Thanks for that, Ken. I must get around to reading your book! It's patiently sitting on my bookshelf
I tried a few calculations. It does seem that there is a trade-off between resolution and wavelength range. I don't know how easy it is to take multiple frames to build up a higher resolution spectrum in a similar manner to a mosaic of a dso? If not a 600 line/mm grating might indeed be a better option. There is the option, I think, of being able to swap gratings.
I did some screen grabs of the summaries:
First two are with the qhy183M:
And with the KAF8300/383l+
Of course, when I get to actually trying it I'll have to see what I can tweak to get the best results for my kit, guiding, and skies. I'll look closer at the lens specs when I get the chance but don't want to change the basic dimensions or anything.
Cheers
Louise