MicrobeHunter.com Microscopy Forum

I'm going to have a quintuple nosepiece. What's the most optimal combination of objectives to buy/use?

I'd imagine 4x BF is essential. I would like to get 1 phase contrast objective in the mix, but it seems that the combination of brightfields (4x, 10x, 20x, 40x, 60x) would be nice to have, which means if I add 1 phase contrast objective, I'll have to exchange objectives every now and then.

If I were to get just one PH objective, which one should it be?

What I'd like to observe would be:
- pond water, sea water, etc.
- everyday stuff from dust (mites), cheese, plants, surface germs, etc.

I don't use the 4x much at all. 10x is fine for scanning the slide, imho. And I love having a mid-magnification oil objective.

Thus, with five spots, I would go: 10x, 20x, 40x Dry, 40x oil, 60x/100x oil.

And for the one phase objective, I think you would be happiest with a 20x.

Always consider 15X eyepieces as well. Many 15X eyepieces for good systems have a field # of 17 or even 17.5. That means that if you use 15X/17 eyepieces you will see about 25% more of the field using a 40X objective than you would using a 60X objective with 10X/20 eyepieces. Even with a paltry f.n. of 15, you will see more of the field at 600X. That way you can refine your objective choices. Seldom is a low N.A. ( .85) 60X objective of much value in a 5 objrctive nosepiece. Adding in 15X eyepieces can turn your objective number from 5 to 9 in one nosepiece.

4X, 10X, 20X, 40X and 100X work well especially with an added pair of W.F. 15X. The N.A. of your objectives needs to be up to the challenge but most good planachro systems are. Better if you can up the N.A. of the 40X. In general, you cannot use 15X eyepieces with average 60X and 100X objectives. They need to be N.A. 1.0 and 1.4 at least respectively.

I agree with a 20X phase choice, better 25X if your system has one. i would then delete the 20X B.F. objective. Some companies offered single diaphragm phase condensers. The condenser was usually a high quality .90 achromat, the phase diaphragm could be in or out for BF. With 15X W.F. eyepieces you would then have 2 phase magnifications albeit not very far apart. I think too, with the 20X phase diaphragm you would get 40 and 60X D.F. with the 4X objective.

+2 to the above.

I'd add that spending a bit more for a microscope with interchangeable nosepieces or six places might be worth considering. Having a 4x or even a 2x allows you to see much more of a slide, so six places is common for people who want to sort through a variety of specimens. It can also be nice to have one turret for "dry" work and another for oil immersion, so there's no possibility of transfer.

At some point, you may want to try special or special-bargain optics (water immersion, no cover for smears, older but cheap apos, iris objectives for darkfield, etc.). All those are easier and safer to swap, test, clean, parfocal shim, etc., on an interchangeable nosepiece. In addition, at some point you may want epi objectives and an epi head.

In the 60x v. 100x oil immersion choice, given the same numerical aperture (e.g., 1.3 or 1.4 na), I prefer the 60x. It usually adds a bit more working distance under the cover slip with no loss of image resolution.

An interesting question..and when deciding which scope would one use?

Options of an interchangeable head and phase capable condenser have been noted..others?

tardibear wrote: ↑

Fri May 26, 2023 9:58 am

if I add 1 phase contrast objective, I'll have to exchange objectives every now and then.

You can use a phase objective to use as brightfield, unless you are going to be taking high resolution images with that objective.

The optimal combination depends on the user profile.

My user profile is:

2.5, 6.3, 16, 40, 100 oil on the petrographic microscope.
10, 25, 40, 63, 100, all oil on the fluorescence microscope
2.5, 6.3, 10, 25, 40 for plant histology
6.3, 16, 40, 50, oil, 100 oil als a standard every day setup

There is no easy answer to your question.

I don't use a 4x or 100x very often and I'm used to 4 objective noses (or even 3), so I typically omit them, but the setup on my 5 hole AO10 is 10x phase, 20x phase, 40x phase, 45x achro due to it's deeper working distance and a 100x. In general I think 10x, 20x, and 40x cover a lot of ground, especially when paired with 15x eyepieces as already mentioned. I use my phase objectives in brightfield and it works for me, but my uses are not particularly demanding and I don't do a lot of imaging.

I bought quintuples a couple of years ago, so now I know what I really want is at least one sextuple

Alexander wrote: ↑

Fri May 26, 2023 10:57 pm

The optimal combination depends on the user profile.

This is what it al boils down to, of course. It's only that subjects so often change and with them the profiles. So, to accomodate as many of them as possible, for transient light I have 4x, 10x, 20x, 40x & 100xh and I use all of them frequently. For incident light I have 5x, 10x, 20x, 40x, 60x and 100x objectives. Until I'll find an affordable 6-ring, I either swap 5x and 100x, or 60x with 100x.

Alexander wrote: ↑

Fri May 26, 2023 10:57 pm

The optimal combination depends on the user profile.

My user profile is:

2.5, 6.3, 16, 40, 100 oil on the petrographic microscope.
10, 25, 40, 63, 100, all oil on the fluorescence microscope
2.5, 6.3, 10, 25, 40 for plant histology
6.3, 16, 40, 50, oil, 100 oil als a standard every day setup

There is no easy answer to your question.

Is user profile the same as application? User profile sounds a bit overly digitized.

apochronaut wrote: ↑

Mon May 29, 2023 12:24 am

Is user profile the same as application? User profile sounds a bit overly digitized.

We're talking nosepieces here, so the profile does come into question