DIC objective for brightfield?

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DIC objective for brightfield?

#1 Post by alschultz94 » Wed Feb 12, 2020 11:31 pm

Hi, everyone! This is my first post here.

I have a Motic microscope for which I currently have infinity Plan Achromat objectives to use in BF. However, I was looking to add a 20x objective to the collection, and came across a low priced used Nikon infinity Plan APO 20X/0.75 DIC N2/0.17 WD 1.0.

I know this is a specialized objective, but will I have issues using this objective for regular brightfield? (I just want to have a good APO objective without having to pay way too much for those. Am I better off just getting a regular 20x plan achromat objective?

I am planning on using the 20x for water and histology sample observation, as well as some microphotography.

Thank you so much for your input, and please let me know if any additional information is needed to answer this question.

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Re: DIC objective for brightfield?

#2 Post by Scarodactyl » Thu Feb 13, 2020 12:31 am

These actually aren't specialized, assuming it's the branded one (unbranded ones are corrected for different cover slip thickness than usual). They're about everything you'd want: perfect color correction, really high resolution, unstrained glass for polarization work (that's what the DIC label means, that it is suitable for DIC for this reason) and complete internal color correction for broad compatibility. Assuming Motic doesn't do corrections in the tube lens it should work very well, though it won't be parfocal so you'll have to be careful focusing, and mag will only be 20x if motic also uses a 200mm tube lens.
They're only cheap because a lot were dumped on the market from an obsolete gene sequencer. Get while the getting is good, it's one of the best objectives you're likely to get all at an insanely low price. I love mine as you might guess.

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Re: DIC objective for brightfield?

#3 Post by PeteM » Thu Feb 13, 2020 1:48 am

Also recognize that you'll have to buy a 25mm to RMS adapter to fit this to your nosepiece. The objective will end up over 15mm longer than your Motics and you should check there is room to drop your stage and condenser that low.

The Motic infinity I had might have been close to Olympus corrections, so you may not get your full $3000 worth out of this objective (approx. orig. list) and the magnification and corrections may be a bit off, but it should still perform very well. Biggest issue might be the ergonomics of having one objective so much longer - but it might end up your favorite objective for photography.

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Re: DIC objective for brightfield?

#4 Post by apochronaut » Thu Feb 13, 2020 2:07 pm

Motic are a little different than the rest of the Chinese microscope pack. The company began in Hong Kong( actually Kowloon Bay), almost 10 years prior to it's repatriation to China. They cut their teeth on making student and small lab scopes for some of the majors and may have taken advantage of some older lapsed patents of some of the majors. The tube length is 180mm, so the objectives may be fully compatible with Olympus.
If the objective works well enough, that is the corrections are acceptable once the image passes through the tube lens and you can get the extra focus travel out of your stage, you can always shim your existing 45mm parfocal objectives in order to get parfocality. Adapting for 15mm is possible. You will get about an 8% increase in the magnifications marked on your Motic objectives, so not a major problem..... but parfocality in such a situation is much more important than the accuracy of the marked magnification.

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