Quote:
Originally Posted by h0ughy
I will be using ND5 solar film that way focus wont be changed - using the method by ozEclipse
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I may have misled you slightly. Anything in the optical path can change focus. I'm sure that at some level, the Baader film does too. With the WO70 f6.3 I use, I find the Baader doesn't change the focus perceptibly in the eyepiece or on the final image and certainly not as much as a glass filter or thicker plastic filter can. I do a final trim on focus on the mountains on the limb about 30-50 seconds before totality just before removing the filter. Don't leave it too late but if you do it too early, the rapidly changing temperature can get you.
But if you use a 400mm f2.8, you might notice something of a focus shift because of the shallow focus.
For an eclipse, optical systems of f6-f8 at ISO 100 require exposures ranging from 1/4000 up to a few seconds from inner to outer corona and 8s for the Earthshine.
Looks like an awesome system Houghy. Looking forward to see the results.
Joe