Jump to content

Narrowband

Meridian flip limitations


8472

Recommended Posts

My first couple of imaging sessions with my AVX have been mysteriously cut short for reasons I initially didn't understand. For some reason, the final third my lights all suffered terrible trails, much like the mount had stopped altogether.

I've since learned, these goto mounts don't like going past the meridian without a flip. To my understanding, this has to be initiated manually. Coming from a Star Adventurer, which will happily track in RA until the batteries go flat, this was a surprise ( I also fitted a timer on the power supply to cut power as and when I wanted). 

I totally get the reasoning, in that it's a safety feature to stop the mount lunching itself unattended, but it kind of kills the idea of running the mount all night without me watching over it until it nears the meridian, which could be at any ungodly hour.

I've set the slew limit to 20 degrees past the meridian, but that is the limit. Not far enough for my needs.

Is there any simple way round this feature other than having to install and run another piece of astro software?

Cheers

Link to comment
Share on other sites

2 hours ago, 8472 said:

I've set the slew limit to 20 degrees past the meridian, but that is the limit. Not far enough for my needs.

Hi 8472,

Is it a mechanical limit and no software at all will overcome this. This is a disadvantage of a German Equatorial mount but the advantage is that when you image you do not need a derotator as your image crop will always be the same and you have no field rotaiton.

A Alt/Azi mount can track through the whole night but you need a derotator because the image crop changes constantly.

As the small star tracker mounts like the star adventurer you mention, as they are sitting hig up on a tripod you can track very long with no mechanical limit when looking at 180° from horizon to horizon.

Rainer

Link to comment
Share on other sites

The reason most mounts require you to carry out a median flip is to avoid the telescope/camera hitting the tripod/pier.  Some mounts will happily carry on all the way through the meridian, such as ASA, but you need an offset pier to do so.

Meridian flips do not necessarily need you to be there for it to happen.  I have a video here which shows a fully automated meridian flip using SGP (image sequencing software) and you will see from it that I was nowhere near the mount when it happened.

Link to comment
Share on other sites

 

1 hour ago, Rainer said:

 

As the small star tracker mounts like the star adventurer you mention, as they are sitting hig up on a tripod you can track very long with no mechanical limit when looking at 180° from horizon to horizon.

 Rainer

Hi Rainer,

I'm not sure what you mean, here.

I have the same collision issues as any regular GEM owner - I have had to make a few mods on my setup to counter this (power source timer and an extended dovetail for mounting between the tracker and the wedge). But then again I have the full astro package. I guess you are referring to just using a ball head to attach a camera to the mount?

 

Link to comment
Share on other sites

1 hour ago, RayD said:

The reason most mounts require you to carry out a median flip is to avoid the telescope/camera hitting the tripod/pier.  Some mounts will happily carry on all the way through the meridian, such as ASA, but you need an offset pier to do so.

Meridian flips do not necessarily need you to be there for it to happen.  I have a video here which shows a fully automated meridian flip using SGP (image sequencing software) and you will see from it that I was nowhere near the mount when it happened.

Yes, I'm aware SGP will do it, but I really didn't want to deal with yet another layer of software. I guess it comes with the territory. 

Can APT do the same?

Link to comment
Share on other sites

12 minutes ago, 8472 said:

Yes, I'm aware SGP will do it, but I really didn't want to deal with yet another layer of software. I guess it comes with the territory. 

Can APT do the same?

As far as I am aware APT can handle automated flips.  As with any flip, the reframing after the flip is the most important thing as it reduces the amount of cropping that may be necessary when stacking images before and after the flip, so plate solving can help here.

As you say, it comes with the territory to add software if unattended flips are required.

Link to comment
Share on other sites

Archived

This topic is now archived and is closed to further replies.

  • Recently Browsing   0 members

    • No registered users viewing this page.
×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue. By using this site, you agree to our Terms of Use.