WTB: 50X Mitutoyo Plan Apo Infinity Corrected LWD Objective
Moderators: rjlittlefield, ChrisR, Chris S., Pau
WTB: 50X Mitutoyo Plan Apo Infinity Corrected LWD Objective
Interested in purchasing the above objective in excellent condition. Please let me know if you have one to sell or are aware of any opportunities to purchase one from known reliable sellers. Thanks much.
You and me both. 
Light Glass Optics has the SL varient listed.
I highly recommend Light Glass. You could contact them and see if they have the standard M plan in stock.
Light Glass Optics has the SL varient listed.
I highly recommend Light Glass. You could contact them and see if they have the standard M plan in stock.
I'm in Canada! Isn't that weird?
I was advised not to purchase the SL model by a colleague on this forum. Here is his logic:
...“SL” model (stands for “super long”). This series has lower numerical apertures (NA) than the regular series. Lower NA means lower resolution.
A proper 50x Mitty has an NA of 0.55 which will often be written as 50x/0.55 or 50/0.55. You may have noticed that your Mitty 20x has an NA of 0.42. This means that the SL 50x will have no more resolution than your 20x. You could obtain much the same result by shooting with your 20x and cropping.
So I strongly suggest you hold out for a Mitutoyo 50x/0.55.
...“SL” model (stands for “super long”). This series has lower numerical apertures (NA) than the regular series. Lower NA means lower resolution.
A proper 50x Mitty has an NA of 0.55 which will often be written as 50x/0.55 or 50/0.55. You may have noticed that your Mitty 20x has an NA of 0.42. This means that the SL 50x will have no more resolution than your 20x. You could obtain much the same result by shooting with your 20x and cropping.
So I strongly suggest you hold out for a Mitutoyo 50x/0.55.
Adalbert wrote:Hi guys,
Could you explain please why the Mitty 50x with the NA=0.42 ?
Why not 20x / 0.42 ?
BR, ADi
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Scarodactyl
- Posts: 1631
- Joined: Sat Apr 14, 2018 10:26 am
I don't think anyone is recommending it as such 
.
I find it pretty remarkable that it's possible to make a lens with a FL of 4mm, which focuses to infinity with a 20.5mm working distance .
I can only imagiine that the SL could be more convenient in some standard setup
where the things WE care about are less important.
All you appear to get from the 50x between these two is more magnification.
Perhaps for where you don't have a mouse with a scroll wheel?
. I find it pretty remarkable that it's possible to make a lens with a FL of 4mm, which focuses to infinity with a 20.5mm working distance .
I can only imagiine that the SL could be more convenient in some standard setup
where the things WE care about are less important.
All you appear to get from the 50x between these two is more magnification.
Perhaps for where you don't have a mouse with a scroll wheel?
Chris R
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enricosavazzi
- Posts: 1475
- Joined: Sat Nov 21, 2009 2:41 pm
- Location: Västerås, Sweden
- Contact:
I agree that NA is the most important consideration when choosing SL versus non-SL Mitutoyo M Plan Apos in the context of photomacrography as done by members of this site.
The longer working distance of the SL series is relevant when a lot of test probes must be used on and around a chip being tested under a microscope. This is not the normal use by members of this site, but important in the semiconductor industry where these objectives are typically used.
Another thing than may be relevant when objectives are mounted on a Mitutoyo microscope turret is that objectives within the SL series are designed to be parfocal with each other, but not necessarily with the M Plan Apo (non-SL) objectives. This means a lot of coarse refocusing is necessary if SL and non-SL objectives are mixed on a microscope turret.
The longer working distance of the SL series is relevant when a lot of test probes must be used on and around a chip being tested under a microscope. This is not the normal use by members of this site, but important in the semiconductor industry where these objectives are typically used.
Another thing than may be relevant when objectives are mounted on a Mitutoyo microscope turret is that objectives within the SL series are designed to be parfocal with each other, but not necessarily with the M Plan Apo (non-SL) objectives. This means a lot of coarse refocusing is necessary if SL and non-SL objectives are mixed on a microscope turret.
--ES