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Old 05-01-2009, 04:53 PM
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dugnsuz (Doug)
to baldly go...

dugnsuz is offline
Join Date: Aug 2005
Location: Hahndorf, South Australia
Posts: 4,200
Originally Posted by John Weaver View Post
Hi all
70-200mm canon f4 or f2.8.
Drooling over Dugnsuz pics (yes i am a Dugnsuz wantabe)I just can't get over wide field.
My question what would be the difference?
Less noise because less exposure time?
Better light grasp?
Twice the price!
I just want to future proof my self as the budget won't allow in my case stuff ups
regards John
Hi John - thanks for the endorsement, that's a first!!

I bought the f4 purely on "bang for buck" many glowing reviews swayed my decision too - and, the f2.8 was/is out of my budget. The lens is used 90% of the time for astro work so IS wasn't needed either.
I would imagine even with the f2.8 you may want to stop it down to sharpen up the stars anyway - could be wrong as I say...imagining!!!
As stated the lens on the 2.8 is 10mm bigger than the f4 - bigger light grasp , less exposure time. But, needs a more costly filter if you go down that route.
I'm very pleased with the lens and extender too and I 've found that I have reached a happy place with my setup where I'm not consumed in drooling/stressing over the next purchase ( I assume this is a temporary state of astro-enlightenment and probably won't last the week!!!!).
f2.8 or 4 - don't think you'll go wrong with either.

Bottom line - if I was in the market for a lens and had the cash I would go for the 2.8, but because of the results I've had with the f4 I won't be saving up for one - the retrospectroscope has saved me some money at last!
All the best
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