parallaxerr

Bit of a thread revival, sorry guys! Has anyone heard any more about the AZ5? I recently bought a new SkyWatcher scope from @FLO and the enclosed flyer had a picture of the AZ5 on it, so hopefully it's still in the pipeline. I want an AZ for my ST120, would hate to buy an AZ4 then have this released!

Just looking in the exact same region for tonights target, specifically the Flaming Star. But like you say, camera sensitivity may be an issue. Horsehead is still a tad late at night for me!

I think I agree Ian. I am definitely a black background junkie! What an amazing swathe of stars! I'd like to have a pop at the veil but not sure my camera has the required red response.

Well here it is, my final image of M33 for now. 6hrs 15mins of exposure taken over 3 nights, 28-30/11/2016 from Caerleon, S. Wales. All three sessions were between approximately 18:30-21:30 and 60°-70° alt, so medium light pollution. Usual setup - William Optics Zenithstar 66SD, Celestron Nexstar SE, Nikon D3200. 750x30s subs, 50 flat & 50 dark flat, no darks. Stacked in DSS and processed in Start Tools with final colour tweaks made in Gimp. I see a different colours between 3 monitors and 2 mobile devices, so who knows which one is right!? I'm glad I added the final session as it's helped distinguish star colours in the spiral arms, after 4hrs they all still looked blue but now I see reds too and the core has a slightly warmer colour. All in all, very happy with the result from a very modest imaging setup!

Yep, I get this all the time too. Quotes from others I mean, not myself! Ken, that second image really is brilliant. I just got up close with it and the level of detail gives it some real depth. I hit Triangulum again last night. I realise I need several nights of data now, to get good images, so I thought I'd use the last clear night to wrap up my M33 project. Total integration time is now 6hrs 15mins, if I see a detail increase like I did after the second imaging session, I'll be very happy!

Filter of some sort Ken?

I know what you mean Neil, I can play with colours all day and never quite know what's right. This little tweak seems to have made it pop a bit, a little more representative of other examples I've seen. Deleted the other images from last two posts as not to clutter up the thread.

I tried masking the stars in ST, but changes to the colour also affected M33. Instead, I reduced the red channel luminosity in the shadows with GIMP, which I think has had the desired effect. Quite pleased with this now. Not sure if adding any more data will help?...

Got over 2hrs of good data on M33 last night. Total integration time now 4hrs 15mins. Definitely more detail coming out but hard to balance detail and background noise.

Of course, no live view for you. Just slewed to Mirach and saw a tiny focus shift. Longest time then spent taking 30s exposures to ensure M33's centered. Are triplets more prone to focus shift? I've heard of the pinched optics problem.

Something I've not considered. I set the camera going on M33 an hour ago, better go check I suppose. Will have to goto a bright star which I'm reluctant to do because it's tracking so well, but no point tracking a blur!

I thought lowering the gain would free up more DR as with DSLRs?

No drizzle, but, to be fair that was a mosaic. I wanted to see the extent of the field rotation and have as much area as possible to crop from. EDIT: How strange, I just loaded a standard (not mosaic) stack of the same image, but X2 drizzle @ 1.08Gb into ST in just a few seconds?

Agreed, I for one am going to attempt to stop opening cans of worms and stick to posting my results, as per the original thread intent!

That looks great Ian. I can't comment on what should/shouldn't be there but the detail in the nebulosity is really fine

Good shout. I'm going to re-run the manual dev as I prefer the result. I'll try the life module.

Yes, the whole image is binned 50%.

Wow these images look ropey on my mobile!!!

And here's the AutoDev'd version. Struggling with colour a bit and as you can see, there's more noise... I think I prefer manual Dev, if only I could pull a bit more detail out. Maybe more subs will increase SNR and enable me to do so.

It's only the loading time that's an issue Ken, once ST has it open, processing is quick enough. Strange.

What a difference a few degrees alt makes! OK, more like 35-40°. After imaging M33 between 60-70° last night I came down to take a quick peek at M42 @ approximately 30°, just look at the difference in LP! I know where I'll be imaging in future! Had a super session last night. I ran with M33 for over 3hrs straight. Due to it being relatively small and having a good FOV with my setup, I allowed for a full 90° of field rotation as I can crop it out. I really wanted to see what a good amount of data could show, so far I've been processing mostly around one hours worth of data, but last night I gathered nearly 2hrs of subs. Even better, due to the tweaks to my mount last week, tracking appeared to be vastly improved. DSS only dropped 4 frames so I got 1hr54m out of a possible 1hr56m I plan to do exactly the same tonight, aiming for 4hrs of data on M33. I've just run last nights data through ST to see what's there. I'm experimenting with the differences between AutoDev and manual Dev. AutoDev seems to bring out more data, but more noise along with it, whereas manual is cleaner but detail is subtler. Here's the result of a quick manual Dev, loading the FITS up again for AutoDev now, but it takes about an hour to load in ST @550mb Final point to note - NO DARK FRAMES

I had to take a day off posting in the thread yesterday after my brain melt on Saturday night! The pace that this thread moves at can be really hard to keep up with at times, so thanks to those who commented on my rather long post, it'd be a mission to try to quote them all so I'll summarise my response. It seems my conclusions attract mixed responses, as expected. One thing I note though is that the modus operandi of individuals seems based purely on preference, whether it be with regard to calibration frames or target selection or whatever. Everyone here is producing excellent results using some significantly different approaches and that makes me happy because it means I'm not doing anything hideously wrong! I have gleaned further information from your responses which, whilst adding to the knowledge bank, also adds more...not confusion...but more to compute, perhaps. One plus point that I'm really happy with is that Mr. Stark claims aperture is not all ruling in AP, so I don't have to fret any longer over 66mm apo or 120mm achro!

Hello, Alt/Az’ers, it’s nice to see some of you had a productive evening yesterday. For me, last night was a tale of two halves. I have nothing to show for my efforts, however, I believe I learnt a LOT about my set-up and the direction I need to go in. This may turn out to be a long post so apologies in advance as I’m finding it hard to get all these thoughts straight in my head, but I find sharing my findings here to be rewarding as someone always responds with a little nougat of previously unknown information! So what went wrong? Well....first off, due to it being the first clear night in a while, I thought I’d make the most of it and hit several targets one after another as Alt and/or FOV limits came in to play. First off was M31, then M33, then I decided to have a pop at the horse head. What this meant, was that I never really got enough subs on any of my targets to produce anything decent with. Secondly, I decided to try a change of ISO, choosing 3200 because Sensorgen.info suggests than read noise for my camera drops off at higher ISO. But, and this is a BIG BUT...despite claiming files are recorded in RAW, Nikon apply an internal de-read noise to RAW files. In years past, this process was known as the “Nikon star eater” filter in the AP world, due to the de-noise process mistaking stars for hot-pixels. However, this is reported not to be the case with more recent Nikons. Finally a flat battery! I have previously been impressed with the battery life of my Nikon, but last night it gave up half way through taking darks. I came away with a load of subs on various targets but after inspection, many were binned due to thin cloud and satellite passes and ultimately I did not record enough darks. Moving on.....The good news is that the tweaks I made to the mount and balancing of the OTA has done away with star trailing on the alt axis that I experienced during my last session. So, I decided to process a few images anyway, without flats/dark flats to see what I had and made some pretty important observations, I think. What I learned... ISO - Previous attempts at M31 have been at ISO 1600. On processing in ST, I struggled with a lot of background noise which I thought was LP. As such, I fitted my Baader semi-apo filter (an LPfilter + fringe killer) to try to combat it, however, I don’t think LP was the issue as I saw exactly the same when processing last nights data, in fact worse. As well as a decrease in read noise, higher ISO brings with it reduced saturation capacity and thus dynamic range – I “think” the noise I’m seeing is a result of the noise floor being too high, i.e. the dynamic range being too small. Histograms aren’t clipped but stretching the image brings out terrible grainy red background sky, which, I did not see when imaging M42 at ISO800 where I have a few more stops of DR to play with. So, whilst I’m not saturating the sensor, maybe I’m not allowing enough to capture the full DR of the target and the noise floor is being brought up in ST. Semi-apo filter – If LP isn’t the cause of the background noise then this isn’t going to cure it. Proven last night. With such a small scope I also think cutting any light wavelengths out is counterproductive and the green tint it casts is a pest in colour processing. Dark frames – I don’t think I need them! Darks frames are dark from my DSLR, as in completely black. No noise, not a jot. I have stacked last nights M31, with & without darks and the difference is ZERO. Recent Nikons are famed for very low read noise sensors and the in-built noise-reduction negates the need for me to take dark frames. (Note – there is an option to turn long exposure noise-reduction off, which I have done, but read noise reduction is still applied). There is a Nikon hack program available called “dark current enabler” which does away with the NR, I have tried it and got darks as we’re used to seeing with the purple/red noise, but it’s a PITA to use and requires a PC. But, if the in-built NR isn’t eating stars, then what’s the point anyway? Aperture – I’m struggling with this. Having tried the ST120 a few weeks back, it’s clear it gathers photons far faster than the ZS66 – half the exposure time produced twice the detail on M33, notwithstanding some heavy CA. Exposure time vs CA? On a bit of a lose lose here as far as my available scopes are concerned, but I found the CA objectionable in the achromat – I wonder if reducing the ISO reduces blue bloat? Either way, not having the alt limit (once I get my new intervalometer cable) with the ZS66 is nice and I’ve ordered a second battery for the camera to allow longer sessions...If only the weather would allow. More data is always a plus, regardless of aperture, it’s just going to take me a little longer to gather the photons. So, I feel like I have come to these conclusions (until I have another great learning experience): · Plan imaging sessions better – one target at a time. · Maximum ISO – 800. · Read noise for my camera is irrelevant. · Semi-apo filter is not required. · Don’t waste exposure time on darks. For any of you that have read this far, I thankyou! Maybe this will give others something to think about and please feel free to correct me where I am mistaken, probably everywhere. Jon