MartinB

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!!

The results are in! https://stargazerslounge.com/topic/403904-sgl-2022-challenge-9-ceph-and-cass/

This challenge has produced a wonderful range of images, from wide expanses of dusty space to close up emission nebulae. As usual the standard has been exceptionally high giving us the usual judging headache. It always feels unpleasant to be limited to 3 winners but for good or ill we have made our selection. 1) AbsolutelyN - LDN 1251 This image has a real sense of depth. Superbly processed 2) Fegato - VdB152, Barnard 175, SNR110.3 + 11.3, Dengel-Hartl5 planetary nebula This image epitomises what is so special about this area of sky. Here we have dark, reflection and emission nebulosity superbly pulled together to make a stunning picture 3) Lee-P - The Elephant's Trunk Nebula As expected, there were some superb emission nebula images. This version of the Elephant's Trunk manages to to be impactful whilst avoiding appearing over processed.

There are so many variables it isn't really possible to use it to compare the 2 scopes, or the 2 cameras. Both cracking images though!

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

This challenge requires you to capture a constellation in its entirety (check your star chart). The choice of constellation and the field of view is entirely up to you. Widefield landscape images will be accepted. Landscape features and deep sky nebulosity may add to the image but we will primarily be judging the quality of the presentation of the constellation. If any of you have any queries please don't hesitate to contact me via pm Start date: 1st December 2022 End date: 28th February 2023 No entries will be accepted after this date 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 start a new topic for each entry. Multiple submissions of the same image, processed differently, will not be accepted. -- To enter please post within this topic, do not start a new topic. Please post as much information as possible - when it was taken, how it was captured and processed, etc. The info won't necessarily be used for judging but will help fellow SGLers looking to learn and improve their knowledge and technique. Please do not post responses to entries since this clutters up the thread, emojis are very welcome however.

The results are in! https://stargazerslounge.com/topic/402768-sgl-2022-challenge-8-pick-a-planet/

It has been a great period for planetary imagers as has been demonstrated by the stunning images entries into this challenge. Solar system imaging challenges always come up against the problem of an unlevel playing field. The higher in the sky the target the less the atmospheric disturbance. This tends to make things more challenging for imagers at higher latitudes. To allow for this we have an overall first place regardless of latitude and then a 1,2,3 for imagers based at 50 degrees and above. The challenge has been difficult to judge with opinions divided, partly because of the sheer variety of images. The star of the show has been jupiter with animations, transits, and the GRS. Saturn has also made a good showing. Mars is always challneging because of its small size and we have taken this into account. First overall Astrovani - Saturn Vani also produced some stunning Jupiter imagers but we kept coming back to this beautifully captured and processed Saturn, complete with moons. Northern latitude (50 degrees and higher) results. 1) Geof Lewis Jupiter animation A very effective animation with superb underlying detail. 2) Kon - Mars Small but perfectly produced 3) Neil Phillips - Jupiter A superb Jupiter which could so easily have taken first place Well done to everyone who has submitted entries. It is well worth having a look through the challenge thread, I am sure you will come up with a different set of winners! https://stargazerslounge.com/topic/397715-sgl-2022-challenge-8-pick-a-planet/

Ah yes, lovely. I can take my sun glasses off now! That has a much greater sense of depth

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

For this challenge we are looking for the presence of dust illuminated by a nearby star(s), reflection nebulosity. There are some "celebrity" targets but plenty of others a little off the beaten track. Of course there may be other elements included in the image which enhance the overall picture but the reflection should be a key feature. IFN, although technically reflection nebulosity is excluded from this challenge, maybe another time! Please include details of equipment used and other capture information. Start date 1st November 2022 End date 31st January 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.

Thanks Olly, it is quite an untidy bit of sky isn't it?

Thanks Sturf. The trouble is there isn't a right or a wrong way! The main thing is to avoid artefacts I suppose.

It's a busy bit of sky, Unfortunately I had to chop half the "Phantom of the Opera's" head off!

I actually imaged this bit of sky 12 months ago, processed it and couldn't get myself excited. As a target it seemed more Jackson Pollack than Rembrandt! Anyway, I rediscovered the calibrated masters in the depths of my portable hard drive and decided to have another try but putting in a bit more care and attention. Scope: Tak FSQ 106 with 0.73 reducer Camera: ZWO 1600mm pro with Baader 7nm filters - Ha, OIII, SII HST I've no idea about overall exposure time. 5min subs 120 gain (?) Processed in PI and PS Second time around I'm a bit happier with it.

Certainly a sinisiter image! Mono really works nicely because of the enhanced contrast.

The wide field view has certainly given Gandalf space to relax. Excellent image

Very nice Alan, the dust is showing well. As for separating the stars, if you have PI, PS or Affinity Photo you can use Russ Croman's StarXterminator. It costs a few bob but well worth it. Alternatively Starnet2 is also brilliant. They are easy tools to use.

That wizard looks great sat there putting his feet up! Very nice

Oh well done with this untracked image! Some nice reflection nebulosity starting to appear as well

Excellent Steve, very detailed but looks smooth and natural

Too absolute beauties, superbly processed. Just about the wettest place in the country. I once had a look at cloud data across the world and discovered that the UK is the cloudiest of the lot, except for a small island in the south atlantic. So well done indeed! It looks like you have a decent sky when the clouds do clear though.

Very nicely detailed dust regions so the long exposure time has certainly paid off. Great work!

Colour wise probably somewhere in between. The ha regions have come through nicely. Beautifully detailed dust lanes