Telescope hits tripod - Forums

Topic starter

Sep 5, 2020

Dear friends

I'm a beginner, and I have the following problem with my Celestron AVX mount:

After the alignment procedure I slew the telescop to NGC 6992, start Autoguiding and taking pictures. Everything works well, but when I return to the mount a couple of hours later I notice the camera has hit a tripod leg and the telescope is blocked, pointing straight up. This has already happened to me with other DSO.
What I'm a doing wrong? My simulator (Telescopius) telles me transit south is at 23h26 at 75°. Is this the problem? Must I set something different on my mount or can I only take pictures before or after the transit?
I have read the manual several times, but I don't find the answer alone.

Many thanks in advance!

Kind regards

Markus

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Francesco

Sep 5, 2020

Hi Marcus! That’s a common problem, specially with long refractors on a tripod. To mount the telescope on an pier extension or a pillar helps. Maybe this solution can be interesting to you to solve the problem: https://www.altairastro.com/celestron-axv-pier-adapter-cnc-2081-p.asp

Markus

Topic starter

Sep 5, 2020

Dear Francesco

Many thanks for your answer and advice. I will check this solution and also try to understand how to practise a meridian flip on the AVX. I guess this is the problem, but I just have no idea how to do this flip.

Kind regards

Markus

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Francesco

Sep 5, 2020

Dear Marcus, you are welcome!
Yes, I forgot to mention the meridian flip, but if the object is near the zenit or anyway hight on the sky, there will be always a risk that the telescope will hit a leg.
So the best is to buy a pillar or a pier extension (I think there are not such matching the AVX, therefore the adapter is necessary).

Meridian flip will be important even with a pillar or an extender, so very good that you are learning how to practice it!
You probably know already that most of the softwares for astrophotography can be set to automatically do a meridian flip (you need plate solving for that, but don’t worry both processes seem more complex than what they really are

Don’t give up and wish you good luck!
Best regards!

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Markus

Topic starter

Sep 6, 2020

Thank you Francesco!

Well, it in fact seems to be complicated! I'm taking pictures with an Astrel 183-X-M, a standalone camera. I will have to check if it can manage a meridian flip. The AVX, as far as I understand, can't do it. Maybe I have not understood what the different settings mean. Sure, I will not give up, but sometimes I'm close to it…

Kind regards

Markus

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Carastro

Sep 6, 2020

I am not familiar with an AVX mount but the EQ mounts that I have (Skywatcher), once you go past the Meridian, if you press the GOTO button again, it will automatically do the flip. You do need to keep an eye on the mount and scopes when imaging near the Zenith. I am in an observatory and even get clash with the pier if the target is high.

The mount extension will certainly help, also if you are able to control your mount with software, there are some software that you can set parameters that won;t take the mount past a certain position and will do the Meridian flip for you, but I never got involved in these myself, but I think SGPro and APT will do this.

Carole

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Markus

Topic starter

Sep 7, 2020

Hi Carole!
Many thanks for your considerations and your help. As a beginner, I didn't know about the meridian flip. Now I have read a lot about it, but still have to learn how to deal with on my AVX. Before buying an expensive pier system, I want to learn how to do the meridian flip manually.
Kind regards
Markus

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Rich Sky

Sep 7, 2020 · Edited: Sep 7, 2020

Hi Markus,
i use this software to automate meridian flips, focus, platesolving etc.

https://www.mainsequencesoftware.com/Products/SGPro

It works with my mount, but note sure if it works with the celestron avx?

you could ask mainsequence.

clear skies

r

Markus

Topic starter

Sep 8, 2020

Hi Rich!
Nice to hear from you! And many thanks for your help. With my Astrel, I probably don't have the possibility to use this software. But I will contact the manufacturer to ask him what is possible.

Kind regards
Markus

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Marius Bednar

Sep 8, 2020

Markus:
The AVX, as far as I understand, can't do it.

This is not quite correct. The AVX, as any other GoTo mount available, will automatically perform a meridian flip. In the hand controller settings you can normally set the mount's behaviour at the meridian (i. e. when the counterweight bar is horizontal): either flip or stop. Also you can set how far beyond (or before) the meridian you wish to track before the flip occurs. If your equipment is at risk of hitting the tripod you can set the mount to track only up to e.g. 10° before reaching the meridian.
What is not guaranteed after a meridian flip is that your framing is 100% accurate/identical, but that depends on how accurately the mount has been set up beforehand. For that reason external solutions (telescope mount controllers such as asiair or PC software) are used to perform plate solving after the flip to drive the mount to the exact same position as before the flip.

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Rey Hernandez

Sep 9, 2020 · Edited: Sep 9, 2020

The AVX van handle probably up to 102mm refractor, any longer than than you need to either move it upwards then add a weight for balance. Also try to test if it hits the camera during a meridian flip like when the counterweight bar is parallel to the ground and a little bit more, if the camera hits the tripod you have a problem. You can also modify the limits so at than particular altitude it will stop tracking, it is in the manual

Markus

Topic starter

Sep 9, 2020

Dear Marius
Dear Rey

Many thanks for your helpful and valuable statements. Now I better understand the problem and the "Meridian" chapter in the AVX manual. Indeed, it's the camera that hits the tripod… I can move it a bit upwards, but I will have to find a solution for adding weight. Not sure this will be sufficient.

Anyway, if I set limits, must I redo the GoTo after the Meridian flip for my object or will the mount go on tracking?

Kind regards
Markus

Marius Bednar

Sep 9, 2020

Alignment of the Goto mount is still fully valid also after a meridian flip. The only thing which you may have to change manually is to reverse the direction of the guiding commands if you are auto guiding. If your mount is connected to your guiding program via serial/USB your guiding program will do that for you.

If you have defined limits note that you will have a "blind spot/area" and you will have to wait before the mount can continue to track from the other side.

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Markus

Topic starter

Sep 10, 2020

Hi Marius
I guess we could communicate in German. Would be easier for me, my English is quite poor. I'm from Switzerland (Tentlingen).

Once again, your explanations are very helpful. I will try this out as soon as I'm back from my stay in the mountains in a couple of days.

Do I understand you well: after the meridian flip I will not have to re-enter the command on the handcontroller to instruct the mount to slew to the desired object?

I use the standalone autoguiding system Mgen3. I imagine the best would be to restart the autoguider after the flip. I'm not sure this system will do the reverse.

It seems to me that there is only little space missing between the camara and the tripod leg. I'm planning to push the tube upwards as much as I can and to elevate the tube clamps for 20-30mm. I hope this should be enough.

In order to test this, can l "cheat" and introduce a fictive time close to the meridian flip of a given object during daytime?

Oops… so many questions! I hope I don't abuse and over-stress your helpfulness.

Kind regards
Markus

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John Tucker

Nov 3, 2020 · Edited: Nov 3, 2020

I 'd suggest just buying an ASI AIR PRO for 300 USD. When you pass the meridian it will

1. Stop taking pictures
2. Turn off the guiding
3. Do the meridian flip
4. Take a picture and plate solve it to check if the meridian flip successfully centered the target in the FOV
5. If not, calculate and perform a corrective movement, take another picture, and ensure that the target is centered
6. Restart and recalibrate guiding
7. Continue taking pictures.

Also, if you are currently doing a three star alignment, you can forget about that, as when you slew to a target it will automatically plate solve and make any corrections needed to ensure the target is centered.

I got this thing after 2 years of using simple camera control software like Backyard EOS and I love it. There are laptop software programs that will do the same thing of course, but this is really point-and-shoot. I had all kinds of trouble installing relatively sophisticated sequence generation programs on my laptop and getting them to work. The ASI PRo was up and running in 30 minutes my first night out.

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