david_taurus83

The EQ6 range of mounts from SW are very good for the money but from my experience, when I started out and had access to a dark site, it gets very mentally tiring when you lug it all out to a dark site, set everything up, get an hour of images until cloud or rain, strip it down back into the boot, and home with little to show. If back garden imaging isn't an option then I would really focus on portability and ease of use.

ASI 2600MC, LP filter (or IR/UV) and a duo-band filter, AM5 mount (yet unproven I believe),an 80mm refractor of your choice and an ASI Air to control it all. Think that would be somewhere near the £5k mark. I really think if you go for a big mount and a big scope you will soon get fed up with it from a portability point of view, unless you are very dedicated and have the time to spend on it away from home until all hours of the morning, and utilise every clear night...

41 minutes ago, Grant said:

The dollar price won’t include 20% U.K. VAT though…

Nor will it probably include the states sales tax. Got stung with that at the tills when I visited some of New Yorks stores!

I was interested in this but if its over £500 then it's too much. Think I'll stick with the AZGti and it's few shortcomings.

Well ita all gone Pete Tong with Green Swamp Server for me. Tried my mini guide scope a few nights ago and wasn't happy with it. At 120mm FL it's too coarse for my liking at over 6"/pp. I went back to an OAG but fitted my as yet unused Starlight Xpress OAG unit. Those of you who are familiar with these will know how solid they are as they are bolted directly to the filter wheel so no thumbscrews to tighten and the prism is nice and big. The issue I found out is the stalk is too long to work with 55mm reducer backpacking as you can't physically get your guide sensor close enough. The remedy? A hacksaw and 10mm shorter! I can now focus my ASI120MM mini at infinity. Happy days! So despite the full moon on Friday night I tried some problem solving. GSS works fine initially with very accurate pointing as usual. Pointed to a star near the equater before the meridian and started a new calibration in PHD. The first 3 attempts below are with GSS.

For whatever reason it just wouldnt calibrate in North/South. Was taking over 20 steps to move North and sometimes wouldn't move at all. At this point I was convinced the mount had some mechanical issues and prob needed backlash or something adjusting out. Fair enough, it's been on the pier for over 6 months so maybe the temperature changes in that time have loosened something. As a sanity check first though, I switched back to EQMod to see if I can replicate the issue.

Spot on first time. What's odd is that the North/South step in EQMod went in the opposite direction to GSS so I don't know what GSS thought it was doing? Yes, I had reverse Dec output after meridian tick in PHD which is required for GSS.

Left the mount guiding in EQMod with PHD's own PPEC algorithm and it returned expected figures for an EQ6 type mount. Took about 15 minutes or so but after a couple of worm cycles it settles down.

I'm a bit disappointed tbh. After working so well out of the box, so to speak, with stock settings, I don't understand why GSS has started to play up? It's almost like even though I had PEC turned off each night, it was still replaying it through the mount as guiding was very erratic. Don't know if I can trust it again unattended? Perhaps keep with EQMod...

2 hours ago, newbie alert said:

I see the 70 has a few improvements on the 60.. I think my 60 is awesome thou.. can't believe how slack those belts were! Shocking

I had to take the hex keys to my CEM25P a few times to adjust things also. Something I expect to on a £££ mount considering what we ask of them. But to see similar issues on their £2.5/£3k+ range put me off them a while ago. When they are good though, they are very good.

Sounds like you want something similar to what I've done. Mini PC and PSU located in my shed and ethernet cable run out to the pier. I have 240v in the shed and run 13.8v out to the PUPB on the scope.

https://stargazerslounge.com/topic/384486-pier-time-today/

2 hours ago, scotty38 said:

Blimey, only just saw this. I assume because you went back to the guide scope it couldn't be tightened up and something had broken?

No nothing broken. The OAG gets close to the pier plate near zenith but I've not had any meridian flips fail but I suppose it's possible there was contact somewhere and possibly loosened it? Or maybe putting on or taking off the TG cover as it's quite heavy? However it's happened, I don't know when so I've been scratching my head for weeks as to why I need to keep doing new PHD calibrations! 

Before I found out it had loosened I had already decided to try a guide scope again as I prefer to use them if possible as can get better guide stars. I don't think I'll image longer than 10 minute subs with the Esprit so hope there's no issues with flexure like I had a year ago or so on another scope. I've drilled and tapped a couple of extra threads into the Esprit finder shoe for better security as it only comes with one. Hoping for a clear night this weekend to test things again.

Hmm...had issues again the other night. Had a look at things again today. This might explain a lot! No idea how or when this happened. I've took out the OAG now and installed my mini guide scope. Hope there's no flexure issues like I had last time I used one.

A 130PDS at 650mm focal length will be too much for a SGP. Even guided it would struggle. Stick to lenses below 300mm or a small scope like a 60mm frac or a Redcat51 etc. 

You might need to change the star size settings in PS2. Have you configured ASPS as well with the required indexes based on the different sensor sizes?

Well, I'm one of the 8% of males that's red/green colour blind so I guess everything is false colour to me! 🙂

Is that a new HEQ5? As already pointed out, may be quite than an older one to start with. My AZEQ6 sounds different to the one I had 3 years ago. I just figured they put different motors in the newer ones.

16 hours ago, vlaiv said:

Yes, really - that is nothing uncommon. Atik has smaller pixels and still some read noise (compared to modern CMOS sensors).

In CCD days - it was not uncommon to use half an hour long narrow band subs because of low LP noise that narrow band filters ensure (they block most of LP spectrum).

Why 25? That number is actually rather arbitrary, but math is rather simple - noise adds like linearly independent vectors - so square root of sum of squares.

We can calculate read noise impact over just having LP noise rather easily and turn it into formula.

Say that read noise is X and that we have some number N (above I used 5 as N - so x5 higher LP noise compared to read noise).

We need to calculate "total" read noise - and that is straight forward

sqrt(X^2 + (N*X)^2) = sqrt(X^2 + N^2*X^2) = sqrt(X^2 * (1+N^2)) = X * sqrt(1+N^2)

Total noise will be X * sqrt(1+N^2) while increase over just LP noise will be X * sqrt(1+N^2) / X*N (total divide with just LP) or

sqrt(1+N^2) / N

Plugging in number will tell you how much higher resulting number will be, let's do it for some numbers like 1,2,3,4,5,6 to see what happens:

1 : sqrt(1+1) / 1 = sqrt(2) = 1.414... = 41.4% increase

2: sqrt(1+4)/2 = sqrt(5)/2 = 1.118... = 11.8% increase

3: sqrt(1+9)/3 = sqrt(10)/3 = 1.0541.... = 5.41% increase

4: sqrt(1+16)/4 = sqrt(17)/4 = 1.0308... = 3.08% increase

5: sqrt(1+25)/5 = sqrt(26)/5 = 1.0198... = 1.98% increase

6: sqrt(1+36)/6 = sqrt(37)/6 = 1.0138... = 1.38% increase

So you see you can use any of above numbers if you accept certain increase in noise over just having LP noise (above are increases over perfect camera with 0 read noise).

Similarly to imaging time - at some point you enter domain of diminishing returns.

There is very small improvement between 5 and 6 (which is quite a bit longer sub as sub duration is related to square of this number 36/25 = 1.44 or 44% increase in sub duration) and there is question if it is forth it.

Some people are ok with ~5.5% increase - and use x3 rule instead of x5 rule. I like to use x5 rule - but again - if you can't make your subs lone enough - don't sweat it, use as long as sensible, and make up small SNR loss by adding few more subs to stack (if you really need to).

I just don't understand the obsession with focusing on the background levels with little signal. If I'm imaging with an Ha filter I'm after that signal. I don't care what the background is doing. Noise can be dealt with in processing. If I took 1 hour long subs the stars would be big and bloated and the image would probably look washed out. Think I'll stick to 10 minutes!

@vlaiv I just ran some recent Atik 460 data through that handy formula above. LRGB were 300s subs and Ha was 600s.

If ive done it right, it says my L subs should only be 235s, R subs 1380s, G subs 308s and B subs 631s. The deal breaker for me is the Ha. Median background value of 350 ADU so 94.5e

25x(5e²) = 625 so 625/94.5 = 6.613 

So 600s x 6.613 = 3968s subs needed. Really? Where does the 25xRN come from btw? Why 25?

What measurement was the Dec axis?

I would say to hold on for the 533 mono. Its 14 bit, similar size to the 460/490 so can still use your 1.25" filters, and no amp glow. I'm considering it myself but I do like my 460. Not sure if it's an upgrade, only newer. Atik are releasing their APX26 soon but expect it to be closer to an eye watering £3000 than its Chinese equivalents. 

On 27/03/2022 at 11:01, Stuart1971 said:

So how does it know the worm period for the attached mount…? And have you tried running this alongside the GSS PPEC, or,is that not possible, I thought I read somewhere this can be done…🤔

No idea how it knows but that 477s looks correct. Perhaps an index encoded somewhere? My guiding got worse as the night went on after the above screenshot..

Anyway, I had a look at things again last night. Left PHD looping frames at Dec 0° and there was a noticeable drift. Checked polar alignment, azimuth was spot on still but altitude was 4 minutes off. Should have realised it would need checking after mounting the Esprit. Set PHD back to hysteresis, redone calibration and PEC trained again. All seemed well for the couple of hours I was imaging last night. 

Not sure if this has been posted up but, wow! How clear is this from a C11 I believe. I seen another article somewhere and it's pointed out that 2 astronauts can be seen on a spacewalk on one of the stacked images!

If it was working fine before I would suggest updating NINA. Current nightly version is 056 and you have 045 in those screenshots.

Trouble as in dust particles don't line up or the stacking software says they are not the same pixel count?

Anyway, I'm having a few calibration issues myself with darks so I've shot a new set by using NINA. Prob best to use the same software and drivers for everything. 

2 hours ago, geordie85 said:

The stacked image is 196 lights taken over 2 nights. It's the same even if I just stack 1 nights worth of data.

Have you got Pixinsight? You could Blink through all the light frames and see if the circles stay in the same place. 

The big one looks like it's in an inverted position on the calibrated light stack. If it's bottom right on the flat, it also looks like it's top left on the stack. I would inspect all your lights and see if something has been flipped around or inverted for whatever reason.

4 minutes ago, wimvb said:

You made the right decision to use short exposures. Since the jet is very close to the core of M87, longer exposures will drown it in the light from the core. Last year I managed to capture it with 150 s exposures at 0 gain through a red filter (to increase contrast).

https://www.astrobin.com/7oj8y8/B/

Oh I like that! 

Thanks guys for the feedback! I was thinking of things to do when the moon is out and this was on the list. There's loads to do like clusters and interesting objects like this. Never waste a clear night!

11 minutes ago, Stuart1971 said:

I would like to try the PHD pec, but not sure what setting I need to fill in to it…🤔 as I think it requires worm wheel cycle time or something….

It works it out itself. I'm sure these are the default settings straight out of PHD.