Heidelberg Linoscan lens mounting details (+ low mag test)

[Beatsy]

In response to a question from dolmadis on another section of the forum - mounting details for my Linoscan film scanner lens (the 92mm one) with a Raynox DCR-150. This gives 1.4x magnification and covers full frame with slight softness in the corners. APS-C crop mode is sharp across the frame.

Parts labelled in the picture are:-

1) M42-NEX adapter (27mm)
2) M42-T2 adapter (10mm)
3) T-mount extension tube (40mm)
4) T-mount extension tube (40mm)
5) 43-42mm adapter ring (5mm)
6) Raynox DCR-150 (31mm)
7) 49-52mm step up ring (4mm)
8 ) RafCamera 40mm diameter tube to M52 adapter
9) Linoscan scanner lens 92mm f/7.1



The distance from the Raynox to the sensor is approximately 155mm (for 1.4x) but there is a lot of leeway to alter this. More extension (tubes or a focus tube) behind the Raynox will increase magnification, but light drops off fairly quickly so about 2x is likely the practical limit. I didn't record the extension amount to achieve that, sorry.

The Linoscan lens needs to be pushed right in (and through) the Rafcamera adapter tube until it touches the front flange of the Raynox or image corners will get very mushy. The Linoscan is mounted with the paint mark away from the specimen (towards the sensor). If the lens is reversed, the image becomes extremely soft in the corners and also soft along all four edges on ff.

Note: this is a complete bodge and I'm surprised it worked at all, let alone so well. The Linoscan is not an infinity corrected lens, but using it with empty tubes for direct projection requires at least twice the extension to reach focus at around the same magnification. Far to unwieldy on my rig. But I'm content with the compromises of this setup...

[dolmadis]

Thank you Steve. This gives me ideas on how to approach my project much better than trial and error thanks to your generous sharing.

BR

John

[Beatsy]

Thank you Steve. This gives me ideas on how to approach my project much better than trial and error thanks to your generous sharing.

BR

John

no probs - you're welcome

[Lou Jost]

Doing it this way instead of via extension probably makes for a brighter image and less diffraction as well. That has to be weighed against moving the lenses from their design point. Looks like in this case it works very well.

[mawyatt]

Steve,

Well your images certainly don't show a "compromise"

Best,

[Beatsy]

Well your images certainly don't show a "compromise"

<blush> Too kind!

But that's the trick you see. Spend a session or two test-stacking and pixel peeping to learn the aberrations and limitations of any given setup, so you know how to mitigate or avoid those issues when stacking "for real".

That's why one of my biggest pet hates is people who butt into discussions on this sort of topic and tell you to stop shooting test charts and just take pictures instead. Grrr! It happens a lot on regular photography forums. Present company excepted of course! You're more likely to be positively *encouraged* to test-shoot and pixel-peep here...

[mawyatt]

But that's the trick you see. Spend a session or two test-stacking and pixel peeping to learn the aberrations and limitations of any given setup, so you know how to mitigate or avoid those issues when stacking "for real".

Agree, kind of like the old saying, "measure twice cut once"

BTW, just noticed your WeMacro rail loading...nice!! And your partial wafer holding, is that clay and does it leave any trace of residue on the wafer?

Best,

[Beatsy]

...And your partial wafer holding, is that clay and does it leave any trace of residue on the wafer?

Not clay, it's BluTak (brand name), for temporarily sticking posters on walls etc. When fresh out of the packet it leaves very little to no residue at all. But after several re-uses and moulding between your fingers it does pick up skin oils, so it can leave what is effectively a light "fingerprint" when pulled off (it never hardens). Easy to clean off though, just as you would any fingerprints.

I have a few pieces of wafer like that, each with their own bit of BluTak attached so they can be stuck upright in the corner of a drawer (avoiding scratches on the surface) and then straight onto the rig when needed. I use it to hold pinned insects and plant parts and the like too. Head of the pin in the BluTak and the point in (or glued to) the specimen. Wait a couple of minutes after setting something in place though as the BluTak will slowly "rebound" a little after moulding - which will cause movement while you're stacking. Once it's "relaxed" though, it holds small lightweight things very stably.

Invaluable for pulling dust and dirt off hard surfaces (rough or smooth) or out of shallow crevices (like the knurling on focus knobs or difficult to reach corners where dust tends to gather). Just dab it on to pick up the bits and lift them away.

Very useful stuff. The macro equivalent of duct tape (or gaffer tape as it's called here). I bet the REALLY fundamental particles holding the universe together will be found to be 'gafferons'

[mawyatt]

Not clay, it's BluTak (brand name), for temporarily sticking posters on walls etc. When fresh out of the packet it leaves very little to no residue at all. But after several re-uses and moulding between your fingers it does pick up skin oils, so it can leave what is effectively a light "fingerprint" when pulled off (it never hardens). Easy to clean off though, just as you would any fingerprints.

I have a few pieces of wafer like that, each with their own bit of BluTak attached so they can be stuck upright in the corner of a drawer (avoiding scratches on the surface) and then straight onto the rig when needed. I use it to hold pinned insects and plant parts and the like too. Head of the pin in the BluTak and the point in (or glued to) the specimen. Wait a couple of minutes after setting something in place though as the BluTak will slowly "rebound" a little after moulding - which will cause movement while you're stacking. Once it's "relaxed" though, it holds small lightweight things very stably.

Invaluable for pulling dust and dirt off hard surfaces (rough or smooth) or out of shallow crevices (like the knurling on focus knobs or difficult to reach corners where dust tends to gather). Just dab it on to pick up the bits and lift them away.

Very useful stuff. The macro equivalent of duct tape (or gaffer tape as it's called here). I bet the REALLY fundamental particles holding the universe together will be found to be 'gafferons'

Thanks, the BluTak looks interesting. Have some clay that I've used but it would leave some residue, so didn't want to use it on chips nor wafers for fear of contamination. Don't have any partial wafers though, only full (6", 8" and 12"). Those old Intel wafers are very nice looking, most of the wafers I have are mundane looking, except the ones that I can't display just yet

Maybe someone will be interested in sharing wafer sections like you have

Best,

[Beatsy]

...Don't have any partial wafers though, only full (6", 8" and 12")

Well, there's a *very* obvious solution to that...

All it takes is a firm but slightly pliable surface and a hard, sharp point pressed smoothly and firmly, straight down into the wafer about a millimetre (or less) from the edge. I use a fake-leather-covered book and a sharp tungsten point that's sold as a glass cutter. The wafer will cleave in straight lines parallel to the die edges (most times).

This guy does it slightly differently, but the principle is the same - https://www.youtube.com/watch?v=IRoIXjxIcBQ

I mean, what use is a giant wafer that won't even fit on your rig? Go on, you know you want to...

[Beatsy]

Another data point on the Linoscan lens. I got a surprise package in the mail yesterday, some nice pinned insects from a very good friend. An unexpected delight indeed!

This blue weevil is particularly nice - near perfect condition with legs and antennae all nicely arranged, but it's over 40mm long! I'd normally use a standard macro lens for a "whole insect" stack of something this size (Sony 90mm, f/2.8 these days). I always do a few test stacks of nice specimens so I can figure out the best poses and lighting before doing full res, retouched pics - and I was very keen to get started on this one...

The rig was still set up as pictured at the top of this thread, and I realised that since I started using the Raynox as a tube lens, I hadn't tried pushing the Linoscan down to lower mag. So I removed one of the extension tubes (number 4 in the pic above) to reduce extension by 40mm which gave 0.78x magnification. Wow! Perfect right across full frame and into the corners with not even a hint of vignetting or distortion. Very impressed - and pleased!

Attached is the result of the test stack of 130 jpg images at 0.25mm spacing. I could easily get away with 0.5mm steps, but didn't know that at the time. No retouching or editing apart from a bit of levels and overlaying an image of a loupe graticule (reticle) for scale (single shot with the same setup).

Pretty impressive I think, and very useful to have an M42-based solution for such low mag. It means less to change around on the rig when moving from higher mags with Mitties or other scanner lenses. Result!



And a couple of 100% crops to show the pixel-level performance.

[rjlittlefield]

overlaying an image of a loupe graticule (reticle) for scale (single shot with the same setup).

That lens is doing well for you!

About the reticle image, this would be a good time to again talk about scale changes due to perspective.

130 images at 0.25 mm spacing implies in-focus depth of about 32 mm. The lower magnification means that the subject was positioned somewhat farther from the lens than in our earlier discussion. I'll pluck 160 mm out of the air for that. Then 32/160 implies about 20% scale change from front to back of your specimen, as seen by the lens. You could tell much more accurately by checking the Scale numbers produced by the alignment process in Zerene Stacker.

Anyway, the point is that a reticle image, no matter what you do with it, can only be exactly right at one depth in this subject shot with this lens. I'm guessing that particular depth is at the rearmost focused point of your subject, because that would have been the "narrow" end that Zerene Stacker likes to start at. If that's correct, then using the same scale to measure something at the front of the subject would give a number that's around 20% too large. Caution is called for, in using scale bars with 3D subjects!

--Rik

[Beatsy]

Caution is called for, in using scale bars with 3D subjects!

Thanks Rik, timely reminder. In my defense, it was just another (parallel) test/dry run as I had some 0.01mm reticles on the way for use with shallower, higher mag stacks. They arrived today. I should have added the "health warning" though, especially as this was discussed only a couple of days ago on the "cog" thread. Soz. BTW, working distance is 125mm at this mag.