Specimen Stage Adjustable in th "Z" direction.

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georgedingwall
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Specimen Stage Adjustable in th "Z" direction.

Post by georgedingwall »

Hi all,

I've recently been doing some shots at the limits of magnification I can get without a microscope ;



Both of these inages were shot with a 150 mm macro lens fitted with a X2 teleconverter and two sets of extensio tubes. The most difficult thing I found when doing the setup for these shots was getting the subject in the right position in the "Z" axis.

I tried adjusting my tripod up and down, but found this very difficult to do in small enough steps at this magnifcation. I had a little more success by using stuff laying around in my studio to build up the base that the subject was sitting on. I.E. Filter cases, match boxes and books of different thickness etc. It works, sort of, but is very hit and miss and requires a lot trial and error to get it right.

I thought it would be nice to have something on my subject table that could be adjusted up and down to make this process a bit easier and more accurate. I did some googling for "XYZ stage" but find most of the results are for expensive microscope components or for heavy engineering tools for positioning metal components for machining.

What I would like to try to do is to make something myself. I have a small workshop in my garage and can do reasonable work in both wood and metal. If anyone has some ideas on how this might me done I would appreciate the input.

Thanks for any help.
Last edited by georgedingwall on Wed Mar 05, 2008 1:47 am, edited 1 time in total.
George Dingwall

Invergordon, Scotland

http://www.georgedingwall.co.uk/

Carl_Constantine
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Post by Carl_Constantine »

well, I have no ideas for you, but I do have a couple questions about your setup. In particular, the order of your lenses. Which is closest to the camera, the 2X TC or the Extension tubes and why?

Also, with a setup like that, how close is your camera lens to the subject?

Sorry, I'm still very much learning a lot about macro and still much about photography in many ways too, so please excuse the obvious questions.

Thanks.

PS: wrt your question, would macro rails help?
Carl B. Constantine

georgedingwall
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Post by georgedingwall »

Hi Carl,
Carl_Constantine wrote:well, I have no ideas for you, but I do have a couple questions about your setup. In particular, the order of your lenses. Which is closest to the camera, the 2X TC or the Extension tubes and why?
I have the teleconverter on the camera and the extension tubes nearest the lens. I read somewhere that you get better results that way, but I'm not really sure if it makes any difference. My main reason for doing it this way is that the teleconverter is a lot heavier than the extension tubes, and puting it close to the camera body helps bring the centre of gravity of the setup closer to the camera, which helps with stability.
Also, with a setup like that, how close is your camera lens to the subject?
when I use the 150mm lens with this setup, the closest point of focus is about 5 inches.

PS: wrt your question, would macro rails help?
Not really. Macro rails give you adjustment in the "X" and "Y" directions. I've not seen any that also give adjustment in the "Z" direction. I sometimes use a drill press vice that has adjustments in the "X" and "Y" axis, but it doesn't help in the third axis.

Bye for now.
George Dingwall

Invergordon, Scotland

http://www.georgedingwall.co.uk/

rjlittlefield
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Re: Specimen Stage Adjustable in th "Z" direction.

Post by rjlittlefield »

georgedingwall wrote:What I would like to try to do is to make something myself. I have a small workshop in my garage and can do reasonable work in both wood and metal. If anyone has some ideas on how this might me done I would appreciate the input.
George,

Try combining a focusing rail with something that does 2 axes. Here's one of my setups, using a 2-axis focusing rail. The 2-axis rail does specimen positioning and the focusing rail does coarse focus positioning.

Image

I've used several variations of this approach with good results. Actually the setup shown here is only a portion of my usual setup. There's an $80 screw-driven machining table, outside the field of this picture, that does very fine focus steps when I need them.

If you already have a 2-axis table and a single-axis rail, then you could mount the specimen on the rail, use the rail for one axis of specimen positioning and the table for focusing and the other axis of positioning.

--Rik

PS. I got my 2-axis rail from Adorama. I have seen apparently identical units advertised on eBay for a lot cheaper.

rjlittlefield
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Post by rjlittlefield »

georgedingwall wrote:
Carl_Constantine wrote:... I do have a couple questions about your setup. In particular, the order of your lenses. Which is closest to the camera, the 2X TC or the Extension tubes and why?
I have the teleconverter on the camera and the extension tubes nearest the lens. I read somewhere that you get better results that way, but I'm not really sure if it makes any difference.
Yes, it does make a difference. TC's have optics that are designed to be mounted directly on the camera. Used in that position, they deliver their quoted magnification and the image will be crisp (or at least, as crisp as it's ever going to get) because the lens aberrations are well corrected for that case.

Put the TC anywhere else, the image quality degrades and the magnification gets weird.

Sometimes it gets extremely weird. Long ago, in the last posting (Dec 16, 2004) at http://www.photomacrography1.net/forum/ ... php?p=4206, Danny (nzmacro) wrote that:
So now about the Nikkor 70-210 + 1.4 tc and a macro of a flies head from over 5 feet away Tom. Whats the answer M8t. Thats the one that has me completely confused. That 1.4 is really doing weird things to the optics and magnification. That is driving me nuts Tom. That one setup is a freak.
That description grabbed my curiosity when I ran into it a few months ago. I got a hold of Danny, and I think we figured out what was going on. That strangely behaving setup consists of a point-and-shoot camera with a long telephoto and digital zoom, staring into a 1.4X teleconverter on which is mounted another long telephoto. The teleconverter is a strong negative lens, and in combination with the long telephoto and a short (4') distance to subject, the system forms a Galilean telescope with the teleconverter playing the role of eyepiece.

So what he ended up with was a long telephoto, plus digital zoom, staring into a short-focus telescope. Lots of magnification. The resolution was not very good because of the small effective F-number, plus there was lot of chromatic aberration, but that fly's head definitely was *very* big!

--Rik

DaveW
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Post by DaveW »

George

You could use the scissor type of Lab Jack for vertical lift, but the adjustment is a bit coarse:-

http://www.labdepotinc.com/Category_Details~id~334.aspx

I did not realise how expensive these were though because I had mine given to me!

Another alternative is to use a vertical set-up using an old enlarger with the head removed as a copy stand. Some enlargers even have the head fixed on with a 1/4" Whitworth bolt which is the standard camera tripod thread. If not you can make a block fixed where the enlarger head used to be to centre your camera on the baseboard and use a 1/4" bolt to fasten the camera to it. The enlarger column has a fairly fine vertical adjustment anyway for positioning the camera.

Your focusing slide with it's X/Y adjustment can be used to mount a specimen stage on the enlargers baseboard to centre the specimen in your cameras field of view.

DaveW

georgedingwall
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Post by georgedingwall »

DaveW wrote:George

You could use the scissor type of Lab Jack for vertical lift, but the adjustment is a bit coarse:-

I did not realise how expensive these were though because I had mine given to me!
Hi Dave,

That's just the sort of thing I've been looking for. I think they should be accurate enough for what I want to do. I did a lot of seaching for "XYZ Stage" and "Scissors Platform", but most of what came up wasn't suitable.

I found a few of these lab jacks on Ebay.uk for a very reasonable price, so I'll keep an eye on them and see how the bids progress.

Thanks for the tip.
George Dingwall

Invergordon, Scotland

http://www.georgedingwall.co.uk/

georgedingwall
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Re: Specimen Stage Adjustable in th "Z" direction.

Post by georgedingwall »

Hi Rik,
George,

Try combining a focusing rail with something that does 2 axes. Here's one of my setups, using a 2-axis focusing rail. The 2-axis rail does specimen positioning and the focusing rail does coarse focus positioning.
You always come up with the goods on equipment for macro setups. I'll keep my eye open for any rails that come up on ebay. In the mean time, I might try one of the Scissors Jacks that DaveW mentioned, as there are some right now on Ebay.uk.

Thanks for your input. Bye for now.
George Dingwall

Invergordon, Scotland

http://www.georgedingwall.co.uk/

DaveW
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Post by DaveW »

The thing I notice about scissor jacks though is that the elevation per turn of the knob seems to vary depending on the position of the scissors.

As Rik says, though you can use a jack to roughly position the subject, you need some form of fine adjustment to move the camera or subject if you are working at a set magnification. If the actual magnification is not important then the lenses focusing may be enough.

DaveW

georgedingwall
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Post by georgedingwall »

Hi Dave,
DaveW wrote:The thing I notice about scissor jacks though is that the elevation per turn of the knob seems to vary depending on the position of the scissors.

DaveW
I don't think that will be a problem for me. All I want to be able to do is move the subject up or down a little while I'm looking through the viewfinder so that the subject is placed in the correct position within the frame.

If I find that the screw pitch is not fine enough for this adjustment, I can probably replace the screw mechanism with a finer pitch of screw.

Bye for now.
George Dingwall

Invergordon, Scotland

http://www.georgedingwall.co.uk/

puzzledpaul
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Post by puzzledpaul »

Depending on the exact configuration and what you have available, I wondered if a (spare?) geared tripod head would be of any use?

Looking at my Gitzo one (ex ebay) one rev produces 16mm of linear travel, therefore 22.5 deg / mm, which may be adequate for relatively coarse adjustment as you seem to be after.

Mounting this particular model would be simplicity itself - bore an 85mm dia hole in some suitable material and let it 'sit' there under it's own weight (if dealing with small, light specimens as I suspect) - or clamp it.

If space allows, I suppose you could even use the whole tripod?

Best of luck, anyway ... (although probably done it by now :) )

pp

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