Belomo loupe; must get one but which and from where?

[Mike Reed]

Have long been considering this after Tony's dissertation a year or two back and some comments since. He recommended the 10x, but it seems that there's a 12x now available, which may be an advantage.

Although I wear specs, I need to remove them for any close work or reading and always use my current old loupes (in the 'funnel' shape with glass at one end) with naked eye.

I'm wary of buying from the U.S. and probably from Belarus (their origin?) might be quicker, with no potential tariffs. Can't understand why there are no stockists here, but even going through Amazon (at a premium price), it still comes from Belarus.

Qu. 1: Should I opt for the tried and tested 10x or go for the slightly enhanced magnification of the 12x? Not sure of the light properties of each, as that's a very important factor.

QU. 2: Which is the better purchase avenue? (I think the 12x may only be available from one country; not sure)

 

[Tony L]

On balance I’d not recommend the 20x. It is just so hard to use compared to the 10, but assuming the 12x is as good optically as the 10 (i.e. as bright and with similar depth of field) it could be the sweet-spot. I have a feeling there is a 15x too. Here’s an obligatory Amazon link to the 10x.

 

[Mike Reed]

Thanks, Tony. Just realised this is in the wrong place; should have been Audio. Sorry about that.

 

[karma67]

i have the 10x,12x and 15. i got mine from amazon,they are not cheap compared to the chinese ones but they are so much better. money well spent for cartridge set up,azimuth etc. the 12x is what i use the most.

 

[deebster]

I bought my 10x direct from Belomo earlier this year. Prices are in $ but worked out cheaper than anywhere else for me. Free shipping too

https://belomostore.com/

 

[Vinny]

My boring warning as ever - higher mag' = shorter focal distance (in other words, the nearer you have to be to the object to be in focus, and the better the lighting you need).

x20 is essentially impossible to use with a mounted cart' unless the headshell is detachable. I suspect that x15 will be very similar based on the fact that a x10 is JUST comfortable/convenient to use.

 

[karma67]

yep you're right 15 is just to close,the 12x is perfect

 

[Tony L]

This is definitely an area where having a detachable headshell or stylus is a huge bonus! I have to admit I’d have no chance of seeing anything without.

 

[Mike Reed]

yep you're right 15 is just too close; the 12x is perfect

Between the two (10x & 12x), is the brightness about the same? Also, do you feel that you're losing out on depth of field? Also, d'you wear glasses when using them? I am very short-sighted; hence the questions. Oh yes; my arms have fixed h/shells so loupe use will be on cart's in situ.

 

[Vinny]

do you feel that you're losing out on depth of field?

There is no such thing as depth of field with a lens. The image is sharp at point x. depth of field is more a function of your eye/brain.

The higher the mag', the less absolute distance there will be between perfect focus and what you struggle to make out.

Brightness will depend on what illumination you use - if all else fails, use a good quality pen torch.

 

[Mike Reed]

There is no such thing as depth of field with a lens.

Why do I have to unlearn stuff I've held to be true all my life, Vinny? In photography, depth of field is the amount of image one can get into focus to be sharp. The wider the lens, the greater the d. of f. Therefore I equate that small focus area to loupes, as they're all lenses which magnify. One of my rather weak old loupes don't have that 'in or out' focussing spot; neither is it that clear either. I expect the Belomo to totally relegate my other two in all aspects.

I understand the trade-off between magnification and d. of f., but surely this 'window' of focus still retains the same terminology as photographic lenses. If not, what's it called?

By 'brightness', I mean the ability to transmit light, similar to the function of F stops, but in this case probably more to do with quality of glass etc. Obv. an exterior light would prove to be beneficial and I have a number of those incredible little LED torches which cost peanuts and last years.

 

[Vinny]

Why do I have to unlearn stuff I've held to be true all my life

LLOL - you don't - silver film and CCD sensors, lenses and light are not the same as lenses, light and your eyes and brain

I haven't the maths or biology to justify my belief but would expect that "depth of field" of any lens used as augmentation to your eye will be within the same ROUGH percentage of the actual focal length - so, picking imaginary numbers - a lens with focal length of 2cm will be seen to be in focus between 1.8cm and 2.2cm, whereas a lens of focal length of 1cm will be seen to be in focus between 0.9cm and 1.1cm. Twitch when using a high mag' loupe, and the object is out of focus.

This must be something on the www, somewhere, but having been "seconded" into a microscopy lab for a while, I am reasonably confident in what I have said. Use a mic' of a few X10 and you can wind the focus knob up and down a "mile", use X100 or higher and you are using the tenth/fine adjustment focus knob to see anything clearly.

 

[Tony L]

I can certainly state the “depth” of the 20x is crazy shallow, to the extent I can’t get the whole of just the tip even remotely sharp. FWIW as a really short-sighted glasses wearer I use these loupes the way a jeweller does, glasses off and held firmly against my eye socket, I then bring the cartridge into view (as stated I have a detachable headshell). It works well and I can see very clearly with the 10x, and if I see anything that slightly concerns me I get the 20x out. I also have a vintage microscope which obviously get a lot closer in a more controlled way, but to be honest the 10x tells me most of what I want to know, which is about cleaning as much as wear really.

 

[Brucedgoose]

There is no such thing as depth of field with a lens...

I think what he actually means is focal length or distance, which is a property of the lens. So what you don’t want to view your mounted stylus is a lens with a very short focal length. Usually, the more powerful the lens, the shorter the focal length. In microscopy, LWD (Long Working Distance) objectives are used in applications that require greater distance between the object being studied and the objective lens. They cost more than standard objectives because they’re harder to produce.

 

[Vinny]

I think what he actually means is focal length or distance, which is a property of the lens

Please see post #6

 

[Brucedgoose]

...but to be honest the 10x tells me most of what I want to know, which is about cleaning as much as wear really.

Yes, that’s true for me, too. I use a 10x “Peak” loupe along with a high-intensity lamp angled nearby to illuminate the stylus. It helps with seeing dust, etc. on the stylus, but you need much, much higher magnification, like 400x, to see wear on the stylus. You can’t hand-hold anything with adequate magnification to see stylus wear. You need to use a microscope that has the proper magnification as well as a long working distance objective to see stylus wear. If you see something that looks like stylus wear with 10x, there is already extremely gross damage to your stylus and it needs replacement right away. Shure used to make a very nice Stylus Microscope that dealer’s would sometimes have available, back in the days of brick-and-mortar audio shops. Once in a while I see one on Ebay - never in good condition, however, since microscopes require regular, specialized maintenance and audio dealers didn’t bother with this.

 

[Brucedgoose]

LLOL - you don't - silver film and CCD sensors, lenses and light are not the same as lenses, light and your eyes and brain

I haven't the maths or biology to justify my belief but would expect that "depth of field" of any lens used as augmentation to your eye will be within the same ROUGH percentage of the actual focal length - so, picking imaginary numbers - a lens with focal length of 2cm will be seen to be in focus between 1.8cm and 2.2cm, whereas a lens of focal length of 1cm will be seen to be in focus between 0.9cm and 1.1cm. Twitch when using a high mag' loupe, and the object is out of focus.

This must be something on the www, somewhere, but having been "seconded" into a microscopy lab for a while, I am reasonably confident in what I have said. Use a mic' of a few X10 and you can wind the focus knob up and down a "mile", use X100 or higher and you are using the tenth/fine adjustment focus knob to see anything clearly.

Unless we’re talking about really cheap plastic lenses, the focal point of a lens with a 2cm length will be 2cm from the lens itself, no more, no less. If you find you need to focus your objective lens to some nearby distance, it is probably because you are compensating for eyesight deficiencies, or a misaligned mechanical connection somewhere in the ‘scope. Good quality lenses are held to tight tolerances as far as focal length is concerned. If they weren’t, the many optical devices that use compound lenses wouldn’t work properly.
I used to be a microscope repairman. I do sort of wish I had put together a ‘scope with LWD objectives for stylus inspection, but practically speaking, I never wear out styluses before I want to upgrade.

...I also have a vintage microscope which obviously get a lot closer in a more controlled way...

Just add a 40x LWD objective (very expensive) to the turret, along with a 10x eyepiece, be sure the tube is properly lubricated to ensure accurate focus, add good illumination, and you’ll be all set.

Here’s how to zero in on proper focus without destroying your stylus: First, securely attach the cartrigpdge to the microscope stage. You can do this with tape. Then, bring the *least powerful* objective down to just above the stylus. Do this while looking Directly at the cartridge, not through the eyepiece, so you don’t smash the needle. Then, while looking through the eyepiece. Slowly bring the tube *upward* and the needle will come into focus (still at low power). At this point, you should be able to rotate the turret to bring the 40c LWD objective into the tube without smashing the needle, but still being near the correct focus. You’ll need to adjust focus very slowly up or down from this point to get the needle into sharp focus. It will be touchy. If you see any bright spots on the surface of the needle, those are wear spots that are somewhat flattened by wear and they are acting like tiny diamond mirrors, sending a bright spot or reflected light into your eye. Big bright spots mean your stylus is badly worn. You won’t see this with 10 or 20x or anything like that.

 

[Tony L]

Here’s how to zero in on proper focus without destroying your stylus: First, securely attach the cartrigpdge to the microscope stage. You can do this with tape. Then, bring the *least powerful* objective down to just above the stylus. Do this while looking Directly at the cartridge, not through the eyepiece, so you don’t smash the needle. Then, while looking through the eyepiece. Slowly bring the tube *upward* and the needle will come into focus (still at low power). At this point, you should be able to rotate the turret to bring the 40c LWD objective into the tube without smashing the needle, but still being near the correct focus. You’ll need to adjust focus very slowly up or down from this point to get the needle into sharp focus. It will be touchy. If you see any bright spots on the surface of the needle, those are wear spots that are somewhat flattened by wear and they are acting like tiny diamond mirrors, sending a bright spot or reflected light into your eye. Big bright spots mean your stylus is badly worn. You won’t see this with 10 or 20x or anything like that.

I fairly quickly figured out crashing the objective into the subject was far from impossible, though thankfully not with a cartridge! I’m lucky in that I use both a arm with a detachable shell and a MM cart with detachable stylus, so I can actually get a good look. I’ve used blu-tac to hold it and LED bike lights, of which I have many, as illumination and its pretty usable.

Here’s the microscope, a 1960s Olympus.

 

[Brucedgoose]

I fairly quickly figured out crashing the objective into the subject was far from impossible, though thankfully not with a cartridge! I’m lucky in that I use both a arm with a detachable shell and a MM cart with detachable stylus, so I can actually get a good look. I’ve used blu-tac to hold it and LED bike lights, of which I have many, as illumination and its pretty usable.

Here’s the microscope, a 1960s Olympus.

That’s a really nice scope! Brings back memories of my youth. I worked for The Technical Instrument Company on San Francisco and repaired ‘scopes like this one at the U.C. Medical Center in SF. Beautiful devices, microscopes!