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The trial and error continues!


DaveGarland
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Okey dokey, these are a bit rough n ready but I literally am just starting with the photography and just took advantage of a clear night to snap a few objects to see what happened. All pictures are just 20 x 40 second lights and 6 darks. My mount is only an EQ5 goto and I've been reading all about the bare minimum requirement being an HEQ5, nor is it guided so all in all I'm fairly pleased. I do realise my set up is limited but I also know I can do much better so please throw as much advice/criticism at me as you like. It's all a positive :)

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The Dumbell

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The Double Cluster

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The Ring

Dave.

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How to improve - do exactly what you're doing but for longer :)

There is a hint of trailing in the ring and the dumbell, I think, so if you want to try and push for longer exposures make sure you are very exacting with your polar alignment.

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Thanks guys :) I do my best with polar aligning but is it as important with a goto? I assumed it relied more on the three star alignment and then tracked using both motors. Or is it the case that it just uses three star alignment to find objects but then just tracks through the RA axis???

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I think you have made a great start.

Polar alignment is very important indeed to ensure the best tracking from your mount which might explain the star trailing that you are getting despite the short (40 secs.) exposures. The three star alignment is purely for mapping your mount against the night sky - the accurate movement of the RA axis to follow the sky is dependant on several things that are currently outside your control (like periodic errors and random drive errors caused by internal friction) BUT accurate polar alignment is something that you can do so it is time well spent.

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Thanks for clarifying that. In future, much more attention to alignment then. I have to ask though, if the trailing I had was do to alignment drift, wouldn't ALL the stars be trailing? The Dumbbell and Ring were both cropped and were towards an edge of the original picture. On the double cluster the stars around the edges seem to trail outwards.

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I hadn't noted that the M27 and M57 images were cropped - I should have though :rolleyes2: !!

What we are seeing here is coma - a natural (but unwanted!) feature of reflectors - a coma corrector will fix this.

My comment regarding polar alignment still stands though, it is key to accurate tracking - don't underestimate its importance, especially for longer exposures.

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Dave these are good efforts on these objects - I have been imaging M57 and M27 with my EQ-5 Synscan GoTo with a 200mm as well recently.

You're right, the advice that a HEQ5 is a minimum for a 200mm newt is true, to an extent. If you don't want to drop £800 on top of the c.£500 you've already spent on a EQ5 then I've found you don't have to. You can get "good" results with a bit of effort on the polar alignment and scope balance - and save the investment - My opinion is that the improvement I might see isn't going to be worth it (...but that is the kiss of death - next time you see my signature on the forum here it will probably have an NEQ6 har har!)

I think you're going to see some great results if you follow the advice submitted by other members above - good luck! :-)

David

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