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.

Moderators: rjlittlefield, ChrisR, Chris S., Pau

jsp
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Post by jsp »

Hi Pau,

Thanks for that. I'll try to look into setting up a good tube lens then. Thanks for answering so clearly. I often do not understand the specifics of what others say, but you have explained so that I can understand.

jsp
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Post by jsp »

Hi Chris,

How do I find "How can I hook up a microscope objective to my camera"? The FAQ seems to be all technical stuff about how to use the forum and this doc doesn't show up in a site search.

Thanks!

johan
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Post by johan »

My extreme-macro.co.uk site, a learning site. Your comments and input there would be gratefully appreciated.

ChrisR
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Post by ChrisR »

JSP
I thought you must have been there before - the FAQ section http://www.photomacrography.net/forum/v ... m.php?f=29 has tons o' stuff, the one you want is about the dozenth at the moment. They bump to the top when someone adds something.
Chris R

jsp
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Post by jsp »

Brilliant! Thanks. :-)

jsp
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Post by jsp »

I did another couple of tests:

These are:

Teleconverter x2
two extension tubes
Canon macro 100mm (set to infinity)
microscope objective
lit by desk lamp.


This is the setup:

Image

This is the 10x objective stack:

Image

This is the 20x objective stack:

Image

Muddling along towards victory...

ChrisR
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Post by ChrisR »

Getting better!
There are 2 things I see here:

1) vibration. Floors wobble all the time - at least mine do.
I think your rig is on a slab of worktop? Try putting the whole thing on a sofa seat cushion, or something soft like that.
You could try flash again. If the subject is moving about, each image will be in a slightly different place but it will be sharp. The stacking software will align them.

2) Can you "lose" the extension tubes? They're moving the lens away from the camera, so it's like you're changing the focus on the lens. Even with it focused at infinity, the tubes mean it would only focus much closer.
That may give you more magnification, but will also hit your image quality.
The reason is that the objective now has to produce bundles of light which are not parallel as though they were going off to infinity.
Actually they have to diverge, which is something Nikon never intended.


What objective is that??

If I'm not clear about something, just ask again!
Chris R

jsp
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Post by jsp »

Thanks for that. I was aiming to get more like 200mm between the objective and sensor. Is adding extensions not a good way to do that. Sorry, I'm a bit confused about that bit.

ChrisR
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Post by ChrisR »

A camera lens already comes with the mechanism to get the glass in the right place.

That's right place "optically" - long camera lenses (telephotos) put extra glass in to make the whole construction physically shorter than (say) 200mm.

eg, a 400mm tele lens I have is about 220mm long, at infinity focus.

If you use a 200mm focal length "simple lens", something like a Raynox which comes without a built in focus mechanism,, then yes you'd need to arrange it to be 200mm from the sensor so it could focus at infinity.
Chris R

jsp
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Post by jsp »

If I just use the macro lens, do I not then need to use extension tubes to make the image large enough to fill the sensor? In my previous test the image came out as a small circle on the sensor. I thought that rather than having to buy a 200mm prime I could just use a long tube with the 100mm macro.

I looked at that page that you quoted before and it had the option of just a long tube or a 200mm zoom. I have a 200mm zoom and I tried it before by the image was not great. I also have lots of cheap extension tubes, but nothing to attach the objective to the end of a plain tube.

Or I have the 100mm macro. I'm not sure if I'm being daft trying to combine the macro and extension tubes.

Why is it that we never see photos by people who use a horizontal setup like this? I've seen Charles Kreb's lovely nettle photo with an upright microscope, and Des Callaghan's moss photos with an upright microscope, but I never see great photos like those coming from a horizontal setup. My supervisor said I could just write a grant proposal to ask for funds for an upright microscope setup and I keep wondering if I should just do that, since that is where all the great photos seem to be coming from. Thanks!

ChrisR
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Post by ChrisR »

If I just use the macro lens, do I not then need to use extension tubes to make the image large enough to fill the sensor? In my previous test the image came out as a small circle on the sensor. I thought that rather than having to buy a 200mm prime I could just use a long tube with the 100mm macro.
The objective has an image circle it's designed to cover. The quality's less good in the corners, but it typically will cover the design diameter and something more. I don't know it for that objective, but it may be 20mm when you use it at 20x, (which means using a 200mm tube lens).

If you reduce magnification you get a proportiionately smaller image circle, though of better potential quality (obviously, it's just less of an "enlargement").

The 2x Converter changes the FL, and that will help you cover your sensor. It's spreading the same image over more pixels of your sensor. It may not show an improvement by the time you've got your final image size. The spreading's going on in the camera instead of at the printer. You're using all your pixels though, which should be better if the converter is good enough.
(Even then you're still expecting more of the ojective than it was designed to do)

The Tubes let you focus closer, but only with errors coming in. Not useful really.


You don't fix an INFINITE ojective to plain tubes, you need a "tube" lens in there as well. 200mm FL for rated magnification.

Horizontal:
Umm, Chris S's Bratcam, fotoopa? The photons don't care, but your subject might be more likely to droop with one than the other.
It's not stopping you at the moment - piece of paper should be no problem.
Chris R

jsp
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Post by jsp »

Yes I was ChrisS's bratcam that I was thinking of. Are there lots of people using a setup like that? I sort of got the impression that there were and was puzzled about why I never saw the photos, but maybe I misunderstood and there are not lots of people doing it. It's party tricky because when I go and ask for funding to buy objectives (the ones I have are borrowed) people ask me to show photos that other people have taken with a similar setup, and I've actually never seen any. I just wondered.

I'm still trying to get my head round the tube length problem. I'll read your post another five times and see if I can get it. Thanks!

jsp
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Post by jsp »

Hi,

I've just bought an Olympus Zuiko 200mm prime lens from Japan over ebay to use as a tube lens, and it's got about 8 little fungal hyphae at the very edge of one of the internal glass elements. The advert said mint condition, but I wouldn't mind keeping and using it as long as I can be sure that it won't spread to my other equipment.

I wondered if anyone has experience of using lenses with tiny amounts of fungus like these. If I dry it really thoroughly in a hot airing cupboard do you think it will arrest the growth and stop spread to my camera body?

I've also just submitted a grant proposal asking for money to buy the 10x Mitutoyo objective that you recommended, and I am crossing my fingers.

Thanks!

jsp
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Post by jsp »

I looked again this morning and can't even see the fibres and they didn't look like the images of fungus I've seen online, so I figure that's okay.

jsp
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Post by jsp »

Hello!

I have some good news!

I have been awarded a £1000 grant to build a setup that is a sort home-whittled version of the Bratcam. The bulk of the money is to be used to buy a good microscope objective and I can use the rest for anything really.

I am to run it using an Arduino computer, which is a bit like the raspberry pi that I already use to drive my current setup. I'm allowed to use the spare money to commission 3D printed parts.

Yay!

This is what I have so far:

http://theitinerantbotanist.blogspot.co ... -mkii.html

Very exciting. :-)

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