29 replies to this topic

[neil phillips]

Space Cowboy said:

Got my answer in another forum. It appears a colour chip is not sensitive enough to use with a UV filter.

Telescope Reviews: UV light and DBK618 bayer matrix

wondered why you was persisting with the idea, Mono is a must yes.sorry i thought you knew that, again my constant comments of a morgans spc fitted with any BW chip even the older chip would work ok, and is  cheaper. long captures with no rotation blur are possible Stuart

[Space Cowboy]

Sorry Neil I thought you meant mono was preferable rather than essential. Unlike Venus I'm not that bright.

[Clayton]

Neil,
Can you explain why "Mono is a must" for Venus with a UV (pass ? ) filter?
I can think of a reason, but would like to hear the conventional wisdom on this.
A UV filter is beyond my means ATM so it's not really vital that I know NOW
But later in the year things might improve.

[neil phillips]

It seems theres both sensetivety issues, and spectral issues to consider.Theres a interesting discussion here Rob.The bayer Matrix in colour cams dont help. Its interesting that imaging source dont consider there cameras good enough in the uv, (even mono ones ) which is both odd and pretty much moot, as dedicated uv cameras are not exactly all over the place. Many very nice uv clouds are being picked up with the chips that imaging source use, so although i feel there being a little harsh on there statements they might be correct that these chips are not the best. But hey we dont have much choice as far as i see it.
http://stargazerslou...-uv-filter.html

[Clayton]

Thanks Neil,
Very interesting discussion.
I wonder how a violet filter would work

[neil phillips]

Clayton said:

Thanks Neil,
Very interesting discussion.
I wonder how a violet filter would work

Something i havent tried, but would like to, just remember you need a ir blocking filter if a violet filter is used, or you will get a ir leak. I wonder if the luminence filter on a Astronomik type 2 set would work. I thought they also had uv cut in the coatings but have never looked into it if anyone knows. Though to be honest owning the Astrodon uv filter, it seems like a step backwards for me. but the violet approach might be interesting for others on a budget, we just need a cheap IR (only ) blocking filter. This could be a option for you Stuart a modded morgans with violet filter and IR blocking.

Edited by neil phillips, 29 February 2012 - 04:32 AM.

[neil phillips]

Ah found it Stuart, this one caught my eye, and is quite spellbinding. Though there is some debate on the usefullness of such images, as apparently some are suggesting the IR wavelengths and UV wavelengths are showing the clouds from different depths. A 3d  image showing us this, now that would be something

Venus in false color August 28 2010 Amateur Astronomy Picture of the Day - Astronomy.FM

[Space Cowboy]

Thanks Neil very interesting! I've seen quite a few false colour examples and they are very striking. I'm guessing the violet filter would allow more light than the UV filter?

Found this too :
http://stargazerslou...ters-venus.html

Edited by Space Cowboy, 29 February 2012 - 11:45 AM.

[neil phillips]

Space Cowboy said:

Thanks Neil very interesting! I've seen quite a few false colour examples and they are very striking. I'm guessing the violet filter would allow more light than the UV filter?

Found this too :
http://stargazerslou...ters-venus.html

To be honest i dont know, i have a cheap w47 here already, but from what Rik said on the link you supplied, my Astronomik lum filter may cut uv.So i cant test it yet in comparison. But i do belive they are also very dark, just not sure by how much compared to uv. A Good cheap easily available IR cut is whats needed, not sure how easy the one mentioned on your link can be got, but size is something mentioned that i didnt quite understand

[bish]

Great pic.