best wattage of lamp used for phase contrast ; Thickness of a plant cell

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p3aul
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best wattage of lamp used for phase contrast ; Thickness of a plant cell

#1 Post by p3aul » Wed Mar 02, 2016 1:33 am

I'm going to sneak two questions in here for the price of one!

[1] I'm purchasing a new microscope with phase contrast and infinity plan objectives. The scope I have now has a thirty watt halogen lamp and seems bright enough for brightfield viewing but this new scope I will be getting has only a 20 watt lamp. I've heard that phase contrast viewing needs a lot of light. Will 20 watts be enough?

[2] I want to view plant cells so to that end I want to get a hand microtome. the best of these seems to be from the "homescience" website and has been discussed here before. for about $45 US It seems to have the features I want. My problem is this: As I said, I want to view plant cells, but I don't know how thick they are. It seems that the thinnest slice I can get is 5 microns. I want to capture the whole cell but only one cell so that I don't get confused by trying to view two or more cells on top of each other. I have tried to Google the thickness of a plant cell but the cell wall comes up every time!

Thanks people! I sure hope you can help me! I don't often have $1500 for a hobby!

Paul
Paul Microscope: Amscope T400b Camera: Amscope MU300
Telescope: Orion xt6 classic Dob, Zhumell z10 classic Dob

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lorez
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Re: best wattage of lamp used for phase contrast ; Thickness of a plant cell

#2 Post by lorez » Wed Mar 02, 2016 3:09 am

I can offer some thoughts on the wattage. I think the success of the phase contrast is more about the condenser, objectives, and phase rings than about the wattage of the lamp. I've seen excellent phase images from microscopes with 10 and 15 watt lamps. Today I compared a 20W Olympus and a 30W B&L system and could see no significant difference. The images were both sharp with good contrast and minimal flare. On lesser systems you will see rings that are not well printed and do not center well. Also there may be more flare around the specimen image. I would worry more about the quality of the optics than the wattage of the lamp.

Plant cells are delicious.

lorez

p3aul
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Joined: Fri Jan 08, 2016 3:16 am
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Re: best wattage of lamp used for phase contrast ; Thickness of a plant cell

#3 Post by p3aul » Wed Mar 02, 2016 3:26 am

Plant cells are delicious.
Red or Golden? :lol:

Thanks Lorez! Well I was looking at Amscope T690 Which is Infinity Plan and comes with a PC kit designed for the scope. It has Full Kohler and I like my present T400b just fine so I think I'll like this one also. I finally found out the thickness of the plant cell at about 10 - 100 microns so the little hand microtome should work out just fine. Meanwhile I'm going to just get a nut and bolt with a straight razor from local beauty supply store and play!

You know, this site has shown me plenty of ideas for this hobby that I can do for little or nothing!

Oh here's the link for a wikibooks free book that is very interesting. https://en.wikibooks.org/wiki/Cell_Biol ... /Cell_size
Paul Microscope: Amscope T400b Camera: Amscope MU300
Telescope: Orion xt6 classic Dob, Zhumell z10 classic Dob

apochronaut
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Re: best wattage of lamp used for phase contrast ; Thickness of a plant cell

#4 Post by apochronaut » Wed Mar 02, 2016 12:52 pm

Plant cells vary widely in their dimensions. Thickness is a relative term because it depends on whether you are slicing the tissue longitudinally or horizontally. The cells in a given plant tissue tend to mimic the tissues structure , when it comes to their dimensions. That is a factor in how the dimension is arrived at by the plant. Root tissue and apical stem tissue for instance, often have zones of cell elongation, which is one of the techniques by which the plant grows, so even though the xylem in this region might have cells 75 mic. in cross section, they can be 2 or 300 mic. in length.

The only thing I would add to lorez's comments are that sometimes , with the 100X phase objective ,the light can be a little dim with certain subjects but in general, there is enough light with in-base illuminators for phase.
One thing that gets overlooked, sometimes in evaluating in-base illuminators, is that not only is the wattage important but the distance that the light must travel to the stage is a factor too. The inverse square law comes into place here. A 15 watt illumination source, placed right under the collector lens, can provide as much illumination as a 30 watt placed 6 inches behind a right angled reflecting mirror. Reflectors and other factors in the light path can affect this dramatically too. Some in -base illuminators are just brighter than others and it isn't always the wattage that determines this.

p3aul
Posts: 79
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Location: Macon, GA USA

Re: best wattage of lamp used for phase contrast ; Thickness of a plant cell

#5 Post by p3aul » Wed Mar 02, 2016 4:10 pm

Thanks for the heads up Phil. I just thought it would be useless to slice right in to the cell or by slicing, capture two cells on top of each other or say slice the top off a cell if it's standing vertically. I've never done this before so I guess I'll know soon enough as I practice.
Paul Microscope: Amscope T400b Camera: Amscope MU300
Telescope: Orion xt6 classic Dob, Zhumell z10 classic Dob

charlie g
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Re: best wattage of lamp used for phase contrast ; Thickness of a plant cell

#6 Post by charlie g » Wed Mar 02, 2016 7:12 pm

Hi, p3aul...congrats on your phase contrast setup! I thought I hears you post: 'it's not yet arrived'...so take a fresh yellow onion, or fresh red onion...and 'hand strip a film of one cell thick layer'...observe this with your current scope.

Your 'hand held screw advance microtome' will be good for tiny young 'shoot tips' of plants freshly erupting from the ground .

But you must trim these tiny growth tips to lay on their side in your screw advance microtome...you will get terrific results.

Adult plants...well only specific plants, only specific plant structures, will easily offer good sections on your hand held/screw advance microtome. But again..you have ton's of plant tissues to work with...congrats!

I have a 30 watt halogen bulb which works with my 100X DL phase observing. Yes. phase works best with thin sections...not layers of cells. Charlie guevara

p3aul
Posts: 79
Joined: Fri Jan 08, 2016 3:16 am
Location: Macon, GA USA

Re: best wattage of lamp used for phase contrast ; Thickness of a plant cell

#7 Post by p3aul » Wed Mar 02, 2016 7:55 pm

Thanks Charlie! It will probably be a coupla weeks for both, but certainly not longer than that. I'm like a kid at Christmas! Mean while I'm going to the hardware store and get a large nut and bolt and a straight razor and practice with that. You can get a straight razor with a replaceable blade at beauty supply places for under $10 US so If I break one it's no big deal.
Paul Microscope: Amscope T400b Camera: Amscope MU300
Telescope: Orion xt6 classic Dob, Zhumell z10 classic Dob

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