Using visual colour filters for observing.

[Flyingpig]

During an observing meeting of the Central Midlands Stargazers at the weekend we used a few of my color Wratten filters to observe Mars and found them very useful.

We used the Red #25, Yellow #12 and Blue #80A; the red improved the visibility of the polar cap region better, although Mars looked un-celestial through it like a red LED rather than a planet, the yellow filter was amazing it revealed the dark areas of surface detail such as maria, and the blue was a good all rounder it revealed other surface details as well as the polar cap.

The inspiration came from an article I recently read by Peter Grego who was writing in a well known uk astronomy magazine about the use of these filters with the planets which prompted the activity, something that I will eagerly experiment with more after seeing the results on Mars.

I am eager to try the two green filters I have #56 and #58A next which I read are excellent to use with Mars and also to try them out on other planets.

Does anyone use these filters regularly, if so would you describe some of the best ones to use and what they work best on etc.

Thanks Phil

[David Smith]

I've found that the #56 Green is probably the filter I use most. Works well on Mars in my experience, highlighting features that may well not show without the filter as they are too subtle. I have also #8, #15 and #23 to isolate certain features but find there effect much less pronounced.

Interesting last night as I was observing Mars some thin wispy cloud parked itself in the line of sight. This actually seemed to help the image! Reducing glare and made the whole thing much easier on the eye.

At next opportunity I think i will try the Moon filter and see if this helps. Have tried this on Venus but felt the improvement was marginal.

Hopefully I have attached a guide that I found on the net a few years back which I still refer to.

Colour Filter Usage.pdf

[Flyingpig]

Thanks David, I'll take a look at that thanks for sharing the link.

I'm really keen to try out the #56 Green now, I might see about getting a few more to try out.

I've used a lunar filter on Venus many times, for me it reduces the glare at higher magnitude when Venus is particularly large and bright.

Cloud can be strange stuff as much as we hate the stuff it sometimes does improve the view of things taking the edge of the brightness just enough to reveal detail.

Phil

[David Smith]

Have yet to try the moon filter on Venus when it is anything more than a very small object (aka recently) so will persevere as it increases in size over the next few weeks.

I don't have access to a variable polariser, the cloud thing last night made me think this might be a good tool to have in the box at some point.

[Flyingpig]

I haven't got a Variable Polariser either, I do have an Astronomik CLS filter to rid of light polution, I have used that on occasion with the moon but I've not really used it with any planets, will have to try that one too.

Phil

[David Smith]

Have just recently received a Baader Neodymium, haven't had chance to try that on Mars yet. Clouds came in before I had chance last night. Will let you know how that goes. Although weather forecast here for the rest of the week is cloud, followed by some more cloud, followed by - guess what, more cloud!

[patomlin76]

Thinking about getting a filter myself, especially for reducing glare when viewing the moon.

Which type of filter would anyone recommend, and is there one filter that can be a 'jack of all trades', so of potential use in viewing the moon as well as other planets? Jupiter seems to suffer from the glare as well, which sometimes makes viewing the cloud belts somewhat difficult...

Cheers!

[Flyingpig]

People generally recommend lunar filters for the moon hence the name, however the wratten filters are very cheap and are useful on all the planets as well as the moon. I got six in my Celestron Eyepiece case. You can try any of the various light polution filters and other than that polarising filters.

Hope that helps.

Phil

[Flyingpig]

Found another really good guide here Astronomical Filters it covers some of the same stuff, but lists many other astronomical filters and their uses.

Phil

[David Smith]

Can't get the link to work, can you repost.

Thanks

Edit: Link works fine - sorry, just me being a little thick! Time for bed I think.

[patomlin76]

Thanks for that link. It states the blue filter should be the one to buy, if you only own one filter, so I will get that. Plus it seems other filters are more useful on larger aperture scopes where the possibility of seeing finer detail is there...

[David Smith]

I've read the same - some are more suitable for large apertures. I own a #47 violet and would definitely suggest this is one for a larger aperture scope as it does not work particularly well with my 80mm frac, except on very bright objects like Venus.

[todd8137]

i have 15 dif colored filters they get used for all sorts of things

[NGC404]

I have a few filters, and find the #56 green is the best for making the

Polar ice caps on Mars stand out more

[David Smith]

So I may have to eat my words here. Just spent a couple of hours out with Mars and found completely the opposite to what I described above. Tonight I found the :-

#80a gave a good result, highlighting lighter regions on the east and west limbs of the planet.

#23a did a really good job of clarifying the dark region around the polar cap as I was having difficulty defining it's borders.

#8 and #56 did not seem to being any benefit. Also tried the Moon filter as I threatened to do above but found it took too much out, leaving a rather dull and featureless image.

Does anyone have an Orange filter? Supposed to be really good for Mars, not sure whether to lash out and buy one.

[Tyr]

hmm colour filters is not something I had previously considered, although I have tried using my moon filter on venus before, which seemed to work quite well. Being able to bring out more contrast on Jupiter and Mars would be quite nice.

I was wondering what makes of colour filters you guys are using and if there's much between them?

So far I've seen Meade 4000, Antares and Skywatcher branded ones. The Antares can be had individually from scopes and skys, so they are looking like a reasonably priced option. However I'm a little wary of the saying you get what you pay for in this case.

Thank you for the interesting thread

Tyr

ps my interests are currently purely visual and not photographic

[David Smith]

Hello Tyr

I bought a Revelation eyepiece kit with my scope a few years ago which included a number of these coloured filters. I have since added a #47 which is quite useful, and am on the look out for a #21. I do not really have a frame of reference in terms of comparing performance as I have only used these filters. Having said that I do find them useful as they do bring out fine detail.

I am a visual only observer as well.

[Flyingpig]

I got my six colour Wratten filters plus a lunar filter with my Celestron eyepiece case. If you need to get a range of standard EP's this is a cheap way to get them. You need to be sure that you are getting the visual Wratten filters and not the imaging ones that also often have Wratten code numbers.

[Tyr]

Noted on the eye piece case sets, I'd seen them before, however I've already got a decent range of EPs for my current setup.

Based on the PDFs attached, notes on SnS website and this thread I found ion the primers section http://stargazerslounge.com/primers-tutorials/38541-primer-planetary-filters-guide.html I thought that these 3 might be worth trying with my 5" scope the 21, 56 and 82a.

I thought the 21 orange seemed to have better light transmission than the darker red filters and the 82a blue the greater transmission in comparison to the 80.

I'm not sure about the light transmission of the 56 green, but it seems to recommended for lunar detail as well so I thought if it was too dim for Mars and Jupiter with my 5inch Mak then I could use it for some lunar observing.

What do you think?

Tyr

[David Smith]

Nice link Tyr, Thanks. Looks like a sensible selection you have their, the 23 is a dark filer even in my 10" Dob. Should think the 56 will be OK but don't hold me to that!

[Tyr]

Cool, well if it's too dark for use on planets then there's a lighter green #11 I could try by the looks of it. So I'll see how I get on.

If only SnS would get on and process the order.

Tyr

[Tyr]

The filters turned up today but SnS sent me an 80A (30% transmission) instead of an 82A (70% transmission) because they were out of stock of the 82A's. I suspect it might be too dark for my scope but having called them I'm going to try it before I send it back.

Hopefully I'll be able to get a clear patch of sky tonight to find out.

They sent me Revelation rather than Antares branded filters, but I expect they are all the same with different names stamped on them as they look otherwise identical.

I'll let you know how I get on, looking forward to trying on Jupiter, the Moon and Mars soon and Saturn next time I can get an early morning session in.

Tyr

[David Smith]

Had a chance to use my Baader Neodymium filter on Mars last night for the first time. Not a great night to try it as there was a lot of mist around but still I was impressed. Seems to take away the glare without taking too much away. Need another session with better conditions to fully understand it's capability but from what I saw it looks very promising.

[Tyr]

I got a quick chance to try them out on Venus, Jupiter, Mars and more so the half moon last night.

Venus (7pm) didn't really show me any more as expected, but by reducing the glare each seemed to work about as well as a neutral density filter in allowing me to see the phase more clearly.

Jupiter (7pm), I'm not sure about yet. I think even the number 21 filter with apparantly 46% transmission was a bit dark, the 80A was a bit dark too, but not as dark as I expected. The 56 seemed to be the most useful at first glance. Sky conditions were rather light and humid.

Mars (10pm) without the filters I wasn't able to see as much surface detail as last weekend, but it was pretty humid out last night so not the best observing conditions. With the filters, all of them were pretty dark on Mars, I think the orange 21 was too dark, I could see the green 56 being useful. The image with the blue 80A was interesting. Mars looked very pale and was brighter than I expected.

Lunar (10pm) is where I was most pleased with the filters, the green 56 in particular made for an interesting view of the moon, shadows seemed to stand out more increasing the contrast of some of the fainter features in the brighter areas. I found if I looked without the filter I could still see those features but I noticed them more readily in the first place with the filter.

As stated above, this wasn't the best evening for observing conditions indeed at the end I was observing the moon through light cloud using the #56. Also a rather short first light, Jupiter wasn't observed at the ideal time either as it wasn't fully dark.

I'm looking forward to trying these on Saturn and I think I'll hang onto the 80A and try to get an 82A at some point in the future, a lighter green filter like an #11 or maybe a yellow #12 as mentioned by the OP might also be worth a poke.

All in all a rather interesting experience, thank you for starting the discussion off or I might not have thought to have a go at this.

Tyr