No name ebay focusing block

[Ludvig Friberg]

I found this focusing block on ebay:

https://www.ebay.com/itm/Stereo-Microsc ... 2869704367?

Does anyone know about it? I have a olympus bh2 and I would like to build a horisontal setup. If this perform similar to my olympus I would be happy with the performance.

Best regards

Ludvig

[ray_parkhurst]

Looks very nice for US$117 but I have no experience with it. I may have a use for it so am considering picking one up myself. Am hoping someone else has already bought one and can give thumbs up/down so I don't waste more $...

[Vector1968]

I think this part was made in China, It's a copy of Nikon's.

[ray_parkhurst]

Which Nikon model is this a copy of?

[Vector1968]

Which Nikon model is this a copy of?

Such as Nikon SMZ645, 745, but with the improvement of fine focusing. And the fucusing looks like Olympus style.

[Vector1968]

[Ludvig Friberg]

I have no experience with Nikon microscopes and certainly not with this copy. But probably it will be similar to other focusblocks? Perhaps a bit shorter life if anything?

Is there anything similar in the same pricerange you would recommend instead? I live in Norway so this free shipping deal is good to me.

[ray_parkhurst]

So it is similar but has the fine focus adjustment, which the Nikon stand does not. I see they also offer a version without fine focus.

[enricosavazzi]

There is no way of knowing for sure without directly testing one of these racks, but there are two basic types of fine focus mechanisms (and I am not talking about the total amount of travel of the fine focus):

• In focus racks for compound microscopes (usually for transmitted illumination at up to about 1,000x magnification), the fine focus knob does not rotate when the coarse focus knob is rotated by hand. Conversely, turning the fine focus knob by hand does not slowly rotate the coarse focus knob. One revolution of the fine focus knob typically moves the rack by 100 or 200 micron.
  
  In focus racks for stereomicroscopes or macroscopes (for example the Leica M420), the fine focus knob rotates quickly when the coarse focus knobs is rotated manually. Rotating by hand the fine focus knob also slowly rotates the coarse focus knob. In other words, the two knobs are permanently engaged with each other via the internal gears. This makes the mechanical construction of the fine focus mechanism considerably simpler and cheaper. One turn of the fine focus knob may move the rack by more than 200 micron.

Since this rack seems to be designed for stereomicroscopes, there is a good chance that the fine focus mechanism is of the second type.

[rjlittlefield]

I notice that the advertisement specifically says "One scale of fine focusing: 0.002 mm".

That's a typical spec for 200 microns per full turn.

I'd guess this is an Olympus look-alike, though probably not an actual clone. It looks like a slightly extended version of what I found in Amscope T490, described at http://www.photomacrography.net/forum/v ... hp?t=24552 . The price is consistent with that also.

--Rik

[ray_parkhurst]

There is no way of knowing for sure without directly testing one of these racks, but there are two basic types of fine focus mechanisms (and I am not talking about the total amount of travel of the fine focus):

• In focus racks for compound microscopes (usually for transmitted illumination at up to about 1,000x magnification), the fine focus knob does not rotate when the coarse focus knob is rotated by hand. Conversely, turning the fine focus knob by hand does not slowly rotate the coarse focus knob. One revolution of the fine focus knob typically moves the rack by 100 or 200 micron.
  
  In focus racks for stereomicroscopes or macroscopes (for example the Leica M420), the fine focus knob rotates quickly when the coarse focus knobs is rotated manually. Rotating by hand the fine focus knob also slowly rotates the coarse focus knob. In other words, the two knobs are permanently engaged with each other via the internal gears. This makes the mechanical construction of the fine focus mechanism considerably simpler and cheaper. One turn of the fine focus knob may move the rack by more than 200 micron.

Since this rack seems to be designed for stereomicroscopes, there is a good chance that the fine focus mechanism is of the second type.

The only mechanisms I am familiar with are the Nikon type (Optiphot, Labophot, Biophot, etc) and these are the geared type where the mechanisms are linked. Which models or brands have separate fine vs coarse focus mechanisms as you describe in your first type? And in that type, does the fine focus mechanism have infinite range? The second type provides infinite range with fine focusing.

[Pau]

In fact there are lots of mechanisms and models...for example most gray Zeiss Standard models have linked fine and coarse focus and 400micron per turn although with high precision while Universal and WL have completely independent mechanics (200 or 100 micron/turn) but only 2mm fine focus travel, Olympus CH, BH and alikes move the coarse knob only when reaching the limit -a good feature to protect mechanics from suffering the typical Nikon broken gear issue, I think.

[ray_parkhurst]

In fact there are lots of mechanisms and models...for example most gray Zeiss Standard models have linked fine and coarse focus and 400micron per turn although with high precision while Universal and WL have completely independent mechanics (200 or 100 micron/turn) but only 2mm fine focus travel, Olympus CH, BH and alikes move the coarse knob only when reaching the limit -a good feature to protect mechanics from suffering the typical Nikon broken gear issue, I think.

All my Nikons do that as well. If I move the coarse knob, the fine knob moves with it. If I reach the end of travel turning the coarse knob, the fine knob runs in reverse to compensate, and same if I move the fine knob with coarse running in reverse.

[Ludvig Friberg]

I found it on AliExpress too. A bit more pictures in theese

https://www.aliexpress.com/item/Metal-R ... 65821.html

https://www.aliexpress.com/item/LeeTun- ... 06464.html

[ray_parkhurst]

I found it on AliExpress too. A bit more pictures in theese

https://www.aliexpress.com/item/Metal-R ... 65821.html

https://www.aliexpress.com/item/LeeTun- ... 06464.html

Nice to see more pics, thanks. A little cheaper too.