The trials of Venus

[Guest Justin]

After finally buying a CCD device I thought I would share the trials of capturing Venus. I took some images of Saturn with the idea of comparing the actual visible size of each planet, all images are of the same magnification. With only a 127mm mirror, the results are nothing to write home about but by early August Venus should be quite a spectacle, if it can still be seen against the glare and close proximity of the Sun.

[Tweedledee]

Well done finding and imaging Venus in daylight.

Not many people do that

Looks like it was probably mid afternoon by your scope position.

I presume the 3 openings in the Hartmann mask were letting too much light in to subdue the glare, or was there a different problem with it?

I never knew Sainsbury's drinking chocolate was useful with planets

What filter did you use?

Good experiment

[Brantuk]

Great effort and result Justin - it'll get better the more experience you gain. One of the best times to image Venus is just before the sun rises or sets. I had a crystal clear view of it once in the Lake District when the sun had just dipped below a hill leaving the planet less affected by the amount of light around.

[Guest Justin]

Venus is fairly easy, just image the Sun, correct setting circles then dial for Venus. It is usually within a degree. The time here was about 2:30pm. I measured the aperture for the Celestron Sun mask and recalculated for three apertures guessing it would work. For the eye it works well, splitting into three images if out of focus but the CCD 'looked' at the centre of the plate - hence no image. 55 and 45mm were still too bright for the CCD so I went as narrow as I dared without causing diffraction and also popped in a green Moon filter. The light allowed by the mask is 310 mm2 or equivalent to a primary mirror of 2cm. The outer mask is a Monster energy can.
I could look for Venus at sunrise and sunset but I would rather go after it when the Sun is high for the novelty and not having to wait around for imaging. Naturally, far better results could be obtained with a 30cm reflector, coupled with Meade optics and 14MP imager but this is a first scope for me and very much for learning.

[Guest Justin]

One of the best times to image Venus is just before the sun rises or sets. I had a crystal clear view of it once in the Lake District when the sun had just dipped below a hill leaving the planet less affected by the amount of light around.

It makes no difference that the Sun is obscured to the magnitude of Venus. The problem here is one of glare. Much as we are dazzled by a headlight or need heavy optical filters for welding. Midday imaging of Venus can often be during 50% cloud cover but since all I need do is wait until the sky is clear above to resume imaging, it isn't a problem. Cloud is far more troublesome at dawn amd dusk due to the angle of view vs cloud layering, if it is cloudy on the horizon it can take many hours to clear. I wondered about the magnitude of Mars when it was very bright last year but didn't reduce aperure at the time. When viewing the Moon, well as you know it can be projected it is that bright and it is also worth reducing aperture for that object.