As shown many times in this forum, various industrial, microfiche and scanner lenses can provide exceptional sharpness and contrast. Unfortunately, frequently the origin, use and manufacturer of such lenses are hard to detect. And worse yet, those „golden samples“ can appear just once on Ebay so knowledge about it's performance is of very limited value for all except for the lucky buyer.
This sequel of my lens test series comes a bit delayed because of five microfiche and one scanner lens that arrived at the last minute so it took couple of days to perform all the additional tests, analyze and include data into already finished charts. As you'll see soon enough, it was worth waiting.The main obstacle when testing those industrial, scanner and microfiche lenses is complete lack of any threads. So my 3D printed adapters I introduced here were very helpful aids: https://www.photomacrography.net/forum/ ... highlight=
I had to print couple of them for different lens diameters and filter frames depending on relay lens threads. And yes, relay lenses again produced better performance than plain extension tubes. A problem here was finding proper shorter tube lenses for those tiny things since their focal length was between 15 and 35 mm. One of the harder requirements was protruding front element that provides optically close mounting. If mounting further from relay lens vignetting often occurs making some otherwise great tube lenses useless. For instance, many standard camera macro lenses have very recessed front element. Fortunately, couple of enlarger lenses in 50 to 150mm range on hand were just the right stuff for that use.
Relay lenses used: TOM50 = Tominon 50mm f4.5, ROD60 = Rodenstock 60mm f4.5, EXT = extension tube only, ROD80 = Rodagon 80mm f4, ROD150 = Rodagon 150mm f5.6, JUP37A = Jupiter 135mm f3.5, POR240 = Porst 240mm f4.5, AGFA = Agfa 107mm f4
Fortunately for me and unfortunately for anybody else is that two best results were achieved by rare lenses of unknown use and design. I suspect Bell & Howell „24x“ lens was used in microfilm reader based on it's external shape. OTOH, UNIC 16.6mm f3.0 has no distinct shape, protrusions or threads so I don't have a clue where and when it was used. Placed third is 3M Company „8.05x“ lens which also could be kind of microfilm reader optics. The very same one is currently offered on Ebay. Those 3 lenses performed best when paired with respectively: Tominon 50mm f4.5 (vintage Polaroid macro lens), Rodenstock 60mm f4.5 (miniature lens with 20mm thread) and old Rodagon 150mm f5.6, of course all of them extended for infinity focus.
Not very far from those 3 is notorious Lomo 3.7x Russian objective producing solid 2670 LW/PH central resolution which drops to still respectable 2010 LW/PH at the edges. Very good results concerning 3x magnification which is out of it's design boundaries. Added to still affordable Ebay price and no need for a relay lens, this is one of the best lenses available in 3x to 4x magnification.
Biggest disappointment came from Tominon 17 and 35mm macro lenses. I was obviously expecting to much from those vintage lenses Tomioka designed for Polaroid technical camera in '70s. It might be, however, that I've purchased below average samples. Both were tested using all available aperture values and those stated gave the best figures.
Somewhere in between are four microfilm lenses without any manufacturers sign (except for „Made in Japan“ sticker) and just numerical designation in 3690-5xx format. I have tested it with and without relay lenses in magnifications from 2x to 5x. The best I could get at 3.2x was 2446/2514 LW/PH from 25mm f3.5 sample when relayed via Rodagon 80mm f4. When paired with Rodenstock 60mm f4.5 magnification drops to 2.4x while central resolution raises to excellent 3480 LW/PH and usable 2250 LW/PH edge value. I believe those four lenses have greater potential so I'll retest them later with other relay lenses / magnifications / settings.
Since I don't have many 4x and 5x lenses and initial test with other lenses at those magnifications didn't look promising, I'll skip that part for now. So the next week comes part VII of my test series with 6 tube lens shootout: 200-210mm paired with 5x infinite Nikon objective.
Enjoy.
Miljenko
