We are often asked how our Model SFA Stereo Microscope Fluorescence Adapter compares with conventional systems for fluorescence stereo microscopy. By ‘conventional’ people typically mean a fluorescence stereo microscope from one of the major microscope suppliers – Nikon/Olympus/Zeiss/Leica (abbreviated NOZL from here on) – and they are asking ‘How does something look under yours vs theirs?’.
There is no simple quantitative answer that covers all cases, but we can make a quick generalization:
Feedback from our users indicates that the SFA is ‘just as good’ or ’90 – 95% as good’ for numerous applications. There are also cases in which fluorescence seen under a NOZL system isn’t visible with the SFA. As with anything in microscopy, the results are very application dependent and the typical fluorescence parameters apply: performance depends on how much fluorescing material is present, how brightly it is fluorescing, and how much background there is. Size alone is not always an issue. We have seen individual GFP-expressing thrombocytes, about 5 micron diameter, circulating in the tail of a zebrafish using the SFA system.
Probably a better question is ‘Will the SFA do the job that I need to do?’ or ‘Can I see what I need to see?’
NIGHTSEA’s SFA is an excellent choice if you want to:
NOZL systems are a better choice if you need to:
Differences in performance are coupled to differences in design, so let’s examine those differences in a bit more detail. The two main elements of any fluorescence system are excitation and emission. A third element is generally a filter shield to screen the user from the intense excitation light directed at the sample.
NOZL systems use coaxial epifluorescence
NIGHTSEA Stereo Microscope Fluorescence Adapter
In the NOZL systems the fluorescence is tightly integrated with the microscope, while the NIGHTSEA SFA is designed as a near-universal adapter to work with virtually any existing stereo microscope, including both Greenough and CMO designs.
Now let’s look at some of the characteristics that users have expressed interest in and compare the systems.
Efficiency in delivering excitation light to the subject
Rapid switching between excitation/emission wavelength combinations
Choice of excitation and emission wavelengths
Portability for demonstration and outreach
Observe fluorescence through the viewing shield
The systems from NOZL are generally terrific and we are sure each of the companies can provide nice things that people say about them. Below are some things that NIGHTSEA users have said about the SFA.
The NIGHTSEA works perfectly for the purpose of animal sorting, is very easy to use, student friendly, very portable and a 10th of the cost of a fluorescent dissecting scope. [Drosophila and C. elegans researcher] For bright specimens they completely replace the need for a traditional fluorescence built into the stereomicroscope. We had some issue detecting red fluorescent proteins with some of our weaker transgenic zebrafish lines, but by shining two LED lights onto the same embryo, most of our weakest GFP and mCherry transgenic lines can now be detected. One light head was fine for reasonably bright specimens, and with two lights, the fluorescence is nearly the same as traditional stereomicroscopes priced $15-20K. [zebrafish researcher] The fluorescence adapters allowed easy viewing of the GFP expression at a magnification needed to view the entire root directly through the petri dishes in which the plants were grown. The fluorescent signal was on par with (if not brighter than) the reporter fluorescence observed at higher magnifications using confocal imaging. [Arabidopsis researcher] The strength of the signal is excellent allowing any individual to identify tissues expressing GFP at multiple magnifications. [Drosophila researcher] I would like to emphasize that I am delighted with the power of the royal blue illuminator. It is nearly as good as the epifluorescence and much more convenient! I will be recommending it to my colleagues for classes. [zebrafish researcher]