Newbie - first post

Starting out in microscopy? Post images and ask questions relating to the microscope and get answers from our more advanced users on the subject.

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Bob Topp
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Location: Huntsville, AL
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Newbie - first post

Post by Bob Topp »

Hello,

I am working with a homemade tube scope, attached to my Nikon D300. For those who are interested in going this route, some early shots of my setup and results are posted at:

http://www.flickr.com/photos/aging_dog_ ... 756761681/

My next step is to build a stable stage that can be adjusted for stacking. As you can see from annotations in my linked post, I have had some success just screwing the objective in and out, but by the time bugs are out, I want to be able to do something more sophisticated.

All comments are welcome.

Regards, Bob
2011- I am building my first tube microscope from a commercial 4x 160mm DIN objective.

ChrisLilley
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Joined: Sat May 01, 2010 6:12 am
Location: Nice, France (I'm British)

Post by ChrisLilley »

Hi, and welcome to the forum.

Your setup looks good so far. I wonder why you used a sensor to objective length of 122mm rather than 150mm - did the full 150mm give quality problems at the edges or corners of the frame?

Your initial shots of ballpens and salt look promising. It seems that your DIN 4x objective is reasonably well colour corrected.

The following FAQs may be helpful for you:

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

FAQ: which lenses are good at more than 1X in a bench setup?

Nikon's 4x CF/CF N Plan Achromat

Next step is, presumably, a means to move either the camera or the subject in small increments. A variety of manual and automated options are available, and you will find postings on this forum discussing a great variety of setups that have been used for that.

Craig Gerard
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Location: Australia

Post by Craig Gerard »

Welcome Bob,

Are your intentions related to studio or in-the-field photography...or both?

Craig
To use a classic quote from 'Antz' - "I almost know exactly what I'm doing!"

SONYNUT
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Joined: Sat Jan 22, 2011 2:27 pm
Location: Minnesota USA

Post by SONYNUT »

focus racks are one way to go......or if you need real fine you can get a stage blocks with a micrometer fairly cheap too.

Bob Topp
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Joined: Fri Jan 21, 2011 5:08 pm
Location: Huntsville, AL
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Post by Bob Topp »

Let's see- in order:

To Chris, although I replied on Flickr, I have tubes that will take me alll the way to 200 mm, but since I'm just using the threads on the objective to adjust for stacking right now, I thought the arrangement would be more stable keeping it short for the time being.

To Craig- I'll be doing micros strictly in my office (or garage, since the concrete floor is very stable). A geologist friend gave me a large collection of rocks that I would like to examine, and I have to try out those beautiful bugeyes that everyone keeps showing off, but I am not ready to go into microbes yet. I have a lot of studying to do regarding quality of light, among other things, and I'm just about to go blind from all the reading I've done recently on lens specs, etc. I'm very much a hobbyist in all phases of photography, although I get paid for some portrait and wedding work now and then.

To SONYNUT- "fairly cheap" is a relative term! I did price some nice micrometer heads yesterday that looked promising, but it was not obvious how to mount them (gotta talk to the manufacturer about that). Right now I'm going to do something very, very homemade: I've about settled on transiting through 2-3 mm, so I'm going to make a 10:1 lever of stiff aluminum stock and drive the long end with a fine-pitch screw. The subject end will start a millimeter or so below level and transit an equal distance above level, so that should minimize too much lateral displacement. The "knob" on the screw will be a six-inch disk with a full 360-degree protractor on it. I will pre-load both ends of the lever with small springs to prevent jumping or slack in the threads, and I'm counting on the mass of the disk and friction in the system to hold each incremental setting. I'm considering a single-edge razor blade for the fulcrum, something which worked well on a homemade beam-balance many years ago. Let's say I use a 10-32 screw and turn it in 10-deg. increments- that would yield displacements at the subject end of: ((25.4/32)/36)/10 = 2.2 micro-meters. Hmmmm 2e-3/2e-6 = 1000... way too many turns. I could back that down to 60-degree turns and get 100-150 shots, which seems to be about the range of slices I'm seeing in the really nice stuff here. Oh, and the choice of a lever also resulted from not wanting to fool with keeping the stage from rotating, which would entail guide rails and bearings and alignment...

I'll post some more when I get there.

Bob
2011- I am building my first tube microscope from a commercial 4x 160mm DIN objective.

rjlittlefield
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Post by rjlittlefield »

Yep, that lever scheme sounds like it will work. I'm not sure where it falls in the spectrum of time/money/effectiveness tradeoffs. Depends in large part on your DIY skills, I guess.

Take a look also at http://www.picaxeforum.co.uk/showthread.php?t=17248 and consider just the mechanics. Essentially this fellow uses a microcontroller and a stepper motor to turn a shaft inside a salvaged DVD player, whose mechanics then end up moving a carriage part of the player by quite small amounts. Seems to me that if you wanted a really inexpensive manual system you could dispense with the controller and stepper motor, and just turn the shaft by hand.

BTW, just for completeness I'll mention that we have a FAQ: What's the best way to focus when stacking?. It contains a brief summary and lots of links to other discussions.

Lots of options, lots of tradeoffs...

--Rik

Craig Gerard
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Location: Australia

Post by Craig Gerard »

Bob,

Before discussing the 'glass' end of the works, here is some additional 'food for thought' whilst considering the details of your project outline.

The StackShot is a more recent arrival which is mentioned in the FAQ. It is exceptional value for money and a very 'tidy' unit.
http://www.cognisys-inc.com/stackshot/stackshot.php

A focusing helicoid attached to your 'cone' presents itself as one addition to your current arrangement which could be implemented without much bother. They can be purchased, or like dsvilko's DVD, re-assigned 8)

Example of re-assignment.
http://oldlenses.blogspot.com/2010/12/d ... coi-d.html

A bellows would also be applicable.

'Lead' screw rails:
  • Velmex UniSlide A2500 20tpi (requires basic modification)
    RRS B150-B Macro Focusing Rail (there appears to have been a recent price increase :? )
    Linear translation stages: from, Newport, Thorlabs, Parker Daedal, etc (require basic modification)
    Proxxon Compound Micro Table
    Particular microscope focus blocks and/or frames.
If any of the above suggestions are of interest or helpful, let us know and links will be forthcoming.


Craig
To use a classic quote from 'Antz' - "I almost know exactly what I'm doing!"

Bob Topp
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Joined: Fri Jan 21, 2011 5:08 pm
Location: Huntsville, AL
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Rail system and focusing in general

Post by Bob Topp »

As always, thanks for the comments. It helps a lot to discuss things and think them through. For instance, by the time I hit the bed, I could see the main weakness of a simple lever: if, for instance, a 4 mm subject were centered only an inch from the fulcrum, there would be about 0.25 mm differential elevation between the far and near ends, which would probably wreak havoc on the stacking software.

Most of today I've been looking a modified vises as a simple way to go. I noticed someone online using a very nice milling vise, which basically has micrometer control. I may shop for one on the used market. In the meantime, I'm going to fool with a cheap bench vise- shim the rails and add a spring to load it all the time. That looks simple and promising.

Thorlabs offers a nice 4 mm non-rotating helical focuser for their 1" stock tubing, at .5 mm per turn. However, it runs $189, so I'm going to hold off that for now, although it's on my shopping list. Thanks again for the other ideas- I'll look into some of the stuff out there.

Regarding that disassembled DVD player- I assume the focuser was made from the mechanics that servo the head; that would be pretty precise I imagine.

Bob
2011- I am building my first tube microscope from a commercial 4x 160mm DIN objective.

rjlittlefield
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Re: Rail system and focusing in general

Post by rjlittlefield »

Bob Topp wrote:Regarding that disassembled DVD player- I assume the focuser was made from the mechanics that servo the head; that would be pretty precise I imagine.
Part of those mechanics anyway. As I understand the Wikipedia article, head positioning is a combination of coarse movement of a "sled" on parallel rails driven by a leadscrew, and fine movement of the read/write head on the sled to maintain tracking during rotation. The combination of these things must be pretty precise, since the specification HERE lists the track pitch as being 0.74 µm (page 12). The author of the DIY article lists one full step of his add-on motor as giving almost exactly 0.01 mm (10 µm).

Finally, I'm thinking the local computer repair place probably has a bin full of dead drives that they'd be happy to sell for cheap, maybe even give away to avoid disposal costs. I'm sure there's something not to love, but offhand I don't know what it is. I'm a little embarrassed I haven't investigated this myself.

If you're really attached to the lever trick, you might consider disconnecting the sled of a DVD drive from its lead screw, spring-loading the thing, and using the lever as an actuator to move the sled. That would solve the problem of rotating the specimen.

--Rik

Craig Gerard
Posts: 2877
Joined: Sat May 01, 2010 1:51 am
Location: Australia

Post by Craig Gerard »

Bob,

http://www.youtube.com/watch?v=XeXjpZpaZns

I love this video. This discussion provides another opportunity to post a link :)

Craig
To use a classic quote from 'Antz' - "I almost know exactly what I'm doing!"

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