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Re: [OM] Lens chatter (wuz 'Greetings and Salutations')

Subject: Re: [OM] Lens chatter (wuz 'Greetings and Salutations')
From: "Lex Jenkins" <lexjenkins@xxxxxxxxxxx>
Date: Wed, 14 Jun 2000 11:52:36 PDT
Me:
I'm also curious about the 85/2 since it's smallish and promoted as
being corrected for close up use. I'm wondering how well corrected when pushed beyond its designed minimum focus range?<<

Gary R.:
Probably not bad for 3D macro subjects, versus 2D which need flat field. Be sure and keep the helical racked out and mix or match auto extension tubes to focus, otherwise you are defeating the abberration correction acheived by the floating elements.<

Ahh, interesting. I've been puzzled about what's appropriate when using other-than-macro lenses with various close up devices (close up diopter lenses, extension tubes, Vivitar's macro focusing 2x teleconverter). For example, is it considered best to leave a normal lens focused at infinity for best results and move the camera or subject to within focus range? Or is it okay to use the lens' focus mechanism to get maximum magnification when combined with diopters, extension tubes, etc.? I've never read a definitive answer on this. My own informal tests of 2D objects doesn't reveal any particular difference, but I may be less critical than some.

G.R.:
...new manual focusing 60mm ? macro for Canon EOS. While it works from 5:1 to 1:1 (5x to 1x), it is clearly optimized for 4:1 Kind of tells us how hard it is to design a macro lens for a wide magnification ratio.<

That reminds me ... with a lens like Vivitar's old 90mm f/2.8 macro (the non-Series 1 version) that goes 1:1 without an extension tube - does this type of design inherently involve either a loss of effective focal length, effective aperture, or both as it's extended to maximum magnification? Again, I haven't been able to find a definitive answer anywhere.

Lex
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