Equatorial Mount Issues

[Maged]

Hi

I have Sky View EQ-4 mount and I was hoping to take some long exposure shots of Orion nebula after installing a RA motor drive. 

All my attempts were a failure, I guess the mount is not good for long exposures, and the motor is not that stable, sometimes it gets jammed and sometimes sped varies which cause drifting and star trails. 

I am using a refractor 106mm aperture and 900mm focal length

Anyways I am thinking of buying a new mount, so any suggestions?

Thanks

[happy-kat]

Have you balanced the telescope really well?

[Maged]

happy-kat I think I will have to check the balancing tonight and see if it works

[Tinker1947]

Balance and Polar Alignment are the keys to good images, your next upgrade close to the bottom end of the mount market would be a HEQ5, if the budget is bigger what's the upper limit..

[Maged]

But just to confirm, does the balancing affect the motor, I mean I can sometimes feel the motor working and even when I use the 8x speed for adjustments I can hear its sound but the telescope is not moving and the motor is jammed.

[RichM63]

If you think about it, then yes of course.

Fully balanced would mean less force required to move things or keep them moving. If you are way out of balance then your poor motor will be trying to push a lot of weight in one direction, conversly it will be in free fall in the other direction.

Your motor can only really exert a small force, and so if the mount arrives at a position where the weight acting on the motor is greater than it can cope with, it will conk out.

Balanced, means that you can unlock the clutches and the rig will stay in the same position until you gently push it, and then it will remain in this new position. (keep a hand on the telescope whenever you have unlocked clutches).

[ronin]

What is "long exposure" duration that you are attempting?

On a driven mount I would guess that 60 seconds is possibly normal.

You may get up to 120 seconds but not more and this all depends on the accuracy of the polar alignment. You will need to spend a fair bit of time in getting the alignment accurate.

The scope is a bit long at 900mm focal length and that adds to the need for good polar alignment.

When balancing people will often have the weight not set central as that allows the scope to "rock" a bit on the play in the gears. Spend a little time to look this up - cannot halp as I have no idea on the correct term to go search for.

The motor should not appear to stop/start.

At normal speed the scope is driven round very slowly, quite a few think it is not moving when it is.

I would check the motor is located correctly and that it meshes with the other one correctly - not too tight and not too loose.

The tripod the mount is on looks like the EQ3-2 tripod here, as it is an Orion and EQ4 I guess you are not UK ???

The tripod is not known for it's stability unfortunately, do not over tighten the screws in the leg clamps, the clamps tend to break.

You should get images of M42, but the arguement will be the length, aim at 60 seconds and get 10 or 20 good ones then stack the best.. However I think the polar alignment will need to be performed fairly accurately. Have you a polar scope ??

If you are hanging a DSLR on the end then remember that a 106 refractor is not lightweight and a DSLR add to that weight. Driving this weight around is (if I am correct) a small 6volt motor.

[Maged]

ronin

Thanks for the advice.

I've been trying maximum 30 sec of exposure, and yes the motor is only 6volt and I can feel the weight including the camera is much for that motor. But I will try to balance and polar align more accurately.

[happy-kat]

Balance with the camera attached so the weight represents all it is having to work with when you try to image.

Good luck, hope you can suss the balance point out.