The other linoscan lens (115/5.2) - a great loupe

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Beatsy
Posts: 2105
Joined: Fri Jul 05, 2013 3:10 am
Location: Malvern, UK

The other linoscan lens (115/5.2) - a great loupe

Post by Beatsy »

If you've seen some of my recent posts, you'll know that I rate the 92mm f/7.1 lens from the Heidelberg Linoscan 1800 as a fantastic find. Used "infinity style" on a 200mm Hoya prime, it gives a super-sharp 2.1x on full frame with just a small clip of corner vignetting. I'm really pleased with that.

I thought the 115mm lens would be best, given it's specs, but it ended up being pretty underwhelming on the Hoya tube (1.8x) and though it resolves fine detail, it lacks the crispness and pop that that the 92mm delivers. It may work better with direct projection, but that requires really long extensions that aren't practical on my rig.

But that's no problem because the 115mm makes a stonking 3.2x loupe with an absolutely flat FoV right to the edges and no fringing or distortions at all. With my glasses on I get a 45mm FoV, without (eye closer) I see a 60mm field. The working (focus) distance is 70mm from the lens. Covered with grippy shrink wrap tube (40mm - for fishing rod handles) and equipped with two push-on caps from old M42 lens mounts, it makes a lovely pocketable loupe for low-power surveying of small objects. I was surprised how useful a "mere" 3.2x magnification can be actually.

So I'm doubly pleased with the outcome of the Linoscan lenses punt :D
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ray_parkhurst
Posts: 3412
Joined: Sat Nov 20, 2010 10:40 am
Location: Santa Clara, CA, USA
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Post by ray_parkhurst »

I've long been a proponent of using well-corrected lenses for loupes. They are not as pocketable as the simple lenses that are generally used, but the quality is so much better that it's not much of an argument.

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