Thread: Southern Cross
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Old 25-03-2012, 12:32 PM
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Quote:
Originally Posted by Martin Pugh View Post
I am going to take it to one more level now and get those stop-down covers - anyone know where I can source one from that would fit the 50mm Canon lens?
Martin,
don't expect a huge improvement with external stop-down aperture.
In my experience they work only on certain, highly asymmetrical lens designs ( telephoto, 200mm and up).
They are not effective at short FL (Gaussian ) designs, see here:http://www.iceinspace.com.au/forum/s...ht=Canon+100mm. On that lens, the external aperture was actually detrimental - I wanted to get rid of CA and all I've got was un-correctable coma
The spikes that you are probably annoyed with are OK for most people (including myself) and if you really want to get rid of them, there are software tools available for this job.
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