my first M42

[abhoriel]

I'm really enjoying this hobby.

It was clear last night, so I thought I'd have a go at M42 as everyone seems to do it! In fact, I was planning on imaging Pleiades, but that turned out to be too near the moon which is now pretty bright. Rather than my 200mm prime, I thought I'd try out the old Tamron 500mm f8 mirror lens to get a bit more reach.

Equipment:

• HEQ5 with goto
• EQMOD + cartes du ciel
• Nikon D5100 (unmodified)
• Tamron adaptall 500mm f8 mirror lens
• Unguided, very rough polar alignment

Acquisition:

• 27x60s lights. I use DSS to select the top 80% of these
• 11 darks
• 33 flats
• 57 bias

Processing:

• stretch and levels in photoshop
• remove gradient by duplicating layer, blurring it and then subtracting it from the original
• more stretch and levels
• slight increase in saturation

I had a few issues.. I was struggling to get the focus right (and clearly wasn't particularly successful!). This lens is notoriously had to focus, and my camera was refusing to go into live view mode for some reason, so I ended up focusing as best as I could through the view finder. Also, I actually had the camera piggy backed on an ST80 which I was using for my first attempt at guiding with my new QHY5Lii. I did get guiding working after adjusting the timings in PHD2, but that was after I had acquired this data, and by that time it was pretty late. The stars aren't completed round, the polar align was pretty rough and ready and there was probably some periodic error as I couldnt get the ST80 and camera balanced on the RA axis (which is a long story.. I think I need to buy the ST80 dovetail bar rather than kludging it with the medium dovetail bar that I drilled).

 

I could have done with more subs as well, but time pressures etc.. Also, I haven't fixed the issue with my PC monitor showing things darker than they're supposed to be. This image looks ok on this screen, but the background will probably look too bright on your computers!

 

Anyway.. apologies for the rambling.. I appreciate any and all suggestions

 

[Starlight 1]

This is very good m42 showing good colour plus holding the core down well.

and the runing man is starting to show with nice round Stars you off to a good start, I  am one for useing odd number odd numbers work best. as you done .

[abhoriel]

thanks for your comments! I have been advised on this forum to be careful about blowing out the core in M42, so I had that in mind.

I didn't know that using an odd number of subs works better.. It just turned out that way due to chance I guess!

 

 

[Qwiati]

very nice first M42! good start into imaging - I am sure you will enjoy it

[Starlight 1]

I see you have done"11 darks/ 57 bias there is bias in darks so you are useing them x 2 so try dss again without the Darks .

[alacant]

Hi

Excellent. Better than my first attempt by a long way! I took the blue down a bit:

https://drive.google.com/file/d/0B_uUt0LyuuEdNUN6Q3E2enJoQnc/view?usp=sharing

Cheers and well done.

 

[abhoriel]

9 hours ago, Starlight 1 said:

I see you have done"11 darks/ 57 bias there is bias in darks so you are useing them x 2 so try dss again without the Darks .

So if I use bias frames, I don't need darks? I thought that the darks provide additional information, like amp glow which builds up during long exposure times

48 minutes ago, alacant said:

Hi

Excellent. Better than my first attempt by a long way! I took the blue down a bit:

https://drive.google.com/file/d/0B_uUt0LyuuEdNUN6Q3E2enJoQnc/view?usp=sharing

Cheers and well done.

 

thanks a lot! Yeah I think I do prefer it with the blue reduced a little. I tried to bring out the red a little by increasing the saturation, but maybe made it too blue.

I want to modify my DSLR now.. Its depressing to think that the Ha light has been travelling for 1344 years from M42, just to get stopped by the IR filter in my camera, a millimetre or so from the sensor!

 

[Astrosurf]

Marvellous! I can't see any trailing on the stars.

I thought that if you take darks, then you don't bother with the bias and just use the darks.

Alexxx

[Starlight 1]

4 hours ago, Astrosurf said:

Marvellous! I can't see any trailing on the stars.

I thought that if you take darks, then you don't bother with the bias and just use the darks.

Alexxx

Yes you are right Alex , I keep forgeting that my CCD do not use Darks only Bias for a bad pix map,  so DSLR use darks and forget the bias as it in the Darks all ready .ps 11 darks is to low go for about 20 to 30 darks.

[abhoriel]

yeah doing bias shots is redundant.. thanks guys - that will save me time next time I get clear skies. It might be worth taking dark flats though?

 

[Astrosurf]

OMG, I'm getting confused now!