New Canon EOS Insert Filters

Thats true John regarding the exposure time.

My main use for this filter will be for widefield shots using my camera lenses (50mm, 85mm, 70-300mm and 170-500mm FL) piggybacked on the CGE11.

Even though I have not got a proper chance to experiment, with exposure times for these lenses on the mount (unguided) before trailing etc., I have managed up to 90 seconds without trailing using the 350D at prime focus at the telescope (FL 2800mm).

It will be interesting to see the max exposure times possible with the shorter Focal Length lenses.

Can't wait to see the results, it's a pity about the longer exposure times, but I suppose you can't have everything

Do keep us posted.....

Keith..

Steve.
I'm seriously considering getting this filter.
Did you manage to get any wide angle shots since
first posting the comparisons?
I'm sure the Astrotrac is well up for the job of
long exposure times but how did you get on with your
set up?
Also - did you price around?
Where did you buy it from?

Thanks.

Just wondering about optical quality...
let's Say a filter is of a certain optical quality and is placed over the fron tof the camera lens. A filter of a similar quality is placed much closer to focus. Which will yield the better image? Will there be much of a difference?
My guess is that the front filter would be better.

The reason I ask is that I spoke to a guy in a camera shop about those gelatin filters which can fit on the back of the new Canon lenses. He advised against them due to poor quality image one gets througn them.

What do you think?

I dunno.
It's hard to say without seeing them in action.
The added benefit of the one that fits over the sensor
is it keeps it free from dust.

My guess about the better image quality would be the one that goes on the front of the lens. I'm thinking simple physics. The surface reflection of the filter, no matter how minimal, may make you alter your F-stop to achieve the brightness and sharpness you want at focus. If you were using a set of the same filters for different gradients/colours/wavelengths, then you can use the same F-stop and lens settings in one sitting without the need for removing the lens to fiddle with it if it was over the sensor, and readjusting each time.

As to the sensor being protected by the inner filter instead, does that not affect daytime/regular photography, and increase the need for fiddling with the sensor area? Something you shouldn't do on a regular basis...

Seanie.