Let's say, all things being equal between two microscopes, except one has a 25mm "fine focus range" and the other has a 30mm "fine focus range", which would be a better choice?
Why? Or does this not really matter much as far as choosing a microscope for a hobbyist?
I searched but sadly found nothing about the details of this topic. Seems to me a ~2 inch difference in the range would be important in some applications, but not in others; I haven't a clue.
Thanks in advance for your insight!
What is "fine focus range"
Re: What is "fine focus range"
What microscopes are you talking about? Compound or stereo?jackieone wrote: ↑Mon Jan 29, 2024 9:12 pmLet's say, all things being equal between two microscopes, except one has a 25mm "fine focus range" and the other has a 30mm "fine focus range", which would be a better choice?
Why? Or does this not really matter much as far as choosing a microscope for a hobbyist?
I searched but sadly found nothing about the details of this topic. Seems to me a ~2 inch difference in the range would be important in some applications, but not in others; I haven't a clue.
Thanks in advance for your insight!
You write in mm then say 2inch. So either it's cm or it is not 2 inch...
I can't think of any application in which that would make a difference. Maybe if you observe a 30mm specimen with a 30+mm working distance objective and you want to use fine focus through the whole specimen, then 25mm won't be enough.
I don't know what is the fine focus range of my microscopes.
Re: What is "fine focus range"
I'm not sure I'd trust today's low-end makers to use the term "fine focus range" in the way it was once understood.
Those ranges (25mm or 30mm) sound like coarse focusing ranges. It may also be the fine focusing range, depending on the mechanism. That is, how much room there is from focusing from the stage and up. You might want a larger range if you're dealing with thick subjects at low magnifications. It could also give you a bit more room for changing objectives.
A microscope with an adjustable stage or an exceptionally long range could also let you use short barrel objectives at some point - such as Lomo water immersion objectives - or long objectives on adapters such as a Nikon 20x Plan Apo. In a lower-cost import microscope, neither option (handling very thick specimens or handling objectives from around 34 to 60mm parfocal distance) may really be available.
In the past, fine focus gears often had a limited range - just a couple of millimeters in some cases. Otherwise excellent microsocopes like the Leitz Dialux and the Zeiss WL required getting coarse focus close and then tweaking it with the fine focus. This limited range sometimes makes a difference if someone wants to use one of these focus mechanisms for focus stacking in something like bug-sized specimens. Focus stacking, as you may know, is a digital imaging method to have thicker specimens imaged sharply at all depths. You wouldn't want to run out of fine focus range part way through a stack.
Bottom line - it probably isn't going to matter much in a lower cost import microscope.
Those ranges (25mm or 30mm) sound like coarse focusing ranges. It may also be the fine focusing range, depending on the mechanism. That is, how much room there is from focusing from the stage and up. You might want a larger range if you're dealing with thick subjects at low magnifications. It could also give you a bit more room for changing objectives.
A microscope with an adjustable stage or an exceptionally long range could also let you use short barrel objectives at some point - such as Lomo water immersion objectives - or long objectives on adapters such as a Nikon 20x Plan Apo. In a lower-cost import microscope, neither option (handling very thick specimens or handling objectives from around 34 to 60mm parfocal distance) may really be available.
In the past, fine focus gears often had a limited range - just a couple of millimeters in some cases. Otherwise excellent microsocopes like the Leitz Dialux and the Zeiss WL required getting coarse focus close and then tweaking it with the fine focus. This limited range sometimes makes a difference if someone wants to use one of these focus mechanisms for focus stacking in something like bug-sized specimens. Focus stacking, as you may know, is a digital imaging method to have thicker specimens imaged sharply at all depths. You wouldn't want to run out of fine focus range part way through a stack.
Bottom line - it probably isn't going to matter much in a lower cost import microscope.
Re: What is "fine focus range"
@imkap - Sorry for not being more clear, I wasn't taking my time to ask the question correctly. These are specs from two compound microscopes, Amscope brand, and the 25mm vs 30mm is the correct measurement. I just eyeballed my ruler and gave the estimate in inches. oops! Thanks for your comment about any applications where this would be important...I wouldn't have a clue as I'm so new to this microscopy hobby. :=)
@PeteM - Thanks, I think I understand a bit more about this "fine focusing" and yes, I'm looking at lower cost overseas imports; so I'll just put this to rest. But I didn't know it was measuring from the stage and up.That's also an interesting observation about leaving a bit more room for changing objectives. I didn't think of that at all.
You know what I really love about this forum (besides the glorious pictures and videos)?
It's being able to learn something new every day. That really is so cool!
@PeteM - Thanks, I think I understand a bit more about this "fine focusing" and yes, I'm looking at lower cost overseas imports; so I'll just put this to rest. But I didn't know it was measuring from the stage and up.That's also an interesting observation about leaving a bit more room for changing objectives. I didn't think of that at all.
You know what I really love about this forum (besides the glorious pictures and videos)?
It's being able to learn something new every day. That really is so cool!
Re: What is "fine focus range"
FWIW, you could think of focusing range from the parfocal tip of the objective down, as well, since the stage is most commonly the part that moves up and down in today's compound scopes.
Many scopes have an adjustable stage stop to avoid crashing a slide into the objective when it's being raised - and not much focusing range beyond that. A few let you adjust things for a much wider range.
Many scopes have an adjustable stage stop to avoid crashing a slide into the objective when it's being raised - and not much focusing range beyond that. A few let you adjust things for a much wider range.