Merlin66

Very neat and tidy!

Jim,

The angle is approx 3.15 deg for a 100 l/mm grating.

The formula:

sin B = n*N*L

where B is the deviation angle, n, the number of lines (l/mm) N is the order of the spectra (usually one) and L the wavelength.

for a 100 l/mm grating, 1st order at 550nm (green)

sin B = 1*100*550*10^-6

B = 3.15 deg.

Ken

Ahhhh

I'm glad Peter corrected me!

I assumed looking at the Black box that is was a Stage 1 mod.

Gina,

As part of the mod it should have already been set up to the correct position.

The focusing on the solar disk is by using the focus knob on the Black body of the PST. The tuning ring is used to fine tune the H alpha wavelength to show the solar detail.

As said Gina, there's no real need to consider a focuser on the scope...

Gina,

You don't have to worry about or consider any focusing of the donor scope.

The etalon NEVER moves relative to the donor after initial set-up. It's always -200mm from the prime focus.

Think about the donor just as a fixed replacement for the original gold tube in the PST.

Final focusing is always achieved behind the etalon - I use a Borg helical focuser on my PST Mod.

Yes, the tilter sits immediately in front of the ASI 174.

Normally you'll need around 1000 frames per exposure - this allows AS! to select the best frames for subsequent stacking, then apply Registax wavelets to bring up the image.

Why the x2 Barlow???

I use the ASI 174MM but need a tilter (1.6 degree) to suppress the Newton Rings.