M7 is an open cluster of stars in the constellation of Scorpius, easily detectable with the naked eye from a dark sky location. M7 has been known since antiquity, being first recorded by the 1st-century Greek-Roman astronomer Ptolemy, who described it as a nebula in 130 AD.
This image however was captured on Wednesday night (31 July) with my Vixen VC200L (with f6.4 reducer) and an astro-modded Canon 1000D
60 x 2min dithered and calibrated subs at ISO1600. Processed with PixInsight 1.8
POW! This image delivers an abrupt wake up call. Excellent work Richard, you certainly got the message across. The open cluster is beautifully rendered against the golden star cloud backdrop. Well done. More please.
Thanks for the nice comments everyone. Agree that colours are kinda 'IN YOUR FACE!!" but does give it a bit more "punch" which I quite like here.
Quote:
Originally Posted by rcheshire
Out of curiosity, would like to see the result at iso 800 or 400 with longer integration time.
From a full well perspective that would have no effect. 2mins at ISO1600 uses up just as much of the well as 4mins at ISO800, as the gain is double at ISO1600. So no improvement from a star colour perspective there.
I did a little experiment a month or so ago with this camera to establish the relative SNR of different ISO and sub durations. ISO1600 comes out ahead of ISO400 and ISO800 for all of the sub durations tested (see attached). I used 2min subs for this image as a) I already had a dark master at this sub length, and b) it would give me lots of subs for the total integration time, and as the subs were dithered it would help to further improve SNR. I also left the scope unattended during this run, so I wanted to ensure I would have as many useable subs as possible (and in the end, i used all of them). FYI I have not actually applied any noise reduction to the image in the original post.
also, based in this experiment, I am now using ISO1600 for all targets now with this camera.
Richard, your photo is absolutely very nice. Color, star shape, sharp, focus, field. And with a DSLR.
As you ask for comments, I always shoot star clusters and some people ask me about sensibility (high ISO or long exposure) when the cluster vanishes beneath other stars in the field.
M7 is well because the main stars have high luminosity, but with others cluster this is a matter to care.
Globular cluster is another very difficult. Normally the core can suffer saturation.
M7 is an open cluster of stars in the constellation of Scorpius, easily detectable with the naked eye from a dark sky location. M7 has been known since antiquity, being first recorded by the 1st-century Greek-Roman astronomer Ptolemy, who described it as a nebula in 130 AD.
This image however was captured on Wednesday night (31 July) with my Vixen VC200L (with f6.4 reducer) and an astro-modded Canon 1000D
60 x 2min dithered and calibrated subs at ISO1600. Processed with PixInsight 1.8
Nice Richard, this is on my list of objects to get imaged. I was just looking at this object last night and working out which orientation I wanted. There are a few dark nebula nearby and worth incorporating into this fine image. I like the saturation. Maybe just ease back on the cyan in the blue stars, but that is personal preference.
where's the comparison with my image 
