A job lot of lenses

barnack-bill · Post by **barnack-bill** » Wed May 11, 2016 12:57 pm

I'm fairly new to macro at 1:1 and beyond using alternative lenses. My first attempts were with a strange device, a Medical Nikkor 200mm f5.6. This has a fixed focus and comes with a set of six auxiliary lenses giving magnifications from the native x1/15 to x3 using the x1 and x2 lenses in combination. It also comes with a built in ring flash and focus assist lamps. The trigger voltage is too high for modern equipment so for now I'm not using the flash.

My next purchase was a Canon MR114mm 1:10.4 microfilm reader lens. I made an adapter for this to use on a bellows and also an auxiliary lens holder to let me use the lenses from the Medical Nikkor. I was pleased with the results of this combination and have posted crystal pictures previously.

Now, in conjunction with a friend I have bought a job lot of microfiche lenses, 29 in all. The last few days have been spent investigating our purchase (or my half of it as we split the haul 50:50) and making adapters so that I can use them.

My set of lenses splits roughly into three groups.

Group 1
Moderate size barrel lenses of 33mm diameter. Mostly Rokkor but also Canon and unidentified. 30mm f2.8 and 50mm f3.5 are marked, others not marked with the the focal length and f stop.

I made a bellows adapter for these and find they give reasonable working distance.

Results from all these are quite good. Flat field with very little distortion. 2:1 easily achievable.
The pc board I used for test is quite useful as the pin pitch is 2.54mm (0.1 inch) standard.

Canon A02 on Sony A7

Rokkor 50mm on A7

Canon A02 on A7 - filament coil is about 4mm long

Group 2
Small barrel lenses 19mm dia. Mainly ON manufacture. 20mm to 17mm focal length. Not sure how to use these.

Group 2 lenses and adapter

I made an adapter to fit M39 (Leica screw) from a group 3 prism holder and can mount these lenses directly onto my Sony A7 or A6000 with a Leica adapter or onto a set of extension tubes. Very short working distance and don't get full frame coverage even on crop sensor (APS) Sony A6000

ON 20mm lens on M39 adapter and Sony A6000

Image from ON 20mm on A6000. M39 adapter only.

Goup 3. Oddballs.

Two had prisms to rotate the viewed documents. One has been remanufactured to make the adapter for group 2 lenses
The lens with the handwheel is marked x21 and has a coarse adjusting thread of 42mm x1.5mm. I can't get any meaningful focus on the Sony with this by freelensing it. The other large lens (which had the prism) is marked x25 and again I can't get a focus on the Sony.
The others in this group are Micro Designs and are similar to but smaller than than group 2 above.
No test pictures from any of these.

It's been a lot of fun. It has helped that I have a bit of a model engineering workshop so can manufacture odds and ends. Average cost per lens, excluding the Medical Nikkor, has been under £3.

I think the Canon A114mm used in conjunction with the Medical Nikkor auxiliary lenses will be the way forward.

Mendel314 · Post by **Mendel314** » Wed May 11, 2016 1:39 pm

That one on the right is a minolta "micro" microfiche lens. Those are great for super macro, but can't be used as is in their case. I have one that I machined off the flange with a lathe and then shortened the barrel on the other side down to about 1mm past the front element. I took the flange off completely so the barrel is flush all the way to the rear, but this makes it unwieldy to adapt, since it is narrower than my m42 extension tubes.

With about 15mm WD, the 24-32 one I have renders better at 10x than a nikon CFN objective. I was so impressed with the results from my 24-32x that I have another one, a 13-17x and a 41x coming in the mail. I am going to machine them a little more carefully and I'll post some pictures from the results when I'm done.

Thanks for posting, I'll be interested to know what else you find

dunksargent · Post by **dunksargent** » Wed May 11, 2016 2:41 pm

Mendel314 wrote:That one on the right is a minolta "micro" microfiche lens. Those are great for super macro, but can't be used as is in their case. I have one that I machined off the flange with a lathe and then shortened the barrel on the other side down to about 1mm past the front element. I took the flange off completely so the barrel is flush all the way to the rear, but this makes it unwieldy to adapt, since it is narrower than my m42 extension tubes.

With about 15mm WD, the 24-32 one I have renders better at 10x than a nikon CFN objective. I was so impressed with the results from my 24-32x that I have another one, a 13-17x and a 41x coming in the mail. I am going to machine them a little more carefully and I'll post some pictures from the results when I'm done.

Thanks for posting, I'll be interested to know what else you find

When Minolta manufactured the micro-microfiche lenses they were probably still manufacturing their own optical glass - which might be a contributory factor to the imaging quality. And being microfiche projection optics, low distortion and flat field images would be expected.

Does anyone else have any high mag. imaging experience with similar microfiche projector lenses?

dunk

barnack-bill · Post by **barnack-bill** » Thu May 12, 2016 1:13 pm

Mendel314 wrote:That one on the right is a minolta "micro" microfiche lens. Those are great for super macro, but can't be used as is in their case. I have one that I machined off the flange with a lathe and then shortened the barrel on the other side down to about 1mm past the front element. I took the flange off completely so the barrel is flush all the way to the rear, but this makes it unwieldy to adapt, since it is narrower than my m42 extension tubes.

I'll be interested in your finished machining. I was thinking of taking off the flange (just weight and bulk) but then leaving the thread which engages enough with an M42 mount to be secure or to machine off the thread completely and fit a ring over the barrel with a proper M42 thread. Either way the lens can then be used on an M42 adapter or on a bellows.

g4lab · Post by **g4lab** » Fri May 13, 2016 2:36 am

I'll be interested in your finished machining

Me three

Pau · Post by **Pau** » Fri May 13, 2016 4:44 am

I'm too very interested in their modification and performance as I'd got two of these Minolta lenses recently. Their design beats me, does anyone know how was it originally mounted in its intended device? If it's for microfilm projection this can be very relevant to figure if it could work better in straight or reversed position (and which is each one

)

barnack-bill · Post by **barnack-bill** » Fri May 13, 2016 7:20 am

I subjected both the bigger lens to ordeal by lathe this morning. I image that I will only use them on my BPM universal mount bellows. Both lenses had quite thick metal walls so I decided after some trial and error that I didn't need to bother about M42 threads and could cut a locating groove directly into the lens tube.

Before

After

The ugly duckling Micro Rokkor with the big flange has turned into a rather handsome brass bodied lens. The groove had to be cut into the thread to maintain the diameter but I removed the excess length of thread and the big flange which is aluminium and should unscrew. I couldn't budge mine so machined it off.

The x25 prism lens was fairly easy, I just cut off the prism section on the lathe and machined a bellows groove into the lens tube. Lots of metal so no problem except that the soft aluminium proved difficult to cut cleanly.

Results. Only a first try but the Micro Rokkor looks promising. PCB, holes 0.1 inch (2.54 mm) standard pitch.

Not so impressed with the prism lens

g4lab · Post by **g4lab** » Fri May 13, 2016 8:42 am

The way the lens on the right mounted to the reader was as follows.

The barrel part has a small slot in it about 6mm wide where the labeling is.
THat is grabbed by the reader printer machine. The scalloped flange is on the bottom and the acme thread allows the user to focus on the microfilm which is below the lens assembly. It really was just a fine focus. The flange is the closest to the object and the acme thread and barrel are the image side. The focus working distance and image distance are probably all constant with the magnification changing by lens selection. The film is always in the same spot reletive to the barrel grabbing claw (t has spring detents to pull the barrel in.) and the screen size is probably usually expected to be 8.5X11 but probably could go as high as 17x17. That was the size of the viewer ground glass and the printer part had a flexible belt type of photoconductor for a xerographic print process.

Each of these lenses has two magnification labels corresponding to two different reader printers they could be used in. The lenses sold for $400 to $700 each twenty or thirty years ago. They were sold through Minolta's microfilm division. Somewhere I have a xeroxed sheet from a service manual that had the actual focal length each magnification. Only two of them are engraved (I think 50 and 35mm) and you have to take the flange part apart to see the focal length. Other mags are not engraved.
Some of them come apart easily and some don't come apart at all. Not all the barrels are brass , some are lunimum.

I would like to figure out a way to mount the barrel to a bellows. and retain that fine focusing ability. The flange is a bit large in diameter and I guess the whole thing is brass so it weighs a bit. The barrel is lunimum iirc. Perhaps a 52mm thread could be cut onto it it or similar size. I think it is too big for a 42.

Pau · Post by **Pau** » Fri May 13, 2016 11:01 am

Gene, thanks for the detailed description, now it makes sense.

I've been able to dismount the 11X lens from the barrel: just unscrewing a small retaining bolt with a hex key it slides out. The lens itself is cylindrical 32mm diameter and 51mm long. Even dismounted it has a built in deep hood, so the working distance will remain short, logical for its intended application but not good for illuminating macro subjects. It can easily mounted reversed on the barrel. A good news is that the big wheel can also easily be unscrewed from the threaded part, so mounting it on M42 tube seems just easy now, although it doesn't fit on automatic Pentax ones without cutting it but will do on simpler tubes.
The thread that fits the big wheel is also 42mm but with fine pitch, maybe 42/0.5, it screws firmly but not fully deep on T2 female screw.

It is labeled "ROKKOR 50/3.5", a typical specification for a normal macro lens.

I'm unable to do the same with the 41X, no retaining bolt but because the barrel looks just the same I'm confident that it also can be done with a lens spanner wrench and some brute force

About magnification, do you know the size of the microfiche and reader screen which the written magnification must be computed for? It could be useful to translate it to subject/sensor equivalence.

(edited several times to fix mistakes and add info)

soldevilla · Post by **soldevilla** » Fri May 13, 2016 1:51 pm

I bought a few years ago a good group of lenses. They were so cheap that I could take a risk without troubles in my pocket. I spent some time to machining barrels (I know that Minolta ...) and to do optical testing with them. Some worked well and others needed to add an eyepiece projection. After testing, I can say that until ... FOV 5 to 8 mm. almost everything works acceptably well. With further increases it is much more complicated.
I have reduced my set of lenses a few now. A x4 and x10 microscope, a pair of x20 LWD Nikon, a JMI and little else. And with those I have achieved good range increases. The first two, not LWD, are very cheap on ebay and the x20LWD, well, there is always a guy in this forum that will sell one to you.
Maybe testing deeply some of my lens is slightly better that the microscope lens, I don´t know, but there are enought for my images, and for to publish in the mineral magazines.

Here is a old thread about my tests.

http://www.photomacrography.net/forum/v ... highlight=

g4lab · Post by **g4lab** » Fri May 13, 2016 3:48 pm

I'm confident that it also can be done with a lens spanner wrench and some brute force

I think you will find that the brute force needed is a pipe wrench.

Somewhere I have such a victim which I will post pix of if I can locate it.

About magnification, do you know the size of the microfiche and reader screen which the written magnification must be computed for? It could be useful to translate it to subject/sensor equivalence.

I think the screen size is mainly 8.5 x 11

rjlittlefield · Post by **rjlittlefield** » Fri May 13, 2016 4:43 pm

g4lab wrote:I think the screen size is mainly 8.5 x 11

Which brings up an important point...

These lenses are designed to work at such high magnifications, creating such a large image, that their optical designs are almost like infinity objectives. You always have to test to be sure, but my expectation is that most of them will work better in combination with a suitable rear lens focused at infinity, than they do alone on the short extension needed to work with a small sensor.

--Rik

barnack-bill · Post by **barnack-bill** » Sat May 14, 2016 1:13 am

I have found that some, especially the micro minolta with the big flange work much better reversed.

I'll try some with a rear lens once I can find out how to do it. I am a newcomer to this game

barnack-bill · Post by **barnack-bill** » Sat May 14, 2016 1:35 pm

Thank you for the suggestions and also thanks to dunksargent for pointing me to some helpful threads.

I rigged up a rough and ready system with an Olympus OM 200mm f4 lens. This was useful because it has a sliding lens hood and I could attach objectives to a modified and reinforced lens cap and get adequate clearance from the front element. Lens alignment may be a little out due to the improvised adapters but I think the results are quite interesting. All images are on full frame Sony A7

Question - is the distance between the rear element of the objective and the front element of tube lens important?

I have only had time to do basic tests using three of the best performing lenses from the previous tests. Same boring old pcb - hole pitch 2.54mm (0.1 inch)

Firstly the Canon AO2. focal length and aperture not marked but about 50mm f3.5 I guess.

Lens normal orientation

Lens reversed in mount

Next the 50mm f3.5 32mm dia Rokkor

Normal orientation. This was difficult as the lens has a deep recess (hood) making for very little working distance

Lens reversed in mount

Finally the modified large flange Minolta

Forward - no focus possible

Reversed

rjlittlefield · Post by **rjlittlefield** » Sat May 14, 2016 2:22 pm

That result from the Canon AO2 surprises me a little, because the "normal orientation" image degrades so badly in the corners.

I can think of a couple of things that may be happening.

First would be if the lens is optimized to look through several mm of carrier glass. In that case, the combination of using the lens in its as-designed focus arrangement but looking through no glass could cause some spherical aberration in the center, and much worse problems off axis.

Second would be if "normal orientation" happens to be the wrong sense. In the world of theory, normal orientation would mean "in the focus relationship for which the lens was designed". But that requires knowing which side of the lens faces the microfilm when the lens is installed in the reader. Are you sure which side that is?

By the way, I'm curious about the nature of the problem. I can see that the corners are quite blurred, but I can't tell whether they're just out of focus because of a curved field, or something more complicated. Have you tried to figure that out?

Question - is the distance between the rear element of the objective and the front element of tube lens important?

That distance is not very important. Usually the biggest problem is vignetting, which will happen if the distance is too large. Other than that, the issue is aberrations away from center. But those are usually small: the sort of thing that you can see by pixel peeping, but not that would show up when the whole frame is reduced to 800 pixels like shown here.

--Rik