NCG 7000

[Desolation4all]

My third try on this subject, and my first somewhat succesful one. Due to the nights not being really dark in Scotland in the summer, subs were limited to about 20s max with this setup.

Camera: Hutech modified Canon EOS 450Da

Lens: Samyang 135mm f/2

Mount: Skywatcher Star Adventurer

 225 Lights (ISO 800, 20s), 47 darks, 15 flats, stacked in DSS and processed in Photoshop (curves and levels).

I have to say though, this lens is really impressive; flat stars through the whole field and it collects an insane amount of light. Maybe I'll put up a review on it when I have tried it some more.

[wimvb]

Lovely. Nice stars, and the nebula is well defined.

The dark corners suggest that your flats aren't optimised yet.

[Desolation4all]

You are right, creating flats still requires some work, I think I should increase the exposure time because at 1/2500 s it doesn't look like the vignetting has really expressed itself.

[steppenwolf]

There is a great PhotoShop plug-in by Noel Carboni called AstroFlat that can help here - I don't suggest that you use it as a replacement for Flats as good Flats can transform an image but I thought you might like to see what it looks like applied to your image with a little Curves adjustment afterwards:-

[Desolation4all]

 

6 hours ago, steppenwolf said:

There is a great PhotoShop plug-in by Noel Carboni called AstroFlat that can help here - I don't suggest that you use it as a replacement for Flats as good Flats can transform an image but I thought you might like to see what it looks like applied to your image with a little Curves adjustment afterwards:-

Looks great, much better than the original, seems like the ''synthetic'' flats also allowed for more stretching given that you have more nebulosity than my image. I'll have to play around with making flats to try and make them, I usually just leave the ISO, aperture and optical train the same and just use aperture priority, but this doesn't work well with this lens it seems. Anyway, thanks.

[steppenwolf]

1 hour ago, Desolation4all said:

I usually just leave the ISO, aperture and optical train the same and just use aperture priority, but this doesn't work well with this lens it seems.

Hmmm, that's odd because that is a perfectly adequate way of producing your Flats from a DSLR camera. Certainly worth experimenting further as good Flats maketh a better image.

2 hours ago, Desolation4all said:

Looks great, much better than the original, seems like the ''synthetic'' flats also allowed for more stretching given that you have more nebulosity than my image.

A flat background gives you more headroom for stretching especially if you lock that background at a sensible level and then use 'Curves' to boost the main event.

[Desolation4all]

6 hours ago, steppenwolf said:

Hmmm, that's odd because that is a perfectly adequate way of producing your Flats from a DSLR camera. Certainly worth experimenting further as good Flats maketh a better image.

A flat background gives you more headroom for stretching especially if you lock that background at a sensible level and then use 'Curves' to boost the main event.

I read earlier in a Cloudynights thread on this lens that some other people got headaches too with producing flats, but someone detailed a method of flat frames production that I have tried with some more success (It does not solve the entire problem but it's better). Currently, a version from home made with an Astronomik CLS is in the oven, I already made a greyscale image because I saved the tiff-file wrong and I could not get the colors right. It's about 1.5 hours of 90 second exposures, with 18 darks and 17 new flats. The significantly longer exposures along with the contrast enhancement of the CLS provide a lot more detail, unfortunately, at 2 minutes I saw trailing, so polar alignment needs some work.

[astro mick]

Nic image.

Well done.

Mick.

[Desolation4all]

Thank you Mick.