Speeds And Barlows

[Kevdan]

Hi All,

Im About to get a motor drive for my eq3-2 mount, But was wondering about the speeds, If the motor drive has 1x 2x and 4x speeds then surley if you use a 3x barlow it wont track as the 2x would be too slow and 4x too fast and I havent seen a 4x barlow on sale but it would be too powerfull for my scope anyway with my current eyepieces.

If I am right 1x = normal viewing through a eyepiece with no barlow

2x is with 2x barlow

4x would be either side of speeds required.

Kev.

[RogerTheDodger]

It doesn't matter what barlow you use, the sidereal rate will always be x1.

[Merlin66]

kev,

The mount speed has nothing to do with the scope. The mount doesn't even know what telescope you use...a short refractor or a very very long reflector.

The x1 is the normal tracking rate to follow the stars. The other x2, x4 etc is for fast slewing between objects.

The x 2 etc for a Barlow just means that's the increase it makes in the focal length of the scope i.e. if you have a 150mm f5, focal length 750mm telescope; with a x2 Barlow it would effectively become a 150mm, f10, focal length 1500mm.

HTH

[Kevdan]

Thanks guys,

So the reason for the object apearing to move faster is then down to a smaller field of view with say a 4mm ep compared to a 25mm ep.

I guess Im going to be a a learning curve for quite some time. and then just when I think I've learnt what I need to know there'll be so much more to learn.

Kev.