Incoming! Olympus BH-2 ...and a question please

[Terry Mc]

Hello all,

After snooping around I decided that a good version of the BH-2 will satisfy my wants for gazing at pond critters. It's loaded with 5 objectives, a combo of Zeiss and Olympus plans.

My question: how much does scattered light inside of a microscope affect contrast? I'm coming from the telescope world in which this is a notable concern.

I've used the amazing "Black 3.0" paint inside of my telescopes and it does make a difference! Black 3.0 is an acrylic paint that is the flattest-black that $$ can buy. It makes spray can flat black look like semi-gloss!

Would painting the interior of a microscope with such a paint have a positive effect??? Or is the light path so tight as to make doing so a wasted effort?

Many thanks,
Terry

[PeteM]

Scattered light is best controlled by setting up "Kohler" illumination and reducing the field and condenser irises so reduce light coming in from the edges of the field of view. A "tight" light path as you suggest. Things like dirty optics, lens coatings worn for excessive cleaning, and scratches can be another source.

Your BH2 should already have matte black finishes inside where they are needed.

Depending upon what objectives and eyepieces you get, could be you'll get better results with a properly matched set.

[Terry Mc]

Scattered light is best controlled by setting up "Kohler" illumination and reducing the field and condenser irises so reduce light coming in from the edges of the field of view. A "tight" light path as you suggest. Things like dirty optics, lens coatings worn for excessive cleaning, and scratches can be another source.

Your BH2 should already have matte black finishes inside where they are needed.

Depending upon what objectives and eyepieces you get, could be you'll get better results with a properly matched set.

Thank you Pete!

Yes, there is far more scattered light in a telescope. Sounds like painting with Black 3.0 would be a wasted effort.

The Olympus is in shipment and so I have no personal eye-time with it yet. It has the stock Olympus WK 10x/20L oculars and two Olympus S-Plan objectives. The remaining three objectives are Zeiss plans. Depending upon the performance, I could always sell the Zeiss' and buy a few S-Plans instead.

[Hobbyst46]

Scattered light is best controlled by setting up "Kohler" illumination and reducing the field and condenser irises so reduce light coming in from the edges of the field of view. A "tight" light path as you suggest. Things like dirty optics, lens coatings worn for excessive cleaning, and scratches can be another source.

Your BH2 should already have matte black finishes inside where they are needed.

Depending upon what objectives and eyepieces you get, could be you'll get better results with a properly matched set.

Thank you Pete!

Yes, there is far more scattered light in a telescope. Sounds like painting with Black 3.0 would be a wasted effort.

The Olympus is in shipment and so I have no personal eye-time with it yet. It has the stock Olympus WK 10x/20L oculars and two Olympus S-Plan objectives. The remaining three objectives are Zeiss plans. Depending upon the performance, I could always sell the Zeiss' and buy a few S-Plans instead.

1. In microscopy, the relative negative contribution of light scattering to the image depends on the mode of illumination.
For brightfield, and even for less bright illumination modes such as phase contrast, oblique, or DIC, the effect of scattering is usually weak and not significant - unless, perhaps, the internal black finish of the optical parts has failed altogether. Highly unlikely that you will need to paint anything black...
For fluorescence microscopy, where sensitivity of the eye/sensor/camera is challenged due to the inherent low intensity of the fluorescence, scattering could become a nuisance. But even for that purpose, I would bet that the internal black finish is OK. Many fluorescence users place the microscope in a shaded, dark corner of the lab.
2. The color corrections of Olympus and Zeiss very different. Replacement of the Zeiss objectives by SPlans will be a very good idea. SPlans are excellent lenses.

[Terry Mc]

Scattered light is best controlled by setting up "Kohler" illumination and reducing the field and condenser irises so reduce light coming in from the edges of the field of view. A "tight" light path as you suggest. Things like dirty optics, lens coatings worn for excessive cleaning, and scratches can be another source.

Your BH2 should already have matte black finishes inside where they are needed.

Depending upon what objectives and eyepieces you get, could be you'll get better results with a properly matched set.

Thank you Pete!

Yes, there is far more scattered light in a telescope. Sounds like painting with Black 3.0 would be a wasted effort.

The Olympus is in shipment and so I have no personal eye-time with it yet. It has the stock Olympus WK 10x/20L oculars and two Olympus S-Plan objectives. The remaining three objectives are Zeiss plans. Depending upon the performance, I could always sell the Zeiss' and buy a few S-Plans instead.

1. In microscopy, the relative negative contribution of light scattering to the image depends on the mode of illumination.
For brightfield, and even for less bright illumination modes such as phase contrast, oblique, or DIC, the effect of scattering is usually weak and not significant - unless, perhaps, the internal black finish of the optical parts has failed altogether. Highly unlikely that you will need to paint anything black...
For fluorescence microscopy, where sensitivity of the eye/sensor/camera is challenged due to the inherent low intensity of the fluorescence, scattering could become a nuisance. But even for that purpose, I would bet that the internal black finish is OK. Many fluorescence users place the microscope in a shaded, dark corner of the lab.
2. The color corrections of Olympus and Zeiss very different. Replacement of the Zeiss objectives by SPlans will be a very good idea. SPlans are excellent lenses.

Your comments are well appreciated sir. Thank you!

[KurtM]

...there is far more scattered light in a telescope...

It's the same thing, really, whereas telescopes suffer from "scattered light" because they're seldom properly baffled, particularly at the focuser. Yes, OT, but I had to say it.