Wit's end...

[dan_adi]

On 28/05/2022 at 18:55, pipnina said:

When I first computerised my mount I expected this hobby to become a bit easier, and certainly for the level of automation to make me able to image more frequently and collect more & better data when I did. Sadly since I made the move to a cooled mono cam with this computerised setup my imaging life has been anything but stress-free.

Has the quality of my images gone up? Certainly. Has it introduced numerous independent problems that make me generally unsatisfied with my equipment, even though it has more than tripled in cost relative to last year? Unfortunately...

Whether it be poor flat frame calibration (neither 130-PDS nor TS-Photon 200/800 are free from this...) tracking/guiding woes, collimation challenges, suspicious levels of vignetting, filter reflections, computer errors, heavy mono cam & filters sagging the focuser or plain not sitting straight, the TS telescope not actually being compatible with their own coma corrector... It's all left me very sad and frustrated and with far less imaging time and lower-quality images than I expected if these problems did not exist.

When I finally got fed up with trying to tinker with my 130P-DS, and went for the only real option in my budget at the moment without sliding backwards in aprture and focal length (TS-Photon F4) I realised that while this scope solved one issue (PDS compression-fittingless focuser and barrel intrusion) it introduced several more such as the coma corrector pushing focus so far out, that the tube can't extend far enough and the corrector has to sit about 3-4cm pulled out, meaning from the stock of the focuser to the flange of my camera I now have a whopping 12cm gap, which is just ludicrous and creating a massive torque on the tube and focuser when my 1.5kg of camera, filters and CC are sitting in it parallel to the ground. This shows in my images as well as stars change shape throughout.

Then the filters, I adopted the "buy once cry once" approach and bought chroma 36mm, which are supposed to be an ideal fit for APS-C sized cameras. But while the LRGB filters seem to be working fine, the even more expensive narrowbands produce horrible reflections around bright stars, no matter the orientation:

As you can see the reflections are present in this 3nm Ha filter whether the coated side is facing the camera or the telescope (I flipped the filter wheel around). This is only a 60s exposure of arcturus. I guess my hopes of a good narrowband session near orion's belt are shattered now! This pattern doesn't show up in lum, so it's definitely something to do with the narrowband filters.

Then there's the suspicious vignetting (ADU in a flat or the background of a luminance frame) of about 50%! This scope advertises it's "90% illuminated zone" at being far larger than the diagonal of my camera... And I have already reduced the distance between my sensor and the filters as much as the 17.5mm backspacing built into my cam allows.

 

And perhaps most frustrating of all, my mount wants to just... turn itself off randomly as of late. Sometimes the INDI control panel says it's outside of its alt-az limits (even if I turn those limits off in EQmod, it still does it), sometimes it claims it wants a meridian flip, sometimes, just nothing at all. All I have to do is press the button in ekos to start tracking again but not having to babysit the scope was meant to be an advantage of computerising it! Plus the drift it causes means I have to re-create the framing all over again.

 

 

At this point I just don't know where to go with this hobby. It's so so good when things are running well, but oh so horrifying when getting death by a thousand cuts when so many thousands of pounds turns out to be not so well spent as expected... What do I do!? Where do I best direct my current astro-savings project money to?! So many problems and (after the computer and camera upgrades) not enough money to just splash out and hope high end gear will fix it.

 

If anyone has any ideas I'll gladly hear them, because this is getting ridiculous : (

Unfortunately astrophotography is hard. I went through the same frustrations when I started. 90% troubleshooting and almost no reward. Factor in cloudy weather and I almost gave up.

The only way it got easier for me was with a good refractor (CFF), OAG(Optec),  focuser (Optec), and a good mount (Mesu 200). I don't think there is a magical way to improve a scope or a mount that is made to a price point, and I ve learned the hard way to adjust my expectations accordingly.

Bottom line, the better the gear, the easier it gets (this was my experience)

[carastro]

I do sympathise, AP is full of frustrations.  A refractor is less problematic than a reflector, but I guess you don;t want to go down that road.  

Quote

 I do nothing via PC which I can do by hand.

I am with Olly on this one.  Less automated things, less to go wrong.  But you seem to have sorted your mount problems.

Hope you get everything sorted soon, but even when you have been imaging for years something will come along to bite you.  When it is all working it's a joy.  

Carole 

[teoria_del_big_bang]

Like all previous replies I too empathise with you, but unfortunately that does nothing to help you.

When I started I too had many problems, some same as yourself and some totally different and I too began to think was it all worth it as I seemed to be always taking one step forward and often two back.
Now I know you are not just starting out but you have several issues and for myself the way that worked for me was to eliminate issues one by one.
And, because clear nights were few and far between it took some weeks to do but if you have many issues trying to solve them all at once will just frustrate you more, so do it one by one.

Personally for now I would remove anything you can remove and still get some sort of images,.
When other issues are solved then start to reintroduce them.

In daylight get everything working the best you can, if you can improve the sag on the focusser then do so, in daylight, you need to eliminate as much issues with the focusser as you can. Sometimes stock focusers are poor when adding heavy cameras and filter wheels and really need upgrading but if for now that is not an option then there are usually tweaks and things you can do with shims to stiffen it all up a bit if you search on line.

Then get any computerised side working flawlessly, again a lot of this you can do in daylight, if you can work from your laptop for now and eliminate the RPi then do so.
However the RPi is well capable of running KStars / Ekos, so, again can introduce later when you have made progress.

Remove the CC for now, okay you will have some misshapen stars but get it all working for now, this may well stop the reflections, put filters the recommended orientation.

Don't bother guiding, again for now, with a HEQ5 well polar aligned you should be able to get good 3 minute subs without significant star trails, even 5 mins might be not so bad if using NB filters and after all the ide is to get what you have working. So even if some slightly elongated stars the aim is to get what you have working reliably and good useable data not the real aim for now.

Then after a couple of nights with that all working, shouldn't be too hard, camera should work ok, FW should be fine, mount should track if well polar aligned, hopefully focusser is holding its own, then try one of the things you removed.
If the focusser continues to make things difficult then maybe you have to accept it is not up to the job and needs upgrading. Not ideal and I am hoping you can get it to work but sometimes you just have to face facts and either lighten the load or upgrade the focusser, or even scope itself.

So CC is probably the next bit. If the reflections are back then that the problem with that and unfortunately all you can do is find out what CC works with your setup and try to save for one.

Then try guiding, often that can take a night or two to get working and set all up correctly.

Then try your RPi again, just make sure to use good quality, shortish (below 3M) USB cables and a good power supply. Again all the initial trials can be done in daylight to make sure it all works reliably. Connect to laptop via an ethernet cable for now to eliminate WiFi issues.

Just do it bit by bit and you will get there and once all setup you will have a reliable piece of kit that just works.
Each night you get another bit working you will feel a real sense of satisfaction I am sure, even if all that work and messing about meant no real useable data that night.

Steve

Edited June 2, 2022 by teoria_del_big_bang

[carastro]

All good suggestions from Teoria.

Carole 

[pipnina]

I have done various tests now with a bunch of hardware combinations.

Hydrogen alpha reflections:

All I've tried so far is switching the CC out for my old Baader MPCC. This showed the same pattern and intensity, so I think if changing the corrector is going to solve anything, it's changing a corrector that I don't own... Didn't get to test it without a corrector that night because it had already reached nearly 1PM and I was coming down with a nasty flu that I'm only just recovering from now.

Vignetting:

The vignetting issue seems a little more interesting. I tried my astrocam with the GPU and the Baader CC and it seems as if the GPU MAY be causing greater vignetting (33% compared to 25%?) But I also noticed that when I tested vignetting with NO corrector on my DSLR and astrocam, that the vignetting pattern changes to be off center. I suspect this might be because of the reflection off of the edge of the secondary mirror.

I also checked my astrocam without corrector and without filters (so the only things in the light path were the bare telescope, bare camera and the focuser barrel. This produced the same vignette pattern as with filters, so I don't think the filters are the cause.

 

Tilt:

Sadly my focus tests for tilt weren't very effective, since I didn't turn on guiding and the stars trailed.  I do notice however that the diffraction spikes in the up-down direction (i.e. the direction the focuser would be tilting in, in theory) are split on both correctors, but not on the left-right direction, where the spikes remain singular/intact.

 

I have some raw files I took if anyone wants to try drawing their own conclusions: https://drive.google.com/drive/folders/17_3ZrMSXAWTfo7O-aUCVFx9kAmT-84GM?usp=sharing

[Clarkey]

I had a quick look at some of you images and there is definitely something going on. In terms of the reflections they are odd. Looking at the size they look like they should be from the filters - the same problem I had with my F4 newtonian as shown below. However, the reflections are very different in location. Also looking at one or two of the other images suggests the collimation may be out in addition to some tilt. There is also a weird diagonal on the Baader Lum focus test?

Even though I had no problems with the F5 newt, I did find getting the F4 Photon right was a real pain. I ended up buying a concentre and a new laser collimator (after new focuser and CC) just to get it somewhere close. Not sure this really helps you, other than to say the TS F4's are not easy to work with.

 

[pipnina]

37 minutes ago, Clarkey said:

I had a quick look at some of you images and there is definitely something going on. In terms of the reflections they are odd. Looking at the size they look like they should be from the filters - the same problem I had with my F4 newtonian as shown below. However, the reflections are very different in location. Also looking at one or two of the other images suggests the collimation may be out in addition to some tilt. There is also a weird diagonal on the Baader Lum focus test?

Even though I had no problems with the F5 newt, I did find getting the F4 Photon right was a real pain. I ended up buying a concentre and a new laser collimator (after new focuser and CC) just to get it somewhere close. Not sure this really helps you, other than to say the TS F4's are not easy to work with.

Indeed my collimation may be beginning to slip a little and I'll be breaking the laser out and the . At the next opportunity I will try testing my Ha filter without a corrector in place to see if it remains. These filters are quoted to work at f4 and chroma is supposed to be top-shelf so I wouldn't expect the filters to be at fault- but it can't hurt to check!

The diagonal in the baader (and the halo around the star) are likely because in my attempts to clean it, I had made things worse. I only have normal glasses cleaning spray and a soft kitchen towel (not micro fiber, very soft however, I keep buying microfiber cloth and it keeps disappearing!). When it comes to equipment that's currently in-use, my approach to cleanliness is to stop it getting dirty in the first place if I can help it, but I thought I was finished with the baader so I toyed around with it a bit (took it apart after noticing a threaded insert in the scope end).

I also agree that this f4 scope is definitely a handful. I have a cocenter which seems to show the secondary having been central and in the correct tilt from the factory, and a baader laser collimator which agrees with that assessment. The laser's dot appears near the edge of the ring on the primary mirror, which seems like it's probably in tolerance to me, unless others know better? I do know that on the laser's own marker, the dot does move from one side of the central hole to the other as I slew the telescope over on dec, but I have collimated it when it is upright so the total movement is not that considerable... Unless even that small movement is enough to upset my images. I'll try and get some pics of the collimation tomorrow.

[pipnina]

@alacant You've suggested to me in the past using a silicone sealant to hold the primary mirror, is the type of sealant used for putting around bath and shower edges in the bathroom appropriate? I have a tube for sealing plastic bits of showers against tiles and glass. I used it on my 130P-DS, but while that allowed me to remove the mirror clips, I didn't notice any difference in how it held collimation (maybe because my 130P-DS held quite well even before, at least by my standards).

Do you recommend using the sealant in only certain places (i.e. for the 130P-DS, the mirror sat on 3 cork pads, would you recommend a line of sealant at the outer edge of the pads or a covering?

Cheers.

[Ratlet]

27 minutes ago, pipnina said:

@alacant You've suggested to me in the past using a silicone sealant to hold the primary mirror, is the type of sealant used for putting around bath and shower edges in the bathroom appropriate? I have a tube for sealing plastic bits of showers against tiles and glass. I used it on my 130P-DS, but while that allowed me to remove the mirror clips, I didn't notice any difference in how it held collimation (maybe because my 130P-DS held quite well even before, at least by my standards).

Do you recommend using the sealant in only certain places (i.e. for the 130P-DS, the mirror sat on 3 cork pads, would you recommend a line of sealant at the outer edge of the pads or a covering?

Cheers.

Not sure about the technique, but on the silicone front, you probably want to use a neutral (also known as alkoxy) silicone.  The other type (which is most common) release acetic acid when they set and will smell similar to vinegar.  The neutral stuff is meant to stick better to certain plastics and glass.  It's the same stuff as you'd use in the bathroom, but will normally say on it if it is a neutral silicone.

[Xilman]

Decades ago, as a chemistry student, I had to know the details of reactions which release acetic acid. I have long since forgotten them and am now far too lazy to find out again.

[pipnina]

17 minutes ago, Ratlet said:

Not sure about the technique, but on the silicone front, you probably want to use a neutral (also known as alkoxy) silicone.  The other type (which is most common) release acetic acid when they set and will smell similar to vinegar.  The neutral stuff is meant to stick better to certain plastics and glass.  It's the same stuff as you'd use in the bathroom, but will normally say on it if it is a neutral silicone.

I do recall the sealant I used having an odd smell to it, so I think it's probably not neutral. Does it cause the stickiness to lessen over time or does it just not smell pleasant?

I gave my 130P-DS a sniff since it had already been sealed, but the smell seems to have dissipated by now.

[iapa]

On 05/06/2022 at 21:36, pipnina said:

Indeed my collimation may be beginning to slip a little and I'll be breaking the laser out and the . At the next opportunity I will try testing my Ha filter without a corrector in place to see if it remains. These filters are quoted to work at f4 and chroma is supposed to be top-shelf so I wouldn't expect the filters to be at fault- but it can't hurt to check!

I also agree that this f4 scope is definitely a handful. I have a cocenter which seems to show the secondary having been central and in the correct tilt from the factory, and a baader laser collimator which agrees with that assessment. The laser's dot appears near the edge of the ring on the primary mirror, which seems like it's probably in tolerance to me, unless others know better? I do know that on the laser's own marker, the dot does move from one side of the central hole to the other as I slew the telescope over on dec, but I have collimated it when it is upright so the total movement is not that considerable... Unless even that small movement is enough to upset my images. I'll try and get some pics of the collimation tomorrow.

Have you checked that the laser itself is collimated? 

• How to collimate a Laze [sic] collimator
• Advanced Newtonian Collimation
• Laser Collimator
• Squaring up that cheap laser collimator

I did a thread few years ago stripping down and collimating a 10" f4 that I can dig up if you thing it useful? It mostly concentrated on the secondary as It was loose and had a twisted vane.

Edited June 14, 2022 by iapa

[alacant]

2 hours ago, pipnina said:

using the sealant in only certain places

Yes. Remove the paper insert and apply a generous blob of silicone to coincide with the original cork. Allow the mirror to seat under gravity (don't push it home) on a level surface until a representative blob under the same ambience returns to shape upon being distorted. Then refit.

Neutral, pH 7ish, without carboxylic acid is best. Any translucent sealant will however do better than none, but note silicone, not acrylic.

The silicone limits the lateral movement of the mirror hence helps retain collimation regardless of tube angle, but don't forget to upgrade the mirror springs too, that the floating part of the mirror support affords the same limitation without locking screw distortion.

HTH

 

Edited June 14, 2022 by alacant

[pipnina]

1 hour ago, iapa said:

Have you checked that the laser itself is collimated? 

I just gave it my best shot at testing it. I locked the collimator in place, took a reading, then rotated it 90 degrees. So now I have 4 pictures at 12, 3, 6, and 9 oclock.

It can be a bit fiddly and I think one of the rotations I may have not seated it properly, since it's the only one that appears to disagree with the other readings. Is this a good test? What do you think of it?

[pipnina]

I got some neutral "low modulus" sealant from screwfix yesterday and just got around to applying it to the mirror cell. Hopefully this is a sufficient application to hold the mirror, which is rather hefty. I did my best to avoid pushing it down while ensuring it was in straight. Tomorrow is pinned to be clear so I will hopefully be able to re-collimate and test it out now that I have not just done this, but also blackened the secondary mirror's edge.

After that, it'll be a matter of seeing if I can help the focuser sag at all...

[alacant]

10 hours ago, pipnina said:

Hopefully this is a sufficient

Here's hoping. The usual rule is: 

On 14/06/2022 at 22:46, alacant said:

apply a generous blob of silicone to coincide with the original cork

So you're sort of half the way there. But hey, at this game pragmatism rules.

EDIT:

Oh, almost forgot...

WARNING: the GSO cell.

You may have noticed that the black-knob mirror tilt screws can me adjusted so that they bear against the underside of the mirror (sic). You may want to put washers to prevent their clockwise motion allowing metal to glass contact. In fact I'd say it's essential. 

Edited June 20, 2022 by alacant

[alacant]

10 hours ago, pipnina said:

hold the mirror, which is rather hefty

Also forgot. Again...

Don't forget to replace the springs. As a minimum, 1.4mm wire. 3 replacements and a further three using the white-knob screws as retainers.

Cheers

Edited June 20, 2022 by alacant

[AstroMuni]

On 29/05/2022 at 23:50, pipnina said:

I used my laptop (Ubuntu 20.04, i7-6700HQ / 16GB ram, high enough end to have a USB C port back in 2016 when I bought it) in place of the raspberry pi, and had it only hosting the indi server and running PHD, while my desktop used Kstars to remote control the PHD2 app and indi drivers.

I started off using my laptop to run Kstars and the RPi running just the INDI server and drivers. This arrangement works great as all the images come back to my laptop directly and I didnt have any problems with this arrangement. For the past few months I have switched to using everything on the RPI and using laptop to simply remote into RPi using VNC. And that works fine too. In both cases I have tried with just the Ekos internal guider and also using PHD2. I have other friends who use this same configuration in their domes and swear by it.

My connectivity between laptop & RPi is ....laptop --wifi--> wifi extender -- ethernet cable --> RPi. This gives me ability to stay indoors with laptop while wifi extender, RPi are outside.

[pipnina]

6 hours ago, alacant said:

Here's hoping. The usual rule is: 

So you're sort of half the way there. But hey, at this game pragmatism rules.

EDIT:

Oh, almost forgot...

WARNING: the GSO cell.

You may have noticed that the black-knob mirror tilt screws can me adjusted so that they bear against the underside of the mirror (sic). You may want to put washers to prevent their clockwise motion allowing metal to glass contact. In fact I'd say it's essential. 

Do you reckon I should have used more? I could still apply some to the edge of the mirror where the side cork (I thought only the middle cork pieces needed to be sealed).

Now that it's sealed in, I suppose I would need to try and slip in some soft metal sheet or fabric from the under side to prevent the thread touching the glass? Is anything that's capable of preventing metal-glass contact sufficient or should some specific material work best?

I'll have a look into the springs although I seem to recall reading someone from FLO saying the newer GSO mirror cell springs are up-rated from the ones that famously needed replacing. Unless they're still wimpy even after that change?

 

Many thanks for the help so far.

[alacant]

3 hours ago, pipnina said:

under side to prevent the thread touching the glass

No, no. The washers go on the outer part of the cell such that when the spring is fully compressed, the screw has not travelled far enough to foul the glass.

To save on washers, we use nuts with a washer either side:

 

Edited June 20, 2022 by alacant

[pipnina]

I got the chance to test the telescope last night with the sealed mirror cell, and it seems to have worked just as you advertised! My laser collimator showed almost, or maybe even no movement swinging the telescope from one side to the other and my bahtinov mask diffraction patterns are now much cleaner and easier to read too! So perhaps poor collimation was upsetting it before.

Some comparisons of my defocused stars and bahtinov patterns:

Before:

 

After:

 

 

I was apprehensive to try modifying the scope as it would void the return policy but I think this has improved the scope so much already, if this is sustained I don't think I'll be re-evaluating this purchase any more.

When I get home to my PC which has the night's imaging on it I can show a proper subframe too, which I think it looking quite good. I seem to have a strange guiding issue however despite my guiding graph never showing spikes above 1.2 seconds-ish. Seeing doubled stars in some images, in different directions each frame.

Edited June 21, 2022 by pipnina

[pipnina]

   

 

NGC_7023_Light_003.fitsNGC_7023_Light_002.fitsNGC_7023_Light_001.fits

I seem to be having two other problems though now : (

My guiding seems to claim I have no peaks above 1.2 seconds, even checking back through the graph history. But my image keeps drifting in one direction and many images have doubled stars... Plus I suspect some dewing at the end of the webm videos.

Seems I still have problems to solve! At least the subs where guiding behaved seem to look pretty good now!

 

(edit, it claims the videos are corrupt, but you just need to right click and download them, I couldn't get Pixinsight's blink to work properly unless I chose webm)

Edited June 21, 2022 by pipnina

[david_taurus83]

That looks like flexure. How are you guiding?

[pipnina]

14 minutes ago, david_taurus83 said:

That looks like flexure. How are you guiding?

It is a guidescope so I suppose there is the potential for flexture.

I am using this scope https://www.firstlightoptics.com/finders/astro-essentials-50mm-guidescope-finderscope.html  In the default shoe of the main scope. It seems to work fine on some occasions and not so on others however. I've tried to get it affixed as tightly as is reasonable. On my last iris nebula attempt I was averaging a 0.35 second RMS, last night i was averaging about 0.8 on the same target.

[alacant]

12 hours ago, pipnina said:

the default shoe of the main scope

If you're staying with it (it can be done, but the telescope has to be mechanically perfect), the guide telescope needs mounting directly to a rigid rail joining the top of the tube rings. We use 2mm wall 60 x 20 box section aluminium.

The rings themselves need mounting further apart on a Losmandy dovetail. For a 203 f4, go for 45cm separation. This provides adequate support for the flimsy gso tube.

If flex remains, the next step is a lightweight secondary support. 

Or just go for an OAG.

HTH

Edited June 22, 2022 by alacant