Small lens suppliers?

[Merlin66]

IMHO, a 600 l/mm grating  would be a good compromise. You can always change it later when you gain more experience.

Have you decided on what cameras you'll use? Guiding and acquisition?

 

 

[Thalestris24]

14 minutes ago, Merlin66 said:

IMHO, a 600 l/mm grating  would be a good compromise. You can always change it later when you gain more experience.

Have you decided on what cameras you'll use? Guiding and acquisition?

Maybe, but it's the same price. I'm not sure how much of the spectrum the Lowspec will be able to make available to the camera at any one time. Not sure which cameras yet. I'll probably try with a qhy5l-ii or minicam5s for autoguiding. Not sure what would be best for recording the spectrum but I've been using the qhy183m with the SA100 - it has a high qe. I have an Atik383l+ mono but it's a bit slow. Otoh, I'll probably not be looking at faint stars/objects so maybe camera speed won't be so critical. I'll have to play with it to get a feel for it. I have to get the Lowspec built and up and running first - that may prove a challenge!

Louise

[Merlin66]

Louise,

I have entered the LowSpec design into the SimSpec spreadsheet, if you use the data you have it should give you a reasonable first approx of the capabilities and spectral coverage.

 

 

SimSpec V4.3_Paul3D.zip

Edited October 27, 2019 by Merlin66
corrected spreadsheet

[Astrobits]

Louise, 

Have a look at Ian Poyser's website.        irpoyser.co.uk.    He has some lenses that might fit your requirements. 

Nigel

[Thalestris24]

1 hour ago, Astrobits said:

Louise, 

Have a look at Ian Poyser's website.        irpoyser.co.uk.    He has some lenses that might fit your requirements. 

Nigel

Ok, cheers!

[Thalestris24]

10 hours ago, Merlin66 said:

Louise,

I have entered the LowSpec design into the SimSpec spreadsheet, if you use the data you have it should give you a reasonable first approx of the capabilities and spectral coverage.

 

 

SimSpec V4.3_Paul3D.zip 24.61 kB · 1 download

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

[Merlin66]

Louise,

Yes, you can combine spectral profiles to present a larger coverage - BASS can do this .

 

[Thalestris24]

56 minutes ago, Merlin66 said:

Louise,

Yes, you can combine spectral profiles to present a larger coverage - BASS can do this .

 

Ah cool! I was wondering, since Paul Gerlach's (daylight) sample spectrum was high resolution but limited wavelength range. Recording multiple spectra covering different wavelength ranges makes sense. 

I keep meaning to download BASS

Cheers

Louise

[Merlin66]

Louise,

You'll find in normal usage that the Hi-res, limited wavelength, is used to record specific detail at nominated target wavelengths - Ha, Hb or some other target. Generally there's no need to combine them.

 

[Thalestris24]

3 hours ago, Merlin66 said:

Louise,

You'll find in normal usage that the Hi-res, limited wavelength, is used to record specific detail at nominated target wavelengths - Ha, Hb or some other target. Generally there's no need to combine them.

 

Ok - copy that!

Louise