MartinB

This is a great image which for me is somewhat marred by the green. I don't have much of a problem with the burnt out core, it is a high dynamic range target and I dislike images which take the brightness and energy out ot the trapezium area for the sake of showing four small stars. It is the impact of the stars which helps make this a wonderful object, not the stars themselves. I couldn't resist having a look at the image without the green and have attached the result.

This is a wonderful image Emil. I like the fact that the full view image hasn't had the glow of the trapezium completely eliminated. The saturation is probably quite high for some but that is purely a matter of personal taste.

Happy New Year! Sorry this challenge is a little late arriving but I have been otherwise engaged! Even experienced Lunar observers can still get goosebumps when they view the moon at high magnification. It looks tantalisingly close, as if you could step onto the surface. This challenge is to create this sensation in an image. So we are looking for close up images of the lunar surface. There are lots of distinctive features worth targeting and then there are curious features created when the suns light hits the surface from a certain angle, the Lunar X being a classic. If you have any queries about the challenge please contact me via PM rather than from within this thread. Please provide information regarding how you went about capturing your image including equipment used. Start date 3rd January 2023 End date 31st March 2023 No entries will be accepted after this date. As previously the winner and runners up will receive an SGL challenge mug showing their image along with a virtual medal-of-honour for their SGL signature. Please post entries directly into this thread To keep the thread manageable for the judges please do not post comments about entries, emoji reactions are welcome of course. -- RULES All data must be captured and processed by you (no collaborative entries). Data must be captured during the challenge start & end dates. Multiple entries are allowed but please make a fresh post within the thread. Multiple submissions of the same image, processed differently, will not be accepted.

The challenge is now closed. The results will be announced within the next 2 weeks.

But an achromatic is light and easy to mount. They can work well through RGB and narrow band filters.

Have you tried PI's photometric colour calibration routine? It is very impressive.

That's a great M31 and you have picked up the outer halo very nicely.

You've picked up the dust in this nebula very nicely with your 40 hours of data. To my eyes I think it would look better if it had a bit less of a stretch so that it was toned down a little.

It looks like you've got some decent detail in the galaxy but the colour scheme is a little strange

Lovely colours in those stars Steve, the cluster looks just right, not over pushed

Yes! So easy as well

Well done Andy, especially given the difficult circumstances. It has a tint of the dreaded green which is, to my eye, just distracting a little from the overall appearance

You are well off the beaten track with this one STu. It's looking great.

Ooh that's one big project an what a gorgeous result! Fabulous image. Y ou mentioned noise. Have you tried Russ Croman's NoiseXterminator? I have found it to be a real game changer

Beautiful James. I didn't know about BlurXterminator, I shall add it to my other Xterminators. This is a very "less is more" process and works very well. I see you have left the sky quite bright which, in a way, adds to the ethereal loveliness! I hate capturing and love processing!

Nicely framed. The Mono does helpto show all the finer details. Great work!

Crikey, that's a busy bit of sky. I love those velvety black areas. Excellent!

Very nice widefield Stu. You've also got the "Phantom of the Opera" nebula.

" but the dust is starting to appear" 😂 That is something of an understatement!! To my eye the dust is better rendered in the first image with a nice sense of depth but the second on allows the NGC to come through a little bit more.

That's beautiful Jody. I love that transition between the reflection nebulosity and the less illuminated dust. Very impressive. It looks like you have a dark sky

Nice work Steve on a rarely imaged target. I've certainly never done it. Are you going to add in some OIII?

A lovely rendition Paul and nice HDR processing. I noticed quite a high level of green in the background which was also creeping into the trapezium area. I applied a correction using HLVG in PS

That's a beauty Andy. The Ha regions look superb. The faint outer regions of M33are always difficult to handle and you've done a great job except there is a slightly smeared look from noise reduction. Have you tried Russ Croman's NoiseXterminator? It is brilliant and is available for PI as a plug in for a moderate fee.

That looks great to me Stu. A little bit of background Ha in there as well.

You are asking 2 very good questions! 1) What total exposure time should I aim for. Olly has explained this perfectly. I think what nearly all of us have done over the years is start with relatively small amounts of data. Doing this on the typical A-list celebrity targets such as M42 and M31 will show the bright parts of the target very nicely but you will discover that the fainter outer regions are very noisy. You will then decide at a later date that you want to revisit this target and "go deeper" by making those dim areas smoother. So, save your existing data so that you can add to it in the future. 2) What parameters should I use for my sub exposures. When you combine sub exposures the signal noise reduction is directly related to the overall exposure time. It is reduced by by the stacking process in exactly the same way as if you had taken one long exposure. However, there is another kind of noise which arises when the voltage information from the pixels in the camera chip is converted to digital pixel value. This is called read noise and isn't eliminated by stacking. Fortunately, the background sky glow will blot out the read noise provided the sub exposure is long enough. Read noise is a serious issue with CCD chips where all pixels are read by a single analogue to digital converter. CMOS cameras (like all DSLRs these days) have lots of analogue to digital converters so the read process is quicker and consequently there is much lower read noise. If you increase the iso you further decrease the read noise but at the expense of dynamic range. The key message is that the quality of your data is dependant on the number of photons being captured by your chip. The ISO has no impact on this. Unless you have a very dark sky, with less sky glow to mask out the read noise, it is likely that 1 minute subs at iso 400 will be a good choice. Obviously you can experiment. The lower the iso the greater the processing headroom you give yourself. So, enough waffle, try this - 60 second subs, iso 400, total subs 60. That's one hour of total data. That should give you something to enjoy!!