Balancing payload on both axis

[TiffsAndAstro]

So I would say the balance of my scope+other attached bits is "good" but I don't have much context as to how good it needs to be.

In turn, with one of the two clutches off,  balance on both axis individually seem perfect. but when I loosen both axis' clutches at the same time and  flip Ra fully east/left it is a tiny bit camera end heavy. When if flip Ra fully west/right it is a tiny bit lens hood side heavy.

Two not very enlightening pics attached. The one in darkness purely to show my counter weight setup in case it helps.

There is a guidescope and cam on other side of the usb hub out of sight.

I balance with lens caps off cos it does seem to help.

 

Edited May 23 by TiffsAndAstro

[Elp]

It depends on how it affects your guiding. My azgti has relatively tight axis so some of the imbalance is taken care of by it, my gem28 however is incredibly smooth and even a half mm difference in balance can make a difference. With the gem I've noticed the imbalance when imaging at 1000mm, at shorter FLs it becomes less critical. It all depends on your imaging pixel scale, your PA accuracy and your autoguiding performance I think to discern how much of a difference it's making. Best practice dictates get it near as good as you can, I have a similar issue, one side it'll be front heavy, then the other back heavy. Or if you're fortunate enough, get a dual axis HD drive mount and forget about balancing...

Edited May 23 by Elp

[TiffsAndAstro]

14 minutes ago, Elp said:

It depends on how it affects your guiding. My azgti has relatively tight axis so some of the imbalance is taken care of by it, my gem28 however is incredibly smooth and even a half mm difference in balance can make a difference. With the gem I've noticed the imbalance when imaging at 1000mm, at shorter FLs it becomes less critical. It all depends on your imaging pixel scale, your PA accuracy and your autoguiding performance I think to discern how much of a difference it's making. Best practice dictates get it near as good as you can, I have a similar issue, one side it'll be front heavy, then the other back heavy. Or if you're fortunate enough, get a dual axis HD drive mount and forget about balancing...

Yeah i've love a strainwave. just plonk my stuff on it any old how and away i go....

i think my balance might change my guiding from poor (1.4") to bad (as much as 2.5") and my image scale is 2.02"

next chance i get i am going to reset phd2 try again from scratch. i also have some other settings for my mount from a video i've seen on youtube, but im not convinced the youtuber is that wise  also some from an astrobin forum post. i can set them back

also going to try changing my guiding exposures from default 1.0 sec to 2 sec. my stars don't look great in phd2, sort of a nice little dot but surrounded by much larger circularish glow. in the target view they seem blobby and nebulous, but i've seen youtubers with similar or worse in the target view.

cheers for the help

[Elp]

It helps if you can mount stuff centrally like on those dual purpose top handles and accessory rails, even with a small asiair mini on one of those offset to the side finder shoes is enough to put it off balance. You can also get z axis balance kits. For my C6 when imaging 1000mm Ive put together a vixen dovetail clamp that has threaded holes through it, I can clamp it up front under the dovetail and screw into it gimbal counterweights to offset the balance. Diy-ing something similar but extended to one side may help, or put a dummy paperweight in a vacant finder shoe.

Edited May 23 by Elp

[TiffsAndAstro]

31 minutes ago, Elp said:

It helps if you can mount stuff centrally like on those dual purpose top handles and accessory rails, even with a small asiair mini on one of those offset to the side finder shoes is enough to put it off balance. You can also get z axis balance kits. For my C6 when imaging 1000mm Ive put together a vixen dovetail clamp that has threaded holes through it, I can clamp it up front under the dovetail and screw into it gimbal counterweights to offset the balance. Diy-ing something similar but extended to one side may help, or put a dummy paperweight in a vacant finder shoe.

Hmm a dummy weight opposite the finder is a possibility.

Also, I have two spare dovetails, one of which might stretch between the two screws on the top of the tube rings. I only have one such screw right now, and also not sure how I'd mount the finder scope on that  dovetail and keep it parallel to main scope, but it's food for though Ty again 

Edited May 23 by TiffsAndAstro

[Vroobel]

Yeah, you can balance your setup as best as possible, if you have e.g. a filter wheel and a heavy electronic focuser, and you want to rotate it to change the composition, then you have to do the balancing again. I also use a lot of Vixen bars around, so another clamp with threaded rod across with a small load would be the solution. Thanks. 🙂

[TiffsAndAstro]

1 hour ago, Vroobel said:

Yeah, you can balance your setup as best as possible, if you have e.g. a filter wheel and a heavy electronic focuser, and you want to rotate it to change the composition, then you have to do the balancing again. I also use a lot of Vixen bars around, so another clamp with threaded rod across with a small load would be the solution. Thanks. 🙂

No filter wheels etc so I'm hoping some weight to counter the guide scope and cam will help. It's not like I'm that far away.

Need to ask flo what kind of screw it is. I think I have to get two guide scope lamp things to mont it on a top vixen, or maybe I can buy a clamp with two screws. Will have a look around ty

[AstroMuni]

17 hours ago, TiffsAndAstro said:

Also, I have two spare dovetails, one of which might stretch between the two screws on the top of the tube rings. I only have one such screw right now, and also not sure how I'd mount the finder scope on that  dovetail and keep it parallel to main scope,

Does your tube ring have a screw for attaching a camera? On my previous OTA I used to attach my guidescope to that, as its easier to keep the balance

[TiffsAndAstro]

23 minutes ago, AstroMuni said:

Does your tube ring have a screw for attaching a camera? On my previous OTA I used to attach my guidescope to that, as its easier to keep the balance

I don't think so but will check. Not keen on this though because your setup looks prone to rotation around the single screw ?

I should be well under payload capacity so will try some counter weight and velcro

Edited May 24 by TiffsAndAstro

[AstroMuni]

3 hours ago, TiffsAndAstro said:

Not keen on this though because your setup looks prone to rotation around the single screw ?

I too had that concern when I started off, but found that it doesnt rotate at at all. This is a tried and trusted attachment for cameras and the locking 'nut' underneath ensures that its held tightly. I didnt have any issues with this arrangement though I used to dismantle the OTA from the mount every night to carry it back inside.

Edited May 24 by AstroMuni

[TiffsAndAstro]

3 minutes ago, AstroMuni said:

Not at all. This is a tried and trusted attachment for cameras and the locking 'nut' underneath ensures that its held tightly. I didnt have any issues with this arrangement though I used to dismantle the OTA from the mount every night to carry it back inside.

I don't like the idea of trying to line this up with my main scope at least using my finder clamp thing it seems close enough.

Going to look at top mounting a spare vixen dovetail on top, and then something with two screws to attach my guidescope and cam I think, but I'll probably give your solution a try first and it's cheaper

Ty for the suggestion and pic

[AstroMuni]

Note: The guide scope does not have to line up with the main scope is my understanding. Its after all trying to figure out the drift of a set of stars and send corrective impulses to the mount. The finder scope does need to align 🙂

Edited May 24 by AstroMuni

[TiffsAndAstro]

Just now, AstroMuni said:

Note: The guide scope does not have to line up with the main scope is my understanding. Its after all trying to figure out the drift of a set of stars and send corrective impulses to the mount.

Yeah that's my understanding too, but (I probably wrong) if your mounting point isn't top center of your OTA, some rotation left or right would actually be across both Ra and Dec? Which might be bad? Not sure I'm explaining that too well. Also my fl is like 420mm so probably wouldn't matter to my set up too much.

[Vroobel]

1 hour ago, TiffsAndAstro said:

I don't like the idea of trying to line this up with my main scope at least using my finder clamp thing it seems close enough.

Going to look at top mounting a spare vixen dovetail on top, and then something with two screws to attach my guidescope and cam I think, but I'll probably give your solution a try first and it's cheaper

Ty for the suggestion and pic

Invest in small Vixen clamps, you can use them to quick attaching the guider, ASIAir, mini PC, dew heaters controller etc. to the top and/or side Vixen bars. You will find them great when you buy another scope. 

[TiffsAndAstro]

35 minutes ago, Vroobel said:

Invest in small Vixen clamps, you can use them to quick attaching the guider, ASIAir, mini PC, dew heaters controller etc. to the top and/or side Vixen bars. You will find them great when you buy another scope. 

Looking on fleabay now

I like Nina too much to go asiair now. Can maybe get a mele quieter for just over £100 at some point nearer the heat death of the universe.

Edited May 24 by TiffsAndAstro

[Vroobel]

This is how I do it. 

 

 

They aren't particularly cheap, but it's really good and easy solution for a longer time. 

Edited May 24 by Vroobel

[TiffsAndAstro]

34 minutes ago, Vroobel said:

This is how I do it. 

 

 

They aren't particularly cheap, but it's really good and easy solution for a longer time. 

Very helpful Ty. Seen a clamp for £30 ish on fleabay so could be worse.

Of course, with hindsight I've realised I've rotated my scope in it's rings because i don't have a rotator. Which means attaching a dovetail on top of the OTA rings is pretty much my only option I think.

I have a spare  dovetail so I should just need a second screw for it and a clamp and screws for it, then plonk my guidescope on the new dovetail and space velcro on my usb hub to it, too.

What fun ill have.