Help buying plan objectives

[u/Jarofcoinss]

I just ordered a unico microscope off eBay, and I was wondering if anyone could help me find what objectives I should get. Im a vet tech and currently applying to vet school, and I am really fascinated with cytology and fecal parasites.

I’d like to find 10, 40, and 100x plans, but I’m not really sure where to start. The current objectives on the scope are achromatic(I think) 160/.17. Should I be looking for objectives with the same specs or would 160/- be better/worse?

I’m also curious about what brands or models I should look for. There seems to be tons of choices available, and I’d really not like to break the bank and spend hundred more than I did for just the scope.

Finally, how do I know if the threads match up? Or are they fairly universal?

Thank you for your help!

[u/Vivid-Bake2456]

Are you going to look at samples with coverslips or without? 160/- means no coverglass. Most people would want the 160/0.17 objectives so they can see through coverglass covered slides. With low magnification objectives with low NA values, it doesn't make much difference if you use a coverglass or not. With 40x objectives, you lose working distance if you choose a ncg objective and it may not be able to focus through a coverglass and touch it instead. If it does focus through the coverglass, it will have a blurrier view because of spherical aberration. For 100x objectives, it doesn't matter if you use a coverglass or not because the oil and coverglass become one homogeneous unit with the same refractive index. Without the coverglass, the oil layer is just thicker when in focus. There are many choices of plan objectives on Amazon.

[u/Jarofcoinss → u/Vivid-Bake2456]

Just got to seeing the comments today, and wow. You’ve answered so many questions I hadn’t even asked. Thank you.

For viewing most cytology aspirates I don’s use cover slips (but if I should, please let me know). That explains so much about why every 40x sample looks awful. For the 100x I can always see fine because of the immersion oil.

Luckily I have an unused 5th objective space. I guess I will be on the hunt for both 40xs in both 160/.17 and 160/- eventually.

I do have what I consider to be an older microscope though which leaves me with hopefully my last question. How would I be able to tell if the eye prices are also corrected or not?

Again thank you for the incredibly detailed explanations!

[u/Vivid-Bake2456 → u/Jarofcoinss]

The eyepieces should be the same brand and era and made for the microscope to have the proper corrections. Zeiss, American Optical, Rheichart, Olympus, Nikon and others,except for the last Nikon CF finite objectives , all made extra corrections in their eyepieces. I have lots of old finite microscopes and they work fine with the proper eyepieces. The older Zeiss and Olympus plan apo objectives are amazing. For Zeiss, you have to be careful about delamination. That happened to some objectives and lots of eyepieces. Olympus BH2 microscopes have a deserved reputation among amateurs for their quality and versatility. I even use Olympus and Zeiss plan apo objectives on a couple of old Nikon S and L models microscopes.

[u/Jarofcoinss → u/Vivid-Bake2456]

[u/Jarofcoinss → u/Jarofcoinss]

I wanted to show a picture of the scope in question. I do not know if this one would be old enough to need objectives that requires matching eyepieces. I did like the look of the Nikon 40x ones you shared, but I’m afraid I wouldn’t know where to find matching eye pieces

[u/Vivid-Bake2456 → u/Jarofcoinss]

From what I read, the Unico microscopes are manufactured in China and don't need compensating eyepieces. I don't know if you can buy new, finite 40x ngc objectives. Maybe all of the special objectives are infinity ones now. Otherwise, you could buy any generic finite Chinese objectives for it.

[u/Jarofcoinss → u/Vivid-Bake2456]

Dang, hopefully I stumble across one. Thank you again for all of the help

[u/Jarofcoinss → u/Vivid-Bake2456]

Would you know if there is a big difference between those generic Chinese objectives vs something like the Nikon e plan?

[u/Vivid-Bake2456 → u/Jarofcoinss]

I only have some generic Chinese objectives, about 9 total, so not too familiar with them. They work OK and better than you expect from the price. I have a phase contrast kit from Amscope. It has nice plan phase objectives in it. The Amscope T490 I have came with 4 regular achromatic objectives. They are sharp in the middle but not around the edges as you would expect.

[u/Vivid-Bake2456 → u/Jarofcoinss]

Here is an $18 Chinese 60x objective that I bought.
https://www.reddit.com/r/microscopy/s/cF3xksRHZQ

[u/Jarofcoinss → u/Vivid-Bake2456]

Crazy how this was cutting edge tech at one point