Epi-plan questions

[Stonius]

Sorry for posting again (newbie with lots of questions 8'll tone it down after this one).

So my new/old microscope (Zeiss Standard) came with 5 Neofluar phase-contrast objectives on one nosepiece, and an epi-illumination nosepiece that comes with 4 Epiplan objectives.

I'm more into pond-water microbes, ocean samples, that sort of thing - watching and filming microbe behaviour, I guess.

As far as I can tell, Epi-illumination is used for minerals and flourescence experiments, none of which I'm likely to do.

The fly in the ointment is that the Epi nosepiece has the wrong dovetail, so I cant just *see how it looks, (plus the objectives have different sized barrels and can't swap out) and the microscope is missing the mirror to bounce the epi beam out into the nosepiece assembly. So there's a bit of work involved to get it to the point where I can even see if I like using the Epi's.

I guess I could just sell them, but given that they are *plan objectives, they should be better for photography, right?

But in looking for a nosepiece with the correct sized mounting holes, I can only find other Epi nosepieces, so I'm wondering;

1) Should Epiplan objectives *only be used with epi-illumination? Is there a reason *not to use them as standard plan objectives?
2)For brightfield and darkfield, will Epiplans give better images than Neofluar Phase-contrast objectives?
3) Would I be best off selling the epi nosepiece and objectives and just buying some nice plan objectives that will simply fit in the current nosepiece?

Many, many thanks you guys.

As I said, I'm quite new to all this, so I really appreciate your valuable insights.

Cheers, Markus

[Scarodactyl]

Epi objectives are set up for observing samples with no cover slip. As such there is little overlap in what they're good for looking at and what conventional biological objectives are good at.

[Stonius]

Thanks, Scarodactyl, I wasn't aware of that. Could that be useful in biological specimens for someone without access to a microtome? ie, looking at mould spores in situ, or a compound eye, for example?

Best,

Markus

[Scarodactyl]

In theory yes--for looking at three dimensional objects, especially in reflected rather than transmitted light, a no cover glass objective is a must. In practice things are a little more involved. Most metallurgical microscopes are designed for looking at flat, shiny subjects. This is where coaxial epi illumination really shines (so to speak) and covers most of the usecases they were designed for. So, much like a biological microscope, there might not be enough play in the vertical focus to look at a particularly three-dimensional object like a larger insect--the stage just won't go low enough to get your objective in focus. In addition most of these subjects benefit from oblique illumination rather than coaxial, which is much fiddlier to achieve unless your objectives have a long enough working distance to accomodate an external light. Basically, in practice it might be more of a pain to look at non-metallurgical subjects with a metallurgical microscope than you'd like unless you get the right frame (with enough focusing distance to accomodate thicker subjects) and the right objectives (with a longer working distance to make lighting easy).
If you already have the objectives and nosepiece it may still be worth putting in some effort to get the parts assembled and give it a try--it gives you a wider range of things you can look at, and it might open up an entirely new avenue for you to explore. And if not you can always sell it off and buy something else you'd rather have.

[BramHuntingNematodes]

Zeiss has some very nice epi darkfield objectives that provide oblique illumination. They are the big chunky ones and sometimes are pretty affordable depending on the era they're from. I look at most anything with them, but that doesn't help you if you are trying to use objectives you already have. Also, dry epi objectives go to NA almost all the way up to one where a 3d specimen is essentially impossible to observe with the depth of field. In fact, .5 is the highest NA epi darkfield objective I have. Of course, these objectives require epi light to work at all, and a special field stop ad well.

[MicroBob]

Hi Markus,
when thinking about accessories it is important to know the precise model, especially for epi illumination. Your mcroscope is a Zeiss Universal 1, second edition, with the newer nosepiece dovetail, a very good model. Your epi condenser would fit a Zeiss Photomikroskop 1 or Universal 1, first editions. Acceesories for the first edition are not that common and you can probably sell the condenser for good money.
If you would like to keep and use the objectives you would need the right epi condenser, the epi field aperture for the Universal (Phomi one doesn't fit) and a lamp mount and lamp at the backside of the column. This would cost you quite a bit of money and time to find the right components. The objectives you have are epi bright- and darkfield objectives, you would select the function with stops in the epi condenser. The epi setup can be used for really flat objects that anre not covered by a cover slip, like a silicon wafer, paper, scratched glass... Epi setups are uncommon in amateur hands and little used. So if you want to make images outside the usual range this could be just fine, but the applications are fairly infrequent.
For fluorescence you would need the lamp holder, a stron LED Lamp with white or blue light and a Zeiss RS III fluorescence condenser with filters, again fairly special stuff with few applications.

Bob

[Stonius]

Yes, i agree Bob. The conundrum has been between the outlay to get it working Vs the enjoyment I'd get from objects I'm not sure I have any interest in.

But given my interest, I reckon I will be better off selling and getting something more appropriate to photography - probably something from a similar era with a flatter field like a plan achromat or something . Besides I've got all the phase contrast objectives to play with in the meantime, which is a whole world in itself!

Thanks so much for the advice.

Markus

EDIT; Also thanks for correcting me on the actual model. I've been reading the old manuals trying to figure out which one mine closest represents, and it's been...kind of confusing. It's good to have someone who just knows, you know?

[MicroBob]

kind of confusing

Especially the important difference between Phomi/Universal 1 first and second edition is not well documented. Then one needs the approriate epi field aperture for Phomi or Universal. Apart from that the Universal is just a member of the Zeiss Standard system and a very good microscope. Perhaps you can find a second nosepiece along the way so you can change whole setups, not individual objectives - very useful.