The Vernier Spectrometer (Vernier Spectrometer, order code V-SPEC, $1,799, Specifications and User Guide) and the Go Direct SpectroVis Plus (Go Direct® SpectroVis® Plus Spectrophotometer, order code GDX-SVISPL, $399, Specifications and User Guide) are both CCD array spectrometers. Both units can measure absorbance, percent transmittance, and emissions from 380 nm to 950 nm. The SVIS-PL can also measure fluorescence with excitation wavelengths centered at 405 nm and 500 nm.
The V-SPEC is more expensive than the GDX-SVISPL for a number of reasons. The V-SPEC is made by a company (Ocean Optics) that makes research quality spectrometers. The V-SPEC comes in a machined aluminum housing. The light source is capable of being detached from the detector, making emissions data easier and more accurate as well as eliminating thermal noise from the detector. There is also a set screw that allows for locking the cuvette in place to minimize slight movements of the cuvette made by students during data collection. In addition, the light source in the V-SPEC is a very expensive collimated light source; the optics inside are more expensive and of higher quality to allow for greater accuracy. Proprietary firmware (software in the spectrometer) also makes the V-SPEC perform better than the GDX-SVISPL in certain ranges and in certain situations. Finally, the fiber optic (400 μm diameter VIS-NIR optical fiber, order code VIS-NIR) that can be attached to V-SPEC is superior in quality.
The GDX-SVISPL is an excellent affordable spectrometer that is designed exclusively for educators. The GDX-SVISPL is housed in a plastic case. The light source is not collimated nor can it be removed from the detector. The cuvette cannot be locked in place using set screws which, if students hold onto the cuvette during data collection, can cause changes in their spectral results. The GDX-SVISPL has lower wavelength accuracy and optical resolution (particularly in the blue region of the spectrum) as compared to the V-SPEC. The photometric accuracy is also poorer compared with the V-SPEC. The fiber optic (Vernier Spectrophotometer Optical Fiber, order code VSP-FIBER, $74) sits in the cuvette holder and is made out of plastic, so it is less accurate at emissions measurements. The GDX-SVISPL has Bluetooth and can connect wirelessly to smart devices with the free Spectral Analysis App.
If you are trying to decide between these two devices, it is very important to consider your application. If you are only doing absorbance measurements (identifying unknowns, Beer's law experiments, etc.), you will most likely not notice any difference in the two devices. The exception to this is if you need highly accurate absorbance values and wavelength values - see each units specifications http://www.vernier.com/products/sensors/spectrometers/visible-range/) before making your decision.
If you compare the two for emissions measurements (e.g., determining the spectral lines of hydrogen) you will notice a difference. The V-SPEC is superior in measuring emissions because it requires higher quality optics and finer resolution to obtain accurate data.
If you are interested in bluetooth connectivity, the GDX-SVISPL is the only spectrometer we offer with this option.
You can compare data generated from all of our spectrometers at the follow website: http://www.vernier.com/spectroscopy/comparison.html
Here is a page comparing all our spectrometers: http://www.vernier.com/products/sensors/spectrometers/