Post by brianb on Nov 25, 2009 10:24:56 GMT
Very nice!
This is not at all surprising, the 50D pixels are smaller reducing the signal to noise ratio. Whilst the modification increases the sensitivity at Ha (by removing the filtering that's present in the standard model) it has no effect on sensitivity across most of the visible spectrum. The nebulae in the Pleiades shine by reflection & fluoresence from the UV emitted by the hot stars embedded in them so removing the Ha has little effect.
The image would be even more striking if you applied flat frames to counter the falloff towards the corners which is evident ... the increased falloff is the major downside of using a larger sensor. (I have 5D (mk I) and 40D so am well aware of the issue.)
On selected non HII areas of the sky the 5D is more than a match for the 50D modified model!
This is not at all surprising, the 50D pixels are smaller reducing the signal to noise ratio. Whilst the modification increases the sensitivity at Ha (by removing the filtering that's present in the standard model) it has no effect on sensitivity across most of the visible spectrum. The nebulae in the Pleiades shine by reflection & fluoresence from the UV emitted by the hot stars embedded in them so removing the Ha has little effect.
The image would be even more striking if you applied flat frames to counter the falloff towards the corners which is evident ... the increased falloff is the major downside of using a larger sensor. (I have 5D (mk I) and 40D so am well aware of the issue.)
