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HI Claudia, 

We like Metal Halide lamps. We have no experience with the Zeiss model. We use primarily the Xcite, but I am guessing they should be similar (or maybe even the same Zeiss sells). Benefits of Metal Halide:

Broad spectrum with good brightness across; if you need to image a new dye, you just need to buy a new filter set

Long life (typically 2,000 hours, we often run ours 3,000-4,000 hours, which can mean 1-2 years before changing bulbs, depending on how much you use your scope)

Easy installation (no alignment needed)

Many of the current models include shutters and variable apertures, and can be computer controlled if needed. 

Potential downside is that as filters get old, some light (including UV) may leak through, but this can be adressed by replacing filters or adding UV/IR blocks. Also, if lamp is turned off, next person will need to wait before getting it back on. No such problem with LEDs. However, current models have built-in safety; lamp won't fire if still hot.

We have two LED or LED-like systems which work great for us; our models have either five or seven excitation bands, which works fine for the particular scopes we use, and they offer plenty of power at all wavelengths. They are not Colibris, and I don't know the specs of Colibri, so can't comment on the power. The fact that Colibri has only four wavelengths could be limiting... it all depends on what you intend to do on your microscope. The pros of LED are: 

Long life (rated 10,000 hours of actual use, which means they should last maybe ten years, although this may bee too new a technology to really know), fast switching, no UV leakage (useful for live imaging), and no need to replace/align bulbs. The fast switching between wavelengths can be a plus for live imaging (such as for FRET or colocalization), because you can use for instance a double band pass emission filter and image two channels without any moving parts (better speed, potentially better registration between channels). Intensity can also be software controlled. Vendors claim better image contrast.... could be true, but hard to know.

The choice between metal halide and LED may depend on what the intended purpose of the microscope is, and perhaps cost (initial cost plus operational cost over the lifetime of the device). If your LED device has all the wavelengths you need (and enough power), I don't really see any downsides. Our LED-based systems provide at least 20 mW at any wavelength (measured at the focal plane with a 10x objective). That's roughly comparable to metal halide. We like the Xcite Metal halide because we can also open/close shutter and control illumination intensity manually. I don't know how Zeiss implements their Colibri, i.e. is it purely software controlled, or can you also control it manually (e.g. from the Zeiss control pad on the microscope)?  Ultimately, Assuming that the Colibri covers your needs in terms of wavelengths available and/or power (which I would suggest you test), you'll be fine with either. If you expect to do five or more channels on your scope, then a Colibri with four excitation bands may not be what you want, and a Metal Halide may be more flexible/versatile. 


--
Julio Vazquez,
Fred Hutchinson Cancer Research Center
Seattle, United States

http://www.fhcrc.org/



On Mar 1, 2013, at 8:05 AM, Claudia Florindo wrote:

> *****
> To join, leave or search the confocal microscopy listserv, go to:
> http://lists.umn.edu/cgi-bin/wa?A0=confocalmicroscopy
> *****
> 
> 
> 
> Dear all
> 
> 
> 
> I was considering buying a zeiss colibri system instead of a HXP system, any
> comments in comparing both systems?
> 
> Any suggestion would be very helpful, 
> 
> 
> 
> Thanks a lot, 
> 
> 
> 
> Claudia.  
> 
> 
> 
> 
> 
> Claudia Florindo, PhD, Microscopy Unit Manager
> 
> <mailto:[log in to unmask]> [log in to unmask] |00351 289244 495
> ext: 7495; 7489; 7484 (mic lab)
> 
> Dept. de Ciências Biomedicas e Medicina
> 
> Uni. Algarve, Campus de Gambelas Ed 8, lab 1.18
> 
> 8005-139 Faro, Portugal.
> 
>