Bojidar Dimitrov wrote:
> ...
> Hi Flavio,
>
> A bit of a warning. Lenses capable of 1:1 usually have either FREE or IF
> designs. This means that using tubes with such lenses has a bigger chance
> of degrading the image quality than when using a "normal" lens. The reason
> is that there fixed (rear) elements have been designed to be at a specific
> distance from the film plane.
Got it. I didn't know. Now that I have a 100mmm f/2.8 FA I'll avoid use
of extension. Thanks.
>
> Second, FREE and IF lenses do not have constant focal lengths. My A100/2.8
> Macro has a focal length of something like 73 mm at 1:1. So 100 mm
> extension will result in higher magnification than expected.
> ...
I knew this, BTW, do you know how it works out with the FA 100?
Shel,
the easiest and cheapest way to reach 2X magnification, IMO is this: buy
two cokin rings of suitable diameter, scrape the paint off the flat
sides and superglue them together. Magnification will be main lens
F.L./stacked lens F.L..
With your 200mm and using a fast 50mm you'll get 4X, with the 100mm 2X
and so on.
Your in-focus field will be as deep as a sheet of paper though...
Flavio
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