Quote:
Originally Posted by jeelan
thanks for all the info on this gents,
I've just ordered the 2" NPB and OIII filters from Dan Mcshane at DGM
cheers
Jeelan
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One word of caution: The DGM O-III isn`t as good as the DGM NPB. The DGM O-III is supposed to be rated at around 12 nanometers or so like other good O-III filters, but it falls short in performance, don`t know why, but it does. I think the bandpass is wider than a good O-III IIRC.
I compared two different DGM O-III filters to two diff Orion Ultrablock filters and the performance was the same on many targets that are supposed to have O-III and UHC-type filters used for optimal performance. The DGM O-III wasn't horrible, but it wasn't the greatest for an O-III either. The DGM NPB is excellent.