[frugal]

The "List of Messier Objects" on Wikipedia gives the list of Messier objects with their apparent magnitude. You can also sort the list by magnitude, so the targets that require the least exposure will appear at the top of the list.

There is also The Ultimate Online Messier List (http://www.davidpaulgreen.com/TUMOL/messier.txt) that has the magnitude and size in a tab delmited file that can be imported into Excel for sorting. the size will be useful to see what sort of framing you will get for the object.

I know that it is not exactly what you are looking for, but certainly a good start. You could use one of these as a starting point, and every time someone posts an image of one of the objects, you could record the exposure time the photo took.