Day time mercury+venus

[Atacamallama]

I have been wondering about doing the above (actually with a view to imaging...), using the technique of first aligning on the sun with a filter and then go-to-ing to the planets. My question is how far away do they need to be from the sun for this to be safe?

[Dave Smith]

With my ongoing Venus project I did get as close as 14 deg from the Sun. I didn't fancy getting any closer. At that time Venus was a 3% crescent.

See Planets

Dave

[brianb]

Dangerous ... if you mount is very accurately aligned you should be able to acquire the planets without going to the sun first, then with a slitted observatory you can have the tube in the shade & be safe down to a couple of degrees from the Sun! There's good reason to have the tube shaded anyway - solar heat does no favours to the seeing quality, especially with dark painted uninsulated tubes; and a partially shaded objective will likely have different focuses for the "warm" & "cool" parts.

Do not scan for the planets unless you're sure the sun can't get to the objective.