Microscope requirements for botany

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Trsmiff
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Microscope requirements for botany

#1 Post by Trsmiff » Sun Jan 09, 2022 10:56 pm

Hello all,

I have been IDing flowering plants successfully for years now with little more than a field guide and a 20x hand lens, but have started to get into bryophytes more recently. This is game changer as IDing of mosses typically requires views of the cellular structure. Whilst I am not a beginner botanist, I am certainly a beginner when it comes to microscopes. This is where I need some help.

I am looking at getting my first compound microscope and having dipped my toe into world of microscopes it is clear to see that there are lots of tools and techniques available for all types of subjects. I currently assume that all I require from a compound microscope is brightfield optics only. I may venture into studies of pollen and perhaps chromosome counts, but would other setups (e.g. phase contrast, DIC etc) be a strict necessity for the applications I'm looking at? If anyone can share their experience on this and what I should be looking for in a 'scope, it would be greatly appreciated.

Ultimately what this boils down to is that I am looking to invest in a 'scope that delivers relatively high quality optical performance without having to pay for extra niceties that I wouldn't really benefit from. I am looking at the used microscope market, to bag a gem at a good price, but getting lost amongst the infinite variety out there. Would I be better off getting a new budget 'scope and not be so worried about optical quality for what I need it to do, or is the prospect of a 2nd hand Alpha brand instrument simply the best way forward?

If either is true, suggestions of what models and features to look out for would be gratefully received. Budget wise I'm looking at somewhere around £1500 to get myself up and running.

Many thanks in advance!

Tom

dtsh
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Re: Microscope requirements for botany

#2 Post by dtsh » Sun Jan 09, 2022 11:37 pm

Hello!

You might find that a stereo microscope delivers more of what you're looking for and provides more utility, but while I've done some reading and looking at bryophytes, I'm ignorant of exaclty what details you need to examine.

I have both compound and stereo, using my Cycloptic stereo as an example as it's what I use frequently. It will do 7x-40x, or 7x-80x with a 2x barlow; the plant cells I've looked at are easily visible at 40x. I'd reach for a compound if you're looking to do botanical slices and staining, but otherwise I find my stereo is far handier most of the time when I am examining plant and insect samples. The stereo tends to provide a greater depth of field, allowing more "depth" to what's in focus; in general, as magnification goes up, the depth of the sample in focus goes down.
There are a lot of models available, all with various tradeoffs and quirks. Are you hoping to use it in the field or at the desk?

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zzffnn
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Re: Microscope requirements for botany

#3 Post by zzffnn » Sun Jan 09, 2022 11:51 pm

Plan achromat objectives are very helpful for botany. Get objectives from 2x to 100x. And objective of around 1x would be nice too, but make sure it works on the same / similar stage height as other more powerful objectives (typical an 1x objective would have too long a working distance).

If you look at a lot of low contrast unstained samples, then phase contrast is useful.

A stereo scope is necessary for processing plant tissues, if you don't have one already.

DIC is likely overkill and difficult to assemble at 150p GBP.

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Re: Microscope requirements for botany

#4 Post by DrPhoxinus » Sun Jan 09, 2022 11:57 pm

Yes,

I am a biologist and I have both compound (15) and stereo (1) scopes.

The question is how often do you need to see things in 3D and at what magnification.

With a stereo scope you can just throw a sample on the viewing stage and with forceps there you go.

Compound scopes require flatter specimens

Trsmiff
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Re: Microscope requirements for botany

#5 Post by Trsmiff » Mon Jan 10, 2022 11:19 am

Many thanks for the responses so far.

Whilst I understand that the stereomicroscope is a more typical and useful tool for general plant observations and dissections (and slide preparation), what I would be looking for requires observations of leaf sections mounted on slides (i.e. 2D flat images). Key aspects including; the strata of leaf cells, leaf cell shape and the presence of pores in cell walls and the measurement of leaf cell size is also important. As such, I think a compound microscope is necessary. Examples to illustrate this can be seen here https://www.britishbryologicalsociety.o ... techniques.

I'll be dealing with plant material, most of which has a natural pigment and staining samples is also not an issue. Therefore I think I can ignore phase contrast techniques and stick with simple brightfield, although further insight from other would be welcomed.

General feedback seems to suggest that lower magnification is more useful (x2, x4, x40, x60 objectives). Are there any suggestions for 'off the shelf' microscopes that can accommodate this versatility in objectives? FYI - I am UK based, and Brunel microscopes have been recommended before.

Would the above set up conflict too much with x100 objectives for viewing pollen, chromosomes and oil droplets. I would be looking at these subjects far less often, would I be better off leaving the latter x100 setup to a different microscope all together?

Thanks again,

Tom

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Re: Microscope requirements for botany

#6 Post by Microscopy_is_fun » Mon Jan 10, 2022 12:57 pm

Hi Tom,

with your budget you could get a very decent new microscope with infinity optics from Motic (e.g. Panthera C2 trinocular) or Zeiss (Primostar 3). If you are willing to look into used microscopes, you might even get additional fluorescence and phase contrast (e.g. https://www.mikroskop-online.de/mikrosk ... mikroskop/).

Regarding 60 vs 100x objectives: This is more a question of oil vs. dry objectives. For maximum resolution you need high numerical aperture (e.g. >1.2), and for this you need immersion oil for the objective and ideally also for the condensor. The resolution is only determined by the N.A., and not by the magnification of the objective. This means that a 63/1.4 lens gives you the same resolution as a 100/1.4 objective. Without immersion oil you will only get up to N.A. of around 0.9, and thus lower resolution.

In your list of magnifications, I think the step from 4x to 40x is too large, I would include a 10x there, or maybe 20x.

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Re: Microscope requirements for botany

#7 Post by mrsonchus » Mon Jan 10, 2022 1:38 pm

Hello Tom,

in my experience of dissecting and mounting moss and liverworts at the macro and microscopic levels I would 100% answer that you need both a compound and a stereo 'scope to fully explore the details. Taxonomic detail as you mention can quite often go into leaf-cell arrangement and/or shape for example.

If you have a look over one of my posts re moss exploration at both stereo and compound levels you'll get a good idea of what each option can give you.

I will add that darkfield, especially at the stereo 'scope level, can be very revealing and useful, not to mention quite beautiful when studying Bryophytes - this feature I would make a requirement when considering a stereo 'scope.
John B

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