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PostPosted: Mon Mar 12, 2012 12:52 pm 
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Hi folks,

It's taken me a year to put the system together (ASA DDM60 Pro mounting, TEC 140 telescope, FLI CenterLine filter wheel and FLI ML16803 camera) but I achieved a very quick "first light" set of exposures using the TEC 140 last night. Just 5 x 200 second unguided lights of the Pleiades through a blue filter. The Pleiades were already getting pretty low to the horizon before I had to get back to work calibrating the mounting. The raw data is quite noisy, I haven't got any "flats" yet so any vignetting is uncorrected and the extreme contrast in brightness probably means that when I return to this subject I'll not only need more exposures but for best results may need to fine tune the exposure time to reduce star bloat. I'll also definitely need to sharpen up my processing skills but hopefully the brightest stars will get a bit tighter when I can add red and green data as well. Anyhoo, enough apologizing! Here's the result, uncropped except for the loss of 48 pixels on each border and then downsized to a forum friendly 768 x 768 pixels:

    Image
The field of view is about 2° edge to edge or 3° corner to corner (for comparison the full Moon is about half a degree) and looking at the original 4096 x 4096 images stars are tight and circular right to the corners of the field and even though the mounting hadn't been retrained for the new configuration unguided tracking was perfectly good for the 200 seconds it took to capture each frame. And the good news for my future convenience is that focusing was entirely automatic courtesy of MaximDL working in conjunction with the Starlight Instruments motorized focuser I retrofitted to the TEC 140 'scope. I'm also happy enough that despite the relatively slow f/7 focal ratio the ML16803 camera (working at -25°C) was able to capture the reflection nebulosity relatively easily. Hopefully it will be clear again tonight so it will be back to calibration work pointing at 30 plus stars and fine tuning the pointing accuracy so that the software controlling the mounting can compensate even better for residual polar alignment errors, flexure in the telescope and atmospheric refraction. The aim is to be able to achieve, at need, at least 1,000 seconds unguided exposures when that's completed! 8)

Bob.

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Olympus OM-D E-M1 + M.Zuiko Digital ED 12-40mm f/2.8, Lumix 7-14mm f/4, Leica DG Summilux 15mm f/1.7 ASPH, M.Zuiko Digital 45mm 1:1.8, M.Zuiko Digital ED 75mm 1:1.8.
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OM-D E-M5, H-PS14042E, Gitzo GT1541T, Arca-Swiss Z1 DP ball-head.
Astrophotography: TEC 140 'scope, FLI ML16803 camera, ASA DDM60 Pro mount.


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PostPosted: Wed Mar 28, 2012 5:36 pm 
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Location: Bristol, UK
I wouldnt apologise for that, a very nice image and a great start.

Its a shame were moving into summer now, just as Ive started to crack this imaging lark!

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PostPosted: Fri Sep 21, 2012 3:35 pm 
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Hi folks,

I returned to the Pleiades and I thought I'd share the latest in the original thread, not just for comparison but because I expect to do more tweaking so this is just a V0.1 image:

    Image

5 x 1,000 seconds and 5 x 200 seconds through the blue filter plus 5 x 200 seconds through each of green and red. The processing has been a challenge to say the least as the bright stars are inseparable from the surrounding reflection nebulosity so I've had to modify my usual "No Stars" workflow but I think I'm improving! :)

Bob.

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Olympus OM-D E-M1 + M.Zuiko Digital ED 12-40mm f/2.8, Lumix 7-14mm f/4, Leica DG Summilux 15mm f/1.7 ASPH, M.Zuiko Digital 45mm 1:1.8, M.Zuiko Digital ED 75mm 1:1.8.
Leica D Vario-Elmar 14mm-150mm f/3.5 - f/5.6 ASPH.
OM-D E-M5, H-PS14042E, Gitzo GT1541T, Arca-Swiss Z1 DP ball-head.
Astrophotography: TEC 140 'scope, FLI ML16803 camera, ASA DDM60 Pro mount.


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PostPosted: Fri Sep 21, 2012 8:11 pm 
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Location: Mexico City, Mexico
I'm impressed with it, looks really awesome! Personally I think it's a large improvement from the first one, I really loved this one :D

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