[Bassnut (Fred)]

Brett

There are other more obscure options for sensitivity, but not FOV unforch, unless the price gets really silly......

Terry

Yes, Ha is 656nm, not 700nm, that was a dumb approximate.

I did the numbers again, cant see how you get yours, for example, you quote 1 hr for the 16803, do mean 1 panel on a ST10 at 1hr at f6 equals 1 hr for 1 panel on the 16803 at f9, how can that be when it has half the Qe and double the exposure time (at f9)= 4hrs ?.

EDIT. OK,on a re read, I see what youve done, a bit confusing, ignore the above rubbish, still dont see how you get your numbers though ;-).

Actually 6 panels on the ST10 is larger FOV and 4 panels is smaller, so its sort of inbetween 6 or 4 hrs on the ST10.

I worked out the ST11k would actually take quite a bit longer than 4 panels on an ST10 for the same result 1hr * 2.7 (30% QE) * 2 (f9, over f6)= 5.4hrs. Actually the 4 ST10 panels at f6 (45*67.6 a/s) are a larger FOV than the 1 ST11k at f9 (36*55) too .

Terry

Its extra FOV im after, not a humungous number of pixels, as Alex says.
Binning is quite a good idea, at f6 the image scale with bin 2 is 1.87 a nd at f9 1.25. Given you should have it about half of seeing, which in my case is usually 3 to 6, then 1.87 would scrape in and 1.25 would be fine, although deconvolute works better sub 1.0 in my experience.

Alex

I cant consider a 16803, it was just for comparison, nothing else I have would take it (apart from the rotator), OTAs, AO, external focuser (when I use it), I just couldnt aford it, and I dont think you can get a wheel that would take a full set of LRGB and NB (with 2 Ha), which would be a pain, I use them all.

No, niether the RC or LX would take it.

The STL6303 comes with an 8 pos FW option, would just do nicely, and yes it appears the A08 will just do too. Its been around a while, so I may be able to get one S/H.

The new STXs have a 6303 version ;-).

You know, ive been thinking of the importance of image scale for a while, and I think things have changed lately that make the old formula not so reliable. Some ppl think sub 0.6 arcsec/pix does make a difference even in 2 arc/sec seeing, yet, and not much is mentioned of this explicitly yet, the new huge cams like the 16803 seem to do very well at 3 arcsec/pix and up simply due to the huge pic size viewed full frame.

Look at Martin Pughs recent demo pic with a tiny refractor, massively undersampled, the stars are blocks, but you have to zoom in a long long way to tell. Viewed full frame, you wouldnt have a clue, and it looks fantastic !.

So, as Terry says, binned ST10 mosaics at a huge final image size changes things significantly (taking into account the above,and anyway not that much undersampled really), that would halve (or more) the exposure time, and start making mosaics very attractive indeed ;-).