Archive for September, 2014

I am in the final stages of setting up a new imaging system based on a Canon 200mm prime lens with M25C OSC imager and a 52 mm IDAS filter on the front of the lens giving me f#3.85 and spikeless images 🙂  As it is that time of the year an obvious target for testing out the star imaging qualities of the rig is the Double Cluster.  With a horrendous sampling of 7.97 arcseconds per pixel it makes you wonder how it can even resolve stars – but clearly it does 🙂  Above the Double Cluster we see the rarely images Stock 2 open cluster, which looks like a stick man on his side.  And at the very top/left you can just see the edges of the Heart & Soul nebulae.

Only 16 x 5-minute subs for this one, and very misty conditions too, a LOT of water vapour in the air – however, as a bonus, there was no Moon.

I think this is going to make a good rig for those BIG winter nebulae.  It is NOT a good rig for those single bright star shots as there are terrible ghost flares from very bright stars, probably resulting from all that glass in the 200mm lens.  Well you can’t have it all I guess.

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I have now removed the Canon 5D MkII from the 200mm lens in the south dome and replaced it with the M25C that used to be on the Hyperstar.

The massive field of view afforded by the 5D MkII on the 200mm lens is truly addictive – but the lack of red sensitivity of an un-modified DSLR and the lack of Peltier cooling drove me to put the M25C back on.

So – a whole Cassiopeia mosaic instead of being a 4-framer with the 5D MkII is now a 6-framer, or very comfortable 9-framer.  The price you pay I guess.


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Put the 5D MkII on the back of a TS80 refractor together with a 5X Barlow (not really called a Barlow then, but the name sticks).

Took 17 subs at 1/200th second and ISO800 which I stacked in Maxim.  This is the result.

See in higher resolution here

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