First Light with DGM NBP filter...

[JohnH]

Here is my first go with this filter, I struggled to find the right colour balance I will have to calibrate against a known (white) source in future. Also my alignmenat was way off as this was my first run after the observing session so I had to re-assemble and re-align everythingn...

Here it is - the tranatula - comments on processing with filters welcome. It is 20*3 mins with in camera NR on. I have some hot pixel problems which I do not understand that has prevented me pushing for the faintest details.

[atalas]

Nice detail John!

[iceman (Mike)]

Nice work John, I have the same filter for visual use and think it does a fantastic job, especially for the low price (compared to the much more expensive astronomik OIII/lumicon UHC).

I didn't think anyone used it photographically... will be interesting to see future results!

[Octane (Humayun)]

John,

That looks amazing! Floating green blob in space.

With regards to your hot pixel problem, have you tried taking manual dark frames rather than the in-camera noise reduction?

Regards,
Humayun

[janoskiss (Steve H)]

Beautiful Wizard of Oz / Borg / Matrix Tarantula.
But what amazes me is the striking variety of star colours!

[JohnH]

Originally Posted by Octane

John,

...have you tried taking manual dark frames rather than the in-camera noise reduction?

Regards,
Humayun

Yes -I used to use manual darks exclusively - but then I ran in to issues with amp glow on the longer exposures - in camera NR seems to be much better at removing that. I am unsure as to the source for the hot pixels - they leave little trails on the stack - could be they came from the bias or flat frames rather than the lights. I will have to check. I thought they should be easy to remove as they are a single colour - but I cannot find an easy way to remove them...

Is anyone else imaging with a UHC type filter in line? Am I mad doing this ? Should I use a LPR rather than UHC to ensure more realistic colours?

[Octane (Humayun)]

John,

Were you taking multiple darks and then median combining them? I find that if I take 15-19 dark frames and median combine them, I don't have amp glow issues, and that's with 10-minute sub-exposures, using a Canon EOS-350D.

I'm not entirely sure if the flats, flat darks or offsets are responsible. I guess you could use the healing tool in Photoshop to clone them out. It's a great tool. There's also a hot pixel remover plug-in which I saw somewhere. You might have to Google for it.

Regards,
Humayun

Originally Posted by JohnH

Yes -I used to use manual darks exclusively - but then I ran in to issues with amp glow on the longer exposures - in camera NR seems to be much better at removing that. I am unsure as to the source for the hot pixels - they leave little trails on the stack - could be they came from the bias or flat frames rather than the lights. I will have to check. I thought they should be easy to remove as they are a single colour - but I cannot find an easy way to remove them...

Is anyone else imaging with a UHC type filter in line? Am I mad doing this ? Should I use a LPR rather than UHC to ensure more realistic colours?

[JohnH]

Originally Posted by Octane

John,

Were you taking multiple darks and then median combining them? I find that if I take 15-19 dark frames and median combine them, I don't have amp glow issues, and that's with 10-minute sub-exposures, using a Canon EOS-350D.

Regards,
Humayun

Yes, multiple - but not that many, typically 8 for me, 19*10 mins wow...you do this for each imaging run? What about temp changes? Do you leave your camera outside to collect the darks?

I found my processing error - I used different Bayer conversions between lights and bias (in error) so here is a re-processed result - still very green though...