@apochronaut -- Thanks for your input.
Is the loss of quality you mentioned for BF also present in BF objectives or only when doing BF through phase contrast objectives? If I wanted to do BF, would I be better off using BF objectives (instead of doing BF through phase contrast objectives)?
Thanks again for all of your replies.
![😊](//twemoji.maxcdn.com/2/svg/1f60a.svg)
[/quote]
Phase contrast objectives have a physical device implanted in them that is part of their specification. This specification is only met during their use in phase contrast. In BF use they do not work to specification.
Since standard BF objectives do not have that, they work up to specification in BF . They can also work to specification in DF as long as certain criteria are met. The main one is that the objective has an N.A. about .2 lower than the condenser.
DF is limited by the condenser , which is the active device that enables it. If the condenser is mediocre, the DF will be average or mediocre. DF is no more difficult than BF, it just requires the proper tools.
If I understand your situation , you are a reasonably experienced astrophotographer with a decent camera. Reading into your aims for photomicrography would lead me to believe that the two microscopes you are looking into will be interesting and challenging to begin with but will become frustrating fairly quickly.
Here's why. Microscope # 1 has 5 objectives, a 20mm f.o.v. and a trinocular tube. All good things for your situation. Beyond that, it is no different than any other microscope , even some much cheaper.
Limitations. Since you are interested in photography, the semi-plan objectives will in many cases force you to crop your images. If you get into stacking, they will cause difficulty. The microscope is limited to B.F. If you make D.F. masks , the quality will be limited by the condenser, which is a standard abbe 1.25; about the cheapest condenser any microscope above hobby grade can have. You probably cannot buy a better condenser for that instrument, you would have to d.i.y. one from another brand. An oil D.F. condenser can likely be purchased for about 150.00 or so. In order to do high resolution D.F., you will also need a 100X objective with an iris diaphragm built in.
The phase contrast system is an insert system. Although they work, they are a bit annoying to use. A rotary or carousel type is much preferable. There are only 3 magnifications for the phase system. You will miss having a 20X.
You don't know the capabilities of the photo eyepiece sticking out of the trinocular tube. The f.o.v. it sees, how well corrected it is? You will need some adapters to your camera and possibly better optics.
Microscope #2. It is phase contrast, which is good. It is fully plan, which is good. It is trinocular. Again , that's about it.
Limitations. It is an insert type and it is only a 3 objective microscope. You will miss the 20X. You will need BF objectives, likely. Certainly if you want to do higher mag. DF but with a 3 objective nosepiece , your objective choices are limited. Changing objectives manually in the middle of use went out in 1915. You may need a DF condenser and a 100X objective with iris diaphragm.
The f.o.v. is only 18mm. That is no longer the default. 20mm is expected these days. However, at 18mm it offers the same plan coverage as the microscope above.
Again, you don't know the capabilities of the photo optic supplied.
Both are led but do not state the wattage. probably 3, which limits DF applications. They are also both 160mm fixed tube microscopes. This may have advantages, since older 160mm D.I.N. optics of better colour correction could be used to improve the optical performance and they are typically cheaper than infinity corrected in general. Some infinity being the exception.
Given all that, your stated goals and your budget, I really think you are barking up the wrong tree buying into an average Chinese system, especially with your budget.
You could look a little higher into the stratosphere for a better Chinese scope. They have research models that are fully upgradeable and wouldn't exceed your budget too much. You can buy them direct from a broker in China, or even direct from the factory in many cases. Shipping to Australia won't be too bad.
A better option is to buy out of the U.S. on ebay where there are many used options off and on for far better microscopes that are upgradeable in the future. Price would be the same roughly, even with the shipping added in. Wait time would definitely be longer but I think it is worth the wait.
I am in Canada and am well familiar with the exchange difference to $US, the wait and the shipping cost. We get no breaks sharing a border and the shipping can be 3-4 weeks. If I bought a microscope out of Syracuse N.Y. , which is 75 miles away, the shipping would be 130-150.00 Canadian $ and it might take 3 or more weeks to get here.