I'm not saying it's not a really good lens, but it sounds to me what they have done is made it the highest possible quality WIDE RANGE MAGNIFICATION lens. i.e. general purpose AND macro. BUT a true macro will probably beat it at close range, especially at 1:1 where a relatively simple symmetrical design kicks ass but of course sucks at infinity....
As far as IF goes, I'm not sure if the rear element has to be the one moving. it could be like a zoom where the middle elements are shifting. In fact some fixed focal length IF designs actually focus closer by shortening the focal length the way a zoom does. Is the focal length still 125mm @ 1:1? (not really sure how you could measure this...). JCO > -----Original Message----- > From: Rob Studdert [mailto:[EMAIL PROTECTED]] > Sent: Tuesday, September 10, 2002 10:54 PM > To: [EMAIL PROTECTED] > Subject: RE: Favourite K mount normal lens poll > > > On 10 Sep 2002 at 22:19, J. C. O'Connell wrote: > > > I THINK YOU HAVE BEEN "HAD". What you have is a long lens > > with a "macro" feature, not a true macro lens. Like I said, > > I've read many articles on optical design and true macro > > lenses are optimized for closeup magnifications not infinity. > > Hi Jon, > > Well I've been "HAD" then, it focuses to 1:1 without tubes, it is > sharper and > has better contrast than any of my "true" Pentax macro lenses (A*200f4, > A100f.2.8 and A50f2.8) or any of the CZ Macro lenses I've owned > over the years > In fact it is visibly more crisp when viewed though a good > finder. So I'm glad > to have been "HAD" in this case and will continue to be with > enthusiasm :-) > > If you had checked the URLs you would have seen that the lens is > constructed of > 11 lens elements, it's rear group doesn't move whilst focussing > either, just > like the A100f2.8 and the A*200f4. A fixed rear element can't > recover lost > resolution however hard it tries. > > In any case my experience bears out the theory that I sited. Have > you actually > used any of these lenses? > > I have an associate off list who is a keen macro shooter and has good > experience with Pentax macro glass of various genres, he has > recently purchased > the Lanthar based on my recommendation. I'll try to find out for > you if he > feels that he's been "HAD". > > Cheers, > > > Rob Studdert > HURSTVILLE AUSTRALIA > Tel +61-2-9554-4110 > UTC(GMT) +10 Hours > [EMAIL PROTECTED] > http://members.ozemail.com.au/~distudio/publications.html >
