Why is the Center of My Microscope Image Lacking Contrast?

Click For Summary

Discussion Overview

The discussion revolves around the issue of lacking contrast in the center of a microscope image, specifically when observing H and E stained tissue samples. Participants explore potential causes and adjustments related to microscope settings, as well as the impact of imaging techniques.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested
  • Experimental/applied

Main Points Raised

  • One participant notes that the contrast is excellent at the periphery but poor in the center, suggesting a potential issue with microscope settings.
  • Another participant inquires about the specific microscope model being used, which is identified as an Olympus BX60M.
  • Adjustments to the field stop/aperture stop are mentioned as providing some improvement in contrast, but not consistently across the entire field of view.
  • There is speculation about whether the issue is related to vignetting or refraction artifacts, with one participant expressing concern about the quality of the image produced.
  • A question is raised about whether the center bright spot could be due to camera saturation, prompting a discussion about the settings of both the illuminating lamp and the camera.
  • One participant acknowledges the contrast issue is present both visually and in the photograph, expressing uncertainty about how to resolve it.
  • Another participant suggests checking if the issue persists with different objectives or eyepieces.
  • A link to an article on specimen contrast is shared, though its relevance to the specific issue is uncertain.
  • Field curvature is proposed as a possible explanation for the contrast issue, indicating that while the center may be in focus, the edges may become defocused.

Areas of Agreement / Disagreement

Participants express various hypotheses about the cause of the contrast issue, and while some adjustments have been suggested, there is no consensus on a definitive solution or explanation for the problem.

Contextual Notes

Participants mention the importance of aligning the microscope correctly, but there are no specific details on the assumptions or conditions under which the adjustments are made.

Who May Find This Useful

This discussion may be useful for individuals new to microscopy, particularly those experiencing similar issues with contrast in their images or seeking to understand the effects of different microscope settings.

remorris44
Messages
5
Reaction score
0
https://www.dropbox.com/sc/eo2c8j4kd12pdvn/AACGJ8YZvk35BSX1BsBoKIIsa

Please view the above image. I am getting awesome contrast on the periphery of the image but hardly any in the center. The sample is an H and E stained tissue and I just got the microscope in today.
I am a rookie with microscopes so any ideas as to how to get this nice contrast across the image? Adjusting the brightness doesn't change much.
 
Science news on Phys.org
What microscope are you using?
 
Drakkith said:
What microscope are you using?
It is an olympus BX60M. Got it for free from the university surplus department.
When I adjust the field stop/aperture stop just right I can see the good contrast around the center but otherwise the entire field of view is at comparable resolution but very poor contrast.
 
remorris44 said:
When I adjust the field stop/aperture stop just right I can see the good contrast around the center but otherwise the entire field of view is at comparable resolution but very poor contrast.

I'm sorry, I'm not actually too familiar with microscopes. Are you saying that if you adjust the stops just right it fixes the problem and you no longer have a contrast issue?
 
Drakkith said:
I'm sorry, I'm not actually too familiar with microscopes. Are you saying that if you adjust the stops just right it fixes the problem and you no longer have a contrast issue?

No worries, just glad to have someone to bounce ideas with.
No, the problem is with nearly every setting. Only when the stops are just right can I get a glimpse of the good contrast.
I want to say that it is a vignetting type of refraction artifact but if so it's pretty sad to say that an artifact region provides the best image...
 
Is the center bright spot just a contrast issue, or is the camera being saturated? You said adjusting the brightness doesn't help, but is that the brightness of the illuminating lamp, or just the brightness setting of the camera?
 
Drakkith said:
Is the center bright spot just a contrast issue, or is the camera being saturated? You said adjusting the brightness doesn't help, but is that the brightness of the illuminating lamp, or just the brightness setting of the camera?

The photo was taken via smartphone so it did pretty much get saturated in the center. The effect is less dramatic in the microscope when looking with the naked eye but still drastic (contrast difference between stained tissue and nothing). With a dimmer setting on the scope the color contrast is still dramatically different. I want the colors to 'pop' like they do on the periphery of the posted photograph.
 
Okay, so the contrast issue is a problem both visually and photographically. Honestly I'm not sure what to do. If I find something that may help you I'll let you know. Hopefully someone else here on PF has more experience in this area and can help you.
 
  • #10
Does it happen with other objectives and/or eyepieces? (i.e. did you get any other objectives or eyepieces?)
 
  • #11
remorris44 said:
https://www.dropbox.com/sc/eo2c8j4kd12pdvn/AACGJ8YZvk35BSX1BsBoKIIsa

Please view the above image. I am getting awesome contrast on the periphery of the image but hardly any in the center. The sample is an H and E stained tissue and I just got the microscope in today.
I am a rookie with microscopes so any ideas as to how to get this nice contrast across the image? Adjusting the brightness doesn't change much.

Assuming you have aligned everything correctly (http://www.well.ox.ac.uk/_asset/file/zeiss-guide-to-microscopy-from-the-very-begiining.pdf is a fantastic place to start), that looks like field curvature- the center may be in focus, but as you move towards the edge of the field of view, the image becomes defocused. What objective lens did you use?
 

Similar threads

  • · Replies 9 ·
Replies
9
Views
2K
Replies
2
Views
8K
  • · Replies 6 ·
Replies
6
Views
6K