Saturday, August 11, 2012

Barlow experiment

I had been wanting to try out a Barlow lens with my Canon T2i and TEC 140 for taking pictures of sunspots with a larger image scale.  I borrowed a Televue 2x "Big Barlow" and unfortunately, seeing conditions this morning were rather poor.  The atmosphere was fairly unsteady and I was trying to grab pictures with passing clouds.   First up, is a full disc image taken with my usual recipe - 1/4000 second at ISO 100.  As it happens, this was the only image I was able to capture without clouds passing across the Sun.  Click the image to enlarge to full size:
Next up is an image using the Televue 2x "Big Barlow" and while the clouds are interesting, I was having to use an even slower shutter speed than I expected.  The image below was taken at 1/200 of a second.  The clouds were frustrating me and I did not think to try some different ISO settings.  That is an experiment for another day (tomorrow?)  Click to enlarge to full size:

So what did I take away from this exercise?  I believe that I need to try some additional barlow lenses.  While the 2x barlow certainly did what I expected, I am curious as to using some higher powered barlows such as 2.5x to 4x. Certainly the TEC 140 has the resolution to support the high power, however, I am not sure at what point I will be routinely fighting the atmosphere...I know, take multiple exposures and integrate them.  Maybe one day, but at the moment my desire to spend a lot of time on image processing is not high.

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