First Light with AVX but...

[Thalestris24]

Hi All

So after getting over my mental block, lol, I got the AVX going yesterday and thought I'd give it a try out

I was very pleased with it's tracking, not so pleased with the noise it makes! I'm probably spoilt with Heq5 setup which slews much more slowly and keeps the slew speed down for changing to not-too-distant objects. I presume this is because the AVX uses servo motors? It overshoots targets then finds it's way back. On the other hand PA adjustment was quite easy - big bolts so fine adjustment takes some practice. Much better than on the heq5, I'd say, although I've always had doubts about the stability of my heq5's adjustment.

Anyway, I had a quick go at the Orion Nebula with my Canon 1100d and 75-300mm lens at 300mm, F8 and unguided. I've not done any calibration frames at all but here is my image. It's made up of 10 x 60s at ISO 400, and 20 x 60s at ISO 800. Quick process in StarTools and cropped a bit:

However, there seems to be a problem with the lens The right hand side, in particular, shows elongated stars. This looks like some sort of tilt of the whole lens assembly? Or individual lens misalignment? Has anyone else experienced this before and have a solution?

Thanks

Louise

[james_screech]

The AVX is a great mount (far better than my previous EQ5), as you say the only minor issue is the noise of the motors.

I don't think they overshoot is due to the servo motors but due to always doing the final part of the slew in the same direction for consistency, so sometimes the mount needs to first move past the target position before moving back. The inbuilt polar alignment system works well too.

James

[Thalestris24]

Hi

Ok, glad you like the AVX . I'm not worried about the overshoot - it was just an observation really.

Anyone have any idea about my lens problem? Might it be fixable? I can't see any obvious problem with either the lens or camera body externally.

Thanks

Louise

[blinky]

What time was that image taken at!  You must have stayed up all night to get Orion at this time of the year!

[Thalestris24]

What time was that image taken at!  You must have stayed up all night to get Orion at this time of the year!

Yep, I think I started Orion at about 4:30! I was iimaging (or trying to!) until it got too light. Started  with other targets  as soon as it had got dark. Have to grab it when I  can  here in Glasgow!

Louise

[wxsatuser]

Hi All

However, there seems to be a problem with the lens The right hand side, in particular, shows elongated stars. This looks like some sort of tilt of the whole lens assembly? Or individual lens misalignment? Has anyone else experienced this before and have a solution?

Thanks

Louise

It may be lateral chromatic abberation.

Would need to see an unprocessed image, if it is this you may see the colours smeared in the elongation.

It has the effect of elongating the stars off axis and they will point towards the centre of the image.

If it is this I would think you are stuck with it.

[Thalestris24]

Hi

Here's a single sub as jpeg, unprocessed but reduced to 30% of original size:

 

Looking back through the archives, the camera+lens didn't used to have this problem but it's a long time since I last used it (Dec '13). So it's something that's crept in... I'm wondering if the lens has taken a knock though I can't recall anything happening. The lens doesn't look like it's an easy matter to take apart? I had the idea that maybe the zoom part of the lens might be the cause as it has a fair bit of potential movement. I'll investigate that further at next opportunity.

Thanks

Louise