Penny macro contest - revisited


Lubbyman

Link Posted 16/02/2021 - 15:03
Just printed and cut out a protractor, fitted it on the nice, big focus ring of the DA300, found some fine wire and a way of holding it in place... Now need the kitchen to be clear of people and cooking. Perhaps have a go this evening when the haze has cleared after pancakes have been cooked and eaten (the smell won't clear for days...).

Steve
Last Edited by Lubbyman on 16/02/2021 - 15:03

Lubbyman

Link Posted 17/02/2021 - 21:35
OK, here we go...

All with DA*300mm + reversed DA35mm f2.8 macro. JPG straight from camera.

This set uses linear focus. Steps of about 1/12mm. One step is enough to take focus from surface of letters to surface of coin, so the letters must be about 0.1mm thick.

1. K3




2. K3 + 1.4TC




3. Q-S1




4. Q-S1 + 1.4TC




And here's the kit.




The needle and rotating protractor method comes next... perhaps a stack or two.

Steve

davidwozhere

Link Posted 18/02/2021 - 01:01
That's a mighty expensive lens to be mucking about around the front element with the edge of another lens! Now try blu tacking the coin to the end of the slider so you can move that in and out rather than the huge unwieldy camera ensemble.
Both the *istDS and the K5 are incurably addicted to old glass

My page on Photocrowd - link

coker

Link Posted 18/02/2021 - 08:33
Just one question, Steve.
How on earth do you "measure" & move(!) your camera +300 f4, one twelfth of a millimetre at a time?






Roger.
The more I look, the more there is to see!

Lubbyman

Link Posted 18/02/2021 - 08:37
davidwozhere wrote:
That's a mighty expensive lens to be mucking about around the front element with the edge of another lens!

That's why I'm EXTREMELY careful !!. First step is to add the reversing and step down rings to the front of the 300, it gives a bit of protection to the front element. Just as big a concern was keeping the aperture of the reversed DA35 macro open. A bit of plastic coated wire bent into a hook at each end does the job, but the rear element is very close and the thought a bent aperture lever is always on the mind...

The reason for putting the coin on a sideways moving rack is because I found sideways alignment was difficult without it. It should be easier now I've realised that shining a light through the lens from the camera end (camera not attached, of course) gives a small dot of light where the subject should be. Position the coin so the dot is over the tiny letters and you're ready to go.

For and aft movement of the camera/lens is actually very smooth, accurate and not at all unwieldy. The Novoflex rack is well engineered, holds the camera/lens very firmly and allows precise movement (steps of about 1/12 mm achieved yesterday). The camera/lens is attached via the tripod mount on the lens, so is well balanced. The only ad-hoc hack was to add a foot under the font end of the rack to eliminate slight up/down movement due to there being a thin rubber 'grippy' mat on the top of the clamp that attaches to the worktop - perfectly OK for 1:1 macro, but not quite good enough at these magnifications. The foot was assembled from a couple of bits with 1/4 in threads, screwed into a hole in the focusing rack. I wouldn't want to try doing all of this with a less robust rack and clamp though!!

More to come using coker's needle and rotating protractor focussing method...

Steve

Lubbyman

Link Posted 18/02/2021 - 09:11
coker wrote:
Just one question, Steve.
How on earth do you "measure" & move(!) your camera +300 f4, one twelfth of a millimetre at a time?

Words first, then a picture.

The Novoflex rack is of the rack and pinion type. It has a scale marked out in cm and mm. The mount is moved along the rack by rotating a smallish knob on the mount. Unaided and with a steady hand, 2 steps per mm are possible. However, Novoflex provide (at a price!) a 'fine adjustment handle' which can be fixed to the knob and allows finer control - same principle as your pointer and protractor. It's attached in the picture below. Rotating the handle by 4 marks on its scale moves the mount by 1mm, so that's 1/4mm per mark. 3 steps per mark are just about possible, so that's 1/12mm per step. The rest is just a matter of being careful and patient. And, of course, it's only possible because of superb engineering by Novoflex - not cheap, but you really do get what you pay for here.




Steve
Last Edited by Lubbyman on 18/02/2021 - 09:12

Lubbyman

Link Posted 18/02/2021 - 11:48
And here's a stack of 7 using coker's pointer and rotating protractor method for adjusting focus. Q-S1 with 30mm and reversed 35mm macro, as above. The pointer is a bit of wire attached to the knob on the 300's tripod collar. Protractor is thin cardboard, fixed by elastic band to the focus ring (thank goodness it's a big one on the 300).




They're getting better. Next steps are to adjust lighting to reduce highlights, improve the wire pointer and do something a bit better for positioning specimens. And perhaps add a tube or two between lens and camera.

Of course, what I'd really like (wouldn't we all...) is the Novoflex stepping motor controlled rack, repeatable steps as small as 0.2 micron (i.e. 1/5,000 mm). But at getting on for 2K (), it's really far too much of an extravagance...

Steve

coker

Link Posted 18/02/2021 - 17:00
Leaps & bounds, Steve, leaps & bounds!

I remember seeing the light through the wrong way as a pointer on Photomacrography site a while ago.
Someone made up a small light unit that clipped onto the viewfinder slots & I was impressed with the elegance of it in use.
But I'd been asleep since then & forgotten all about it......
But i've just shone a torch in the viewfinder of the K5 & VOILA!! A spot on the coin!

I've also, by utilising a cheap micrometer I got from Banggood a while ago, related the degrees on the protractor to the linear advancement of the focus.
It works out that 0.5 of a degree on the protractor represents 0.05 movement of focus of the lens (at that extension) plus whatever more is gained by stopping down.
Below is my latest, 200 + rev. 50, 150 ext.on the bellows, stack of 7 in CZP.
No crop.
Heavily (paper) diffused AF200T flash, but highlights still a problem.....


https://www.flickr.com/photos/188519063@N07/50955820743/in/datetaken-ff/


Good here, isn't it!

Roger.
The more I look, the more there is to see!

Lubbyman

Link Posted 18/02/2021 - 18:57
Ah, I hadn't thought of shining a light through the viewfinder. Not sure it would work with a Q though...

These pennies do seem to bring out the worst in highlights, don't they? You need a new, clean penny for its crisp features, then the wretched thing reflects light from lots of tiny surfaces that you didn't know existed.

I'm not entirely sure what you mean by "0.5 of a degree on the protractor represents 0.05 movement of focus of the lens". Is it 0.05 of the full rotation of the focus ring (from closest focus to furthest focus)?

Yes, it is good here!

Steve

coker

Link Posted 18/02/2021 - 19:41
Quite simple...

If I turn the focus ring of the 200 by say, 4 x 1/2 degrees as shown on the protractor, the focus point of the 200 with the 50 attached will be 4 x 0.05 mm. further into the subject, for that given extension (only),
The more receding the subject plane, e.g.as in the side of a ball, the greater the number & the smaller the size of steps required for "continuous" focus around the contour in the stack.
Hope this helps,

Roger.
The more I look, the more there is to see!

Lubbyman

Link Posted 18/02/2021 - 20:23
Got it!

And got an old micrometer, too. So old that it measures in inches. Inherited from my father in law and hardly been used by me. Perhaps it's time to get it out again.

Steve

coker

Link Posted 18/02/2021 - 22:44
One of these wouldn't exactly break the bank....

https://uk.banggood.com/0-13mm-Range-Round-Type-Micrometer-Calipers-Head-Measure...

Roger.
The more I look, the more there is to see!

coker

Link Posted 28/02/2021 - 13:54
Latest!

X10 microscope objective, full bellows extension plus a 12mm ext tube.

Trial stack of six, focus via the rear standard on the bellows, of just the top surface of the letters on the 2p piece.



https://www.flickr.com/photos/188519063@N07/50988966966/in/datetaken-ff/


Roger.
The more I look, the more there is to see!
Last Edited by coker on 28/02/2021 - 13:59

Lubbyman

Link Posted 01/03/2021 - 09:35
Excellent. I like the 3-D effect from selective focus on the top surface of the letters.

What's the working distance between microscope lens and penny?

Steve

Lubbyman

Link Posted 01/03/2021 - 14:15
Here we go with the latest attempt...

A 40.5mm step-up ring has arrived, which means it's now possible to reverse the Q-01 prime (8.5mm FL) on the front of the DA300mm. First thing was to persuade the lens to keep it's aperture open by going against all instincts and habits and removing lens from camera with the camera on. Unexpectedly scary! The working distance was even smaller than I expected (a couple of mm), which made getting light onto the face of the penny very difficult. Edge lighting only at the moment, unless I (or you) have a bright idea that's cheap and practical.

And so to the pictures. First, the sharp end so you can see the practical problems. Second, a stack with K3 attached to the 300mm. Third, a stack with Q-S1 attached to the 300mm. Lots of sparkles, not a lot of sharpness. It wouldn't surprise me if diffraction is as much a limitation here as the resolution of the Q-01. Perhaps a bit more can be squeezed out if the lighting can be improved.

1. The sharp end



2. K3



3. Q-S1



Steve
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