Shooting through water 3: Example

[Lou Jost]

In my previous post in this series here:
https://www.photomacrography.net/forum/viewtopic.php?t=40659&postdays=0&postorder=asc&start=0
I proposed using reversed Micro Four Thirds lenses on tube lenses to shoot subjects through water at low magnifications (1-8x). Micro Four Thirds lenses work well for this, because they are designed to send their image through a thick sensor filter pack about 4.2mm thick. That mean that when they are reversed, they are corrected to shoot through 4.2mm glass or 4.8mm water, (the optical equivalent of that much glass). There should be a "tolerance range" of a few millimeters centered on this depth, and this tolerance range will be a function of NA. The advantage of using a lens that is corrected to shoot through a thick medium is that we can take advantage of both the + and - sides of this tolerance range. A lens with the same NA but corrected for zero medium thickness will only have half the usable range of depths.

I'm putting these ideas to work now in my orchid research. I have had excellent results with the Panasonic 42.5mm f/1.7 and the Olympus 75mm f/1.8, both reversed on a Mamiya Apo medium format 200mm lens on the Panasonic S1R FF camera. Here is an example using the latter lens, for m=2.6, at f/3.2. This is an undescribed Teagueia orchid I am currently describing:


All parts are sharp, from the most shallow (that organ sticking up from the center) to the deepest (the recurved sepal and petal tips). Here is a 100% crop of the tip of the flower:


Here is another new species using the 42.5mm lens at f/3.2 for m=4.6:


I am very happy with these! The flowers are so thin and fragile that they collapse within minutes after being cut if left in air. Now I can photograph them as much as I want.
_________________
Lou Jost
www.ecomingafoundation.wordpress.com
www.loujost.com

[rjlittlefield]

Lovely images, and a profound improvement in technique.

I expect the designers of these lenses had no idea that their lenses would ever be used this way.

For that matter, I also expect that the designers of the Micro Four Thirds specification had no idea that its thick filter pack would have positive value, except as a great way of preventing dust spots on a small sensor.

What a wonderful bit of serendipity!

--Rik

[Lou Jost]

Thanks Rik!

In fact we can do this with any Canon or Nikon lens too! Remember the discussion on the Lensrental blog about the Speedbooster not functioning well in their testing lab until they put a 4mm glass filter behind it? A Speedbooster designed for MFT (not the BlackMagic versions) converts any reversed lens into a lens corrected to shoot through water!

This should also work for enlarger lenses, etc if the distance between lens and Speedbooster is adjusted correctly; attach via Nikon BR-2 reversing ring and thin helicoid.

Speedbooster goes on the side facing the subject.

I'll be testing this idea soon. The disadvantage is that these converted lenses might not be telecentric like native MFT lenses.
_________________
Lou Jost
www.ecomingafoundation.wordpress.com
www.loujost.com

[JH]

Very nice, and a good proof of concept.

When I try to take photos of objects in water I have some trouble keeping them in one location. Not having such delicate and uniqe specimens that you have I use to pin them down. Do you have any tricks to hold your orchides in place?

Best regards
Jörgen Hellberg
_________________
Jörgen Hellberg, my webbsite www.hellberg.photo

[Lou Jost]

Jorgen, that is the hardest part of the whole operation. The traditional solution is to use personal lubricant (for example KY jelly) or hand disinfectant gel on the bottom of the receptacle. This is a very convenient method. But it can suck the water out of a delicate specimen via osmosis, and it messes up the specimen. It also tends to dissolve during the stack, causing the subject to move. One solution is to let it age under water before layi ng the specimen on it. I'm using that technique on the flowers I am photographing today.

But for both the orchids shown above, I held them still by sticking a minim pin into their ovary (not penetrating all the way through it). I don't pin them to anything. With that little bit of extra weight and leverage, they stay perfectly still.

But it is also hard to spear these with a minim without being able to hold onto them. So sometimes I drop a coverslip on top of them. That keeps them still. Other times I use tiny stones or glass fragments to constrain them, and then retouch them out. This can be hard too.

Another solution is to use oil instead of water. This has its own disadvantages. With flowers, the colors last longer because the pigments don't leach out, but there is sometimes a shiny layer between the oil and the flower. This can be ok though.

So I would say that this is the biggest unsolved problem for shooting under water.
_________________
Lou Jost
www.ecomingafoundation.wordpress.com
www.loujost.com

[JH]

Thanks a lot for the information!
For small un pinnable insects I have used eye drops (methylcellulose).
Best regards
Jörgen Hellberg
_________________
Jörgen Hellberg, my webbsite www.hellberg.photo

[Chris S.]

[chris_ma]

I have absolutely no experience with any of this, but at first thought Glycerol could be worth a try. Light transmission seems to be very good as well.

Then again it's probably so obvious that everybody tried that already.
chris

[Lou Jost]

Chris S, thanks for that information about gelling agents. maybe some of them would work, and next year when I go to the US I will buy some of those to test.

Chris_ma, I have tried glycerin+water, but it sucks the water out of my flowers and makes them deform.
_________________
Lou Jost
www.ecomingafoundation.wordpress.com
www.loujost.com

[Pau]

[Lou Jost]

Pau, I think the oils seem to not have osmotic effects? Mayeb there is an oil with a refractive index similar to water's so it would not make a shiny interface?

Hmm, internet says yes....
_________________
Lou Jost
www.ecomingafoundation.wordpress.com
www.loujost.com

[Pau]

Yes, oil doesn't induce osmotic effects just because it doesn't mix with water nor with most water soluble molecules like ions (as you most likely know osmosis is due to the movement of water, not of solutes)
But this can induce unwanted interfaces...if you find an adequate oil please let us know.
_________________
Pau

[Ichthyophthirius]

Hi,

Classically, glass needles were used to mount objects nearly invisibly under water.

How about mounting on a bed of agar? Cast a layer of agarose gel in a Petri dish, then cover with physiological saline (for plants) and mount with glass needles, pieces of cover glass or transparent plastic.

Regards, Ichty

[Adalbert]

Hi Lou,
Interesting method, very nice pictures!
BR, ADi

[zed]