Stifling Science

Tesselator · Post by **Tesselator** » Sun Nov 27, 2011 6:51 am

I took these for another discussion and thought they might be interesting here:

Polyurethane Condom Stretched to 400% and photographed at 1,500x

My Spermatozoa In Relationship - at 150x

ChrisR · Post by **ChrisR** » Sun Nov 27, 2011 8:07 am

Ah, one of Leeuwenhoek's "animalcules"!
But he would have used pig's bladder for the other...

rjlittlefield · Post by **rjlittlefield** » Sun Nov 27, 2011 10:22 am

Interesting pictures indeed!

I assume these numbers must mean magnification on sensor? Otherwise the animalcule seems rather larger than the value quoted at Wikipedia: "head 5 µm by 3 µm and a tail 41 µm long".

So, what sort of optics do you use to photograph at 1500X on sensor?

--Rik

Tesselator · Post by **Tesselator** » Tue Nov 29, 2011 5:02 am

I dunno. I didn't really give it too much thought.

For 1,500x the Objective was 100 and the eyepieces were 15x. Although the camera connects directly on front without passing through the EPs it was about 50% the of the image circle seen through the EPs. You can see the Olympus camera mount on front of the IMT-2 here:

Or view p.3 http://www.alanwood.net/downloads/olymp ... ctions.pdf

The multiplier just below the objective holder ("Magnification Changer Ring") was set to 1.5x and setting the light-path selector knob to "OM" displays an overlay that says "2.5X". Then of course the sensor is 1/2 the size of FF... And on top of that I reduced the images to 30% of original and cropped them by about 50%. But, it didn't seem right nor accurate to solve using all those magnifications and percentages:

100 x 15 x 1.5 x 2.5 x 2 ÷ 3 =

...so I just put 1500x without trying to figure anything out.

This does sound like something Leeuwenhoek would do for sure... LOL

The 150x was taken using a 10x Zeiss objective.

rjlittlefield · Post by **rjlittlefield** » Tue Nov 29, 2011 9:42 am

Got it, thanks.

So, paraphrasing, "This is a small part of the frame that you'd see through the eyepieces at 1500X."

It's hard to compute the scale using this sort of setup, and of course what each viewer sees depends on his monitor size anyway. Scale bars are the way to go. If you plan to do very much microscopy, I suggest to just get a "stage micrometer" (essentially a tiny ruler on a microscope slide), image it using the same optics, then use Photoshop to overlay the two images and construct a scale bar.

Stage micrometers are cheap and easy to get these days. Just search eBay to find new ones for $29.

Interesting images, nonetheless.

--Rik

Tesselator · Post by **Tesselator** » Wed Nov 30, 2011 1:24 am

Yeah, I've read about those here who have a stage mic. but I don't think I'll be able to find one in Japan. At least they don't seem to exist on the auction sites...

Is there some other way? Is there something common with a known size that will fit on a slide?

Any ideas?

Pau · Post by **Pau** » Wed Nov 30, 2011 2:23 am

Search for micrometer slide, there are plenty of them on eBay

Tesselator · Post by **Tesselator** » Wed Nov 30, 2011 7:00 am

Yeah, I did that but they're like $25 and up and that's just too ridiculous for a $2 to $5 item. In Japan I did actually find one but it's a bundle of 10 of them for about $60 : http://page9.auctions.yahoo.co.jp/jp/auction/k135473640

At $6 a piece for something MUCH better than what I saw on ebay it's almost tempting but still... a 25 to 60 buck pay-out??

There's gotta be another way.

Mitch640 · Post by **Mitch640** » Wed Nov 30, 2011 7:40 am

They use to go for $100 not long ago.

You can use a simple stainless steel machinists ruler, 6" long and inscribe with the measuring marks. Would work, but for coarse only as the micrometer slide scale is too small to even see with the eye.

rjlittlefield · Post by **rjlittlefield** » Wed Nov 30, 2011 1:00 pm

Tesselator wrote:There's gotta be another way.

Sure -- just do what Mitch says to calibrate your system with a low power objective, then scale up for other objectives in proportion to the objective's magnification. It's rather more tedious, but it works OK. Just another example of "time is money", I guess.

By the way, those micrometer slides are typically chrome plated on glass, then covered and cemented for use with high power objectives that need to look through cover glass. It'd be an interesting exercise to make money by manufacturing and selling them as individual units at $2 to $5 each. On the bright side, I suspect you'd have no trouble cornering the market if you can figure out how to do it.

--Rik

Tesselator · Post by **Tesselator** » Thu Dec 01, 2011 3:46 am

Heh, yeah I bet I could corner the entire market - all 25 customers.

But there are dot addressable printers that do 2,400 dpi so that's like 0.06 mm. And I guess paint or ink templates can be made much finer than that.

I know, I'm such a smarty-pants...

I might try that ruler thing...

Tesselator · Post by **Tesselator** » Thu Dec 01, 2011 10:52 am

OK here it is. Full width strips from 4 images scaled from 4000 pix wide to 1000 pix wide (25%).

This image is from a Panasonic GH1 in 4:3 mode which has an active area of 17.3x13mm according to Camera Labs dot com

rjlittlefield · Post by **rjlittlefield** » Thu Dec 01, 2011 11:22 am

Looks as expected -- the span in pixels is nicely proportional to the objective magnification and to the mag dial setting. Now all you need to do is work the math for higher power objectives.

--Rik

Tesselator · Post by **Tesselator** » Thu Dec 01, 2011 8:20 pm

Should be easy enough.

Objective: 4
Optical Magnification at imaging sensor: 10.4x
Screen Magnification PR 1:1 (23" LCD): 312x
Screen Magnification after 25% image scaling: 78x

Objective: 10
Optical Magnification at imaging sensor: 26x
Screen Magnification PR 1:1 (23" LCD): 780x
Screen Magnification after 25% image scaling: 195x

Objective: 20
Optical Magnification at imaging sensor: 52x
Screen Magnification PR 1:1 (23" LCD): 1,560x
Screen Magnification after 25% image scaling: 390x

Objective: 40
Optical Magnification at sensor: 104x
Screen Magnification PR 1:1 (23" LCD): 3,120x
Screen Magnification after 25% image scaling: 780x

Objective: 100
Optical Magnification at imaging sensor: 260x
Screen Magnification PR 1:1 (23" LCD): 7,800x
Screen Magnification after 25% image scaling: 1,950x

And then multiply everything times 1.5 when the mag dial is set to 1.5x of course