astrophotography Astrophotography Tracking Problem

[deanchapman2705]

Hi guys, hoping you can help with the tracking problems I'm coming across with my astrophotography setup. I've been using it since August 2020 and have kind of put up with the problem until last night where I think it's getting worse...

Specs below (let me know if you need anything else):

• William Optics Zenithstar 61 II (360mm F6.1) - Zenithstar 61Adjustable Field Flattener
• iOptron SkyGuider Pro Camera Mount Full Package
• K&F Concept Aluminium Tripod with 2kg weight
• Canon EOS 250d (cropped sensor 1.6x)

The problem:

I take roughly 40 pics with each being 1 minute long at 1600 ISO and stack them on DeepSkyStacker. From a few people I know on the internet, it seems as though, with a very similar setup and same focal length, they can get around 3 mins of exposure with no problem. And that's without a guide camera.

With my 1 minute exposure, roughly 10 of 40 images are reasonable but the rest have star trailing or double stars (see attached downscaled, unedited pics of Orion nebula)

What I think it could be:

My first idea was the tripod, it's not the best but it's not cheap plastic, and it should be fine for a 1 min exposure. Then I thought it could be the iOptron tracker that could be faulty?

Every screw has been tightened, there's no play in any of the adapters/mounts.

 

I thought I'd post this here to see if anyone else has the same problem or has more experience/knowledge that could help. Also to see if there's an obvious problem before I spend hundreds on a new tripod or send the tracker back for a replacement.

Any help would be much appreciated!

Thanks,

Dean

 

[PEMS]

Cannot see any mention of polar alignment and unsure of polar alignment options of the tracker in use. The scale will be approximate but no more.

First image almost looks like the mount is sticking a bit then jumping. And the amount of items on the tracker looks a fair amount. The ZS61 is 2.2Kg, add another 0.5 for the flattener and 1Kg for the DSLR and you are at 3.7Kg. Would expect the weights you have added need to be included so that is 2Kg. Now at 5.7Kg. If you add in say 0.3Kg for the finder and other bits you are at 6Kg.  Odd question: If the weights are 2Kg what weight is the bar, bet it weighs something, but is ignored.

I suggest the system is operating at over capacity and so beginning to fail. And will also suggest ignoring what people say they are able to achieve.

[SMF]

This might be a bit random, but I had the same issues. Totally different set up but same problem, two stars (and other random patterns) on about two thirds of all images.

I set up on my driveway just outside my workshop. Perfect level tripod, perfect polar alignment on what looked like a solid concrete surface.

Taking long exposures I get bored so use my dob whilst doing so. It’s located a few metres away. Shorter exposures I stayed still at the imaging scope.

This means I move about.

I found the problem was that one section of my concrete drive (the one the tripod was on) had become slightly loose where my truck wheel parked on a edge of it over time.

The exposure would start with me at the tripod then about half way through I’ve moved to the dob and the concrete has now tilted ever so slightly. Now I’ve got two stars. If I moved around a lot I ended up with blurring, zig zag star patterns and all sorts of funny shapes.

But on the occasions I stayed still at the tripod I’d get good results.

Are your patio slaps perfectly fixed or are you treading on the corner of a loose one mid exposure?

The movement might be imperceptible to you but the image will record it.

Steve 

 

 

Edited January 10, 2021 by SMF

[deanchapman2705]

55 minutes ago, PEMS said:

Cannot see any mention of polar alignment and unsure of polar alignment options of the tracker in use. The scale will be approximate but no more.

First image almost looks like the mount is sticking a bit then jumping. And the amount of items on the tracker looks a fair amount. The ZS61 is 2.2Kg, add another 0.5 for the flattener and 1Kg for the DSLR and you are at 3.7Kg. Would expect the weights you have added need to be included so that is 2Kg. Now at 5.7Kg. If you add in say 0.3Kg for the finder and other bits you are at 6Kg.  Odd question: If the weights are 2Kg what weight is the bar, bet it weighs something, but is ignored.

I suggest the system is operating at over capacity and so beginning to fail. And will also suggest ignoring what people say they are able to achieve.

Thanks PEMS, I polar align it almost perfectly every time and sometimes do it again half way through to check it and It's still perfect.

For the weight, this was one of the things that concerned me at first (can't remember how much it weighed) but I do remember everything was under the weight limit for the tracker by quite a bit. I've seen people with an extension rod to fit two counter weights lower to balance their equipment, so I don't think that could be the problem.

Thanks for the help though!

[deanchapman2705]

41 minutes ago, SMF said:

This might be a bit random, but I had the same issues. Totally different set up but same problem, two stars (and other random patterns) on about two thirds of all images.

I set up on my driveway just outside my workshop. Perfect level tripod, perfect polar alignment on what looked like a solid concrete surface.

Taking long exposures I get bored so use my dob whilst doing so. It’s located a few metres away. Shorter exposures I stayed still at the imaging scope.

This means I move about.

I found the problem was that one section of my concrete drive (the one the tripod was on) had become slightly loose where my truck wheel parked on a edge of it over time.

The exposure would start with me at the tripod then about half way through I’ve moved to the dob and the concrete has now tilted ever so slightly. Now I’ve got two stars. If I moved around a lot I ended up with blurring, zig zag star patterns and all sorts of funny shapes.

But on the occasions I stayed still at the tripod I’d get good results.

Are your patio slaps perfectly fixed or are you treading on the corner of a loose one mid exposure?

The movement might be imperceptible to you but the image will record it.

Steve 

 

 

Thanks Steve, that's a very good point. My patio slabs are quite wobbly when walking on them. The only problem though is that I set a timer for 10 secs before it starts taking 30, 1 minute, pictures and I go indoors for 30 mins before coming out again to check it. So can't see why it would be moving that much in-between. However, It might be what's causing the double stars though.

With the star trails, I've never had any zig zag lines, just straight lines that all go in the same direction, all the same length.

In fact, I've just flicked through the pics really quickly almost making an animation, and it looks like it drops slightly (creating a double star) and then over 10 pics, slowly corrects itself (creating trails) and keeps repeating... It's like it's tracking too fast, then stops to go back and starts again. The stars in the first and last pictures are pretty much in the exact same place as well.

 

[SMF]

That’s got to be very frustrating given it’s during a sequence of shots. Rules out my thoughts I think.

I don’t have a timer on my old DSLR so fire the remote for each shot. 

Hope you get to the bottom of it, I’m sure if it’s equipment related someone on here will know. 

[JemC]

Max payload for Ioptron tracker is 5kg
ZS61 is 2.2Kg,  0.27 for the flattener and 0.449kg according to Canon for the DSLR, Red dot finder approx 0.115 Kg. 2Kg for counter weight Now at 5.034Kg so just slightly over max payload,

Is the setup protected from the elements such as wind, also you have a free hanging weight on the tripod which could be moving about if open to wind, it won't take much wind to have an impact on the setup in my opinion, 

just my thoughts on what could be causing it,

[callisto]

Why don't you give it a bash without the dovetail bar and handle and see how it goes

[deanchapman2705]

17 minutes ago, JemC said:

Max payload for Ioptron tracker is 5kg
ZS61 is 2.2Kg,  0.27 for the flattener and 0.449kg according to Canon for the DSLR, Red dot finder approx 0.115 Kg. 2Kg for counter weight Now at 5.034Kg so just slightly over max payload,

Is the setup protected from the elements such as wind, also you have a free hanging weight on the tripod which could be moving about if open to wind, it won't take much wind to have an impact on the setup in my opinion, 

just my thoughts on what could be causing it,

Thanks JemC - Ah, forgot that when I first measured it that it didn't have the flattener so I have just weighed it again with the scope and flattener along with the camera (with battery) and red dot finder etc and it comes to 2.8Kg and the counterweight is 1.4Kg. So in total, 4.2Kg.

To be fair, it's not far off the weight limit but should still be okay and the fact that I can move the CW even further down and even buy an extension rod suggests it could take more weight.

[deanchapman2705]

33 minutes ago, callisto said:

Why don't you give it a bash without the dovetail bar and handle and see how it goes

Thanks for the suggestion Callisto, however, without the dovetail plate, it becomes too back heavy. This would probably put stress on the motor if it's unbalanced