Olympus OM Zuiko 80/4 with 170mm close up lens: A question

austrokiwi1 · Post by **austrokiwi1** » Wed Apr 27, 2016 2:22 am

Has any one had any experience with the 170mm close up lens produced for use with the Oly 80mm Bellows lens? I understand it enables the lens to go to 2X magnification. Its a 5.9 diopter lens.

Also can any one tell me how it effects the effective aperture? I suspect it would have the effect of making the lens faster but I have no idea by how much ( I suspect a stop would be too much to expect).

ChrisR · Post by **ChrisR** » Wed Apr 27, 2016 3:19 am

http://www.alanwood.net/photography/oly ... s-170.html

Experience:

It arrived with an 80mm
I put it in a box.

austrokiwi1 · Post by **austrokiwi1** » Wed Apr 27, 2016 3:57 am

Ok at least I have been reading the right websites

Alan Wood · Post by **Alan Wood** » Wed Apr 27, 2016 5:30 am

I am ashamed to admit that mine is also LNIB, never used.

Alan Wood

austrokiwi1 · Post by **austrokiwi1** » Wed Apr 27, 2016 9:24 am

Alan Wood wrote:I am ashamed to admit that mine is also LNIB, never used.

Alan Wood

Your website is brilliant

rjlittlefield · Post by **rjlittlefield** » Wed Apr 27, 2016 10:09 am

I've used mine, a little. It worked well, as expected for a matched add-on. I never did a critical evaluation of image quality or any other optical characteristics.

Yes, the added lens will widen the effective aperture, like any other add-on diopter that does not restrict the pupil. The exact effect will depend on spacing and I've never measured it. As a rough calculation, usin thin lens model without spacing, the 80/4 by itself has a 20 mm pupil and the combined focal length is 1/(1/80+1/170) = 54.4 mm, so the combined nominal aperture is 54.4/20 = f/2.7, just a hair over 1 stop wider. In practice it will be less than that, but I don't know by how much.

Searching with Google, I find it used in one of my image posts from back in 2007, HERE.

--Rik

austrokiwi1 · Post by **austrokiwi1** » Wed Apr 27, 2016 10:16 am

Thanks Rik, that spider shot was/is impressive. That add-on lens actually seems to perform better than I would have expected. However given that for others it has simply sat in the box suggests to me there are better ways of getting 2X magnification, or that 2X is a seldom used magnification?

Alan Wood · Post by **Alan Wood** » Sun May 07, 2017 9:27 am

I recently had an urgent need to photograph a small weevil using a longer working distance than my Olympus 38mm bellows macro lens provides, and I used my 80+170 combination for the first time, with enough extension to give 2x magnification.

I needed the working distance because the weevil was inside a shadowless illuminator (LED ring-light shining up into an inverted white bowl with its base removed.

I also have an Apo-Rodagon-N 1:4 f=80mm that I think is optimised for 2x, so I have done a quick comparison of the 80+170 and the reversed Rodagon, both at f/5.6. The subject is a Graticules Ltd stage micrometer, the smallest divisions are 0.1 mm. The image is stacked, 100%, no adjustments, cropped to 1024 wide.

The Olympus is the top one. The uneven background with the Rodagon is probably paper that is not quite out of focus.

Alan Wood

ChrisR · Post by **ChrisR** » Sun May 07, 2017 9:56 am

Not bad!

Apo-Rodagon-N 1:4 f=80mm that I think is optimised for 2x

That sounds like the enlarger lens, which is not the same as the 2x "D" duplication(?) lens, which is an f/4.5.
The mag range specified is 2x to 15x, so you're at the end (assuming you reversed it).