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UV venus, what am i doing wrong?

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7 replies to this topic

#1 bill w

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Posted 05 February 2025 - 12:59 AM

i've captured cloud detail on venus in the past with a UV filter

but have repeatedly failed more recently

at someone's suggestion, i've tried a different filter which should be better for SCT's 

thor labs 400 nm, 40 nm band width

still getting minimal detail

 

 

2025-02-02-0157_7-venus-UV-400x40.jpg

2025-02-02 01:57 UTC

full details and some banter at the blog:

https://astrowhw.blo...conjuction.html

 

 

prior captures with cloud detail

https://astrowhw.blo...d-uv-91321.html

https://astrowhw.blo...ltra-venus.html

 

thanks for reading

any help would be appreciated



#2 KiwiRay

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Posted 05 February 2025 - 01:18 AM

I can see some detail in the image, but it might just be you had poor seeing. I've captured Venus recently with the same filter and a C9.25 and got very little detail, whereas in better conditions, I've captured some nice-looking images given the limitations of my equipment (which includes using a colour camera), eg, http://alpo-j.sakura...3/v231028f1.png


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#3 bill w

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Posted 05 February 2025 - 02:03 AM

thanks for your reply

seeing was relativley good that evening and venus relatively high (have some nice captures of jupiter and mars coming).  

you've got a lot more detail in that image.


Edited by bill w, 05 February 2025 - 02:03 AM.


#4 Overtime

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Posted 05 February 2025 - 03:50 AM

I tried to capture some pictures of Venus and didn't get anything good. Be patient with this target it isn't the easiest.



#5 Lacaille

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Posted 05 February 2025 - 04:07 AM

Looking back at images on ALPO Japan over the last week or so, it does look as if the cloud patterns in UV are not particularly pronounced at the moment. This happens from time to time.This could be the explanation.

In the meantime, maybe check your capture settings (e.g. peak histogram ideally around 70%). Capture videos ideally of 5 min duration.

I am assuming you haven’t added glass (say in the form of a Barlow or ADC) to the imaging train since your last successful session - these will of course absorb UV.

Edited by Lacaille, 05 February 2025 - 04:07 AM.

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#6 bill w

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Posted 05 February 2025 - 10:57 PM

thanks for the tips

after previous fails, made sure there was no barlow nor ADC

histogram was 88%, but no clipping

only 120 seconds here, though i've tried up to 9 minutes recently and not captured much

 

will just keep trying i guess



#7 John Boudreau

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Posted Yesterday, 12:06 AM

It appears with the capture time and your location that you were imaging well after sunset. You'll find that it's preferable to image Venus in UV in a relatively bright daylight/near daylight sky with Venus visible naked eye and the Sun ranging from shortly before sunset to shortly after sunset. UV gets scattered easily, and there's more contrast-robbing scattering as it gets lower in the sky usually along with poorer seeing. Also, I'd watch the histogram and not max the curve beyond about 75%.

 

As is, there's certainly some features faintly visible.


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#8 bill w

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Posted Yesterday, 12:36 AM

thanks john

it was about 40 minutes after sunset at 35 degrees elevation

seeing was quite pretty good that evening

better than during many of may daylight attempts

will try more during daylight

and hope for the magic combination of good seeing and nice structure visible

have to post my compendium of recent fails ;)




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