On Apr 5, 2005, at 7:16 PM, Rob Studdert wrote:
On 5 Apr 2005 at 19:07, Godfrey DiGiorgi wrote:
I learn by using my own lens, thank you. There's been nothing in this thread to learn from. 40-odd messages worrying about a lens that is well known to be a good performer, if not as good as the finest prime, is just stupid.
Ahh, it seems you may have missed the point again. Not all of us have to funds,
facilities, opportunities to get hands on certain lenses, however if compared
to a lens we do know then we have a reference.
Relying upon a casual test as definitive is to me foolish, regardless of how well your 'trusted reference lens' performs in this situation.
When I worked for NASA/JPL and was helping to select lenses for a data acquisition project, we'd have manufacturers send us 20 examples of their best primes in the focal lengths required. I put them on the light table and did resolution chart tests, and all the ones that didn't hit the top numbers within 1 sigma were returned. There were usually three of them that hit within 1 sigma of the same quality in any batch of 20; that's normal variation. This goes for any brand of mass-produced lenses.
Godfrey
And for the record I've owned
many Pentax lenses in multiples over the years (for instance I only have 3 x
A50/1.2 at the moment) and there is very little variation between samples in
their primes. So using Pentax primes as reference is a pretty reliable way of
long distance lens comparison. You are indeed fortunate if you can afford to
buy and then test a lens.
Big nose,
Rob Studdert HURSTVILLE AUSTRALIA Tel +61-2-9554-4110 UTC(GMT) +10 Hours [EMAIL PROTECTED] http://members.ozemail.com.au/~distudio/publications/ Pentax user since 1986, PDMLer since 1998
