eggs question whilst guiding

[mgirdwood]

hi all, 

currently trying to sort out the set up again after months on no action.  target at the the moment is M42 and i wonder if anyone can give me hint as to the probable cause of the attached photo of a 320 sec sub taken 1130pm CET.  earlier with M45 i was able to use 600 sec subs with nice round stars.  M42 is lower of course and now the scope is almost horizontal, so i am wondering if this is now a specific weight balance issue. ?

i have lowered the weights further down the arm (east) which i think is the correct positioning - i.e. east heavy, but i don't have much more travel left so i wonder if i am missing something ?

Thanks for any suggestions

Mark

[gkec]

If you release the clutches in that position does the scope move? If it does then it is out of balance.

Also with M42 being "lower" so further away from the NCP the apparent movement across the sky is greater so polar misalignment issues are magnified.

[Freddie]

You say this is whilst guiding. Can you give some more info. on what your guide graph looks like and is the elongation aligned with dec or RA or neither?

[lensman57]

hi all, 

currently trying to sort out the set up again after months on no action.  target at the the moment is M42 and i wonder if anyone can give me hint as to the probable cause of the attached photo of a 320 sec sub taken 1130pm CET.  earlier with M45 i was able to use 600 sec subs with nice round stars.  M42 is lower of course and now the scope is almost horizontal, so i am wondering if this is now a specific weight balance issue. ?

i have lowered the weights further down the arm (east) which i think is the correct positioning - i.e. east heavy, but i don't have much more travel left so i wonder if i am missing something ?

Thanks for any suggestions

Mark

Guiding at low elevation requires the balance to be spot on. The guiding software also needs to recalibrate itself to the new elevation, if this is not done bad guiding is the result, you must also make 100% sure that there is no flexure in the imaging terain as the mount's orienration changes. You can try and correct slight star trails in PS. Copy the layer then change the blend mode of the copy (top layer) in the layers palette to Darken (from the drop down list) then go to filters, other, offset and dial in one pixel at a time in the horizontal and vertical panes until the stars look round, if it does not work after a few tries then it is not going to work as it may distort the image. Once done flatten with normal blend, use multiple cycles of small adjustments. Here is a quick play to show you that is if you didn't know already.

A.G

[Astrosurf]

I always recalibrate when moving to a new object, as A.G. said. It's interesting though, I often find if the balance is off my guiding works better. It's said it's best to have the heavier side on the rising side, but I never can get that in my head so I don't bother! Normally for me guiding is rough when at the zenith.

Alexxx

[Freddie]

I always recalibrate when moving to a new object, as A.G. said. It's interesting though, I often find if the balance is off my guiding works better. It's said it's best to have the heavier side on the rising side, but I never can get that in my head so I don't bother! Normally for me guiding is rough when at the zenith.

Alexxx

Just think of it as needing to move the weights towards the east.

[Astrosurf]

Thanks Freddie. My weights for the 200P are already at the end of the bar. I'd have to get an extention. It's a possibility!

[swag72]

I found that there were just some areas of the sky that my mount did not like and would not guide well in - low south became almost impossible to be honest, despite doing all sorts of odd things with balance and the like.

[Freddie]

Thanks Freddie. My weights for the 200P are already at the end of the bar. I'd have to get an extention. It's a possibility!

Or an extra small weight. When you move across the meridian and do a flip you would obviously need to move the weights away from the end of the bar.

[Astrosurf]

Too true.

[IanL]

I found that there were just some areas of the sky that my mount did not like and would not guide well in - low south became almost impossible to be honest, despite doing all sorts of odd things with balance and the like.

Same here, low South-East always seems to produce much worse guiding for me.  On the other hand, tracking through and beyond the meridian (even up at the zenith) works fine, though theoretically it should be the one place where a cheap mount would definitely have problems.  Go figure!