Question on EQ6 jiggles

[Zuts]

Hi All,

I have a 9mm meade illuminated reticle. When 2 by barlowed on my 480mm scope what would be the angular size of the square in the middle of the reticle. And what would be the equivalent size with the 400d at prime focus.

I want to know because that will tell me how big the jiggling on my eq6 is. After drift aligning with a barlow a star will jiggle around inside the squre, back and forth.

is this correct

480 mm scope
9 mm reticle
2 by barlow

reticle is meade plossl and i assume 50 degree field of view


so 480 / 4.5 = 106.6 magnification

and actual field of view = roughly .47 degrees

if the centre square of the reticle is about an 80th of the width of the reticle then this angle would be about 0.006 degrees or about 2 arc seconds.

So the fact that the star jiggles around inside the square would not be a problem and should not be visible on my images with a 400d at prime focus?

What do you guys think; and do other eq6 owners get the jiggles?

Paul

[Alchemy (Clive)]

instead of doing high tech math i just turn off the drive and count how many seconds it takes to move accross the field of view.

given a star moves 15 arc seconds per second you will get the exact amount of movement and size of your frame.

2 arc seconds would be just scintillation.... seeing....the effect of the different temperature layers and movement in the atmosphere,

any movement will have an effect on images its just a matter of degree of acceptability.

[[1ponders] (Paul)]

Definately just do a drift measurement. It is much easier, though if you need to work out your FOV then there are plenty of free ones around. In fact I think someone or two have posted a couple on the site here.

[JohnG (John)]

If it is jumping around 2 arc seconds, sure sounds like seeing to me as well so I agree with what Paul and Alchemy have said.

Here is a link to the Pickering Seeing scale, you might be able to judge from these examples as to what your seeing was:

http://uk.geocities.com/dpeach_78/pickering.htm

If you still think that your mount might be vibrating, you appear to only have a light load on it, you can try doing what we had to do years ago to solve that problem, hang a sandbag under the center of the mount, used to solve damping problems almost instananeously.

Cheers

[wasyoungonce (Brendan)]

I remember a cloudy night review of the EQ6 stating the mount had "jitter" in RA, mainly observable at higher magnification. I believe the fix was to "un-balance" the setup slightly. This placed pressure on the gears eliminating the problem.

Hope this helps?

http://www.cloudynights.com/documents/eq6.pdf