Lighting for macro photography of fern gametophytes

A forum to ask questions, post setups, and generally discuss anything having to do with photomacrography and photomicroscopy.

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Peter M. Macdonald
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Post by Peter M. Macdonald »

Jennifer,

Here are a few other things for you to throw into the mix for thinking about.

The easiest way to position one or more flashguns is to use a dial indicator stand. These are available very cheaply on ebay, e.g. http://www.ebay.co.uk/itm/261804804767? ... EBIDX%3AIT at a price of £11.95 including postage.

Image

That knurled cylinder at the upper right is interesting. It unscrews to reveal a threaded cylinder. The thread on that is 1/4 inch x 20 tpi. That is the same as the thread on a standard tripod and the base of your camera. If you attach a flash to your camera with an off camera cord, it will have such a socket in its underside. The cheap off camera cords on ebay are at least as good as the Canon originals, having on of each. The Canon ones are coiled and have a tendency to pull. The no brand ones have straight cables and are easier to pose.

These indicator stands have a strong magnet in their bases. This can be rotated in and out by means of the lever on the side. All you need is a steel base under your work onto which you can magnetically attach the stand(s). If you look in the hardware isles at your local B and Q you will find sheet metal in various sizes. I have a sheet from them which is about 25 x 50 cm. When you buy these sheets they come encapsulated in a thick plastic pouch, like a laminated menu card. If you never open the pouch, the steel within does not rust. I have had mine for about four years, and it still looks like it did when I bought it. The price was between £6 and £7, so once again it is fairly gentle on the budget.

I normally use two flashes. One is a Canon flash tethered to the camera hot shoe with an off camera cord. The other is an old Vivitar 283 with a continuously variable manual power module. You can either look for a Vivitar original on ebay or make your own. There are details on Charles Krebs' website. I trigger it with a photo slave. As some of my 283s are from the beginning of their manufacturing range, I use a photo slave which is designed for a high trigger voltage, so a little more expensive - about another £12. Old 283s can be picked up quite cheaply on ebay. Each of the two flashes has its own indicator stand. One is placed each side of the subject.

As for step focussing of a Canon autofocus lens (not, of course, your MPE) there is relatively inexpensive software available to do this. It is Helicon Remote. The Windows version is free for users of Helicon Focus. There are also versions available which can interface with smart phones.

I have to say that I gave up on the knob turning and remote release method about two years ago. I bought a second hand stack shot from another forum member and had it sent here from America. Even with the VAT and the Royal Mail handling fee, I have never regretted the purchase.

Although I gave up on Helicon Focus when Zerene Stacker came out, I do still use Helicon Remote when I want to stack above about life size as focus shifting gives better results than changing the camera to subject distance once one goes much above life size.

We are all now looking forward to seeing some really nice fern pictures from you.

Regards,

Peter

jsp
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Location: United Kingdom

Post by jsp »

Thanks Peter and Rik,

I've got a whole lot to think about now, and various possible ways to go, each of which will take a bit of time. However, just as soon as I get anything that is either good to look at, or at least shows where I'm going wrong next, I'll be right back to show it. :-)

I must say, I'm very tempted by the secondhand stackshot idea, but I think I'd have to save up a bit for that. Probably I'll be looking into a set of Yongnuo flashes and a polarising filter though. They sound doable. :-) Hopefully with those I can have a bit of fun and bring you something interesting to look at. :-)

Charles Krebs
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Post by Charles Krebs »

Jennifer,
May I ask - do you think there's any point trying this without having absolutely scads of cash to throw at it?
Most definitely! I just re-read most of this thread. We are an enthusiastic group when it comes to "problem solving", and there is a great deal of valid and good information presented here. But I really think we are making this sound way too involved than it needs to be (at least initially unless you are certain you have an external vibration problem... most people do not).
The camera was not on live view and I just triggered it with an infra red control. I think it had silent shutter enabled, but I'm not sure.
It sounds like you have not yet tried your camera with continuous light with the proper settings to eliminate camera vibrations! If not, doing so might be a real eye-opener when you see the results.

For continuous light with the Canon 5D2...

1) Set the choice for Silent Mode 1 or Silent Mode 2 in the "Live View/Movie func. set" menu.

2) Always release the shutter with the camera in live-view

Image

Unless you have environmental vibration problems (or your subject moves) you will get razor-sharp images because there will be no camera vibration during the exposure.
(Note: If you use a non-Canon dedicated electronic flash instead of continuous light you need to set the Silent Shoot setting to "Disable")

Try doing this with continuous light and a rigid subject and I think you will be impressed. And again, unless you determine that you really do have an environmental vibration issue, continuous light is very nice to use. Two or three of the Ikea Jansjo lights will cost less than $30 (at least in the US), and they are very versatile and need no additional stands or holders.
In my mind it's pretty clear that the vibration is caused by the fern rocking on the little bit of blue tack that it's mounted on. Ferns are very delicate and it's not possible to fix the fern down
Beside not having the camera set properly, I think this is your other major problem. The slightest bit of subject movement (relative to other parts of the subject) will make for a very difficult stack. It doesn't matter what equipment set-up you have, or if you are using flash or continuous light, you must work at getting your subject mounted or held so that it does not move during image stack acquisition. As mentioned earlier, this is often a very significant challenge with live plant material. (My experience when working with some plant subjects is that far more stacks get discarded than used).

You should also try to see what your actual step size is when using the scanners. With a full-frame camera like the 5DII and the 65mm MPE you should be able to use the full magnification range (1X to 5X) if you can get the step size down to about 0.035-0.050mm (35-50 microns). Perhaps you can run about 300 steps or so at the smallest step size and measure the distance traveled. This would enable you to get a pretty good idea of the step size even if you don't have very high precision measuring instruments.

jsp
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Location: United Kingdom

Post by jsp »

Hi Charles,

Thanks so much for reading all of that. It is a lot. :-)

I do think you are right about the problem of anchoring the subject. I think that a polarising filter will help a lot too. I'm going to fiddle around with a few ideas now and see what I can get. It might take a while as I am up to my eyeballs in looking after my son, but I will report back just as soon as I can get something. :-)

btw What I really mean is that if you don't hear from me for 6 months then it's just because I'm trying to do a proper job on it, but I will back and definitely with photos. I've been working on this project for 22 years already, and at least another 22 years of enthusiasm for it in me.

Update coming asap, and I'll watch for a stackshot in the equipment exchange section. :-)

Thanks!

jsp
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Post by jsp »

Hi,

My new scanner is proving tricky to setup so I went back and measured the minimum step length of my original scanner and it is 0.042mm, which is perhaps about twice the step length that I need. So that's one problem identified at least.

Jen

jsp
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Post by jsp »

I am going back to setting up the new scanner. It's going a bit slowly, but it is going.

Charles Krebs
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Post by Charles Krebs »

I went back and measured the minimum step length of my original scanner and it is 0.042mm
With a 42 micron step size you should be able to work just fine with your 65mm MPE through most of it's range (at 5X it is a bit marginal... need to try it, the results would probably be OK in most cases)

For starting points you might want to try the following set apertures and number of steps:

1X... f/8 and 11 steps
2X... f/5.6 and 5 steps
3X... between f4 and f.5,6, 2 or 3 steps
4X... f/4 and 2 steps
5x... between f2.8 and f4, or f4, 1 step

What is the scanner movement like?... fast and abrupt or gentle and smooth? Normally moving either the subject or the camera will work about the same. Since you are concerned with very delicate and supple subjects I think you will want a very gentle and smooth movement if you move the subject.
Last edited by Charles Krebs on Tue Dec 08, 2015 12:54 pm, edited 1 time in total.

jsp
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Post by jsp »

Hi Charles,

The movement is very clunky actually. It even makes a loud *Clunk* noise on each step. That was what made me think that it was probably causing the trouble. I think it may be moving the same on each step. That would fit with the coin going so well, because it was fixed very strongly to the arm.

We chose this model because it is quite old and the arm is made of very solid strong material, but I don't think it would be strong enough to hold the camera.

Image

The new scanner motor is now moving in response to the Rp. We just haven't got it moving in a controlled way yet. It has four wires instead of five so is taking a bit of adjustment in the system.

[Admission: My husband is a computer scientist. I did the stripping down of the scanner and the soldering, but he's figuring out how to solve the switch from five wires to four wires. At this point, I gots no idea.]

--AdminCS formatting edit

jsp
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Post by jsp »

Just thinking a bit more about it, about way to stop the subject movement:

I wonder if I could mount a small bowl-shaped bit of blue tack on the scanner arm, and then put in a drop of liquid gelatine into the tiny bowl. Then I could drop the fern and its bit of soil into the gelatine. If I then wait for the gelatine to harden then that would hold the fern totally solid. It might be enough to stop the movement. Does that seem like an idea? I'm not sure how cool the gelatine can get before it hardens. Obviously if it is too hot then it will cook the ferm. I might mess around a bit and see what can be done.

Lou Jost
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Post by Lou Jost »

Do you mean you want to completely embed it in the gelatine? If you are going to go to that extreme, better to use a viscous liquid like glycerine, which should damp most vibrations if you let it sit briefly after each movement. But maybe I misunderstand you.

jsp
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Post by jsp »

No I just mean putting the very bottom of the soil in it, like standing a tall leaf in and eggcup full of glue so that it will stay standing upright. Gelatine sounds like a good option if it will absorb the knocks but keep the plant still.

Lou Jost
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Post by Lou Jost »

Oh. If gelatine there means the same thing as it does in the US or Ecuador, that would seem to be about the worst possible thing if you have environmental vibrations....
Camera and subject need to be connected by an absolutely rigid assembly. The whole rigid camera+subject assembly should be put on a damping medium, like cork or Sorbothane or yellow rubber squishy men (see other recent threads).

jsp
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Post by jsp »

Okay. That was why I was thinking about Making a thick jelly and embedding the fern in it. That would be as rigid a substrate as could be had. In a science lab we'd grow the fern on agar which would give a solid substrate and hold the fern still, but I can't do that because I'd need expensive agar, and nutrient medium and fungicides that I can't use at home.

Lou Jost
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Post by Lou Jost »

Maybe I am still not understanding something. Gelatine, at least here, wiggles. It is not rigid. It is like a soft spring. It could even amplify vibration movement.

jsp
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Post by jsp »

Sort of. But if I make the gelatine thick enough then the fern roots and the soil that they are attached to will be so well stuck that there will be no movement.

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