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Celestron 'breather vents'
Thanks for your thoughts about the heater. This is good advice but in my view if a manufacturer introduces an innovation, they should ensure that it performs well under all normal operating conditions. It demonstrably does not.
If this innovation did require some extra accessory, that should be explained and the accessory supplied. The innovation was heralded, but silence on the rest. The poor punter was led to believe it was stand alone.
If a SCT manufacturer wanted something extra, they could try designing a retractable dew shield or something really useful like that. Hmm...might cost too much... Hmmm might be able to sell it separately...
Why am I not keen on EDGE. Well, the corrector lenses are tucked away and difficult to access or clean. What (shudder) if they should dew up?
Then, in order to use to full advantage, the focus is very critical at a precise spot. Now we often stick some filters or other 'stuff' in the optical train, say an ADC (Atmospheric Dispersion Corrector) unit and this means the focal point most likely needs to be adjusted. Okay it is not optional for a standard SCT either, but the difference in that case is minimal.
For myself a totally flat field is not a major issue. I use the very centre of the field, or maybe close to it - only. (Lunar occultations and stuff.) True, the field is curved and a full prime focus image of the Moon on the C11 adequately demonstrated that. (The Moon was sliding past a star, and the image of limb and star were not pretty!) Using the F6.3 reducer and field flattener on the same instrument with an APS-C SLR (smaller sensor) sorted that out at much the same picture scale. Okay, it is a generic Celestron reducer and undoubtedly not as precise as the EDGE or its dedicated reducer, but it does me.
The strength of the EDGE is the perfect images for scientific wide field work. In effect, research grade optics at an amateur price, and it is superlative in this application. I know at least one fellow with a C14 EDGE doing top line research work. A superlative instrument, but not for me.
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