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Archive 2013 · Set Up Capable of Capturing 10 Microns or Less

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p.1 #1 · p.1 #1 · Set Up Capable of Capturing 10 Microns or Less

Hi There,
I am a new member here and this is my first post. I am a Mechanical Engineering Student and am working on a project where I need close up images of droplets of liquid being sprayed. I need a working distance of probably around 25 mm. I have a Canon Rebel T1i with a 100mm macro lens. This can (accurately) measure droplet sizes of 0.05mm. Using a Canon 5D Mark II with the Canon MP-E 65 mm Ultra Macro Lens, it could distinguish 10 micron distances but not as well as I would have liked. Does anyone have any ideas or suggestions for a set up that would be able to measure these types of small distances with that focal distance? I am really up for anything at this point and need some expert advice. I was told maybe bellows and extension tubes and some other combination may work but I am unsure at this point. I really appreciate any response. I have pictures and can email them to anyone if they would like more information (I am not trying to spam, it's my university email address which is how I got here).
Thank you very much!

Jan 29, 2013 at 11:28 PM

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p.1 #2 · p.1 #2 · Set Up Capable of Capturing 10 Microns or Less

I currently take a number of water drop photos. I take most of my photos with a 100mm macro and obtain photos like this.

The Bubbleship by CalevPhoto, on Flickr

Keep in mind this is not 1:1. I haven't used my MP-E 65 too much for water drops but it was used for this one. The needle should give you an idea of size. This is about 2x.

A Drop of Me by CalevPhoto, on Flickr

My understanding is a needle is about .5mm, so my educated guess is if you photographed at 5x then you should be able to discern .05mm increments. At 5x the working distance is 41mm.

If you want to go above this, then you are mainly looking at microscope objectives. Working distance and DOF will be issues though. I have a Nikon 10x .25 but it only offers 10.5mm of working distance, which is actually not bad. The Mitutoyo objectives offer better working distances of 33.5mm on the 10x and 20mm on the 20x (I have this one). I'm not sure what you would do about the DOF though as it is certainly too narrow for a spray of water drops - but maybe you could figure something out that would tell you what you need to know from a scientific aspect.

Jan 30, 2013 at 01:32 AM

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p.1 #3 · p.1 #3 · Set Up Capable of Capturing 10 Microns or Less

Thanks. I will check out the Mitutoyo products. The reason I need a (relatively) large focal distance is because the water spray is being induced by an potential difference. Using low flow rates through the needle tip (1 - 20 mL/h) will initially produce dripping from the tip but when the voltage is applied it forms a spray which is used commercially in some applications to create sub micron droplets. We are just looking for micron scale droplets. If I get too close with the camera then the current will flow through the camera and burn it which is not desirable. The DOF should not be an issue because to measure these droplets, I need them to be in the same plane as a reference object that I know the dimensions of. I will then remove the object and create the spray. As long as the DOF is greater than the diameter of the droplets it should be fine.

The advantage of having the camera set up is it's accessibility (we can use it whenever we want) and adjust it to our experimental set up. How small have you gone with your 20x at 20mm? 20 mm focal distance is small but it may be large enough.


Jan 30, 2013 at 03:15 AM
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p.1 #4 · p.1 #4 · Set Up Capable of Capturing 10 Microns or Less

Not an answer but suspect there are far more knowledgeable folks about this type of microphotography at http://photomacrography.net/forum/ who may be able to help.
Brian v.

Jan 30, 2013 at 07:04 AM

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