Expectations from a second night

[AlistairW]

Hello,

Second proper night for me on my imaging rig. I am thinking I concentrate on the Cluster on Hercules and see how I can improve on it each night. So using the equipment in my signature below I did these:

15 Lights 300s ISO 800

15 Darks 300s ISO 800

30 Bias 1/4000th of a second

20 Flats ... using a setting in Backyard EOS called AV Flat. Same orientation\focus position on camera, with a T-shirt over the dew shield, and a laptop on max brightness with notepad open.

Yesterday I had some great info in this forum on using the Bhatinov Mask (which I have , and used last night) and Bhatinov grabber. I managed to get the critical focus and it looked perfect to me. I did this all on Vega, which was a bright object near Hercules. (Focus did ever so slightly change when the tension screw was done up).

I used PHD2 guiding and that worked fine on a star with a Signal to Noise of 20-30. Never dropped tracking, though the graphs of DEC and RA looked choppy, but I was dithering. Still not sure how to interpret these at the moment.

Then I stacked in DSS using recommended settings.

Then I used Photoshop to do a stretch and curves, and finally saved as a jpeg.

Please remember this is only the second real session I have had (mainly due to UK weather) after putting all this rig together and much reading of these forums, and the bible Making Every Photon Count.

So I have attached my second attempt at Hercules, but I am not really sure what my expectation with this kit is , I know I have countless more things to learn. But this is a non cropped jpeg of the .tiff I created. I am happy with my progress, but what would be a reasonable goal ? Should I be able to crop this image to display only the cluster ? - I did try that but stars started to look bloated.

Think I still have a lot to learn. But if I know what is achievable then I feel I will know what I need to ask.

All comments and help much appreciated.

Thanks

Alistair

[xtreemchaos]

thats a lovely image mate, great widefield shot,well done.   thanks for sharing   charl

[michael.h.f.wilkinson]

Very nice M13. You caught the galaxy nearby as well (NGC 6217 if I remember correctly)

[michael.h.f.wilkinson]

Make that NGC 6207.

[AlistairW]

Thanks for the comments. One question i do have is how much should i be able to crop the photo and maintain a fair degree of accuracy in the resulting image ?

[alan4908]

Hi Alistair

To me this image looks very good. I have only recently started guiding with dithering and I also find it difficult to quantify the guiding tracking error graph, eg I'd like a methodology to distinguish between good and excellent guiding. Personally, I've found manual focussing to be the most challenging aspect of imaging but you seem to have a obtained a good result here. I've recently made the transition to automated focussing which uses a minimum in the FWHM to determine optimum focus. If the seeing was constant, I was thinking that perhaps the best way to quantify the focus/guiding for a particular image would be to measure to FWHM and roundness of the stars in the resultant stacked image?

Alan

[laudropb]

Very nice image. Thanks for posting.

[glowingturnip]

for a 2nd image that's really good - very good guiding, good focus, you should definitely be proud with that, I would be. 

You could try playing with the colour saturation too, should be able to get a bit of star colour showing from that (in photoshop, duplicate a layer, change the blend mode of the top layer to 'color' (sic), and start increasing the saturation - lots of small increases in satn are better than one big one.  Maybe mask it for the stars only if it starts doing unsavoury things to the background).

Playing devil's advocate, a bit of deconvolution would give you nice sharp stars and let you go closer, but Photoshop doesn't have deconvolution...

[Jimtom]

Looks like you're well on the way there Alistair. Tracking and guiding are spot on. M13 was my first imaging target but that was long ago, I'm now much more experienced than you with 4 imaging nights but I've still to get more than  half decent 20 second plus shots. Well done.