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Star adventurer

gary1968

By gary1968
in Discussions - Mounts

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Davey-T

Davey-T

Posted
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Did a bit of experimenting and it appears not to be drifting but tracking too slowly.

What lens are you using ? don't know if 300mm is pushing it.

I've bought a new set of high Ah rechargeable batteries and left it running all day to bed in, will have another go when / if the stars come out.

60secs with 300mm f/4 does get a 40% histogram on the Pleiades so that may be all I need,

Dave

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gary1968

gary1968

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Hi Dave,

I was using a EF50 1.8. I have seen some pretty good images online from the SA with a 300mm lens so, in theory, it must be up to the job. I wont be able to test mine at that length until after Santa has been. It will be a disappointment if it cant do that.

Gaz

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Davey-T

Davey-T

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Roll on Christmas  :icon_santa:  :icon_rendeer:  :icon_rendeer:  :icon_rendeer: I was supposed to wait 'till Christmas but temptation got the better of me  :grin:

One thing I did today was file out the slot in the L bracket so I could fit the Polar scope in it, can't see much point PAing and then mounting the camera and weight, will now be able to leave it in whilst imaging so I can check the PA .

Dave

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Davey-T

Davey-T

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I will be using mine for the first time tonight, hopefully all goes well.

Polar scope didn't really need aligning, if I'm going above 200mm then I may give it a tweek but for now I will leave it just in case I mess it up.

Did you have any luck ?

Dave

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Alien 13

Alien 13

Posted
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Did a bit of experimenting and it appears not to be drifting but tracking too slowly.

What lens are you using ? don't know if 300mm is pushing it.

I've bought a new set of high Ah rechargeable batteries and left it running all day to bed in, will have another go when / if the stars come out.

60secs with 300mm f/4 does get a 40% histogram on the Pleiades so that may be all I need,

Dave

Just a thought but rechargable batteries have a lower output voltage compared to normal alkalines 1.2 vs 1.5V.

Alan

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Davey-T

Davey-T

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Just a thought but rechargable batteries have a lower output voltage compared to normal alkalines 1.2 vs 1.5V.

Alan

Thanks Alan 

In the manual it just says "AA" batteries, so presumably rechargeable should work, got 2450 mah batteries, 4.8V , runs on 5V nominal so who knows, will get some "normal" ones and try.

Dave

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gary1968

gary1968

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Just a bit of info, after some rooting about on the net I found that someone has carried out a fairly intensive study on the SA, or at least his example. He recons that the SA should be able to manage a 200mm lens unguided..... This is based on accurate PA and takes PE into account.

If mine proves this to be true then I'll be fairly happy, I am happy to guide for longer exposures.

Sent from my Vodafone Smart 4 turbo

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Davey-T

Davey-T

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I was at work when I found it, he was doing 2mins at 200mm. O can't find the link on my phone, will look on the works PC tomoz and post a link.

Sent from my Vodafone Smart 4 turbo

Thanks Gary, don't work too hard  :grin:

Dave

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Davey-T

Davey-T

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Thanks for the link Gary, makes interesting reading, particularly as he thinks 300mm should be possible.

On the Polar scope subject I've filed out the slot in the dovetail enough to clip the Polar scope in so it can used with the mount loaded, works OK so don't know why it isn't made like that to start with.

Dave 

post-21198-0-65023600-1417098464_thumb.j

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hobsey

hobsey

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Just a couple of things you could try.

If you're using that dovetail, try it with the counter weight because to me without it it looks top heavy and the other thing you could try is using just the small dovetail with a ballhead to mount the camera.

You never know, one of these may sort your eggy stars.

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Davey-T

Davey-T

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No still waiting for a decent night, maybe this weekend but you can't trust those weather forecasters 

I had a knee replacement op a few years ago, worked a treat, knee is great, just need the rest of me fixing now  :grin:

Dave

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Davey-T

Davey-T

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So finally got a clear night to check this out and it still appears to be tracking too slowly, I've tried rechargeable and alkaline batteries an USB output from power pack and all results are the same.

Also checked Polar Scope alignment which is spot on and left it set up for several hours and Polaris tracked perfectly round the P'Scope reticle circle.

This is an animated GIF of Capella two 10min images taken 10min apart, the star movement is in RA caused by the mount not keeping up with the stars.

Canon 60Da and Canon 300mm f/4, not planning to use 300mm routinely just to demonstrate.

Dave

post-21198-0-87810200-1417971351.gif

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Davey-T

Davey-T

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So, what now then Dave? You gonna send it back or try guiding?

Sent from my Vodafone Smart 4 turbo

Don't know, will have a word with FLO to see if I'm expecting too much. Can't see how guiding will help, don't think it can make the mount go faster.

Dave

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Davey-T

Davey-T

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I want to go out tonight to test mine out as I haven't yet but it's pointless with the moon out.

Not if it's like mine, did all my testing the other night with the Moon, just JPEGS  to see how it tracked.

Dave

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