I don't know if the glass is softer than other lens glass, but a good number of objectives crop up which have small chips or other marks.
I've tried horrible-looking camera lenses without being able to induce any flare or other results. When I was a lad it was common to see lenses with bubbles in the glass - usually coupled with an excuse that the glass was hard to make, which may have had some validity at one time.
Obviously the size of the chip is important relative to the size of the lens, but are there any particularly bad places to have such things?
Is there any frequently-seen bad effect?
Is there anything which can be done about them?
I see there are microscopists' goos with specific refractive index, so wonder if there might be any point filling a sharp chip.
As a case in point I have a low mag objective with a small chip in the rear. At least it will be well out of focus.
Chips and marks on microscope objectives
Moderators: rjlittlefield, ChrisR, Chris S., Pau
Most front surface marks come from over enthusiastic focus racking. I was taught to focus by looking from the side while racking in as close as possible and then look tthrough the eyepiece while racking out. Of course I don't do it all the time ... and when you have a motorised stage, gulp. I mount my subjects on a magnetic base so when I drive straight through the focal plane the subject moves before the mounting pin gets embedded in the objective. In principle anyway.
To answer your question (how to fix them) - no idea !
Andrew
To answer your question (how to fix them) - no idea !
Andrew
Charles passed on an elegant tip.
If you mount the lens on bellows and look from the rear, and can see a bright spot where the chip is, put a tiny dot of black paint into the chip.
I have an objective with a largish rear element, which has a small chip. It reflects incident light rather alarmingly, but through the bellows, all I can make out, and only just, is a slightly dark spot. That's without any black paint. As a percentage of the lens area it's tiny, so I'm not expecting trouble from that one.
If you mount the lens on bellows and look from the rear, and can see a bright spot where the chip is, put a tiny dot of black paint into the chip.
I have an objective with a largish rear element, which has a small chip. It reflects incident light rather alarmingly, but through the bellows, all I can make out, and only just, is a slightly dark spot. That's without any black paint. As a percentage of the lens area it's tiny, so I'm not expecting trouble from that one.