There is a plethora of suppliers on the biomarket that provide numerous cameras targeted toward an equally large number of applications. Therefore, when choosing an appropriate camera for a microscopy system it is important to decide which applications the microscope will be used for. For example, a lab that performs live cell imaging of fluorescently tagged proteins would benefit from a highly sensitive camera with electron multiplying (EM)-CCD technology. This would reduce exposure times significantly and as such reduce cellular toxicity. Imaging of transiently transfected cells, which are usually very bright, would only need a moderately sensitive camera. For those primarily interested in imaging fine cellular structure at higher power objectives (e.g. 60x and above) the pixel size becomes important and in these cases a camera with a small pixel size would be advantageous.
Our current lab microscope setup consists of an Olympus IX81 base, filter turrets equipped with cubes (DAPI, FITC, and TRITC) to allow visualization of fluorescently stained samples, a mercury arc lamp light source, and a rear-mounted disc-spinning unit (DSU) to enable acquisition of confocal images. The majority of our microscopy work involves the acquisition of single, dual, and triple colored images from fixed tissues or cells that have been labeled with specific primary antibodies and fluorescent-conjugated secondary antibodies.
We have been using a QImaging Retiga EXi camera for the past 5 years and during this time we have been happy with its performance. In our hands the camera performs very well when acquiring images under regular fluorescent, phase, and brightfield conditions. However, we have found that when we use our DSU (which significantly reduces the amount of light exciting the sample), our exposure times are increased from the millisecond to the second range. For this reason, it is recommended that DSU users consider investing in a more sensitive EM-CCD camera, which would significantly reduce exposure times.
The Retiga EXi comes bundled with QCapture Suite software, which allows control of the camera, acquisition of images, and some analytical features. Although a monochrome camera, one of the great built-in features of the QCapture Suite software is its ability to control a color (RGB) filter, which allows the Retiga EXi to acquire color brightfield images, e.g. H&E stained sections. However, the use and functionality of QCapture Suite is limited to basic acquisition and analysis unless you purchase QCapture Pro. In addition, it is anticipated that most users will want to interface a camera with their existing, third party image acquisition and analysis software. We have found that the Retiga EXi integrates seamlessly with IP Lab Version 4.0.4 but cannot speak for other mainstream image acquisition software packages (e.g. MetaMorph). Although the Retiga EXi model discussed here has been discontinued, the new Retiga EXi Aqua model has superseded it and, at least on paper, has very similar specifications.
Retiga EXi Fast 1394 CCD Camera from QImaging
High image resolution (1.4 megapixels); small pixel size (6.45 x 6.45um); ease of use; firewire connectivity.
Discontinued but equivalent replacement (EXi Aqua); lack of sensitivity under low light conditions.
The Bottom Line
The QImaging Retiga EXi Fast 1394 CCD camera represents a good, entry-level camera to mount on a research-grade microscope. Although discontinued by QImaging the new EXi Aqua CCD camera is equivalent in most aspects.