Desmids On My Mind

[KurtM]

Just got confirmation: 3W LED. It's a lot brighter than it sounds like...

[einman]

Well.... You may not want to hear this ....and hopefully you wont be annoyed at me for saying so but..


Your photos are AWESOME! Truly beautiful.

Like yourself I have an AO 120 and an AO Polstar. I love the old AO's. You skills definitely bring out the best in these old scopes.

[KurtM]

Dang, I was getting all set for some heavy duty criticism there for a minute. And almost disappointed it was a kind compliment instead! I actually like getting criticism because it helps me learn, and I would much rather advance my knowledge and skills than feed my ego.

Still, thank you kindly all the same! Don't you also have the AO DIC scope, that's made of 95% pure unobtainium? Talk about AWESOME! I'll be in DIC soon, but not in AO flavor, more like that old Zeiss stuff. How I'd love to be getting it in AO instead (I think, I mean, what do I know?).

[zzffnn]

To get light output equivalent to an 100w halogen, you need a LED of at least 16W (ssuming best possible LED and worst possible halogen). I made a similar error before and Phil corrected me. High efficiency LED nowadays produce around 70-90 lumens per watt when heat-sinked well, but low efficiency ones make as less as 30 lumens per watt.

[KurtM]

It's easy to say these things, but how do we REALLY know? How can light output be quantified? All I really know is what I see: that if for some reason I catch a glimpse of full-on light in the eyepieces it's so brilliant as to be perfectly blinding, like looking at the Sun - there's certainly no lingering! Also, I never "run low on light", as I do with with my 1810 (admittedly lackluster lamp), and Series 10 with 1031 illuminator (halogen). Also, all the images earlier in this thread were made at ISO 100, the camera's lowest ISO setting. Sounds like a lot of light, to me.

[billbillt]

Hi Kurt,
I guess you could quantify the light output with a light meter, for what it is worth...I feel the same way... W 3 watt and above LED will almost blind you... I have an LED setup that I sometimes use for older stands that only have a mirror and it is 10 watt..... No person could bear to look directly into it.. It provides more than enough light.. I just use what works for me... Thanks for providing the info...

BillT

[zzffnn]

In most plain brightfield conditions with most subjects, 40x objective or under, 1-3w LED would be blinding. But there are extreme conditions.

I have used my 40w LED at max under extreme oblique+pol with 70x objective for a transparent ciliate. Still, video quality is not very good: https://youtu.be/3Cs0-9s2Jyw But ASU researchers had to stop down their DIC to get decent image out of that ciliate, so it is a difficult subject.

Main reason for the light requirement and imaging difficulty is tiny size, thin and very low contrast - with that darkfield or dark phase may actually work better than DIC or oblique+pol. When I was at it, I had to block away most of light to get decent contrast, so what eyepieces/camera were getting was probably way less than what 1w LED would produce in brightfield (even though 40w LED was used at max).

High magnification (100x) darkfield needs lots of light too, because lots of light output is wasted or not used.

[KurtM]

... needs lots of light too, because lots of light output is wasted or not used.

I swear, I don't think I'll ever understand all this stuff. At least I can say my new scope will have genuine 100W halogen horsepower.

Thanks Fan. As you see, hammering an education into my head requires the patience of Job...

[billbillt]

Hi Fan and Kurt,

Doing the calculations on this gives some interesting data.. A 40W LED produces 2400 lm which is equvilent to a 120 W Halogen... The 40W LED should provide more than ample light to work with all set ups.. There must be other factors involved here that are not obvious... I for one would like to know more about it!..

The Best,
BillT

[gekko]

Very beautiful, excellent images! All of them. The "plain" brightfield desmid image is superb, in my view.

[einman]

Dang, I was getting all set for some heavy duty criticism there for a minute. And almost disappointed it was a kind compliment instead! I actually like getting criticism because it helps me learn, and I would much rather advance my knowledge and skills than feed my ego.

Still, thank you kindly all the same! Don't you also have the AO DIC scope, that's made of 95% pure unobtainium? Talk about AWESOME! I'll be in DIC soon, but not in AO flavor, more like that old Zeiss stuff. How I'd love to be getting it in AO instead (I think, I mean, what do I know?).

Oh I have no problem critiquing you. Just not on these photos!

Yes I have the DIC which no one seems to even know existed. At least not Miller or Martin Microscopes. Bolden was aware of having seen one.

By the way I picked up an extra AO DIC turret with prisms and condenser. I haven't decided what to do with it. All it needs is a n AO 10/20 stand and the nose turret with the slider/analyzer and you would have a complete DIC set-up as everything else is built into the turret.

I will probably sell it. Given its rarity I just don't know what I should ask. I tried it on an AO 10 and the resolution via the 1.3 aplanatic/achromatic is quite impressive in itself compared to a regular condenser.

[KurtM]

Thanks Gekko. The reason I'm kinda down on the bright field image is because of the edge artifacts left over from the stacking, and because Desmids are very three-dimensional things and bright field just doesn't convey it. Looks flat as a fritter in other words, like it got steam rollered. I'm glad others are more charitable towards it, however, because it makes me give it more thought, and wonder what can be done to improve it.

einman, I'd love to get my hands on that AO DIC stuff, and even have an AO 20 on the way to becoming something some day, hasn't yet decided if it wants to be Phase Star or what when it grows up. I know Charles has some of the AO DIC bits too, but don't quite remember which, nor have a clue how hot he is to complete an AO DIC scope. He already has a more comprehensive collection than I ever will, and if he ever opens, or donates to, a museum it would probably be better off there -- except that museum pieces don't get used and that's always a shame (to be clear, Charles does not run a museum (yet)!). As for what price to ask, what it's actually worth is a mighty interesting question I'd like to know the answer to as well.

Your comment on the condenser is interesting. While I lack the technical knowledge to lecture on the subject, my eyeball intuition tell me that the AO/Spencer infinity optics are limited by the condensers, possibly significantly so. Be interesting to hear what Phil might have to say with regard to this particular point.

I'm currently in the process of having a Zeiss DIC scope built, so in no hurry to spend any more money at the moment. I understand you're in no rush either, but thought I'd mention it just the same. My new scope should be ready practically any old time now, incidentally. Ooh! Ooh! Can't wait, lol.

[JimT]

Probably time to put this thread to bed but I really like your newly discovered element, "95% pure unobtainium"

Never saw an unzipping desmid before. Great find.

JimT