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  #1  
Old 15-10-2018, 10:51 PM
Mickoid (Michael)
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Lens Test

With good conditions in Victoria last Friday, it was time to test out this Sigma 50-200mm apo lens I got off Gumtree for $80. The lens was made in about 1985 but looked in reasonable condition and back then they claimed it had almost zero CA with several ED glass elements. Well we all know how demanding astrophotography is on lens performance. Almost zero CA for daylight terrestrial photography maybe but for night time star shots, well, I'd rate it OK but CA was still evident.

Here's a few quickies I did Friday night from near Woodend, Victoria, where Melbourne's urban skyglow is still quite noticeable. IC 2118 was probably a bit ambitious from here and only 32 x 90 sec subs could be managed because this dam wind blew up from no where so I decided to pack up. Before I put everything away back in the car, I shot 6 x 90 secs subs of M45 and 4 x 90 secs subs of the belt and sword of Orion. All shots taken with the modded Canon 550d at 1600 iso F 5.6 on a HEQ5pro mount unguided.

PS. And yes, I did use StarTools to assist in processing these images but finished off in Photoshop.
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Last edited by Mickoid; 15-10-2018 at 11:28 PM. Reason: Add text
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  #2  
Old 16-10-2018, 06:36 AM
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Anth10 (Anthony M)
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Cool pics Mick! Like the star spikes for a different look. Plenty of color. I like the Witch!
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  #3  
Old 16-10-2018, 07:07 AM
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I'd say this is excellent lens.
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  #4  
Old 16-10-2018, 07:35 AM
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RickS (Rick)
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That's a promising start!
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  #5  
Old 16-10-2018, 10:26 AM
Mickoid (Michael)
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Quote:
Originally Posted by Anth10 View Post
Cool pics Mick! Like the star spikes for a different look. Plenty of color. I like the Witch!
Thanks Anthony, plenty of colour yes, I think I may have overdone the saturation on these. They looked fine on my laptop but they look a bit rich when viewed on this forum. I may tame them a little and replace them with one's that look more natural.

Quote:
Originally Posted by bojan View Post
I'd say this is excellent lens.
Yes, I think it's a keeper, pity it's not a bit faster, maximum aperture at 200mm is just f 4.5. I shot these at f 5.6 but f8 would be better. At f 8, a 3min sub would be too much to ask unguided, could shoot at 3200ISO and maintain the exposure time but noise would then be a problem.

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Originally Posted by RickS View Post
That's a promising start!
Thanks Rick, had to start somewhere, might try it out on the SMC & LMC next new moon.
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  #6  
Old 16-10-2018, 10:50 AM
Imme (Jon)
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The witch is absolutely great Mickoid....awesome.

It's amazing that you can pull these kind of pics out with a 30 year old lens from gumtree isn't it. So much for spending mega bucks on scopes!
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  #7  
Old 16-10-2018, 12:06 PM
raymo
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The lens does a good job Michael. I find it interesting that I have a set of
6x 100secs f/2.8 ISO 1600 taken with my nifty fifty, and there is no trace of the witch.
raymo
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  #8  
Old 16-10-2018, 02:13 PM
Mickoid (Michael)
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Raymo, this reflection nebula is very dim, lit by the star Rigel. You have to get yourself out to a relatively dark sky to have any chance of capturing it. Don't know why you couldn't see it with essentially the same amount of exposure, though at 50mm it would have been small. There were a few taken at f4.5 amongst the 32 subs only because I forgot to stop down after refocusing but the majority were at f 5.6. It may have been in your processing that restricted the witch from displaying her features, your blacks certainly can't afford to be clipped. You could hardly see her in a single sub and only because I knew what to look for. To the untrained eye she would be invisable. Not until I stacked the 32 subs did she reveal herself and I would have liked to have taken a lot more, had the wind not been a problem.

Try reprocessing your old data differently, maybe stretch it a bit more but that will be difficult with only 6 subs. Noise will then become your enemy.

Last edited by Mickoid; 16-10-2018 at 03:08 PM.
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  #9  
Old 16-10-2018, 02:51 PM
raymo
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I'll have a go Michael, thanks. My sky is Bortle 3.
raymo
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  #10  
Old 16-10-2018, 03:33 PM
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This is a pretty good result.
Sigma weren't high on peoples list of preferred lenses back then, and the quality was the reason why. They were certainly heading toward where they are positioned today, but the camera makers own brand lenses and Tamron were most popular. Part of this was that they made some very cheap lenses for Pentax/Ricoh to go on the cheaper cameras like the P30 in the 28/35-70 range as a kit lens. And again in a basic 70-200 range zoom. This was basically the image they had; Cheap kit lenses
This would have to be among their first forays into ED type lenses for the photographic market (as opposed to scientific lens market) and tests pretty good. As did their 100-500 (which was a monster of a lens that sold for around $3000 in 1985).
A good pick score, and for $80!

Trev
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  #11  
Old 16-10-2018, 04:23 PM
Mickoid (Michael)
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Thanks for the info and knowledge on these ED lenses, Trevor. Sigma did try getting into the higher end of the market with the release of these models. They look like the Canon USM lenses as this one I have is light grey, actually looks quite nice. The added bonus too is a locking screw on the side of the lens to keep it at the correct focus and focal length. Very handy if you're pointing the camera toward the zenith.

Last edited by Mickoid; 17-10-2018 at 10:38 AM.
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