On a roll with these wide field shots

[rmuhlack (Richard)]

Loving these wide field shots (and the ease to set up is a bonus too!). This time its a M8 / M20 wide field, taken with a modded 400D and a Nikkor 200mm AI f4 prime camera lens wide open at f4.

Guided 21 x 8min subs @ ISO800, plus darks, flats and dark flats. Stacked in DSS, adjusted in Darktable (linux equivalent of Lightroom). Had another 90mins of subs which I had to discard as the dew set it. Those dew heaters I have ordered cant come soon enough!

As always, comments or advice

[cjamo9 (Clinton)]

that looks fantastic are you going to process it like you did with eta, how do you get such wide fields?

[jjjnettie (Jeanette)]

Wide fields are so much fun aren't they.
Love your back ground star field in this one.
You need to tone down the processing on the nebulas though. They're rather burnt out. I'd like to see more detail in the Lagoon.

[rmuhlack (Richard)]

the wide field comes from using a f4 camera lens with a focal length of 200mm, versus my imaging newtonian which has a focal length of 800mm

[rmuhlack (Richard)]

Thanks jjjnettie, that's very helpful. Will revisit the curves on this later this evening to see what I can do

[jjjnettie (Jeanette)]

definitely more detail now.

[rmuhlack (Richard)]

have adjusted the curves (again) - a definite improvement i think. Thanks

[cjamo9 (Clinton)]

that looks fantastic to see the lagoon and triffid rite next to each other like that and so clear. is all that other stuff around them gas or stars?

[rmuhlack (Richard)]

Originally Posted by cjamo9

that looks fantastic to see the lagoon and triffid rite next to each other like that and so clear. is all that other stuff around them gas or stars?

both i guess. Its in a very dense part of the milky way, towards the direction of the galactic centre

[rmuhlack (Richard)]

An Antares wide field - Guided 17 x 8min subs @ ISO800 (dark, flats and dark flats) with the same Nikkor 200mm f4 camera lens.

Perhaps its my imagination, but is there some diagonal banding in the dust lanes, and if so what could be causing that? (A result of removing the anti-alias filter during the camera mod as well as the stock IR filter...?) I haven't been taking bias frames as I had read elsewhere here on IIS that the bias is already contained within both lights and darks, so doesn't need to be done again, but...could that banding be associated with bias/offset? Only 11 dark frames as well - perhaps that's not enough...? Also looks to be a dust bunny at the top of frame to the right of Antares, which is also in the previous M8/M20 shot. looks like i need to redo my flats

Nonetheless I do find it a pleasing image and im happy with the composition. For a non-ED lens this 200mm Nikkor from the late 1970s is doing remarkably well

Any comments welcome

[jjjnettie (Jeanette)]

I'd say the diagonal banding is thermal noise Richard.
I get that with my 550D but much much worse. It's pointless doing long exposures with mine unless the temperature is below 10C.

[swannies1983 (Dan)]

Love some of those shots. Well done!

Re banding: Noel's Astronomy Tools (http://www.prodigitalsoftware.com/As...l_Version.html) has two actions to reduce/eliminate horizontal and vertical banding. Tools cost about $20 but there are many other very useful functions that can save processing time.

[iceman (Mike)]

Nice work!

[rmuhlack (Richard)]

thanks guys!

[rmuhlack (Richard)]

Antares region with a Nikkor 50mm f1.8 @ f4
Guided 23 x 4min subs @ ISO800

One of my favourites so far i think