Well, another issue with my microscope

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Lilly Begonia
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Joined: Sat Jan 27, 2018 6:00 pm
Location: Cape Coma FL

Well, another issue with my microscope

#1 Post by Lilly Begonia » Mon Mar 05, 2018 5:20 pm

I've been noticing for a while now that when I go to a higher power objective and have to crank the condenser upward to get enough light, it will not stay where I put it. At first there is enough light, and then it slowly gets darker and darker until it's too dark, and then I have to crank the condenser back up because it slowly sinks back down, and sometimes not so slowly. It should not be doing this. I feel it should stay where I put it. This, together with the focusing slip makes it look like I got something of a lemon here.

Has anyone else seen that behavior with their condenser? I'm thinking maybe I should have gone with Amscope.

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75RR
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Re: Well, another issue with my microscope

#2 Post by 75RR » Mon Mar 05, 2018 5:37 pm

The condenser should indeed stay where you put it. There should be a screw you can tighten somewhere.
One should not adjust the light intensity by raising and lowering the condenser.
Adjust the light intensity by turning the dimmer.
Condenser should be placed a couple of mm below the slide and left there if you do not have Köhler illumination.

By the way, are you using the blue filter that came with your microscope? It helps to overcome the yellow tinge that incandescent bulbs have.
Zeiss Standard WL (somewhat fashion challenged) & Wild M8
Olympus E-P2 (Micro Four Thirds Camera)

Lilly Begonia
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Re: Well, another issue with my microscope

#3 Post by Lilly Begonia » Mon Mar 05, 2018 6:13 pm

75RR wrote:The condenser should indeed stay where you put it. There should be a screw you can tighten somewhere.
One should not adjust the light intensity by raising and lowering the condenser.
Adjust the light intensity by turning the dimmer.
Condenser should be placed a couple of mm below the slide and left there if you do not have Köhler illumination.

By the way, are you using the blue filter that came with your microscope? It helps to overcome the yellow tinge that incandescent bulbs have.
Well, with the 40/0.65 objective the dimmer cannot give me enough light to see anything and I have to use the condenser, with the dimmer turned nearly all the way up. I'll look for that screw and put the condenser where you said to. I didn't get a blue filter with this scope, but I did get a green one. I can't think of why I'd want to use it though. I'm afraid I don't know what Köhler illumination is.

MichaelG.
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Location: North Wales

Re: Well, another issue with my microscope

#4 Post by MichaelG. » Mon Mar 05, 2018 6:46 pm

Lilly Begonia wrote:
75RR wrote:The condenser should indeed stay where you put it. There should be a screw you can tighten somewhere.
One should not adjust the light intensity by raising and lowering the condenser.
Adjust the light intensity by turning the dimmer.
Condenser should be placed a couple of mm below the slide and left there if you do not have Köhler illumination.

By the way, are you using the blue filter that came with your microscope? It helps to overcome the yellow tinge that incandescent bulbs have.
Well, with the 40/0.65 objective the dimmer cannot give me enough light to see anything and I have to use the condenser, with the dimmer turned nearly all the way up. I'll look for that screw and put the condenser where you said to. I didn't get a blue filter with this scope, but I did get a green one. I can't think of why I'd want to use it though. I'm afraid I don't know what Köhler illumination is.
.
Correct me please, if I'm wrong ... but I think the OMAX in question has LED illumination, not tungsten.
http://www.microscopenet.com/omax-40x20 ... -9100.html

Note: The green filter would probably be most useful when using a monochrome camera ... peak sensitivity is usually in that range.

MichaelG.
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einman
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Re: Well, another issue with my microscope

#5 Post by einman » Mon Mar 05, 2018 7:04 pm

Are you adjusting the aperture on the condenser? Opening and closing for optimal lighting and contrast once the condenser is set properly should take care of your problem in regards to lighting provided the condenser is where it is supposed to be.
Last edited by einman on Mon Mar 05, 2018 10:18 pm, edited 1 time in total.

Hobbyst46
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Re: Well, another issue with my microscope

#6 Post by Hobbyst46 » Mon Mar 05, 2018 7:58 pm

Looking at the OMAX picture on eBay, it seems indeed to have a blue filter on top of the illuminator.
Perhaps the photo means to show a similarity of the spectrum of its LED light to either incandescent or halogen lamp light?
A green filter is also advantageous for phase contrast. Do you have phase contrast components on the scope?

apochronaut
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Re: Well, another issue with my microscope

#7 Post by apochronaut » Mon Mar 05, 2018 8:16 pm

It sounds like the rack and pinion mechanism for the condenser is too loose and is letting the condenser drift downwards by gravity.
There is nothing really wrong with using the condenser lower on it's track for very low power objectives. On some microscopes, that is the only way you can fill the field with some of them . However, when you do raise the condenser on it's track, in order to increase the N.A. for the higher power objectives, it should stay put. Less expensive microscopes are unlikely to have any way of adjusting that mechanism; it is reliant on fit and to a lesser degree the damping of the grease on the shaft and gears.

Normally, one can shim the focus block in order to tighten up the fit but since your microscope is fairly new, it needs to be returned for a professional service or replacement....unless you want to tackle it yourself and shim the focus block and or put some damping grease on the gears ....that would do it.

First, find out for sure if the condenser is drifting and if so I would contact the supplier and explain your dilemma; I am sure they are familiar with it.

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