Orpington Astronomical Society

Astronomy => Astrophotography => Topic started by: Rocket Pooch on Feb 08, 2012, 05:34:36

Title: Has anyone seen this...
Post by: Rocket Pooch on Feb 08, 2012, 05:34:36
Hi,

Bumped into this image taken with a 70-200L canon lens at 200mm F5.6, I think its amazing.  And I have one of those lenses

http://www.caliu.fotografiaastronomica.com/grancampo/grancampo.htm

(http://www.caliu.fotografiaastronomica.com/grancampo/M45W_1200.jpg)
Title: Re: Has anyone seen this...
Post by: Fay on Feb 08, 2012, 08:31:43
That is lovely Chris. it looks like Thors Helmet
Title: Re: Has anyone seen this...
Post by: doug on Feb 08, 2012, 08:32:43
It`s the Pleiades........
Title: Re: Has anyone seen this...
Post by: mickw on Feb 08, 2012, 09:41:53
A modified 5D - Brave man :o

Does look a bit like Thors Helmet
Title: Re: Has anyone seen this...
Post by: Mac on Feb 08, 2012, 14:24:37
Just goes to show what you can actually achieve with anything.
and thats only with 4 hours exposure.

Thats a pretty darn good photo.

Hmmm time to dust of the D3 and get out there.

now wheres my screwdriver and knife.

Mac.

The challenge is to get 4 hours of clear skies over here though. :cheesy:
Title: Re: Has anyone seen this...
Post by: Fay on Feb 08, 2012, 22:11:43
i know its the Pleiades, but the shape is similar to TH
Title: Re: Has anyone seen this...
Post by: Rocket Pooch on Feb 09, 2012, 08:09:32
Olly sent me one of his new as yet unpublished ones and he has taken a heath robinson approach to removing the spikes and it works perfectly!

Title: Re: Has anyone seen this...
Post by: RobertM on Feb 09, 2012, 08:32:16
That's a very nice image, shame about the spikes though.  I do wish Canon would put decent curved iris blades in their lenses.  The only other way that I know of removing them is with a circular aperture restruction before the front lens and I think that's what Olly does.  It's easy enough to do but it's a shame to spend all that money on expensive glass when you don't use all of it !

Robert
Title: Re: Has anyone seen this...
Post by: PhilB on Feb 09, 2012, 18:45:56
The problem with photographic lenses has always been that photographers have always expected the full aperture performance of their expensive glasses to be inferior to that of the same lens system when stopped down   :(  As for star bursts due to the lens iris, this is seen as a desirable artistic effect :cry:  as is light bouncing about inside the lens causing all manner of artefacts
Title: Re: Has anyone seen this...
Post by: Rocket Pooch on Feb 11, 2012, 09:28:39
Phil, Robert is right Olly has used compas cutters to cut an apature mask for the front of his lens.  As for the70-200L F4 canon Lens I don't really know why anyone would stop it down its very sharp at F4 and quite flat as well.  I'm going to give mine a try when the big nebula's come upin the summer, lots of Ha me thinks.