Lee_P

10 hours ago, Elp said:

Yes but I suspect they draw a lot of amps and not necessarily in a controlled manner. You'll immediately know by switching your setup on and removing them to see if you get the issue, can try this during the day, have your cameras cooling and running, mount tracking etc to replicate night time use.

Definitely not dew heaters. I removed them from the equation entirely but the fault remains.

1 minute ago, Elp said:

Yes but I suspect they draw a lot of amps and not necessarily in a controlled manner. You'll immediately know by switching your setup on and removing them to see if you get the issue, can try this during the day, have your cameras cooling and running, mount tracking etc to replicate night time use.

Yes, this is a good idea. Thanks. I've actually been running things all day and it's been fine. Intermittent issues are the worst 😅

3 minutes ago, Elp said:

Early on I knew not to use dew heaters with the airs, you only have to use them with their own batteries to know how power hungry they are, I can power my whole setup without dew heaters using one battery whilst if the single dew heater were to use the same battery will drain the same amount of power in the same operating time if not quicker. Don't discount their internal structure breaking down either, it is a heating element after all even though relatively low power. Not all dew heaters are built equally either, some are less efficient than others I've found.

Note that I use mains power, so am not bothered at the prospect of dew heaters being power hungry.

6 minutes ago, Fegato said:

Strange to call that a quad filter, as that bandpass is more like a LP filter than quad narrowband. It doesn’t seem that different to the L-Pro.

Do you know how they are marketing it?

I thought that too. I did ask, but they said that more info is coming tomorrow.

1 minute ago, Stuart1971 said:

Looking at that I would suspect it’s the draw of the dew heaters, hence the intermittent issues, when they kick in they can take power from elsewhere and cause disconnects, can you not put those on a separate supply…?

Well I'm sure I could if necessary -- but I've been using the dew heaters like this for years and they've never caused any issues, so I'm not sure they're the culprit. But I'll certainly add them to the suspect list 😂

7 minutes ago, Elp said:

Regarding 12v cables you need to make sure they're the 5.5 x 2.1 type, I was getting asiair restarts using the larger type as its seating in the 12v in could be prone to lateral movement either directly or when the setup was slewing.

Also check your total power draw hasn't changed, you can see this in the asiair power output window with the plus but I don't know how accurate it is. In the earlier days once I had all autoguiding setup the first few sessions setup was fine and the moment I went indoors I'd go back out to find my 183 had disconnected. I narrowed it down to the WiFi extender I was using at the time (with the pro) drawing too much amps via the usb power, also why I don't run dew heaters via the air as they're the most power hungry out the lot.

I think I'm ok on that front. Everything's been fine with this kit for literally years, so it's a head-scratcher for sure. 

6 minutes ago, Stuart1971 said:

So the next thing is to try the set up on a PC and not the ASIair to rule that out…👍🏻

Yep, the trouble there is that I use my ASIAIR as a power hub as well. So it's a bit tricky. But it's getting to that stage.

It actually all ran fine last night. My ASIAIR has two USB3 ports -- one for the camera, one for the flash drive. I swapped these around, in case the physical port is dodgy. It all worked fine -- but this problem is intermittent, so I want lots more flawless nights before I can say that's the root cause with any confidence.

Optolong will be announcing a new filter tomorrow (10 October 2023): the Optolong L-Quad Enhance. They're sending me one to test, so if anyone's interested I'll write a review once I've given it a good try.

On 08/10/2023 at 09:01, Stuart1971 said:

I assume now you are NOT using any ZWO supplied USB cables as they are complete junk…also have you tried the camera on other software like Sharpcap or NINA on a PC, to rule out the ASIair being the issue…as at the end of the day it’s just an RPI inside and they can fail too…

I thought that the ZWO cables might be the issue, so I swapped them out for new ones. Alas, the problem persists.

19 hours ago, ONIKKINEN said:

Control the setup with something other than the Asiair to close out the possibility of it being the issue. Maybe you have a laptop you could jury rig to take the Asiair's place?

You could also crack out the multimeter and check the power supply, just to be sure it is actually working properly, voltage drops could easily cause weird connectivity issues if they happen.

Yes, good thinking. A friend is coming over today with his multimeter to do just this!

18 hours ago, tomato said:

I change my scope/camera configuration regularly, and I quite often get connection reliability problems when I first start up, but after a few cable unplugs (USB and power) they usually settle down. The one exception is an Atik EFW2 which can take a few sessions before it will connect up reliably. I fix this by connecting the wheel directly to the laptop port (always works) and then working out towards the scope a connection at a time. I am putting this down to the USB connections starting to become worn but who knows?

Dodgy USB connections could explain it...

12 hours ago, GoldTop57 said:

Lee I've seen this sort of error because of a loose 12v barrel connection to the Asiair, you might be able to replicate it by giving the barrel a very light tap with your finger. To mitigate this I bought a Lynx Astro power cable which has quite a snug barrel connection and then use velcro ties to ensure there is no cable snag on the power cable when slewing.

The barrel connection to the ASIAIR isn't the best. A light tap does knock the power out -- but entirely, rather than reproducing the specific issue I'm having trouble with. I wrap the cable (Lynx Astro!) around the OTA's tube ring locking screw to take the strain off, and am looking into getting some extra custom support 3D printed. I'd be interested to see your Velcro tie solution, if you've time to post a photo.

12 hours ago, GoldTop57 said:

Sorry just re-read your post - could the power connector to the camera be loose?

A good idea, but I've checked and rechecked. All fine. Even tried new power cables.

Hi SGL Hive Mind, I've run into a tricky tech issue and would appreciate some advice!

I'm getting error messages about my camera (2600MC) failing; and my EAF dropping out too. I'm using an ASIAIR Plus to control things. I run my EAF through the camera's hub, so I think this points to the camera being the source issue, but don't want to make any assumptions. The problem is intermittent - every other night approximately, and could occur at any point during an imaging run. I've swapped out USB cables and the black power cables, but this hasn't fixed it. My guidecam is also being run through the ASIAIR and is working perfectly. I'm using a Nevada PS-08 6-8A Regulated Linear Power Supply. Everything's run fine for more than a year and I didn't change anything prior to this issue. Any ideas what could be causing this?
 

Looks great, goob job!

Thanks for posting this image, I've just been using it to help frame my own attempt.

@vlaiv I'd be interested to get your thoughts on this video that just popped up in my feed. It seems that the author is comparing pixel scales and suggesting that the finer pixel scale is better, but there's no mention of matching working resolution to pixel scale 🥴

5 minutes ago, vlaiv said:

Once you measure FWHM - then you have idea what are Goldilocks pixels in above sense - you take FWHM divide that value with 1.6 and this gives you sampling rate you should be aiming for (take that into account and your focal length and /or any focal reducers to get wanted pixel size - then bin accordingly or replace camera if that makes more sense - or as last option - don't bother - if you can live with SNR loss due to over sampling).

 

Ok thanks, I think I'm starting to get it -- slooooowly...

I've taken a friend's data to analyse. Their sampling rate is 1.29"/px. Measured FWHM is 3.255. Divide by 1.6 and we get 2.03"/px. So they're a bit oversampled. But if I bin the data, then the sampling rate is 2.59"/px, so they're a bit undersampled. In this case, to bin or not to bin?

56 minutes ago, vlaiv said:

How did you get that figure? I'm guessing that you took 1000mm of focal length of your scope and you took 3.76um pixel size and you calculated 206.3 * 3.76 / 1000mm = 0.76"/px, right?

👍

Ok, analog / digital is a good way for me to understand it. Converting analog light into digital signal to then process.

Is it accurate to say that sampling rate is a measure of a telescope / camera combination's ability to record detail? And then an image's FWHM indicates how much resolution you've actually recorded? You want the two to match, so to do that you divide FWHM by 1.6, then if necessary bin your data so the sampling rate is close?

Thanks vlaiv, insightful as ever.

1 hour ago, vlaiv said:

To reiterate - arc seconds per pixel that you get for certain focal length and certain pixel size is not directly related to potential resolution. Rather, think of it millimeter scale on your caliper. Machining precision of caliper (how precisely it can physically measure) - that is potential resolution, that is telescope aperture + seeing + mount. It serves you no good to have very fine micrometer scale if your caliper is loose and you can't physically measure precisely enough.

I'm having trouble getting my head around this bit. When I said "potential resolution", I meant if everything were perfect -- my telescope was transported into space, tracking was spot-on, and the optics were flawless. Would I then be able to achieve 0.78"/px?

On 12/09/2021 at 22:46, vlaiv said:

That really depends on scope in question and sky conditions.

In general - I don't think that 1"/px is feasible resolution for most people. 8"+ of aperture, premium mount and those few nights a year when seeing is great - then yes, 1"/px could be pulled off.

I'd say that for most people - it would be somewhere in the middle - 1.5-1.8"/px. If you use small scope - like 4" or less - just go for 2"/px without worrying too much about it.

Resolution of image to some degree depends on scope aperture as well (it sort of goes into the mix).

If you want to know what sort of resolution your setup makes - just take some of your images - stacked data in linear stage before processing and look at FWHM of stars in that image. Divide value with 1.6 - that is resolution you should be aiming for.

If you get that your FWHM is closer to 1.6" - then go for 1"/px, but if it is 3" or more - then 2"/px makes more sense.

I've just come across this post and wonder if I could ask for some clarification. Is my understanding here correct:

I'm using an Askar 130PHQ and a 2600MC camera. This gives the potential resolution of my system as 0.78"/px. However, atmospheric conditions and mount inaccuracies mean that in reality the resolution is lower. To calculate what would be optimal for my equipment and sky conditions, I can take the FWHM of an image fresh from integration and divide by 1.6. (2.94 / 1.6 = 1.84"/px). So, 0.78"/px is definitely oversampled. If I bin2, then the working resolution is 1.56"/px, which is close to 1.84"/px. And as a sense check, it fits the general rule of thumb that between 1 and 2 "/px is usually good working resolution. 

The same idea, using old Askar FRA400 and 2600MC data:

Potential resolution of 1.93"/px. FWHM of 2.24/1.6 = 1.39"/px. No need to bin.

1 hour ago, Roy Foreman said:

40 hrs in 3 weeks. I don't get that much clear sky in an entire year ! Hence I have to grab as much data as possible in a couple of hours.

Nice work and an excellent result. Well done.

We're only 45 miles apart -- surely the weather can't be that different?

59 minutes ago, Ouroboros said:

Wow. That is amazing. Like a breaking wave of surf!   Well done, Lee. You just seem to get better and better. 

Thanks, I try to make each picture better than the last one, but it doesn't always work out that way 😂

4 minutes ago, tooth_dr said:

Lovely Lee, really nicely done.  I'm in the same camp as you, and just image one target when we get a 'clear spell'.  I'm currently trying to stack 46 hours on IC1396 and but after 12 hours of processing in APP the PC crashed.  M2 harddrive glitch, thank God it was recoverable.  How do you stack your large number of files?

I feel your pain. I use PixInsight, and recently was integrating 2100 subframes (102GB) and it failed after 72 hours of number crunching. It was recoverable though. Normally I'm integrating around 600 subframes, and that takes around 12 - 14 hours. So, I start it in the evening and leave it going all night.

8 minutes ago, tomato said:

A great result. I also prefer not to dwell too long on a single target, but if you want a stunning image like this and you are under a city sky, I don’t think you have much choice but to put the hours in.

You could argue a permanent observatory makes more sense in a light polluted location, as it will greatly increase your potential imaging time compared to setting up and taking down each session.

Definitely, I agree. I use a pier, but move the telescope in and out of the shed as needed. So my set-up time is about five minutes. It's like a permanent observatory on a budget! 

2 hours ago, knobby said:

Lee your work from Bortle 8 is amazing, I just wish I could find time to put 40 hours into an image, your efforts really pay off !

Thanks! The trick is to have a quick set-up and pack-down routine, then just get into the habit of imaging at every opportunity. 

59 minutes ago, simmo39 said:

Yep, v nice! but to long on one target for me. Get in and out fast!

Haha, I think of astrophotography as a marathon, but you prefer the sprint approach 👍

Here's The Cygnus Wall, taken using an OSC camera from the centre of Bristol. I collected 18 hours of data using an Optolong L-Ultimate filter for Ha and OIII; 19 hours using an Askar D2 for SII and OIII; and three hours with no filter for the stars and RGB data. So, 40 hours in total. I gave everything a stir in PixInsight to produce this SHO+RGB image. I used an Askar 130PHQ telescope and ZWO ASI2600MC-Pro camera.

Here's another image trying to push what can be done from a city centre with an OSC camera. I used an Optolong L-Ultimate for Ha/OIII; combined with an Askar D2 for SII/OIII; and no filter for colourful stars and RGB data. It's 40 hours of exposure time in total, taken across three weeks. This was the first time I used the PixInsight ScreenStars utility by Bill Blanshan and Mike Cranfield. I found it to be very effective, in conjunction with StarNet2, for removing and later reinserting stars. Imaging details are under the picture, and as ever more info is on my website here. 

* 25 August – 15 September 2023 (three weeks)
* Bristol, UK (Bortle 8 )
* Telescope: Askar 130PHQ Flatfield Astrograph
* Camera: ZWO ASI 2600MC-PRO
* Mount: Sky-Watcher EQ6-R PRO
* Guide: William Optics 50mm Guidescope with 1.25″ RotoLock; ZWO ASI 120MM Mini
* Control: ASIAIR Plus
* Software: PixInsight, Lightroom
* Filters:
– Optolong L-Ultimate (Ha / OIII): 540 x 120 seconds (18 hours)
– Askar Colour Magic D2 (SII / OIII): 570 x 120 seconds (19 hours)
– No filter (RGB): 90 x 120 seconds (3 hours)

Total exposure time: 40 hours

By Lee Pullen

Great, thanks!

Forget "Silver and Gold", this is the "Powerlord Palette"! I like it, and the idea behind it. Bravo.

I like my pictures to be very sharp -- enough to cut your finger on -- although atmospheric limitations mean I tend to overcook sharpening during processing to compensate. In particular, I'm pretty heavy-handed with PixInsight's UnsharpMask. What I'm wondering is, are there any tips or techniques to judge how much to apply? Or how to know if you've gone too far, other than eyeballing it?

For example, I used to apply too much noise reduction. I then picked up a tip from @vlaiv about keeping an eye on the smallest pin-prick stars in an image. If I wipe those out using noise reduction, then I've gone too far. Are there any similar tips for sharpening?