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Settlement plates photography


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#1 tamar

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Posted 23 April 2010 - 10:17 PM

Hello All,

My name is Tamar and I'm a marine ecology student from Israel.

I'm working on larval settlement and recruitment in the Mediterranean, currently dealing with some barnacles, bivalves and periwinkles species in the intertidal zone.

For assessing settlement and recruitment I'm using 10*10cm PVC plates covered with a plastic polymer which is a great substrate for the spats and cyprids (settling larvae).
Each plate is examined and countered under a dissecting microscope- while the specimens size begins from 0.3mm.
I am using binocular microscope camera (Olympus XC30) with a 10*10 grid in order to photograph each plate (for a later image processing) - however, this requires 100 frames per each plate, and therefore is a big pain in the ass.

Is there any camera with such a resolution on which I can photograph one frame of 10*10cm and will be able to spot objects <0.5mm?
Or, do you have any other idea which will make this task bearable?

I'm attaching both settlement plates field photo and a lab photo of a spat (length ~0.4mm).

Thanks in advance,
Tamar

Posted Image Posted Image

Edited by tamar, 24 April 2010 - 04:45 AM.


#2 Paul Kay

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Posted 27 April 2010 - 04:30 AM

Tamar

Most dSLRs should produce what you need but not necessarily in one photo. You will need a decent dSLR (~10MPixel) with a good macro lens capable of 1:1 photography. You can then try taking say 3x3 shots (= 9 of each plate) which should give a good yield of information. Good 'stitching (panorama) software is available these days and this will allow the images to be stitched together to produce one large file if required so that you don't over-count things. The biggest problem that you face is positioning the camera and if I were doing this, I'd make up a small frame which allowed the camera to be positioned accurately and repeatedly to make taking the photos quick and easy - something like a plate with 9 holes i for the lens to drop into - you'll need to be ingenious to sort it out but it shouldn't be impossible and there are a number of ways to do this. I have a similar job where I need to photograph a very rare plant colony for monitoring purposes. I take multiple shots and these are then stitched together and each individual plan can then counted - it works very effectively indeed.
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#3 photovan

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Posted 27 April 2010 - 04:38 AM

following on from paul's suggestion, could you keep the camera fixed and move the plates beneath it?that way lighting and camera position/ image plane could be fixed.

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#4 Paul Kay

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Posted 27 April 2010 - 08:38 AM

following on from paul's suggestion, could you keep the camera fixed and move the plates beneath it?that way lighting and camera position/ image plane could be fixed.

Looks to me like the plates are bolted down? What I think is needed is some form of step and repeat mechanism - I could sort something out in my head but putting it down here is tricky. Ideally this sort of experiment should be designed with a simple way of doing such photography in mind before starting - easily said after the event! If the plates ARE removable, as photovan says, you need a repeatable camera set up and something like a giant version of a microscope stage to mount the plate on and move it around underneath the camera.
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#5 bvanant

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Posted 30 April 2010 - 04:33 PM

If it were my lab, I would not try to use a still camera at all, but rather put the plate down on a programmable grid and aim a video camera at it. You don't need a microscope and if you are clever enough, you can write pattern recognition software to count for you.
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#6 tamar

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Posted 01 May 2010 - 12:52 AM

Tamar

Most dSLRs should produce what you need but not necessarily in one photo. You will need a decent dSLR (~10MPixel) with a good macro lens capable of 1:1 photography. You can then try taking say 3x3 shots (= 9 of each plate) which should give a good yield of information. Good 'stitching (panorama) software is available these days and this will allow the images to be stitched together to produce one large file if required so that you don't over-count things. The biggest problem that you face is positioning the camera and if I were doing this, I'd make up a small frame which allowed the camera to be positioned accurately and repeatedly to make taking the photos quick and easy - something like a plate with 9 holes i for the lens to drop into - you'll need to be ingenious to sort it out but it shouldn't be impossible and there are a number of ways to do this. I have a similar job where I need to photograph a very rare plant colony for monitoring purposes. I take multiple shots and these are then stitched together and each individual plan can then counted - it works very effectively indeed.


Thanks Paul!
Can you recommend such a suitable dSLR (minimum price vs best efficiency)?

#7 tamar

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Posted 01 May 2010 - 12:54 AM

following on from paul's suggestion, could you keep the camera fixed and move the plates beneath it?that way lighting and camera position/ image plane could be fixed.


Yes, I also thought about building a frame with a fixed lighting.

#8 tamar

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Posted 01 May 2010 - 01:05 AM

Ideally this sort of experiment should be designed with a simple way of doing such photography in mind before starting - easily said after the event!

:) true.. It was planned to be done manually, but after a while I decided that in order to keep my sanity safe I must find some automatic solution (also, using photography and analysis software can yield some additional data - size and distances between specimens, etc).
The plates are indeed removable - and counted in lab.

#9 tamar

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Posted 01 May 2010 - 01:17 AM

If it were my lab, I would not try to use a still camera at all, but rather put the plate down on a programmable grid and aim a video camera at it. You don't need a microscope and if you are clever enough, you can write pattern recognition software to count for you.
Bill


Thanks Bill,
I really have zero knowledge in photography, but I intend to learn.

I guess using a video camera would require a sliding mechanism for the plates to ensure a fixed rate of movement - or not necessarily?
Can you elaborate on the technical details?
Thanks!

#10 Paul Kay

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Posted 01 May 2010 - 02:06 AM

The plates are indeed removable - and counted in lab.

Well for cost/simplicity, why not make up a jig with a 10MPixel still camera and macro lens so that the plates can be photographed 4 times - each time aligning a different corner in the jig. With just a little overlap and by rotating and stitching the images you will end up with a substantial single file from each plate which should have more than adequate resolution for your needs - you will have to figure out how to build the jig but it should not be difficult nor expensive - and most 10MPixel dSLRs with 60mm macro lenses would be fine. Video may well be a better solution but sound like it might be a more difficult system to set up initially (to me!).
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