pipnina

My Chroma LRGB set arrived a few days ago, and I managed to solve some issues with my coma corrector, so last night was then night to test out LRGB instead of shooting mono only!

Quite pleased with the filter set, since I can't discern any changes in focus between them (very nice since I don't have an autofocuser yet! set and forget has worked so far, fingers crossed)

I did 3 hours of L, plus 45min of R G B each. Having my setup repeat the pattern of 4x L then R G B the whole night (seems to have worked well at keeping the gradients in line with eachother)

Any suggestions for improvement welcome! I think I may need to increase the % of RGB in relation to L, but not sure by how much.

I've been thinking my secondary collimation was wrong for ages, finally spent an afternoon tweaking it and it seems to look good as best as I can tell.

I went to test it by putting my camera back on, putting the cloth over it and pointing it at the sky out of the window to find the vignetting had maybe improved. But I was still seeing it appear brighter on one side than the other (left in landscape, right when I turned the camera 180 degrees!)

I also noticed it was changing based on focus position, weirdly, with the focus wound in it seemed to be worst, while it got better as focus was wound out, FITS files:

Has anyone else noticed this with the 130-PDS? Is this a kind of focuser sag or something to do with the size of the primary changing (from perspective of camera) as focus shifts, or my collimation not being right? I have noticed my Baader MPCC MK3 won't sit completely snugly in the focused (it always has just the smallest amount of play, whatever I do)

I'm a little confused myself as to the exact cause.

Cheers

HALF-WAY.fits ALL-OUT.fits ALL-IN.fits

Sadly the dongle isn't plug-and-play any more, perhaps they changed the chip inside of it at some point without changing the product listing (happens more than we'd like to think...)

I managed to get the driver installed now regardless. I'm going to see if it behaves itself tomorrow when I get home from work.

Thanks for your help guys : D

After Vlaiv and Olly kindly helped me solve my issues with getting flats to behave in DSS, I started realising my flats still weren't right even once they were being handled correctly in software.

Digging into the issue, I realised my 130-PDS was leaking light, and not just by a little, and not just in one place. 10 second exposures in a darkened room (though still daylight, only curtains closed) were enough to reveal notciable patterns of light ingress... AFTER I put two layers of electerical tape over the back of the primary mirror cell!

Several hours later, having taped the seam along the side of the scope, the joint between the rear mirror cell and tube (as well as previous tape over the back of it!), around the join between the focuser and the tube, the joint between the dust cover holder and the tube, and finally between the focuser tube and focuser body, I finally managed to take a 20 minute exposure without noticable light coming through in a bright room. Buit even then, the dust cover turned out to be a major source of light ingress no matter how much I made sure it was on the front securely! I had to cover it up with multiple black t-shirts and fleeces to remove it as a variable...

All in all, my 130-PDS is now more tape than telescope, and I think the images I took on friday during the full moon must have been truly contaminated in a way flats can no longer correct for. Let alone the reduction in ability to focus I now suffer!

This all screams to me that the scope has major quality issues, which I suppose could be expected considering its low price, but many recommend it as a scope for imaging with!

Does anyone else have this problem? Do all newts suffer this problem? How do you guys deal with light ingress during flats/bias/darks? If this is an issue with the scope, (especially the dust cap not sealing light out properly!) i'll be seriously looking at moving to a higher quality optic for my imaging rig : /

3 hours ago, vlaiv said:

Ideally you would want:

lights and matching darks (which you already have) and flats and matching flat darks.

You don't seem to have flat darks - but from what I've seen - your bias subs are in fact of the same exposure as flats, right? That would make them flat darks.

Even if they are not fully matched in exposure length - it is better to use bias as flat darks then to skip them completely.

I thought about how you mentioned the stacking process may be cause, and thought about the settings I could change with regards to it.

Turns out, DSS will butcher flats if I use the median kappa-sigma setting, perhaps it was the normal kappa-sigma I had good results with before and I simply picked the wrong one.

On average stacking for the lights I don't get the banding issue any more, but if I select certain combinations of bias/flatbias or dark frames in my stcaking the flats stop working all-together.

I also need to re-take my flats outside I think. none of the artificial sources I've tried are producing flats that are particularly even.

Thanks for your help!

3 minutes ago, vlaiv said:

Actually - hold on a second.

Did you use same bias you shot for flats - for your lights instead of darks?

If you do that - this happens:

 

Now, I'm not sure if it is down to flats or if it has something to do with bias, but something strange is going on here.

It is not concentric pattern you are getting - but it looks like it might be after stacking - that every sub has some of it and then after stacking multiple concentric rings form instead of just one dark ring.

Ok, so yes - do try dedicated darks so we can see if that is the problem.

My setup in DSS was:
Lights

Bias (600 at the same gain as flats and light)

Flat (50 at same gain as bias and light)

I also have a library of 500 darks at the same exposure as my lights, same gain as all 3 above, same temp on TEC cooler used for all of these frames -5c)

I am stacking the image now with only flats and darks, am I supposed to use all four types of images in one?

4 minutes ago, vlaiv said:

Indeed, it would be good to see both raw light frames and raw calibration frames (one of each - whatever you are using, flats, darks, bias, etc ...).

Image you presented has some clipping so things can't be seen clearly - but it looks like you have some mismatch in your flats - maybe something moved between lights and flats, or you changed focus position.

Here is suspect part of the image

Background appears to have "emboss" effect on it - this usually happens on camera rotation for example or shift of some sorts.

M_81_Light_010.fits

Also yea I am struggling to stop my camera rotating at the moment- the grub screws holding my baader MPCC into the focuser are obscured by the filter wheel. Next time I'll be bringing out the pliers to tighten them much more completely!

I've attached some raw files here if you'd like to have a look yourself (ignore the odd file names, I made mistakes when taking them in Ekos, my flats and bias don't have a 60s exposure time haha)

minus5-60second_Flat_001.fits minus5-60second_Bias_001.fits

5 minutes ago, ollypenrice said:

Is it like this a) in the flats themselves and b) in the stacked lights if you don't apply the flats?

Olly

Here's my stretched flat frame (it's off center, I need to work out my collimation a bit more... it's all tilted correctly, but the secondary is too far into the tube)

Stretched sub

Stretched stacked image without any calibration

I also did a stack which included bias frames but no flats, and it looked the same as the one that used no calibration files at all : /

I got my first light with my RisingCam IMX 571 (aka. alternative ASI 2600mm) mono cam, and although the image below is very impressive for only 20 minutes of data, the flat frames are causing this horrific banding (and to be honest my vignetting is rather harsh, 32000 peak and 14000 minimum when taking flats in my 16-bit capture, owch)

I have put a coat over my prinary mirror cell to stop light ingress, and my optical setup is: a very wide, diffuse, and bright bulb (3300 lumen 5500k colour temp). Followed by two sheets of 80gsm printer paper right up against the telescope aperture, then my Skywatcher 130-PDS, which goes into a Baader MPCC MK3 coma corrector, through an ASI 36mm 7-slot filter wheel (no filters yet) and finally into my RisingCam 571. This effect occured when my histogram peaked at 95% saturation and when it peaked at 50%, both the same pattern and intensity of banding in both versions. I assume it must be something in my optical system since this is the second camera I have seen this effect on : (

My Nikon D3200 had the same effect and I'm pulling my hair out trying to guess why it's doing this! I'm using Deep Sky Stacker 4.2.6, flats set to median mode, lights set to Median Kappa-Sigma, bias frames set to median.

Any help greatly appreciated!

Thanks

1 hour ago, Stuart1971 said:

The one I used was plug and play…link below, it’s gone up a bit in price as I paid £15 about 18 months ago….now it’s £23, there is a “Like new” one available for just over £19 not sure if that just for prime customers or not, look in bottom right of linked page…

https://www.amazon.co.uk/BrosTrend-1200Mbps-Raspbian-raspberry-AC1L/dp/B07FCNP2VL/ref=asc_df_B07FCNP2VL/?tag=googshopuk-21&linkCode=df0&hvadid=310776295886&hvpos=&hvnetw=g&hvrand=11940051960967236863&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9046174&hvtargid=pla-551382897533&psc=1

 

Seems ideal! I picked up a plastic case on there too for my RPI4 for only £8 too.

Turns out taking the metal lid off of the case took me from no to very limited connection to a far far better one, but I'm still having networking issues after a while so maybe this dongle will help.

I can use Ekos/INDI remotely after a while but eventually something goes wrong, control ability stops and the ping (with ping command from my laptop) to the RPi goes from 10-20 to several thousand! hard to say if networking or a blocking process but worth a shot with the dongle anyway.

Many thanks!

12 minutes ago, alacant said:

Nice one:)

I wonder what it is which makes so many struggle with plate solving and computer control software in general? Age? We have a regular visitor who brings along his grandson to hook it all up for him and make the mount move. The boy just gets it.

I think it might be the density of terminology involved, plus knowledge of the coordinate system, hardware capability, software familiarity etc.

I am no computer novice but sometimes computer things simply don't go to plan haha. I'm sure once I've bashed heads with it for long enough I will end up forming a passing agreement with the system however.

1 hour ago, Stuart1971 said:

Good point,

I use a solid metal case, and yes it is an issue for Wi-Fi, but I no longer use the internal Wi-Fi, I use a USB 3.0, 1200mbps version, and it’s flawless…so worth a thought as they are only a tenner…👍🏼

If you can link me to the dongle you're using for your PI I'll be very grateful! There are a lot of ifs and buts when it comes to wifi kit on Linux, was it plug and play or did you need to install some drivers yourself?

Thanks again

4 hours ago, wimvb said:

It’s difficult to diagnose software issues, but start by making sure that at least there are no hardware issues:

power source that can supply at least the requirements (3A I believe)

usb cables that work without a glitch

ethernet cable to your router while testing

I’ve had my fair share of problems with kstars, but mostly while the software was still under initial development. Since the releases are divided into stable and nightly builds, it has become much more reliable. And using an ethernet cable has further improved stability.

28 minutes ago, Stuart1971 said:

Firstly don’t even bother trying to platesolve on Polaris, it just will not work,

Secondly use ASTAP as your platesolve, I never used the internal one so can’t comment on that…ASTAP was always flawless for me, and make sure you install the catalogue file too.

Thirdly, and very important, you need a good solid 4 amp power source for the RPI, this will make a huge difference, if not you will get freezes and more importantly wifi and network connection issues, with lack of power the Wi-Fi and network is the first to suffer.

Next you say the toupcam driver will not run off the laptop but will run off the PI, well all the drivers run off the PI so I am not sure what this means, it makes no difference whether you run Kstars off the laptop or the PI, the indi drivers are running from the indi server on the PI all the time…so there is another issue here, do,you have your laptop Ekos setting set to remote and not to local as this will cause the same issue you are getting.

I suggest for your next trip out, you set your scope in the home position, then power on and start Ekos, your scope crosshairs on the sky map, should be on Polaris, or very close to it, then slew and centre on an object in the east or west, once it’s solved, then right click and sync, then do the same on an object in the opposite side of the sky, and do the same, then you should be good to go to any other object and have good goto accuracy.

Always park your mount at the end of a session, in a pre defined position..

hope this all helps, anything else you need to know give me a shout..👍🏼

 

3 minutes ago, teoria_del_big_bang said:

I would agree with the above comments not to platesolve on Polaris

Also I would be tempted to start off using an ethernet connection if the scope is not too far away from the house, you can get some very long flat cables that can go through very narrow gaps in almost closed windows so n need to leave doors wide open. 
I say this just to eliminate any WIFI issues as they can just add to the frustration, when everything is working then go onto WIFI then and if y=using a RPi I would really recommend using a WIFI dongle, I could never get the RPi internal WIFI to work reliably at all and if it is in a metal case then forget it.

So if all is in place in KStars correctly just select a target on KStars that should be visible, but away from Polaris, and slew to the target then platesolve using ASTAP.

Steve

All very good information! I am going to try my raspberry pi on a fresh install of the software and use my phone's fast charger which I believe supports 5A for the PI, who knows what quality the plug is that came with the pi initially... Also, my PI kit unfortunately came in a metal case, so maybe there are issues there too... That's a hard one to solve quickly sadly.

I did try to plate solve on Procyon and Betelgeuse too, and I had similar issues there. The mount would take its guess at goto-ing to it, and be realtively close (maybe a few deg off) I would click "solve and slew" and it would maybe try to make one correction before it "gave up" (or at least, decided to plate solve where it was already looking...) I'll give the alternative platesolvers a go today!

Now there's also something I did not do... Mount in home position. I believe that is, for the HEQ5, where the telescope is at the top, counterweight underneath, and pointed at DEC 90deg right? So if I allow my mount to park with it in that position (undone clutches while it lets itself think/move?) then lock the clutches and unpark the mount and begin slewing, it should be more reliable?

The last issue is with setting the mount's RA limits properly, but hopefully I can do that in the daytime now.

At least I started having these issues during bright moon!

Many thanks for all of your help, I will try and get these corrections going!

I don't know how many people use Ekos/INDI/Kstars as a software setup but I tried to use it for my now computerised imaging setup tonight for the first time. It has been a disaster.

If i turn all my kit on, and get into the astroberry VNC interface to turn on the INDI server, all is ok so far. I can connect to the INDI server using Kstars. Using the Ekos manager in Kstars I can get the polar alignment feature to work just fine (1m 30sec and 0m 58sec error on alt/az), but the plate solving to center on a target *would not work*

First I actually had to install the astrometry data packs from a download in the Ekos manager, then, while it would detect the telescope's current position correctly, if I slew to a target and asked it to solve and slew, it MIGHT do one iteration of solving to that target (i.e. alt f5, select polaris or select polaris, hit options, and ask to slew) but even if it does, it then changes the object name from "polaris" to "star" and it just stops narrowing down to the correct location.

(example of the area I'm looking at below, but not actual screen cap of what happened tonight)

Also, having sync plate solved the mount to the real position of the telescope, and trying to slew with horizon proection on, even objects at the zenith can cause Kstars or Ekos or whatever it is to think that the mount will collide or point at the ground. I had to turn the safety feature off to get anything done, but that doesn't sound right!

To make matters worse, on my laptop (Ubuntu 18.04) the toupcam INDI driver *will not work*, it just crashes no matter what I do. So I need to run it off of my raspberry pi. Because the raspberry pi's wifi can't reach the house's but my laptop's can, I had to bridge the laptop's wifi to the raspberry pi. Sadly, either this setup isn't agreeable or astroberry OS in general is borked, or my raspberry pi 4 is borked on a hardware level, because periodically Kstars on the RPI will just lock up the whole system and need a reboot. By the end the system didn't even recover from cycling the power.

I'm at my wit's end, what am I doing wrong!?! So many people do this remote astrophotography (or at least lappy controlled astro) with relative ease! Mine refuses to even point at the parts of the sky I ask for...

Any ideas or suggestions for how to fix this mess I've made for myself greatly appreciated and desperately needed!

many thanks

44 minutes ago, Nrmh02 said:

Thanks for your input. It’s very much appreciated 

so currently using mod 600D. 
 

I’ve looked at AliExpress but there’s a lot of fake items etc going though that website so I’d be rather hesitant to spend 1K with little to non cover etc. 

I might take another look though. Thanks 

I just recieved my RisingCam 571 yesterday and got it going very easily (with toupcam drivers, tho it does provide its own in the box) , I ordered mine from ebay and didn't even get any notice of customs charges (yet? do they send that in the post later or does it coming through ebay include that charge somehow?) I'd say it's legit. I have heard good things about this cam from a LOT of sources and so far my own (albeit limited) testing shows it may be true. I get some good weather this weekend according to clearoutside so I am itching to give it a proper test!

8 minutes ago, ollypenrice said:

-snip-

Olly

 

I just got my first cooled mono cam and hope I can achieve something half as good as that! Even after I removed the IR filter from my Nikon I was still suffering in terms of noise and colour banding of flats. That said I won't have any filters or guider for almost two months, so everything I shoot will be mono and unguided until my ASI120mm-mini and chroma lrgb set arrive : (

I also need an autofocuser, but what's good and bad kit wise in that realm is a bit confusing to me atm.

I am putting together my first computerised setup, and after just receiving the CMOS camera for it, and testing mount, camera, filter wheel control etc, I have realized an autofocuser is probably going to be necessary, given that the CMOS over wifi refreshes at about 0.5 frames a second, and my scope has lost focus to delta temperature before!

The skywatcher focuser (https://www.firstlightoptics.com/skywatcher-focusers/skywatcher-auto-focuser.html)  seems very cheap, and I hear will work over a usb to RJ-9 converter. This would be ideal for my little raspberry pi 4 (astroberry) but I don't know if it has the appropriate drivers to run it! Skywatcher autofocus isn't in the driver list but items like "usbfocus 3" and "astroberry focuser" are listed, with support for stepper motor controllers. I have no idea what focuser to buy or how much money I need to spend!

EDIT: This is for a Skywatcher 130-PDS telescope, with the default 10:1 dual speed focuser

Side note: can some peripherals (auto focus, filter wheel etc) be used via a USB hub? My poor PI is already out of USB ports and I haven't even finished yet!

Any help appreciated : (

4 hours ago, The Lazy Astronomer said:

I don't know what software you use, but rather than set the black point subjectively (by judging the brightness by eye), you could consider setting it more objectively, by moving the black points such that the pixel values of the background have equal intensity in RGB, and are around 5 - 10% of the maximum pixel value.

That's a good idea. I fiddled with it a bit more and got the average backrgound value somewhere around 10% (so because of noise pixels in the background are going between 6 and 14%)

I also found that RawTherapee supports adjusting saturation by brightness level as a curve, so I have made the background look a lot cleaner too as a result.

I am still not sure how to solve the atmospheric chromatic abberation I see throughout my image however : ( it's almost making triple galaxies in the backrgound in one or two places.

Thanks for the tip : D

2 hours ago, scotty38 said:

Looks pretty good to me but is it possibly black clipped a little and hence why you're missing a bit of the galaxies?

Yeah it was hard for me to choose a black point. Technically this isn't clipping because I think all of the pixels have a non-zero brightness. But the background is a bit dark. I couldn't work out a balance between the background looking pitch black when my monitor was on 0 brightness vs it looking washed out and grey when my monitor was at 100 brightness...

I believe the main benefit is for people using auto-focusing systems. So the filter can switch over, and the auto-focuser refocuses, and imaging can continue : D

I've done a few images this week, including one (which I've considered a bit of a failure) of the california nebula. I am however rather pleased with this leo triplet image, which represents the longest integration of any image I've made to date. Despite that it has caused me issues and poses questions.

First is the odd radial colour banding which occurs when I apply flats, as well as that flats seem to over-correct no matter what exposure I take them at (I tried getting one channel almost touching clipping, then 1/3 stops down until all three channels are averaging around the middle of the histogram, all do the same thing seemingly, maybe the centrally-histogrammed ones over-corrected slightly less). Googling suggests this is either because of my Nikon D3200's RAW frame compression, or perhaps to do with its method of white balance that dynamically adjusts the gain of each channel, or maybe it's the micro lenses, who knows.

The other, is that I feel I am not going very "deep" OR "clean" given the time I am putting into these images. I felt rather good when it comes to my earlier M42 this week but considering this Leo image consists of almost 5 hours or light frames, I thought the galaxies might appear cleaner or I'd be able to see more signs of their fainter "auoras". How does this image compare to some of what you guys have gotten in the same time? I'm wondering if my DSS settings might be non-ideal or if maybe I need to think more seriously about spending on a proper astro-cam.

Either way, it seems the weather is set to change for the worse astro-wise now, and I'm pretty pleased to have gotten the images I have from this week.

Hope you guys got similar luck with the weather.

I was setting up my scope to image the leo triplet and while talking to my brother I turn to the sky and see what looked like a mag -2 star like brightness, as if it were a planet like Jupiter or venus, pure white in colour. I thought it was odd at first and when I continued to look at it it started to fade, and within 10 or so seconds it was barely visible, a few seconds more and there was nothing to see.

It didn't seem to be moving, so it seems less likely to be a meteor or satellite, unless it was maybe a geostationary one? Are there any kinds of supernovae that are so flash-in-the-pan that they can be so easy to miss if one isn't looking? It would be very unlikely, but exiting to think about.

Wondering if anyone else looking up tonight may have seen it too? I'm down in Plymouth.

Edit: A screenshot showing the area I think I saw it in (I selected the closest star to the event I saw)

35 minutes ago, david_taurus83 said:

Im not sure of the exact specs for the HEQ5 but I can tell you a conservative figure for my AZEQ6 periodic error is say 30 arc seconds peak to peak over the 7 minute worm cycle. Thats a shift of over 4 arc seconds per minute and would be 8.5 seconds over one of your 2 minute subs. If you are using a 250P then I reckon you are shooting at less than 1 second per pixel so on my mount that would be an 8 pixel movement over the 2 minutes. Perfect polar alignment wont fix this I'm afraid. As David points out above, it is probably a combination of all things considered. If you are shooting with a focal length of 300/500mm then you will have a better chance.

20 minutes ago, City9Town0 said:

From my HEQ5....

-snip-

I see, expecting too much of my kit as usual I suppose!

I am using the 130-PDS so I have a 650mm fl. At around 1.22 arcsec/pixel, so that could still be 5pixels or so drift by your measurements assuming good polar alignment too...

I can feel my bank account shrinking already, time to google for permanent mounting solutions and guiding equipment haha.

Thanks for the pointers guys!

5 hours ago, david_taurus83 said:

Are you not guiding?

Sadly not at the moment, which of course would be great to add to my setup but I hear even without guiding my HEQ5 should manage some shorter times (like these 2 min shots) without effects as severe as those shown?

I was worried it might be a bit blurry once stacked since many of the subframes showed stretched or wonky stars, but it seems to have faired quite well and I think it might be the best astrograph I've taken so far!

Look at those reds! worth breaking my camera's aperture control arm for I think : D

Looking forward to shooting my next target! M78, or Horsehead and flame, or maybe california?

Taken with Nikon D3200 (full-spectrum mod), Skywatcher 130PDS, HEQ5-PRO

1 hour ago, Budgie1 said:

How are you doing the Polar Alignment and is the mount level?

On my own HEQ5 the built-in spirit level has been put in on the skew, so I've fitted my own and use that.  

I do polar alignment in a lightly naughty way: I let the mount tell me what hour angle it's meant to be, and roughly get it to that hour angle in the guide inside the mount's optic, but it is on the edge of that circle and pretty close I'd guess, even though they designed a system where that optic is pretty much impossible to get to the right position...

As for if the mount is level... Hmm. I hadn't considered such matters! I didn't even check the sight glass on the mount. I will have to see what it looks like in the morning, since I just took the camera off and came indoors leaving the mount in the garden.

Here are some close-ups from the camera, about an hour apart and in center frame,