Nikon Diaphot TMD condenser compatibility (part 1)

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mtuell
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Nikon Diaphot TMD condenser compatibility (part 1)

Post by mtuell »

In my gallery post with the onion mitosis slide http://www.photomacrography.net/forum/v ... hp?t=35128, I was testing out some new Plan Apos on my Diaphot, using a 1.25 Phase Contrast condenser instead of the typical LWD condensers.

It was requested that I address the compatibility of non-LWD condensers on the Diaphot, so I've been doing a little testing with a set of phase objectives. To see how well it handled very low NA objectives, I also tested a 2x Plan Apo. All objectives are 160 mm Nikon.

2x Plan Apo 0.08 160/-
4x PhL DL Plan 0.13 160/-
10x Ph1 DL Plan 0.30 160/0.17
20x Ph2 DL 0.4 160/0-2
40x Ph3 DL 0.55 LWD 160/0-2

So, part 1 will be the 2x:

The lens that is on the condenser stage seems to be mostly important at low magnifications. Here is the field with the lens out:
Image

The view through the Bertrand lens can also be informative. Here we see a fairly uniform but dimmer illumination disc with the lens out of the system, but with a reduced field as well.
Image

And, putting the lens back in place looks like this
Image

Brightfield, 6x size reduction
Image

Brightfield, crop
Image

Darkfield, 6x size reduction
Image

Darkfield, crop
Image

Ph2 offset annulus, 6x size reduction
Image

Ph2 offset annulus, crop
Image

Ph3 annulus, 6x size reduction
Image

Ph3 annulus, crop
Image

And, finally, what the condenser looks like mounted on a Diaphot. As pictured, it is very close to the slide, attempting to improve darkfield. The more normal position was a millimeter or two above the back of the slide.

Condenser with built-in lens installed
Image

Condenser with lens removed
Image

Sorry for the long post!
Mike

Cactusdave
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Post by Cactusdave »

Thanks for showing these Mike, especially the images of the alternative condenser in place. As a Diaphot TMD owner, I've always wondered if it would be possible to swap in a higher NA condenser to my 0.52 LWD for occasions when a high NA objective warrants it. It looks from your images as if it's quite doable. Is the actual process of condenser swapping and re-centring straightforward. I assume the silver knob to the right of your last two images and partially hidden by and behind a centring knob is the condenser clamping screw?
Leitz Ortholux 1, Zeiss standard, Nikon Diaphot inverted, Canon photographic gear

mtuell
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Joined: Wed May 11, 2016 12:42 pm
Location: Tucson, AZ
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Post by mtuell »

Yes, Dave, that is the knob to release and clamp the condenser. Yes, it is straightforward to swap them and get it centered.

I'll post some conclusions when I get through a few more objectives, but I think the basic answer is going to be that it works, but the low NA objectives do not have full-field illumination coverage. The built-in lens helps considerably to increase the field at low NA.

Well slides with open water drops can be a little tricky because you don't want to touch the water with the condenser lens, but you want it very close. With it 1-2 mm above open water, it evaporates and re-condenses right on your "condenser" lens, so you have to pay attention to that.

Thanks for asking - it is a valid question. I want to try out other condensers, too, and see if they have limitations on a Diaphot.

Mike

mtuell
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Location: Tucson, AZ
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Post by mtuell »

While I haven't gone farther than 40x yet, I think the basic conclusion is sound that it works just fine (with a couple of caveats) on a Diaphot TMD.

I finally got around to putting this together on a "comparison gallery" on my site. One interesting thing I put together is an animation showing the effect of opening up the condenser aperture stop, with the trade-off between contrast and resolution. (2 MB .GIF)

https://lavinia.as.arizona.edu/~mtuell/ ... low-NA.gif

Mike

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