There is a bit of flare due to the camera being held freehand or possibly dirty optical elements. I might start a thread on "cleaning optics" to learn how often it should be done.
Water plant leaf
100x taken through the EP with a cell phone.
Darkfield Success
Darkfield Success
I finally discovered how to get my el-cheapo darkfield disks to work on my Oly ECE upright. I had to open the field diaphragm fully and the condenser iris fully, then raise the condenser. The field diaphragm was what I had missed in my first efforts.
There is a bit of flare due to the camera being held freehand or possibly dirty optical elements. I might start a thread on "cleaning optics" to learn how often it should be done.
Water plant leaf
100x taken through the EP with a cell phone.
There is a bit of flare due to the camera being held freehand or possibly dirty optical elements. I might start a thread on "cleaning optics" to learn how often it should be done.
Water plant leaf
100x taken through the EP with a cell phone.
Re: Darkfield Success
Quote: "I might start a thread on "cleaning optics" to learn how often it should be done"
- seldom, in my opinion. I prefer to prevent "dirt" by covering the microscope with a tailored home-maid heavy cloth cover (not plastic) between sessions. Plus I wipe all parts that contact immersion oil after use.
Congratulations on your DF success - it feels great to overcome a nagging difficulty!
- seldom, in my opinion. I prefer to prevent "dirt" by covering the microscope with a tailored home-maid heavy cloth cover (not plastic) between sessions. Plus I wipe all parts that contact immersion oil after use.
Congratulations on your DF success - it feels great to overcome a nagging difficulty!
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apochronaut
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Re: Darkfield Success
Dirt in the optical system is not usually more apparent in DF but debris and residue on slides and coverslips is. DF produces conditions that cause debris on slides and coverslips to illuminate, as part of the sample and become more apparent than they otherwise would be in BF. This can show up as a glow or flare and diminish the contrast of the surrounding area in the view.
Background flare or a lack of a truly dark background is usually caused by some issue in the condenser itself, usually a poor condenser/objective N.A ratio or the slide thickness. The condenser N.A. needs to be 30% greater than the objective N.A. at least and the DF stop large enough to to block all light up to about 20% greater. That's a generalization but is about the ratio. The closer the two N.A.'s get, the greyer the background. If the stop is not precisely centered, the background will have an uneven grey scale and part of the field will look as though there is flare, somewhere.
Background flare or a lack of a truly dark background is usually caused by some issue in the condenser itself, usually a poor condenser/objective N.A ratio or the slide thickness. The condenser N.A. needs to be 30% greater than the objective N.A. at least and the DF stop large enough to to block all light up to about 20% greater. That's a generalization but is about the ratio. The closer the two N.A.'s get, the greyer the background. If the stop is not precisely centered, the background will have an uneven grey scale and part of the field will look as though there is flare, somewhere.
Re: Darkfield Success
I think you did a good job!... the flare is not that bad, certainly not bad enough to distract from the subject....
BillT
BillT