Big Bang!

An update:  I had some further issues with poor guidance and would typically lose 50% of my frames due to seriously dreadful star shapes.  I tried guiding the rig with the 16200 switched off and then switched on to look for differences.  Instantly the problem was clear: the guide-star shape and profile were much fatter with the camera running but, when switched, off guidance dropped to 0.33RMS and the star profile shrank.   So in the end I had to send the 16200 back to Atik.  Really fabulous customer service at a difficult time for everybody.  They apparently found some play in the fan mounting and they replaced the fan itself. 

Just got it back; I have run the rig for 4 hours on 15 minute exposures starting low in the sky and working up to 55 degrees.  There is still a minor vibration on it (just visible in the PHD2 profile) but it is barely noticeable and my stars are now perfectly round over 15 min exposures.  Thus far I haven't lost a single frame and the guidance is good even when low down.  

So a big thank you to Atik. 😅

Gus

1 hour ago, RayD said:

Well it certainly seems to be pointing to that as being the issue.  It must be pretty bad to be affecting the guiding this much so I would say it is definitely one or two faulty fans.

Drop Vince a line at Atik, he usually replies pretty quickly and will know for sure, but I definitely don't see this on mine, so it certainly can't be right.

Thank you all so much for your help - I am not sufficiently expert to be able to address such problems by myself.  

Having reinstalled and re-calibrated PHD2 the guidance stabilised at 0.3"RMS again - suggesting to me that it was a PHD issue and that guidance is not being impacted by the vibration off the 16200.

I am in discussions with Atik.

Gus  

And here it is after a PHD reinstall and re-calibrate.

Gus

1 hour ago, RayD said:

What mount is this?  I just can't see it being the camera vibrations causing this as it would have to be pretty bad and then I would expect it to be there in the non guided image.  Is this a separate guide scope or OAG?

It's a 10 Micron 1000HPS, routinely guides to 0.5" and regularly does less than 0.3".  The new camera is the only change that could have any impact on it. Separate guide scope.  Same set up as before, which didn't have any of these issues. 

The vibration can barely be felt on the Esprit 120 itself but easily felt on its EFW and 16200.    However, it is most clearly felt on the guide camera and surely this has to be guidance related because the unguided is essential good?  Well, the only problem I can find on guidance is the vibration on the camera, everything else is the same as before the Atik 16200 upgrade.  If it is clear again tomorrow I may put the Atik One back on the rig and see if the issue is still present.

Gus

On the left, 15 minutes unguided; PixInsight gives it .40 eccentricity.  On the right, taken immediately afterwards, 15 minutes guided with its guide data.  From a set up that bottomed out at 0.22" RMS last night.  

Gus

Video of the vibrations

5 hours ago, Skipper Billy said:

The fans on mine run all the time but there is no noticeable vibration.

If your guiding is good (it is) but your stars are not then that would point to focuser droop/slop. IE the scope is pointing exactly where it should be but the camera is moving about.

My thoughts exactly.

Thank you.  Yes, that all makes sense.  Comparing short exposures either side of the pier sounds like a good idea.

The vibration is instantly detectable through my fingers as soon as I touch either the EFW3, 16200 the or the guide camera so somehow it is being transmitted through about 18kgs of kit.  It is also faintly detectable when I touch the Esprit 120 itself.  Regardless of what is or is not happening with guidance, surely the camera should not be vibrating to the extent that the vibration is detectable through the filter wheel and into the optics?  My plan is to point the rig vertically and put a light class of water on the EFW to see if I can see any vibration on the surface.  

Any other ideas?

Gus

Thank you.  The guiding is inconsistent though - it went from that to over 1.0" in half an hour and I cannot understand why.  With the above guiding performance I would have expected a perfect image but it wasn't.  Can you think of anything else that might cause a poor image with excellent guiding?  I am worried that there is something wrong with the camera.

Gus

I wonder if there is anybody on here who has experience with the Atik 16200 who might be able to help me. 

I have just upgraded from an Atik One 9.0 to an Atik 16200 to give me a Large Format capability.  The Atik One has been superb with no issues of any kind; a real pleasure to use.  The Atik 16200 has a significantly higher cooling capacity (-50c against -38c) achieved by higher capacity fans and heat sink.  It is therefore a heavier camera - 1.3kgs against 0.9kgs.  Last night I noticed my guide stars were out of shape and when I checked that the guide camera was secure in its scope I could feel significant vibration on it.  This vibration was not in evidence in the main imaging optics, the focuser or the flatener but it was in the EFW3 and the camera.  It is there when the fans are running regardless of whether the cooler is engaged.  

I am not sufficiently expert to know but I cannot imagine such vibration is to be expected and I am sure it has been impacting my imaging performance.  One night my guiding bottomed out at 0.22" RMS but the corresponding 20 minute image had oval stars in it - which confused me.  At the time my thinking was that whilst the guidance may have been spot on and the main optics secure, something else in the imaging train must have been moving and now I have a chief suspect - but I really wouldn't know how to go about proving that or isolating it.

Is there anybody here who has any experience of the like, either with a 16200 or any other camera.  Do we think this is normal.  If not then as the camera is new I can go back to the vendor; if this is normal how does one damp out the vibrations?

Many thanks.

Gus

On 21/05/2020 at 09:30, banjaxed said:

Only just seen this thread and am very sorry you have to repair the damage to your dome caused by low life. What I would like to do to them is not printable. 😖

They need to be made to fear the consequences, which they don't.

5 minutes ago, Nigella Bryant said:

Yeah, I agree Alan, I do feel sorry for them in as much as they don't know any different and probably drug related to support the habit.

As one who has a role within the judiciary I can tell you you are absolutely spot-on. I see it all the time, theft to support a habit.  Were it down to me I would order compensation to the value of your loss because making a thief actually work to pay for what he has stolen/damaged brings home the cost of the error. 

Very sorry to hear this.

Having seen the video I now understand.  Thank you.

Gus

2 hours ago, Midnight_lightning said:

When balancing it with the EFW anywhere other than vertically up of down (home position) I can only get balance on one side of the pier or the other. So balance it one side and I can let go in any position and it just stays. Move to the other side and its not balanced. Took me a while to work it out but its because the CoG isn't symmetrical without the EFW vertical - it only affects Dec balance.

That doesn't sound quite right to me.  The distance to the pivot point doesn't change and so surely the "moment" doesn't change?   

Gus

19 minutes ago, ollypenrice said:

But what would I buy without pushing your initial parameters? An Esprit 120 from FLO.

Olly

Absolutely spot-on.  On the basis of my experience and everything I have heard you say on here it's a no-brainer - buy the Esprit 120EDPro.  Compared to everything else I have seen it is by far the best value for money, even if it might not be quite in the Tak  or Tec class; that coupled to the flat field right into the corners and a 44mm imaging circle... Be realistic.

Gus

This was the first un-guided test image (30 minutes) just to test the back focus on the Esprit/flattener/Atik combination - it might need a slight tweak; no cooling so hot pixels everywhere.  PixInsight Eccentricity puts it at .40

Gus

I have an Esprit 120ED Pro.  Utterly delighted, can't fault it.  I remember reading the reviews at the time I bought it that suggested it was essentially as good as anything else that most people can afford.  I bought the flattener with it at the time.

I have just upgraded my camera from an Atik One to an Atik 16200 to take advantage of the 44mm imaging circle this Esprit offers.  First light was two nights ago - round stars all the way to the corners.  

On the basis of my knowledge I would say the Esprit is very good value for money.

Gus

The profile of the astronomy community needs to be raised so that these issues don't develop in the first place.   Ideally, councils need to add our needs to their developments' check lists, in the same way they do for disabilities or special needs.  Just a little bit of thought could make a huge difference.  Elon Musk has made an effort with his satellites - which have been a real pain of late.  

I would also like to see the BBC weather people include something about likely seeing conditions in their forecasts so that we can plan better - just like they do for UV or pollen.  

Gus

Good job!

Gus

That explains that then!

Gus

1 hour ago, Knight of Clear Skies said:

Looking at your location fewer contrails is the most likely explanation, followed by less air pollution. SQM readings have been very good down here in Cornwall recently, had a record-equalling 21.88 the other night.

May I ask where you get your SQM readings? 

Gus

Has anybody else noticed an apparent improvement in the SNR on PHD recently or am I imagining it?  I haven't changed anything yet over the last three weeks I've noticed really high SNR on the guide scope.  If I am not imagining it then I can only assume we a have significantly clearer atmosphere at the moment.

Gus

I have just ordered an Atik 16200 and an EFW3 to go on an Exprit 120EDPro.  Is there anybody with experience of this camera/wheel combination who can advise me on how to get the best out of it?  This is a leap into Large Format and I don't really know enough about it. 

Many thanks

Gus