lots of smaller exposures or longer one on galaxies

[mindburner]

hi

I managerd to get out last night for a few hours and took some images of M101

I tried 3x 15 minute images with darks

the result is below:

I was quite pleased a this sis only my second imaging session and I suffer from bad Light Pollution. I have a Lp filter but it doesn't fit the vixen flip mirror I have as yet.

I wondering is it better to take more shorter exposures to limit noise. If I take less will I not reduce the fainter areas in the galaxy arms?

Here is another of M13

3x 2 minute exposures

It came out with a bit of a bluish tint

[nmoushon]

The data you have looks great. To answer your question longer exposures do allow you to have more detail for that single image than a shorter exposure. But when you start stacking them then its different. The total amount of time stacked will determine the amount of detail you have. In regards to the noise it all depends on what camera you have and its Signal-to-noise ratio.

[JimStan]

It would be great to know which kit you are using to take each picture. I do not find the color shift objectionable , and I can even see a bit of the "Y" that many people report in the core of M13!

Make sure that all three channels are centered on one another, and you shouldn't be having a major problem with shifted colors. See my much smaller avatar, and compare your results with several other M13 photos. I believe that the color is probably very close to what you would see if your eyes were sensitive enough to color at those levels.

Note the little galactic image in the lower left corner of the frame! That is one other thing I like about photography. You often pick up an image you really were NOT expecting to be able to capture, at all !

Jim S.

[mindburner]

hi, sorry should have stated this in the OP. I have a Medae 127APO, on NEQ6, guided with a ST80/QHY5/PHD/combo.

The mount is controlled via EQmod which is wonderful

The camera is an unmodded Nikon D5000 (and camera control pro software) attached with a vixen flip mirror. The use the other flip mirror port to align the scope. It's good because I can get a bit of visual on the side. Like with m13 I could see the stars nicely, not as good as my 12 inch dob but still nice. Then just flip up for imaging.

Yes I loved the little galaxy? possibly in the image. I tried on-line to find out what it was but not had any luck.

[mindburner]

The data you have looks great. To answer your question longer exposures do allow you to have more detail for that single image than a shorter exposure. But when you start stacking them then its different. The total amount of time stacked will determine the amount of detail you have. In regards to the noise it all depends on what camera you have and its Signal-to-noise ratio.

thanks for that. Yes I noticed with m13 that less was more. Longer exposures tended to bloat out the stars but 1-2 minutes seemed good. I only took a couple as it was end of the night, and I had to bring the NEQ6 etc. indoors.

[JimStan]

TheSky 6 identifies it as IC 4617, a 15.2 magnitude galaxy with a visible size of 1.2 by 0.4 arc minutes . That's pretty small, and pretty dim! Nice catch !

JimS.

[mindburner]

TheSky 6 identifies it as IC 4617, a 15.2 magnitude galaxy with a visible size of 1.2 by 0.4 arc minutes . That's pretty small, and pretty dim! Nice catch !

JimS.

Nice one!

15.2 mag. I was going to crop it out, but very glad now I didn't

It just blows me away each time I see any astro images. I have to pinch myself & realise what I am actually seeing. My partner just goes, very nice dear:)

[sologuitarist61]

Nice one!

15.2 mag. I was going to crop it out, but very glad now I didn't

It just blows me away each time I see any astro images. I have to pinch myself & realise what I am actually seeing. My partner just goes, very nice dear:)

Am I lucky I wonder that my partner is almost as interested as I am? My boy is also into it as well. Now thinking of moving so that I get a better night sky when clear.

[mindburner]

Am I lucky I wonder that my partner is almost as interested as I am? My boy is also into it as well. Now thinking of moving so that I get a better night sky when clear.

I hope my little boy will get into it. At the moment he is too young and just likes to swing off the tripod and handset

[sologuitarist61]

I think the thing with all children is make it fun and don't be too strict on doing it the right way.

I remember that I was keen on gardening as a small boy, but Dad was always going on about doing it his way, 'don't plant that there' and so on and it put me off completely.

If they don't want to look at what you show them, let them decide on where to look, just stand aside and give words of encouragement whilst keeping a close eye on all that expensive equipment!!

[nmoushon]

thanks for that. Yes I noticed with m13 that less was more. Longer exposures tended to bloat out the stars but 1-2 minutes seemed good. I only took a couple as it was end of the night, and I had to bring the NEQ6 etc. indoors.

Thats exactly what you needed to do! Especially with star clusters you will want to shorten your subs so you dont blow out the stars and they turn to blurry blobs. You even got to watch when you get to HDR object like M42 and objects like Rosetta Nebula where theres the faint nebula but theres the bright small open cluster at the core. But the fun is in the challenge.

[mindburner]

Thats exactly what you needed to do! Especially with star clusters you will want to shorten your subs so you dont blow out the stars and they turn to blurry blobs. You even got to watch when you get to HDR object like M42 and objects like Rosetta Nebula where theres the faint nebula but theres the bright small open cluster at the core. But the fun is in the challenge.

that's good advice. I noticed in some of the hubble type images in m13 that there are quite a few yellow stars in the cluster. It would be nice to pick out some of these, but I am probably way off on this.

For m42 I found that about 1-2 minutes was about right, otherwise the core was obliterated. I must say that I am really starting to enjoy the scope and mount and learning so much along the way

[nmoushon]

M42 is a bit different. It is an object with high dynamic range so you actually need to combine multiple exposure times to get to faint detail of the outer nebula without blowing the core. Then you get to do layer masks in PS or GIMP to get it just right.

But I noticed the yellow stars in HST images too before. I'm not sure what you have to do to really enhance star color. That I have no experience in and would like to find out how. I think I remember reading something somewhere that theres a couple different programs/plug-ins that help with that, but not sure.