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Venus 20 March 2009

Dave Smith

By Dave Smith
in Imaging - Planetary

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Dave Smith

Dave Smith

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Getting so thin. I spent most of the afternoon getting this onto the webcam chip and in focus. I find it quite straightforward finding Venus in the eyepiece during the day but getting it with the webcam a totally different story. When only a little out of focus it does not show and of course if a bit of contrail covers it it becomes impossible. After about two hours I found it at around 4.30pm

As before, Celestron 9.25" f10 with a 2x barlow. About 300 frames out of 2000.

Dave

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Dave Smith

Dave Smith

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Very nice Dave.

Your right it is very thin and very low now...

You've done really well getting that during the day :) How many more days do you think we have?

Cheers

Ant

I hope you appreciate Ant, that it is your inspirational shots of Venus that have got me into this game. Thank you.

Theoretically with day time imaging it could be possible to go though until Venus is on the other side of the Sun but the sky would need to be very clear with no contrail remnants as it is difficult to see it through the finder with such low contrast. So basically it depends on the sky conditions. This fine weather is going to stop soon. A week ago I thought we might only have one more opportunity.

I must sort out how to get focus quickly.

Dave

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Starman

Starman

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Great shot Dave. Venus misses the Sun by nearly 8.5 degrees during this conjunction so it should be fairly straightforward to keep up with it given clear skies. It is dangerous through because of its proximity to the Sun. The planet's crescent stays in the same general orientation then suddenly does a quite rapid flip if you can follow it.

My closest ever capture of Venus relative to the Sun was 2.8 degrees separation and the capture took me out of my comfort zone with the Sun to be honest.

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Ant

Ant

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Very nice of you to say that Dave. :)

With the quick focus issue, my top tip is to leave the camera attached in the previously correct focus position.

Works a treat for me. There is almost always some slight adjustment needed - but to be fair it's only ever a fine tune.

As the 180 is my lunar / planetary imaging scope the DMK only gets taken off the scope when I need it for guiding on the side by side setup.

I'd like to thank Pete for the reminder about the sun. I don't think I'll be following venus through conjunction - too damn risky for me.

Another go planned for tonight Dave? Tomorrow is forecast to be raining over much of the country so it could be the last chance?!?

Cheers

Ant

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Dave Smith

Dave Smith

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Thanks for the advice Ant re the focussing. Unfortunately I need to put a diagonal and eyepiece in to get Venus centred. I am unable to use the finder to centre it accurately, as it will have moved slightly from one day to the next. The focussing knob does something like 30 turns from one extreme to the other and once it has been turned back and forth a few times there is no way of telling where in its travel it is. There is no trouble with a night time object as there is lots of contrast and even well off focus it can be seen on the chip of the webcam. Another serious problem is the presence of contrails and their remnants as they further reduce the contrast or even hide Venus altogether. Using a barlow also adds to the difficulty. A final problem with only a Solar System align on the Sun (using the finder scope only in projection mode) there is some drift in the image and so have to rely on the finder scope to keep it near the field of view. The image is only visible on my laptop when it central and in focus and if there are no wisps of cloud so is very much trial and error.

I will not be trying again today as I am preparing to go to our clubs dark site on the Dengie peninsula. I would like to capture one image showing the cusps separated by more than 180 degrees.

When the Moon is next around I will have a serious play with this and practice going from the eyepiece to the webcam noting how many turns etc.

Dave

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