Tricky micro set up for a beginner

Jolly Roger · Post by **Jolly Roger** » Fri Jan 20, 2012 2:08 pm

Hi to all, another newcomer to the fold. I have a specific newbie request. I am a technical photographer and normally take shots of machinery and power tools, both static and in use.

What I need to do now is get some real close up shots of tool edges and timber surfaces, between 20 and 50X. As the tooling and samples are often quite big I cannot use a conventional microscope. Instead I have looked at the type on an etended arm which would seem to do the job, sorry I don't know the proper term.

However as I have a copy stand, am I perhaps better going down the route of buying an adapter and microscope lens and fitting it directly to the camera? I have a variety of different cameras so that part is no problem. The finished images will never be used more than A4.

Alternatively are any of the usb type cameras any good, they seem too cheap to me to be properly effective. As this is more for my own interest and amusemant rather than commercial gain, budget is limited to a max spend of £500. Can I get anything respectable within this?

Sorry for all the questions stright off and thanks in advance for any replies. If you never need any advicewith woodworking equipment or power tools I would be glad to help in return!

Cheers,

Roger

rjlittlefield · Post by **rjlittlefield** » Fri Jan 20, 2012 2:30 pm

Roger, welcome aboard!

Yes, you're probably better off going with the copy stand and some adapters.

But before we get into details, I need to make sure that I'm properly understanding what you want to do.

When you say "between 20 and 50X", I suspect that what you mean is what you'd see through a 20-50X microscope, that is, a subject field width of about 10 mm down to 4 mm.

Is that correct?

Second question: what type cameras do you have?

--Rik

Jolly Roger · Post by **Jolly Roger** » Fri Jan 20, 2012 2:56 pm

Thanks Rik.

What I want to see is the subject magnified between 20 to 50X real life, which is what I think you mean (sorry if I am being stupid here).

I have a variety of Canon digital cameras, 10, 20, 40D and my current workhorse a 5D which has a full frame sensor, though I cannot get my head around whether the crop factor is relevent or not, I suspect not, hopefully someone will correct me.

I also still use film, so have a Canon EOS 3 and a variety of Pentax medium format, just love the 645 format!!

Cheers,

Alan

rjlittlefield · Post by **rjlittlefield** » Fri Jan 20, 2012 3:43 pm

I think I get it, but it's really important that we be on the same page here. If we get off track at this stage, further conversations are going to be very confusing. Please bear with me.

Let's suppose you want to make a final image (a print, say) that is 8 x 12 inches, call it 200 x 300 mm, and you want that image to show something that is 20 to 50 times bigger than real life. Then the real-life thing must be someplace between 10x15 mm (at 20X) and 4 x 6 mm (at 50X).

So, what you're looking for is some convenient arrangement of optics that takes an area between 10x15 mm and 4 x 6 mm, and projects that area so that it covers your camera's sensor.

Now suppose you're using that 5D, which has a full-frame 24x36 mm sensor. The magnification you're talking about, on sensor, ranges between 2.4X and 6X. If instead you use one of those smaller sensors, roughly 15 x 22 mm, then the on-sensor magnification drops to between 1.5X and 3.75X .

You can see why it's important to get a common understanding of what magnification you really mean. If I'm thinking magnification on sensor and you're thinking magnification in the final image, then we're thinking about two very different beasts!

OK, back to optics.

To do what I think you want, the simplest solution is to reverse an ordinary lens on bellows or extension tubes. Do you have stuff to do that?

--Rik

Jolly Roger · Post by **Jolly Roger** » Sat Jan 21, 2012 9:20 am

Thanks again Rik. You will have to be gentle as I am a bit slow on the uptake!

I think I am thinking about magnification of the final image. What I want to do is look at the cutting edge of a piece of tooling and see minute detail of the metallic structure and how it has worn in use and also look very close up at timber surfaces and see how they have been affected by the different types of cutter.

So I want to magnify the surface to see this detail. I have looked at other peoples shots where you can see the microscopic detail of the timber structure and they all seem to be labelled between "30x and 50". I also appreciate the potential problems of depth of field. What I have been looking at are shots of prepared slides on a very level plane. I shall not be able to achieve that on large specimens other than by focus stacking.

I have tried reversing a 50mm prime lens but it didn't give me much better detail than my 105mm macro. There must be a way!

Cheers,

Alan

naturephoto1 · Post by **naturephoto1** » Sat Jan 21, 2012 9:43 am

Jolly Roger wrote:Thanks again Rik. You will have to be gentle as I am a bit slow on the uptake!

I think I am thinking about magnification of the final image. What I want to do is look at the cutting edge of a piece of tooling and see minute detail of the metallic structure and how it has worn in use and also look very close up at timber surfaces and see how they have been affected by the different types of cutter.

So I want to magnify the surface to see this detail. I have looked at other peoples shots where you can see the microscopic detail of the timber structure and they all seem to be labelled between "30x and 50". I also appreciate the potential problems of depth of field. What I have been looking at are shots of prepared slides on a very level plane. I shall not be able to achieve that on large specimens other than by focus stacking.

I have tried reversing a 50mm prime lens but it didn't give me much better detail than my 105mm macro. There must be a way!

Cheers,

Alan

Hi Alan,

I am not sure if you wish to go this route and I am not to that point yet, but you may wish to consider stitching together images (using shift adapters or shift lenses). I think that this would be possible with stacking but I would suspect it would be quite a bit of computer time to do this.

You may wish to look at this to give you some idea:

http://www.cambridgeincolour.com/tutori ... enses1.htm

The shift adapters could take the place of a shift lens to do this but it would require using lenses for a larger format on the camera to use the shift adapters (as an example using 35mm lenses on a Micro 4/3 camera).

I hope to do a little of this myself in the future.

I will let others with more experience comment.

Craig Gerard · Post by **Craig Gerard** » Sat Jan 21, 2012 2:41 pm

Alan,

Is this (see link below) within the range of magnification you seek?
http://www.photomacrography.net/forum/v ... php?t=4416

Craig

elf · Post by **elf** » Sat Jan 21, 2012 7:57 pm

Is this what you want to do? These are shots of a 5/16" square HSS toolbit shaped for cutting 60 degree threads.

elf · Post by **elf** » Sat Jan 21, 2012 9:41 pm

Here's a fresh one just taken tonight. It's focus stacked from 124 images. Magnification is about 6X. The subject is a 5/8" bowl gouge for woodturning. It was recently sharpened, used for a bit, then lay on the workbench of a while. The tool is slightly magnetic and the black spikes are iron/steel filings.

Note to self: Quit doing metalwork on the wood workbench

And here is a 100% crop:

Camera: Olympus e330
Lens: JML 21mm f/3.5
Lighting: 2 Ott lights and a Janso LED

The Ott lights had paper towel difusers and were above and to the left of the subject. The Janso didn't have any difusion, which is one reason for the specular highlights. If this had been a product or fine art shot, I would have spent much more time adjusting the lights.

rjlittlefield · Post by **rjlittlefield** » Sat Jan 21, 2012 11:09 pm

elf wrote:Magnification is about 6X.

Ed, we're trying to keep straight about magnification here. I presume "6X" means on-sensor, but what camera are we talking about here?

--Rik

elf · Post by **elf** » Sat Jan 21, 2012 11:22 pm

rjlittlefield wrote:
elf wrote:Magnification is about 6X.
Ed, we're trying to keep straight about magnification here. I presume "6X" means on-sensor, but what camera are we talking about here?

--Rik

6X at the sensor is correct. The sensor is 4/3rds (17.3mm X 13mm).

I suspect that more magnification is needed to really be able to analyze the cutting edge. However, the light reflecting off the tip of the tool shows that this one would need sharpening before making the final finishing cut. The edge will work well for roughing cuts.

Here's a link to a larger version: http://img.photobucket.com/albums/v649/ ... 1-3435.jpg

rjlittlefield · Post by **rjlittlefield** » Sat Jan 21, 2012 11:51 pm

elf wrote:6X at the sensor is correct. The sensor is 4/3rds (17.3mm X 13mm).

OK, then assuming you haven't cropped, we're looking at an area that is only 2.88 mm wide (=17.3mm/6X).

Using my 200x300 mm print example (8x12 inches), that would be about 104X on the print (=300mm/2.88mm ).

--Rik

PS. Roger, you can add to your amusement list the fact that "4/3rds" is really a name, not a number in any useful sense. Quoting from Wikipedia,

The name of the system stems from the size of the image sensor used in the cameras, which is commonly referred to as a 4/3" type or 4/3 type sensor. The common inch-based sizing system is derived from vacuum image-sensing video camera tubes, which are now obsolete. The imaging area of a Four Thirds sensor is equal to that of a video camera tube of 4/3" diameter.

rjlittlefield · Post by **rjlittlefield** » Sun Jan 22, 2012 12:30 am

Roger, I posted into a different thread some pictures that may be helpful to your quest.

See Slicing open an (empty) can of whipped cream.

--Rik

Jolly Roger · Post by **Jolly Roger** » Sun Jan 22, 2012 9:45 am

ok guys thanks for the replies so far, this is getting interesting. I see now that my idea of 'magnification' is not what i thought. The pictures posted by elf of the cutting edges are getting near to what I want, probably slightly higher 'magnification' needed though.

The link posted by Craig to Riks timber close-ups is exactly what I want, just need to sort out what I need for the camera now as regards tube and lens and this is where I would apprecitae a few pointers.

Thank you so much for your input and patience so far.

Cheers.

rjlittlefield · Post by **rjlittlefield** » Sun Jan 22, 2012 10:26 am

Jolly Roger wrote:The link posted by Craig to Riks timber close-ups is exactly what I want, just need to sort out what I need for the camera now as regards tube and lens and this is where I would apprecitae a few pointers.

We have two reference threads that will be helpful:

FAQ: How can I hook a microscope objective to my camera?

FAQ: What's the best way to focus when stacking?

The second thread covers a wide range of possibilities that are appropriate for an equally wide range of magnifications. It sounds to me like you're interested in the 10X-on-sensor range, where depth of field gets down to around 10 microns (0.010 mm). In that range, you'll be needing either a screw-driven rail or linear stage, or possibly an infinity objective combined with an internally focusing long lens to be used as a "tube lens". See AF motor focusing with a microscope objective for more information about that.

--Rik