First-time scope for darkfield photomicroscopy of radiolaria

[jasonwebb]

I'm interested in experimenting with dark-field photomicroscopy of radiolaria and diatoms, so I've started hunting for a decent sub-$200 microscope that will let me get my feet wet and not get too-terrible results.

I really just want to clearly document a variety of forms to inform some of my other interests (generative 3D design and 3D printing), so I don't really want to become a hardcore microscopy "expert", at least not yet But who knows, I may get hooked if I start getting good results early on!

From the reading I've done so far here and at other websites, I think the features that I would like to have include:

- Compound - if I understand correctly, compound scopes have more magnification range.
- DIN achromatic objectives (I'm thinking 300x - 1000x with eyepiece is good)
- Sturdy metal body
- Fine and coarse stage adjustment
- A color filter holder or condenser so I can easily add a simple mask for dark field work.
- Mechanical XY stage (maybe)

For the photography aspect, I plan to 3D print an adapter for my smartphone, or experiment with using a Raspberry Pi camera. I may also add a servo to the focus knobs to do some automated focus stacking in the future too.

I've heard some good arguments for staying away from used scopes (unpredictable wear-and-tear and possible customization), but the cost of a new "good" scope seems like it might be a bit beyond what I'm willing to commit right now.

However, I've come across a few scopes on eBay that are teasing me a bit. They seem to be quite nice scopes, and claim to be made by Amscope, though cost only about $160. One even includes a 5 year warrenty, so I'm very close to pulling the trigger and buying one. Take a look at let me know whether this is worth getting for the type of work I'm interested in: http://www.ebay.com/itm/40X-2500X-LED-L ... 5d376dd9f5

If that scope isn't good for me, can anyone suggest which scope to get that fits my needs and interests?

[phil m]

That's a lot of microscope for about 250.00, including shipping, i but....
I'm one of the ones that would always investigate used equipment, whenever possible. For 250.00, one can get a really good used microscope, a little more , a really great used microscope. The catch is, you have to know what you are looking for and be capable of noticing any problems with a unit and know what questions to ask. As a beginner , you are a bit handicapped, unless you can rely on others to help you out.
If the Precisionworld microscope performs to specification and lasts well, then it is probably a good deal but from the description of your intentions( dark field,photo.) and what I see with this instrument, I'm not sure it is exactly what you are looking for.

Here are a few problems I can see.
1) They rely on the reputation of other companies.. It doesn't matter if the big 4 make their cheaper scopes in the same factory. They also make wheelbarrow tires in Goodyear factories too( or did).
2) When I see the words "high power", I get nervous. There is no mention of the illumination output or the electronics. Almost for sure it is a pretty basic rig down there and probably will not be suitable for dark field, which requires quite high lumens , especially for the 100x objective.
3) A number of the components are expounded upon as being something special.. "DIN objectives", "Abbe condenser" "Seidentopf head" " coaxial focus". These are all completely standard features on almost all but entry level microscopes these days. As far as DIN objectives go, it doesn't matter whether objectives are DIN or not, they can still be stupendous and most of the shorter tube objectives I know of, I guarantee you would outperform the ones on this microscope, which are not planachromats; they are achromats and probably have considerable curvature of field-----not very suitable for photography, nor is an Abbe condenser , usually.
4) They have weirdly offered it with 25x eyepieces?? 25x eyepieces used to be more common, when some relatively low power objectives had really high N.A.'s., For instance Bausch & Lomb used to make a 61x 1.4 N.A. apochromat, oil immersion which you could have used a 25 with and gotten good results. A 25x eyepiece is theoretically usable on a 10x .25N.A. objective without giving empty magnification but to be useful with a 40x, the N.A. would have to be 1 or higher, and to use a 100x to get this microscopes vaunted 2500x, they N.A. would have to be the impossible figure of 2.5.
With the optics on this microscope, the 25x eyepieces will be almost useless.
I guess it is supposed to sound impressive , anyway----kind of like the 450x telescopes that Tasco used to sell.
There is no mention of whether the microscope can receive a trinocular head. That will be necessary for intended photography or video.

If you want this microscope for photo/video and darkfield, you will need 1) a darkfield condenser 2) a 100x plan objective with an iris 3) a trinocular head and likely a photo eyepiece. 4) possibly , 3 replacement plan objectives. This will add , about 4-500.00 minimum to it's cost.
Perhaps you could call them and get an idea , whether the added specs. are possible with this instrument or if there is another they have that would fit the bill, and be cheaper as a package.
Generally, I figure that to get dark field, bright field and trinocular in a good working 4 objective microscope, you have to spend about 500.00 minimum. They are around, used,sometimes a little less, if you aren't picky about the age of the unit. Older microscopes were built to last a a lifetime and once put into nick by a competent repairman, you won't need a 5 year warranty. I note that their's doesn't seem to cover shipping, so it might make the warranty a little wimpy.

[jasonwebb]

Where are you getting the $250 figure? The scope I linked to is listed at $158 with free shipping. Also, I said my budget is sub-$200, since I'm not planning to be very seriously interested in microscopy, but want to get some decent photos.

The scope I linked to is purported to be an AmScope B120C. I thought Amscope was one of the reputable brands?

As for doing dark-field work, I was under the impression that one could make a suitable DIY solution using various materials, like a penny: http://www.avtanski.net/diy/?p=15. I am also planning to experiment with making my own parts using a 3D printer.

I've not read anything about eyepieces with irises before, how necessary might they be and why?

As for the trinocular head, I instead plan to attach my smartphone or RasPi camera directly to an eyepiece using a 3D printed mating connector, such as http://www.thingiverse.com/thing:59344

As for the illumination aspect, I am an electronics nerd, so I was planning to retrofit it with high-powered white LEDs anyway, so that shouldn't be an issue

Finally, the replacement plan objectives sound interesting. If I understand correctly, plan objectives create a flatter field. I may upgrade to them latter, but I'm curious how bad my results would be without them.

My ultimate goal is to find the cheapest combination of scope and DIY modifications to do basic darkfield photos of radiolaria and (maybe) diatoms. I definitely don't want to invest $500+ on this hobby at this stage.

[phil m]

The link I went to had 93.00 shipping quoted. Perhaps it is because I am not in the U.S.
DIY darkfield is possible but is practical for low magnifications only. Once you get to using the 40x objective likely and the 100x for sure the precision required to get the system centred and sending the light in from the correct angle requires very precise alignment.
Dark field illumination also demands an N.A. of around .85, as a maximum. Your 100x objective is a standard 1.25 N.A. , so you will need some way of stopping that down. Typically ,this is done with an iris diaphragm built into the objective. I see inexpensive iris equipped Chinese objectives selling for around 300.00+. It is possible to stop down the existing objective using some form of field restrictor. This might be possible with the supplied objective but not having seen it's internals, I don't know. Again precision and centering are key. When a restricter is used for dark field, it must be removed for bright field, otherwise you reduce the N.A. too much for bright field and the image will be blurry.
I missed that you intend to use a phone, camera. You can do this bur it is hard to know what the results will be. Usually with afocal photography , in order to get sensor coverage, there needs to be a little zoom applied.
Achromatic objectives all have curvature of field. Depending on how much of the field you capture in a picture the curvature will be more or less annoying. Plan objectives offer varying degrees of flat fields, depending on the objective and the eyepiece, employed.
I wasn't trying to knock your choice, as I said the microscope seems to be good value for the money but stretching it into an acceptable dark field photo microscope might be asking more than it is capable of. To look at it another way, a dark field condenser, even a Chinese one sells for almost as much as this entire microscope. They are pretty precise devices.

[jasonwebb]

Thanks for the information. There doesn't seem to be very much quality information online about microscopy in general, or about dark field photomicroscopy in particular when it comes to what equipment (and where) to buy - just overviews and explanations of the process.

Most of the resources I've found so far make it sound like you only need to have some sort of "patch stop" on a normal condenser to turn the scope into a darkfield one. I'm not looking for amazing laboratory-grade stuff, just a basic documentation rig for checking out the aesthetics of radiolaria. For example:

- https://www.youtube.com/watch?v=Mkqi3fL84sg
- http://www.microbehunter.com/darkfield-microscopy/
- https://www.microscopeworld.com/t-darkf ... scopy.aspx
- http://www.microbehunter.com/how-to-mak ... e-filters/

However, it does sound like this only works with lower magnifications. What level of magnification would I need to clearly see details on radiolaria?

[phil m]

yes, such a simple system would limit you to 400x or less. generally , the background gets grayer and many of the benefits of dark field get lost because the precision and registration of components aren't there.

Radiolaria have details that go beyond the capability of the light microscope to resolve. For general structure and form low mags. would do, though.
You know, I see complete dark field systems on ebay from time to time. There were a lot of Spencer and Bausch & Lomb systems sold prior to the war and if binocular, that had a separate dedicated photo tube. The performance is first class, as good as most of the professional level stuff available today, if clean and properly settup.,..... such things a DIYer should be able to do easily. Prices vary but have been from under 100.00 and seldom over 2 .Might take some patience looking and finding ,though but they are there..

[jasonwebb]

Thanks! That is really great info, I'm glad to hear that there is some possibility to do some basic work with affordable equipment. I will definitely be keeping an eye out for those brands on eBay, but I may go ahead and pick up that ~$160 Amscope to begin tinkering a bit, unless you would strongly recommend against it.

Now I may be mistaken, but I *believe* I've read a few that places that for radiolaria I don't need to go much further than 300x, and some people are quite happy at around 40x. Does that sound reasonable? Since I haven't done any microscopy yet, I don't really have an intuition for what these magnifications would result int. I have read that radiolaria tend to be around .1mm to .2mm in size, if that helps.

[rjlittlefield]

I may go ahead and pick up that ~$160 Amscope to begin tinkering a bit

If you do happen to pick up that scope, I would be very interested to know about the focusing mechanism. I recently purchased the two Amscope units "on either side" of that one and found that the $85 M150 actually had very coarse focusing despite its superficial similarity to the $275 T490B. The difference was a factor of almost 15X: 2.9 mm per rotation for the M150 versus 0.200 mm per rotation for the T490. See test reports HERE and HERE. The focus knobs I see on your scope look exactly like those of the M150. That's not a good sign, but conceivably only the knobs are the same and internally it works like the T490. If you get it, please let me know.

--Rik

[phil m]

certainly for general structure and form 300x is adequate but always there are details at any magnification of almost anything that are unresolvable by the human eye, so the temptation to magnify more is omnipresent..
What level of detail you will see, also depends on the illumination and condensing apparatus. LEDs emit a very different form of light than microscope optics were designed for and have been only partially successfull to date. Generally I have found their use for incident illumination to be pretty good, transmission illumination less good but that may be just because the systems I have tried needed tweaking.
good luck with it. i would certainly like to hear a report back because any time someone can buy a decent higher power microscope for that kind of money---it needs to be noted.

Thanks! That is really great info, I'm glad to hear that there is some possibility to do some basic work with affordable equipment. I will definitely be keeping an eye out for those brands on eBay, but I may go ahead and pick up that ~$160 Amscope to begin tinkering a bit, unless you would strongly recommend against it.

Now I may be mistaken, but I *believe* I've read a few that places that for radiolaria I don't need to go much further than 300x, and some people are quite happy at around 40x. Does that sound reasonable? Since I haven't done any microscopy yet, I don't really have an intuition for what these magnifications would result int. I have read that radiolaria tend to be around .1mm to .2mm in size, if that helps.