Hello,
I decided to try some close-up photography with my Tachihara over the last weekend . As I do not have any dedicated macro lens - I decided to try Caltar 210 plus close-up lens from Nikon - 6t which is supposed to have 3 dioptres. I went to the text book of Optics and computed that the focal lengt of this setup should be approximately 120mm. Indeed when I tryed to focus to infinity the lens behaved like that.
Let me just mention that I have very good experience with this nikon close-up lens in small format.
So - I started to focus on a nice sunflower we have at home. For simplicity I kept both standards and the floweritself paralel. Well - I first focused on the central part of the flower (the most distant part - it was close to 1:1) and then I tried to get into focus the yellow leaves of the flower. I could not find the focus so I was focusing closer and closer...and sudenly the central part of the flower came into focus again - now of course somewhat beyond 1:1.
Yes - I checked it twice (I'm kidding - I checked it at least 10 times) - the focus behaviour of this setup was really like that. I've put the flower on the side and took a metalic ruller , focused the lens as far as the bellows was long, then placed the ruller NEARLY parallel to the lens axis (nearly touching the lens surface) - so I could see where the focus is - and started to move the lens back - what in normal way would mean to focus towards the infinity - BUT - the focus started first move in opposite direction as expected - 1 or 2 cm and only then (I kept moveing the lens back) stopped and started to move towards infinity.
Well - I am physicist (though my field is not optics) and this must be a normal behaviour of a compound lens of such a type, but have any of you experienced such a behaviour?
P.S. Concering the pictures - as I was rather confused - I used my fujinon 125/5.6 and made couple of photos at about 1:2 - trying to apply the rule of best f-stop as mentioned in the lasr issue of VC (I did apply the apparent f-stop). Let's see what the result will be....
Matus..
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