Looking for Entry/Mid Range Scope

[Geode]

Hello!

Based on a bunch of research I've done, and with the help of several users on and off the forum, I'd like to advertise that I'm looking for a used mid-range/entry-level microscope (which is upgradable).
This list exemplifies the sort of (age, brand, features, price, etc.) I'm looking for if anyone has any leads. Of course, any other brands/models which are equivalent to these are applicable:

- Olympus BH2
- Accuscope 3025
- Motic BA310E/410
- Leica DM750
- Labomed Lx400
- Zeiss Primostar

The essential features I'm looking for:
1. Trinocular
2. All plan achromat objectives or better.
3. LED light
4. Full-Kohler Illumination (with a condenser focus knob)
4. The possibility for upgrades (the Primostar falls short here from my experience) - for example, the addition of a turret condenser, phase contrast, polarization, DIC (potentially), etc...
5. Phase contrast at 40x included would be awesome.

Any leads/advice is appreciated!

[PeteM]

The Leica DM750, like the Zeiss Primostar, is pretty much a cost-reduced student version - both made in China I believe. You might consider a used DMLS instead? These were made in the US or Austria and are pretty robust. They use a 25mm rather than RMS objective thread, but can take either Leica infinity objectives or Nikon infinity objectives. The availability of a cheap Nikon 20x Plan Apo objective from gene sequencers means you can get around a $3000 objective for not much more than $100. Might be of interest if most of your soils work will be around 200x? The Leica infinity objectives are also good - just no amazing deals to be readily had on them.

You'll still need at least 400 to 1000x to get the shapes of bacteria; probably both since the 40x can be dry for quick use and the 100x oiled for a much better view with not too much effort. You could likely get a used DMLS,well equipped, under $1500. A DMLB would be the next step up, with DIC maybe available around $3K.

Some of the Labomed scopes were made in India. Don't have any experience with the 400 model, but I haven't been impressed with the few Indian-made scopes I've seen. Someone here may have used or owned one?

[BramHuntingNematodes]

You should buy Bill's Axiomat. Show up to lab with it in a wagon all like, "hey teach is this one ok?"

[Hobbyst46]

Please note that the BH2 scopes are originally fitted with halogen lamps, not LEDs, so if LED is a must have (not in my opinion anyway), choosing a BH2 means getting a LED retrofit. These exist on the market though.

[Geode]

You should buy Bill's Axiomat. Show up to lab with it in a wagon all like, "hey teach is this one ok?"

I always wanted a wagon! Lol

[Geode]

You should buy Bill's Axiomat. Show up to lab with it in a wagon all like, "hey teach is this one ok?"

Yes, I'll definitely want the LED. I'm keeping a look for out that.

[PeteM]

FWIW, the pros and cons of LED lamps have been covered on the forum before.

Pros are that they are cheaper to build into a scope, the bulbs run cool, and they rarely (with the good ones) burn out.

Cons are that they usually have spotty color rendition. A tungsten halogen bulb has a CRI (color rendering index) near 100. Most LEDS are nearer to 70 to 90. With modern photo software the color balance in a final picture can be set anywhere if there's an even illumination throughout the spectrum. Harder when there are a lot of peaks in the output as with things like LED or even far worse sodium and mercury vapor bulbs.

Tungsten halogen bulbs put out about 25 lumens per watt. For LEDS it's around 72 lumens per watt. A 20 watt halogen lamp has 500 lumens, pretty evenly distributed for Kohler illumination and enough for most any imaging task. The typical 1 to 3 watt LED lamp in newer student level microscopes puts out a bit over 70 to 200 lumens, sometimes distorted by a dome over the LED die.

LEDS are pretty much the future, but it takes the newest generation of 10 to 20 watt LEDS with higher CRI and a carefully engineered light system to match up with the best of the previous generation tungsten halogen systems - particularly those above 20 watts. The forum will have notes on various attempts to use the latest LEDS in various home-built and retrofit systems. I use a lot of LEDS -- often as low as 1 watt and an optimistically claimed 100 lumens -- to retrofit old generation scopes with tungsten (not tungsten halogen) bulbs and they're a simple and good system for brightfield and low magnification darkfield and phase contrast. For a modern quality scope, I'd look for at least a 10 watt LED die and a CRI over 93 or so.

[Geode]

FWIW, the pros and cons of LED lamps have been covered on the forum before.

Pros are that they are cheaper to build into a scope, the bulbs run cool, and they rarely (with the good ones) burn out.

Cons are that they usually have spotty color rendition. A tungsten halogen bulb has a CRI (color rendering index) near 100. Most LEDS are nearer to 70 to 90. With modern photo software the color balance in a final picture can be set anywhere if there's an even illumination throughout the spectrum. Harder when there are a lot of peaks in the output as with things like LED or even far worse sodium and mercury vapor bulbs.

Tungsten halogen bulbs put out about 25 lumens per watt. For LEDS it's around 72 lumens per watt. A 20 watt halogen lamp has 500 lumens, pretty evenly distributed for Kohler illumination and enough for most any imaging task. The typical 1 to 3 watt LED lamp in newer student level microscopes puts out a bit over 70 to 200 lumens, sometimes distorted by a dome over the LED die.

LEDS are pretty much the future, but it takes the newest generation of 10 to 20 watt LEDS with higher CRI and a carefully engineered light system to match up with the best of the previous generation tungsten halogen systems - particularly those above 20 watts. The forum will have notes on various attempts to use the latest LEDS in various home-built and retrofit systems. I use a lot of LEDS -- often as low as 1 watt and an optimistically claimed 100 lumens -- to retrofit old generation scopes with tungsten (not tungsten halogen) bulbs and they're a simple and good system for brightfield and low magnification darkfield and phase contrast. For a modern quality scope, I'd look for at least a 10 watt LED die and a CRI over 93 or so.

Awesome advice, Pete! Thanks