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Reprocessed SuperNewt Double Cluster

Catanonia

By Catanonia
in Imaging - Deep Sky

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Catanonia

Catanonia

Posted
Posted

More learning curves this time with flats. I took some more flats and this time they looked much better. Really should have checked before. Learning curves with new equipment eh :)

So here is a "Proper" image of the double cluster with 22 x 1 minute subs at 568mm F2.8 Total time was 88 min unbinned LRGB

Full sized image here showing my colllimation issues.

http://dl.dropbox.com/u/10801850/Astro%20Pictures/Large%20Files/Double%20Cluster%2088min%20SuperNewt.jpg 6mb download.

post-16631-133877705693_thumb.jpg

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Catanonia

Catanonia

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22 mins and just look a the star colours, that is really nice.

yup, 22 times 1 min subs for each LRGB channel. Super fast and the reason I got the scope to allow me to image in the rubbish UK weather and hopefully allow me to get an image a night rather than over 2 - 3 nights.

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Catanonia

Catanonia

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Thanks Olly.

I have given up on sight tube collimation incorporated with a laser collimator, as people have said, it just isn't good enough even after 4 stripdowns and rebuilds / collimations.

So hopefully I shall be getting a call from Steve (FLO) tomorrow to order a BlackCat triple combo set and do it the expensive way :icon_salut::D

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harry page

harry page

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Hi

As said focusing away from the centre is a good idea :)

Also collimation of the scope may not be your problem now it might be how square the camera is to the focal plane :icon_salut:

try rotating the camera in the focuser and see if the dodgey stars follow the camera ?

Harry

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Catanonia

Catanonia

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Hi

As said focusing away from the centre is a good idea :)

Also collimation of the scope may not be your problem now it might be how square the camera is to the focal plane :icon_salut:

try rotating the camera in the focuser and see if the dodgey stars follow the camera ?

Harry

mmm, happens in all orientations of the camera, always top/ bottom left / right depending on processing..... I have imaged in loads of places in the focuser. The focuser is dead square checked it today and totally rigid with no flex or sag. Focuser with laser hits perfectly opposite side of the OTA and passed directly through the spider centre with a bar attached.

Now you have got me concerned it may be the camera and CCD not being square, but it makes perfect sense. Doesn't seem right that 4 collimations results show the same problem in the same place in the image with the random inaccuracy factor. That said however the laser collimator I have is pretty pants and shows a slightly different dot on the primary each time you remove and replace it. It is collimated as much I can tell, but that may be the major problem.

Well hopefully I will have a catseye system soon, will be good to have one anyway as I have no real collimation tools other than a made up pin hole and a cheap laser pointer with a Orion self centre connection. (think Holtech). That should tell for sure.

I will in the meantime, strip the camera and connectors to ensure no crossed threads or loose parts that may put the CCD off centre.

Tonight I re-colimated and focused off centre as suggested and it seemed to reduce the effects a bit, but still comet tails on the top left section of the sub.

Personally I think it is collimation errors of the F4 being amplified by the reducer. Hopefully the catseye will solve this.

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Tim

Tim

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Good choice on the catseye stuff. Once you have it you will see for certain that you have optical alignment, any errors then will be the focuser out etc.

I'd say looking at the stars that you have a slightly rotated secondary and focuser that is tilted slightly from the optical plane.

When you get your kit, let us know how well centred the centre donut is. Mine was a couple of mm out on my GSO. The catsye hotspotting method is great and works a treat.

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Catanonia

Catanonia

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Good choice on the catseye stuff. Once you have it you will see for certain that you have optical alignment, any errors then will be the focuser out etc.

I'd say looking at the stars that you have a slightly rotated secondary and focuser that is tilted slightly from the optical plane.

When you get your kit, let us know how well centred the centre donut is. Mine was a couple of mm out on my GSO. The catsye hotspotting method is great and works a treat.

Sure thing Tim. Just a quck question, how do you remove the old donut from the primary ?

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Merlin66

Merlin66

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You'll get some nice tight star images at f2.8, the Airy disk is only 3.75 micron in diameter!!!!!

If the seeing is very steady you'll get some tremendous results!

You may need to watch your plate scale/ pixel size for optimum sampling....

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