DaveS

Although it's a bit of an old chestnut, M13 is bright and crosses the meridian at a good altitude so a nice target in these twilight nights. Can even be imaged under LP.

I revisited M13 with the ODK rig over 4 nights at the beginning of June, 4th, 9th, 12th and 13th. This is just 15 subs each RGB in G2v calibration. Unfortunately the Luminance was unusable as it was both overexposed, and only 4 subs were useable due to cloud. For what it's worth, here it is Will try to get some short Luminance subs.

Can't be doing with PI. I ran the trial but it did my head in, even with Warren's book, In the end I deleted it to save space on my old boot drive (Since upgraded), and the 45 day trial period is long gone. Sticking with AstroArt 7 that I first used when it was v5 a good few years ago. I have the Star Tools trial on my computer, but it didn't like the alignment edges that I had on my subs.

If it's Astronomik, then because the glass is only 1 mm thick they mount them in a thin metal ring to bring the thickness up to a suitable depth for mounting, and to make them a little more robust.

Damn, missed the start as I was painting the front door. I remember her from a Sky @ Night "Beyond Vision".

On tonight, followed on BBC4 by Sky at Night.

Oh yes, that is most excellent!

Then you'd better tell FLo as that's where I got it from.

I see you're using an Esprit 100, which is a triplet apo, so the colour correction will be very good but not perfect. For that reason I'd be inclined to go with the Astronomik set with the L2 filter

Astronomik do a range of L filters for different colour correction

No, that a GOOD thing to get [OIII] showing the "correct" teal colour, I was referring to the Blue and Red limits at the extremes of the spectral range.

The Baader would be fine if you have perfect, or near perfect colour correction (eg a Newt), but I would expect blue / red bloat with a less than perfectly corrected 'frac. In that case keep the spectral range more like 430-680 ish.

And Astronomik. Note the Blue and Red cut-off points.

The spectral range extends below 400 nm and above 700 nm

Baader are very good but they have a wider spectral window so might give bloat if your colour correction is less than perfect.

Fog / low cloud here so no chance.

As can be seen in my sig, I have an ODK12 which is natively sampling at 0.61 "/px, and is carried be a mount that can certainly support that plate scale, but a recent experiment with binning in software suggests that there is little to be gained in my location from going below 1.2"/px, except perhaps on the most exceptional nights. Don't confuse seeing with transparency / darkness, as the visual guys frequently report the best / steadiest seeing on nights of mediocre transparency.

This might be rather nice if you had a spare million or sso kicking around.

Maybe I'll ask Rupert next time I email him.

ASA make their own optics, up to 2 metre class.

He he, I ordered mine at Astrofest, at a hefty discount. But back to the OP's question, I think GSO make telescopes for a number of retailers to put their brand on, TS included. I was considering the GSO 12" RC vs the CFF 300mm RC, when I saw that OOUK had a discount on the ODK which split the difference, and was a UK company (Nothing jingoistic, just easier to deal with if anything needs fixing). A GSO RC, under whichever brand you go for, would be a solid choice, though I'd upgrade the focuser, especially if you were thinking of a heavy camera.

Sorry, yes I know it's not a RC, but it falls into the same general astrograph category. Have a look at my sig

The Orion Optics equivalent is the ODK, a more complex and eye-wateringly expensive line, with a ridiculous lead time.

I had been imaging at Bin 1 with the ODK rig, but that has a sampling rate of 0.61"/px which my seeing won't support. The 'scope and mount will easily support this resolution though (Move the whole lot to Chile?). Therefore it would make sense to run at Bin 2 and 1.22"/px However the daytime temp is making getting calibration frames at -25c problematic, as I currently use T-shirt flats in daylight. I have a flip cap with flat field panel on order but it's being delayed. Options therefore are 1) Bin 2x2 after calibration and stacking, 2) Bin master calibration frames 2x2. I am using a CCD camera which I think is better binned in hardware, but binning in software wouldn't be disastrous. Your thoughts?

We need a "Jeezus God!" emoticon!