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Focusable eyepieces or not?

omegahunter
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omegahunter Member

omegahunter

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I am looking at microscopes and have narrowed it down to Amscope SM-4TP or SM-4NTP.  I can barely wrap my head around focal length, FOV and depth of field and would appreciate any assistance.

From what I can discern the 4NTP has focusable eyepieces while the 4TP has an integrated dioptric adjuster.  The 4TP is a little cheaper.  What are the pros and cons of each?  Does it matter for practical watch repair workflow?

Would appreciate any input from owners of these 2 types of microscopes.

Waggy Distinguished Member

Waggy

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Here is a great review and hints on the features that are key for watchmaking. I have an Amscope, but wish i had watched this first. I bought directly from the Amscope site as they had a good discount on their site, so worth checking out too.

 

 

omegahunter Member

omegahunter

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Hey waggy that is a good video but I think he gets the magnification wrong.  The objective lens is actually .7x to 4.5x so with 10x eyepieces it is effectively 7x to 45x.

He also doesn't mention focusable eyepieces vs a built in diopter.  Looking at this video and others like it I think where you adjust focus doesn't really matter, but please anyone correct me if I'm mistaken.

spectre6000 Distinguished Member

spectre6000

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9 hours ago, omegahunter said:

I am looking at microscopes and have narrowed it down to Amscope SM-4TP or SM-4NTP.  I can barely wrap my head around focal length, FOV and depth of field and would appreciate any assistance.

From what I can discern the 4NTP has focusable eyepieces while the 4TP has an integrated dioptric adjuster.  The 4TP is a little cheaper.  What are the pros and cons of each?  Does it matter for practical watch repair workflow?

Would appreciate any input from owners of these 2 types of microscopes.

Focal length doesn't super matter for our purposes here. More than anything, it dictates the size of the scope. We're not super sensitive to that parameter. It's used in the SM head to vary the level of magnification, but since the size of the scope is what it is, and it's not extreme in any way, it's moot.

A wider FOV (field of vision) means you can see more at once. That's a good thing. I forget what they call it, but they have microscops with a "superwide field" or something, and that's not something to skip if the cost delta doesn't matter to you (or exists). 

Depth of field is the range of whatever is being magnified that can be in focus at once. With really high levels of magnification, your depth of field becomes zero, and you can only see an area the size of your FOV in a plane. We're not talking about those levels here, but since you're working with three dimensional objects where the point of interest could be some Z distance away from the plane, it's good to have some depth of field. More is better for our purposes.

HOKAY. So. Last and most impactful question in your line of inquiry there: Where does the adjuster go? The difference is just what part the eyepiece adjuster is attached to. It ends up in pretty much the same place either way. It functions pretty much the same either way. The difference is that you pay for it once if it's integrated into the head, and you pay for it with every set of eyepieces if it's not. If you have no intention of ever swapping eyepieces, get whichever is cheaper. If you think you might like some 20X eyepieces for some reason (maybe watchmaking related, may not, I use mine to fix skipping records), the eyepieces are cheaper if you're not also paying for the adjusters. It sounds like in this case, you get a double whammy cost savings in that the integrated adjuster is cheaper, so that's a no-brainer.

I own an SM-4TP, and I shopped around to get the cheapest price on the auxiliary parts between Amscope direct, Amazon, eBay, etc. It's one of those white label Chinese manufacturer things where dozens of outfits are selling the same exact product with a different logo on the sticker. In the junk drawer microscope thread toward the end, I believe someone found a decent model for appreciably cheaper than the AmScope, so it might be worth looking into. I don't recall the exact permutation, but they may have a variety of options if they're still around.

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