a models from Canon were reported as not getting as much Ha sensitivity boost as modified cameras.niels123 said:Djaaf said:Ha stands for H-Alpha, one of the primary emission band of the Hydrogen.
It's a deep red that's pretty much invisible to human eyes and so the filters before the sensor tend to cut it out.
But in the Astro-photo domain, that's the principal band of light since most of the universe is Hydrogen (emmission nebula emits mostly in that band (M42, California, Laguna, etc...) It's not that important for galaxies or stellar cluster which emits light in pretty much every band).
So conventionnal Canon DSLRs cut out something like 60-70% of your most useful frequency in Astro..
That's mostly why there's a few companies providing filter replacement for DSLR. Once the new filter is installed, you have to use a custom white-balance to take daylight picture because the red channel will be a lot stronger than before, but you can still use the camera normally.
The filter replacement operation is not cheap though (around 300-400€ depending on the camera) and the warranty is immediatly voided by the operation. So, Canon offering "a" models is mostly a good news.
If you still got questions, shoot, i'll try to answer.
Djaaf
Would an a model be the same as a modified camera where the low-pass filter has been removed: is there a difference between full-spectrum modification and the a-model in terms of IR-landscape photography? (I use clip-in filters, so I don't want a visibile-light block filter on my sensor).
Thanx!
Niels
I guess a modified 6D camera is the best value for money... (and possibly just best for now...)
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