first light with the WO zs66 DS Apo, 3rd M51 attempt

[Chris]

Hi folks:) After dreaming of owning some ED glass for while now I've managed to find a nice little doublet Apo - Williams Optics Zenithstar 66mm:D, I was hoping to give first light to the Rosette neb but its setting past my house quite early in the evening:( however, Ursa Major is postioned very nicely at present so I though I'd have a third attempt at M51. Sorry for posting a third recent M51 but I hope they are getting better each time, and I would love some advice on how to improve things, I'm not sure I've got the processing pinned down, and I know I need to learn about flats.

37x60 seconds plus 7x45seconds plus 140x30seconds with Darks at 30 seconds and 60 seconds. Stacked in DSS and sharpened slightly in Digital Photo Pro.

Kind Regards, Chris:)

[Zul]

Nice!

[Catweazel]

Very nice

[Anweniel]

I imagine its a case of just longer subs to improve on that, its pretty detailed in the arms and a good capture

[Daniel-K]

mighty fine effort just wish i never sold my 66 now but at the time it needed to go

[Chris]

Thanks guys, and Daniel its not the first time I've heard people say they regret selling their WO66, I think I'll take heed and keep mine unless a become bankrupt:D it is a great little scope and I've also got a 0.8 reducer flattener on its why from FLO which will make it even better:D

[Chris]

Theres been way to much cloud recently so I've been playing with my previous M51 data, although this time I've used the 2xDrizzle function in DSS and had a play with my new toy PaintShop Pro, lots to learn with this software:)

[ollypenrice]

The ZS 66 does not exactly have a galaxy-hunting focal length so you've done very well!

But what's all this zipping around with sub exposure lengths about? There is nothing you are likely to overexpose in this target even in 10 minute subs so I would just make a decision on sub length and stick to it. Make it as long as your guiding and camera thermal noise will allow. (The camera should be OK for 5 to 8 minutes in winter, I'd have thought, but I don't use DSLRs at night myself.)

Since you are beginning to pick up the outer halo even in these very short subs I think you'd be amazed by what you'd get in longer ones.

Make flats a priority, though the crop here means you get away with it.

Olly

[Chris]

Thanks Olly your advice is much appreciated:)

The different exposure times is just me experimenting with what works with an old mk1 HEQ5, I've not had this mount long and it was an upgrade from an old eq5 which I only manged to get 20 second subs from, any longer and I was binning more subs than I was keeping:D Therefore I wanted to see how many subs where kept at different exposure times with my upgraded mount? Answer= 100% at 30 sec, about 80% at 45 sec, and about 60-70% at 60 seconds, so a big improvement for me:) Next time I get good seeing I will try my hardest to get a good polar allignment and push for subs all at 75 seconds:) I will eventually get guiding I'm going to build a shedservatory first to keep all the bits and bobs required, laptop, wires, de-humidifier etc.

a quick question if you don't mind - what would a good focal length/cheap ota be for imaging galaxies?

Regards

Chris:)

[ollypenrice]

A good FL for galaxes starts at a metre and ends when you can afford a 20 inch Plane Wave on a big, big mount. However, don't even think about going to a longer FL if you are not autoguiding, and accurately, with what you have. Longer FLs need ever more accurate tracking, unfortunately. Think of picking up a bit of chicken with chopsticks. Can be tricky. Now make the chopsticks three metres long. More tricky again!

Until you have a good autoguided mount keep your imaging FL short and go for other targets. For your 66, Markarian's Chain in Virgo would keep you occupied and off the streets! And it's itching for a go at M31 later in the year.

Olly

[Chris]

Thanks Olly:) I'm doing a bit of planning ahead for when I'm set up in a shed guiding with Phd and a soldered in ST4 port from Shoestring:)

I've ordered a WO 0.8 reducer/flattener for my ZS66 to help improve unguided tracking and light grasp in the mean time, but for small galaxies and planetary nebs this means even more cropping and reduced spatial resolution, so I would like to get hold of a scope suitable for smaller DSO's at some point. From what you've said, a SW PDS Newt springs to mind, they are around a metre focal length and fast:)

Good chopstick analogy by the way:D