Markarian Chain from Kelling Heath DSLR

[Carole]

I have been in two minds whether to post this up at all as there are some decidedly iffy stars.
Not used the DSLR for ages for imaging, but I changed it over for doing another area, and did this while I was waiting.

16 x 600secs @ 400iso
Modified Canon 450D + FR x 0.8
Skywatcher ED80

[Kenny]

I would love to do an image as good as that. Never heard of this region though. Where is it?

[Carole]

It's behind the tail end of Leo (and down a bit).  The two larger galaxies on the right are M84 and M86.

Carole

[The Thing]

Virgo.

I have a go a an excerpt of the Chain a couple of weeks ago but didn't get anything as good as this. As to blobby stars, I have found Mr. Bahtinov has a cure. Either that or the seeing in RGB wavelengths was pants spreading the light around, which was my problem. I would also try shorter exposures, I never use over 300s with a Canon DSLR.

[Carole]

I was referring to the shape of the stars Duncan as being "dodgy". 

I have also experimented in the past as have others with lowering the iso and doing longer subs and it seems to reduce the noise better than 800iso and 300sec subs, at least it does in a dark site, I've not tried it at home as I hardly ever use the DSLR any more.

Carole

[MarkS]

Nicely composed and you have some quite reasonable data there. 

As for optimum ISO for obtaining best signal to noise, it varies incredibly from camera to camera depending on various individual factors.  You need to increase ISO to the point where you have close to unity gain and then carry on increasing it if by doing so you can obtain a beneficial reduction in read noise.  For the 450D I agree that ISO 400 is optimum and given the slowish F-ratio, the longer subs are probably worthwhile given the dark location - to  enable the skyglow noise to swamp the read noise.

Mark

[Carole]

Thanks Mark also for your technical input on my decision to do 400iso and 10min subs.

Carole