The Panasonic GH1 is a micro four third camera. It is now replaced by the Panasonic GH2, built around a different sensor.
Whys is this camera suitable for photomicrography.
- Interchangeable lens.
- Permanent live view (no mirror)
- The sensor size almost as large as the size of the light beam in a trinocular head of a microscope. The sensor crop a large part of the image given by the microscope.
- Tilting ans swivelling screen which allow to use it whatever is the position of the camera (good for looking to the screen while the camera is on the top of a trinocular head).
- No mirror as in many bigger camera. That reduce the risk of vibration while taking pictures.
- Possibility to use an external electronic trigger to release the shutter (not very expensive on Ebay).
- Good video quality
- Very bright electronic viewfinder, good for focusing with low light.
My checklist while using it :
- Set the knob on « A » (aperture priority)
- Check if the numerical zoom is on 4X or not.
- Check the ISO
- Check the dioptric setting to avoid complete out of focus shots.
- Run a white balance setting.
- Insert the cable release shutter (mine need to force a little bit to run properly)
Considerations about the sensor.
Specifications.
- The sensor size is 17.3mm x 13mm
- The maximum resolution is 4000×3000 pixels.
- This implies 230 pixels per mm or a 0.231µm pixel size
- I’ve found a circle of confusion of 17.3µm.
Effect of the digital zoom.
Using the 4X zoom reduce by a factor 2 the size of the resulting file (a white page). It may be not an empty magnification. Usually it’s the NA of the objective the limiting factor of magnification. I have to run some test to check this camera feature.
The white balance.
I have still to find how to set up the white balance. A lot of my picture are either too yellow or to blueish for the moment.
High ISO versus high pause time.
Here are some reason why it may be better to prefer a higher pause time.
- If you are in a focus stacking process, you need an immobile subject and high shutter speed is useless in this case.
- The noise coming from an higher pause time is less a problem that the loss of quality induced by high ISO.
- Even without mirror, the shutter produce some vibrations. These vibrations are less a concern in case of high pause time.
- In his paper on photomicrography with microscope objective and bellow, Charles Krebs explain that he set the lighting of the subject to get a 3 second shutter time.
Some concern.
- As there is no mirror in the camera, the sensor is exposed when you remove the lens. Dust can easily reach it and as dust is a big problem in photomicrography. Normally, this concern is addressed by a feature of the GH1 : a dust removal through vibrating the sensor. This vibration is send each time the camera is turned on.
Links
- Panasonic GH1 on Wikipedia.
- Charles Krebs wrote a complete and precise article on using microscope objective on camera bellow.
Panasonic GH1
