Meridian flips necessary?

[ONIKKINEN]

May be a silly question but here goes:

Do i have to do a meridian flip if the scope isnt hitting the tripod anytime soon or anything is on risk of being snagged?

My gut says no, because why would the mount care? Could be wrong of course but just wondering.

Imaging maybe an hour past the meridian doesnt look like trouble and gives me more time with the target at its highest so its a preferable choice for me.

[Realtimedoctor]

More experienced members may give a better opinion. 

But if you are using a very short telescope, and nothing is going to hit your tripod legs, and no cables pulled then, the answer is as you said, you can carry on way past meridian. 

Having said that, depending on the mount you are using, some have an internal meridian limit, and will stop tracking once it hits that limit irrespective of any other factors. 

I usually image 30 mins past meridian with my 200p, but anything more than that I get into the territory of too close for comfort. Meridian flips, are quick and completely automated for me. I only align, after a meridian flip and guiding is resumed with the previous calibration ( some would disagree with this, that I should go another calibration). I only recalibrate guiding, if I switch targets. My focus is checked throughout the session, and usually I just focus after a certain degree of drop in temp, so don't bother re-focusing after flips. 

Hope that helps. 

Cheers, 

Nish 

[Same old newbie alert]

Most Gem have a limit on how far past the meridian they can track , then they have to flip.. the Avalon is one that can... 

[Chefgage]

If the mount allows it then no you do not need to do a meridian flip as long as nothing is getting snagged or trapped/hit.  An example is last night. I was imaging the rosette nebula with a heq5 pro and 72 ed refractor. As this target is low in the sky I was able to image 2 hours past the meridian.

[ONIKKINEN]

14 hours ago, Realtimedoctor said:

More experienced members may give a better opinion. 

But if you are using a very short telescope, and nothing is going to hit your tripod legs, and no cables pulled then, the answer is as you said, you can carry on way past meridian. 

Having said that, depending on the mount you are using, some have an internal meridian limit, and will stop tracking once it hits that limit irrespective of any other factors. 

I usually image 30 mins past meridian with my 200p, but anything more than that I get into the territory of too close for comfort. Meridian flips, are quick and completely automated for me. I only align, after a meridian flip and guiding is resumed with the previous calibration ( some would disagree with this, that I should go another calibration). I only recalibrate guiding, if I switch targets. My focus is checked throughout the session, and usually I just focus after a certain degree of drop in temp, so don't bother re-focusing after flips. 

Hope that helps. 

Cheers, 

Nish 

I use NINA so the flip itself is not really an issue. Platesolving will take the scope to where it needs to be after the flip. The image rotation that will happen with the flip is something i may have to deal with manually, and that would require new flats which i would rather not take. Also would require refocusing. Takes maybe 5-10 minutes total but i was planning on staying no longer than an hour so its a chunk of time lost. I havent heard of this internal limit before on Skywatcher mounts, but i think this is a thing in Ioptron CEM mounts with their internal cable routings. I should test this with mine.

14 hours ago, Same old newbie alert said:

Most Gem have a limit on how far past the meridian they can track , then they have to flip.. the Avalon is one that can... 

I was window shopping Avalon mounts and the M-uno looked really nice with full night rotation and no flips necessary. Would have to sell a kidney for that though...

1 hour ago, Chefgage said:

If the mount allows it then no you do not need to do a meridian flip as long as nothing is getting snagged or trapped/hit.  An example is last night. I was imaging the rosette nebula with a heq5 pro and 72 ed refractor. As this target is low in the sky I was able to image 2 hours past the meridian.

I am imaging with a VX8 and an AZ-EQ6 and ended up going 1 hour past the meridian and then went home. At this point there was no extra room left and i would have had to flip soon. The AZ-EQ6 and i believe the EQ6r have the tripod legs "backwards" where 2 of the 3 legs are towards the north side unlike most models where 2 legs are on the south side. This means the legs are pretty far away and even fat long tubes like my newt dont really hit the tripod legs anytime soon.

[scotty38]

@ONIKKINEN no need to worry about the rotation as star alignment will take care of that and no need for different flats, just flip and carry on……

[ONIKKINEN]

13 minutes ago, scotty38 said:

@ONIKKINEN no need to worry about the rotation as star alignment will take care of that and no need for different flats, just flip and carry on……

Ah, i meant if i dont have sensor real estate to spare. I am imaging a target where i dont really want to have to crop anything off, and having rotation means some parts have to be cropped. If the target is small enough then yes i dont care about it at all.

[carastro]

I often go well past the Meridian with no problems.  Just keep an eye on your scope and make sure to flip (or stop) before it hits either the tripod/pier.

I have a bit of cone error to images rotate slightly after a Meridian so I have to take slight crop off the edges.

Carole  

[alacant]

16 hours ago, ONIKKINEN said:

meridian flip if the scope isnt hitting the tripod anytime soon

No obligation to do so except that unless you do, you lose prime imaging time the other side of the meridian when the object is at its highest.

I'd say flip say 10 minutes after the meridian, and keep going until the target gets too low. If you've decent polar alignment and your telescope is reasonably aligned with DEC on the dovetail, you'll lose precious little of the field of view by performing a flip.

Set the mount to park at sunrise and you also get more sleep:)

HTH

[scotty38]

1 hour ago, ONIKKINEN said:

Ah, i meant if i dont have sensor real estate to spare. I am imaging a target where i dont really want to have to crop anything off, and having rotation means some parts have to be cropped. If the target is small enough then yes i dont care about it at all.

You shouldn't have to lose much at all, just a fraction off the edges and not a great deal more than you'd probably take off anyway really.

[Padraic M]

As above - you don't need to do flips if you're not going to hit anything. SW EQ5/EQ6 mounts don't have fixed limits but there may be limits set in EQMOD that can be cleared.

That said, I've had tripod crashes with the Esprit 80 which is not a big scope, and it looks really weird to see a scope hanging over backwards on a mount and still tracking. With NINA, flips are not that big a deal. I'm happy now to let a sequence run overnight, with automated flips, and a park to home at the end, while I sleep. I've rarely had an issue.

You don't need new flats as nothing is changing in the optical path, and your processing software will automatically register and rotate the lights when stacking.

[ONIKKINEN]

1 minute ago, scotty38 said:

You shouldn't have to lose much at all, just a fraction off the edges and not a great deal more than you'd probably take off anyway really.

I have considerable cone error somewhere in my scope which i have not bothered to fix yet. The tube itself is a bit crooked and the rings/plate are a bit agricultural for imaging purposes in the VX8 so both will probably have to be tended to at one point. I could probably try and shim it and make it a bit better since its so obviously off, but i try not to fix things that aren't too badly broken as to not create more problems. More in the ever growing list of things to fix and tinker with in astrophotography 😬.

[scotty38]

19 minutes ago, ONIKKINEN said:

I have considerable cone error somewhere in my scope which i have not bothered to fix yet. The tube itself is a bit crooked and the rings/plate are a bit agricultural for imaging purposes in the VX8 so both will probably have to be tended to at one point. I could probably try and shim it and make it a bit better since its so obviously off, but i try not to fix things that aren't too badly broken as to not create more problems. More in the ever growing list of things to fix and tinker with in astrophotography 😬.

Ah ok fair enough, if you have other gremlins in the system. Just that the flip in itself shouldn't cause you the issues but understood.....