100X magnification - 100x 18mm WD objective has a NA of 0.50

Clintonwake · Post by **Clintonwake** » Mon Dec 15, 2014 4:56 pm

Hi All

I contacted this company to see if I can test their objective and would like your opinion if I am wasting my time on this m/obj. Below is a reply I received

Wondering what your thoughts are?

(18mm WD objective has a NA of 0.50, Diffraction limited performance: 399nm, 532nm and 556nm, 100X magnification.)

cheers
Denis

----------------START OF THEIR RESPONSE/EMAIL -----------------
Dear Denis,

Thanks for your interest in Shanghai Optics.

The 18mm WD objective has a NA of 0.50, Diffraction limited performance: 399nm, 532nm and 556nm, 100X magnification.

In regarding your inquiry, would you mind to let me know what is the application and specifications of the objective that you need? This unique objective is custom made for our customer's application, so it may not works for your application, or it may be overkill. If you can share your inquiry in detail, we're more than happy to evaluate and feedback to you.

Here's a brief introduction about Shanghai Optics: We are a one-stop custom optics design, fabrication, and lens assembly house with over 54 years of experience. We are a leading optics supplier in China for companies such as Nikon, Canon, Olympus, Epson, Philips, Optic España. We deliver the best cost performance ratio products across photonics industry.

I’ve included our digital brochure in this email for your reference. Our website: www.shanghai-optics.com also has a lot of detailed introduction on SO product lines and capabilities.

Thanks again and I look forward to hearing from you.
----------------------END OF THEIR EMAIL ----------------------------

MY QUESTION TO THEM===========
Offline Message left on 12 Dec 2014, 08:59 AM (GMT+0)

What is price of "Ultra Long WD 18mm 100X Objective". What is the NA of this lens? Can you send for me to test?

cheers Denis

ChrisR · Post by **ChrisR** » Mon Dec 15, 2014 5:42 pm

Thought is that the NA isn't attractive. You'd be working at effective f/100.

You HAVE of course an NA 0.55 at 50x. Slightly more resolution, and a lot more field of view.
For 100x, you could get a NA 0.7 or 0.8 with (just) enough WD to use. The Mitutoyo is the obvious LWD choice. The Nikon ELWD is only 2mm iirc, though that's quite usable.

Though you may see a bit more detail with a higher magnification objective at the same NA as a lower one, it's not much, if it's there at all.

Clintonwake · Post by **Clintonwake** » Mon Dec 15, 2014 6:41 pm

Thanks Chris. I thought the 18mm WD is good but the NA is more important for resolution.

So is the one you are referring to?

MITUTOYO M PLAN APO SL100/0.55 F=200 100X MICROSCOPE OBJECTIVE 378-813

cheers
Denis

Chris S. · Post by **Chris S.** » Mon Dec 15, 2014 7:23 pm

No Denis. The one you refer to is the 100x/0.55, of the "SL" (super long) series, which have low numerical apertures..

ChrisR refers to--rightly, my opinion--Mitutoyo part number 378-806-3, the 100X/0.70 Mitutoyo Plan Apo Infinity-Corrected Long WD Objective. The working distance for this objective is 6mm.

But be aware that since you already have the Mitutoyo 50x/0.55, the difference between the objective I listed above, and the one you already have, is not earth-shaking. To be sure, the 100x/0.70 does resolve a bit more than the 50x/0.55--but it's not the dramatic difference some might expect.

I would like to test drive the Mitutoyo 100x/0.90 HR objective, even though its working distance is only 1.3mm.

--Chris S.

Clintonwake · Post by **Clintonwake** » Mon Dec 15, 2014 8:45 pm

Thanks Chris S.

I think I might just test & improve my skills with the Nikon CF Plan 50x/.55 before even considering the 100x.

thanks once again

cheers
Denis

Chris S. · Post by **Chris S.** » Tue Dec 16, 2014 1:06 am

Oops, Denis--I thought you had a Mitty 50x, but it's a Nikon you have. Probably both very nice lenses. But the Mitty, being an apo, likely has less CA.

Anyway, I think you're on wise track, becoming accustomed to your 50x/0.55 before considering a 100x/0.70. (Unless one comes along at an attractive price, of course!

) I don't regret my 100x/0.70 Mitty for a minute, and use it constantly--but also think that it is not for everybody.

Cheers,

--Chris

Pau · Post by **Pau** » Tue Dec 16, 2014 5:40 am

Just a add a point: Oil immersion biological objectives have NA from 1.25 to 1.4 (and virtually no working distance), even then the camera sensor "outresolves*" the objective very by a big factor , 0.50 for me would be unacceptable for my microscope work, but it's the price to pay for dry and ELWD

*yes, I know that it's not an accurate term...

Clintonwake · Post by **Clintonwake** » Tue Dec 16, 2014 6:29 pm

Thanks Chris S.

I went to the hardware store and got some rubber washer to block the light at the rear.

thanks
Denis

Clintonwake · Post by **Clintonwake** » Tue Dec 16, 2014 6:30 pm

Thanks Pau.

Long way for me to go to reach and understand using the 100x.

cheers
Denis