Venus Take 2 23/04/...
 
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Venus Take 2 23/04/15

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Astrograph
(@astrograph)
Posts: 129
Estimable Member
Topic starter
 

Made a few changes to the filtering and post processing and managed to get some cloud definition and a better colour reproduction. Mind you, I've never been to Venus so it could be bright orange for all I know.

Venus 2 by astrograph ltd, on Flickr

 
Posted : 24/04/2015 4:19 pm
Mike Meynell
(@mikem)
Posts: 875
Prominent Member
 

Are you sure you weren't mistakenly pointed at Mars 😉

Seriously, though... that's a stunning image... cloud definition is fabulous. What filters did you use?

 
Posted : 24/04/2015 5:39 pm
Astrograph
(@astrograph)
Posts: 129
Estimable Member
Topic starter
 

Thanks Mike

Are you having a go at my colour balance? Just for you I have done a colour sample from an ESA image!

Venus 2 false colour by astrograph ltd, on Flickr

Image was first adjusted visually with an ADC at 450x. I then used an Astronomik IR642 to give me a base image for the Red channel. That was featureless.

For the Blue channel I used a Wratten No 47 filter in combination with a UV/IR cut filter. This is because a #47 passes IR in addition to UV from about 350nm up to about 450nm. An Astronomik UV/IR cut deals with the IR and does not cut UV until 350nm. As the clouds are only visible at the UV wavelengths, it is important to have a fairly tight bandpass around the UV area to get the best contrast.

I do have an Astrodon 'UVenus' filter which only passes light in the 3-400nm band. Unfortunately, it renders Venus so dark at the f24 I was using it was not usable. The #47 keeps things relatively bright.

This was only a 2 minute exposure (about 15000 frames). As Venus rotates very slowly, I may well try again near elongation with double or triple the exposure to try and bring out the clouds in more detail.

 

 
Posted : 24/04/2015 8:16 pm
Mike Meynell
(@mikem)
Posts: 875
Prominent Member
 

Are you having a go at my colour balance? Just for you I have done a colour sample from an ESA image!

Ah yes, this is more aesthetically pleasing to my eye!

Interesting about the tight bandpass around the UV area... makes a lot of sense. Very impressed with the amount of detail you've been able to pick up using this method.

 
Posted : 24/04/2015 8:31 pm
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