What am i doing wrong?

Here you can discuss different microscopic techniques and illumination methods, such as Brightfield, Darkfield, Phase Contrast, DIC, Oblique illumination, etc.
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Greg Howald
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What am i doing wrong?

#1 Post by Greg Howald » Mon Apr 05, 2021 8:53 pm

I received a new oil dark field condenser today. I can see down in there well enough to center without an eyepiece but it's not very bright. When I put in the Eyepieces and a specimen All I get is total darkness and no image. Seems it doesn't pass enough light. This is true when mounted in three different scopes. The condenser is up all the way with no change if I back it off. Its brand new just out of the box and has me frustrated so I'm asking for a little instruction.
Greg

Hobbyst46
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Re: What am i doing wrong?

#2 Post by Hobbyst46 » Mon Apr 05, 2021 9:50 pm

Perhaps it is designed to be oiled to the bottom of the slide. with immersion oil.

Greg Howald
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Re: What am i doing wrong?

#3 Post by Greg Howald » Mon Apr 05, 2021 9:53 pm

Yep. No light.

dtsh
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Re: What am i doing wrong?

#4 Post by dtsh » Mon Apr 05, 2021 10:59 pm

What little I know of darkfield ondensers is limited to the one I have. With it I need to oil (I tend to use a drop of water) between the condenser and the bottom of the slide. It is very particular about condenser height and the condenser being centered. I have been using it with a 20w halogen, but I think more light would be nice. I have used it with some of the other illuminators and it works with less light (15w or so, probably even less), but it isn't pleasant. Double check filters aren't cutting down on what's getting transmitted.

If you aren't seeing any light at all, I would expect either the height isn't right or it isn't centered.
What type of illuminator are you using and how many watts?

Voyager-1
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Re: What am i doing wrong?

#5 Post by Voyager-1 » Tue Apr 06, 2021 12:04 am

Greg,
Raise the nose piece (objectives) out of the way.
Put a white piece of paper on the stage with the light on.
Raise the paper up and down by hand, do you see any circle of light?
Center dark circle should get bigger or smaller, depends on which condenser lens for the dark field.
If dimly lit, polarizers and wave plates out of the way?
If you do not see any circle, make sure all diaphragms are open fully.
Phase objectives, dark m objectives etc will make images very dark, they cancel out the dark field cone.
Presuming that the objectives you are using are for oil....

V

Greg Howald
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Re: What am i doing wrong?

#6 Post by Greg Howald » Tue Apr 06, 2021 12:57 am

Thanks guys. I centered the light bulb in the housing and then centered the condenser. I finally got an image using type b oil. I think the bulb needs replacing and I need new oil. The oil I have is extremely thick I think cause it's old. But I at least finally got an image. That's a starting point.
Greg

dtsh
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Re: What am i doing wrong?

#7 Post by dtsh » Tue Apr 06, 2021 4:57 am

What brand and model of darkfield condenser are you using?
Does the manual for it (assuming there is one) have instructions for setup?

Greg Howald
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Re: What am i doing wrong?

#8 Post by Greg Howald » Tue Apr 06, 2021 7:29 am

Its for an Amscope b660. It is the largest and most robust finite scope that Amscope sells. There is no instruction manual for this oil condenser. It's just taking more time to set up than I had ever expected. I'm going to check for a you tube video on the subject tomorrow. There's bound to be one out there. Now that I have figured out how to fix the condenser height I can try different oils. I have a little type a ( 1.5 1 ) and some mineral oil ( 1.46). I may also try some clove oil. It has an R/I of 1.54. I can also try going from a 20 watt bulb to a 30. I might as well just settle in and enjoy the tinkering.

MichaelG.
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Re: What am i doing wrong?

#9 Post by MichaelG. » Tue Apr 06, 2021 7:47 am

I have absolutely no experience with Amscope products, but this looks a reasonable set-up tutorial:
https://youtu.be/coD33VcSL5A

MichaelG.
Too many 'projects'

Hobbyst46
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Re: What am i doing wrong?

#10 Post by Hobbyst46 » Tue Apr 06, 2021 8:04 am

Type B immersion oil is highly viscous whether new or old. Type A is much less viscous and serves well.

Greg Howald
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Re: What am i doing wrong?

#11 Post by Greg Howald » Tue Apr 06, 2021 9:27 am

I watched the video. It was good instruction. Thanks.

Greg Howald
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Re: What am i doing wrong?

#12 Post by Greg Howald » Tue Apr 06, 2021 8:18 pm

And today it worked! Wonderful dark field images at 10, 20, 40 and 100x. And a good thing I got the iris with the 100x. Thanks for the help from all of you. Much appreciated.
Greg

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