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BillP

Using Filters for Lunar-Planetary Observing

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After half a century of reading internet sites touting how seemingly every color filter made enhances just about everything for planets, I decided to buy a set and compare them on the planets, and also compare them to a few specialty filters like the Baader Contrast Booster, Moon & Skyglow, and Semi-APO filters.  Spent almost 4 months observing and comparing and here is what I saw.  Enjoy!

Using Filters for Lunar-Planetary Observing v20200917 (lowres).pdf

Edited by BillP
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Great report Bill - thanks for the link :smiley:

This passage especially stood out for me:

".........So my recommendation is that before you venture into the realm of filters to
improve your planetary views, first make sure that you are getting detailed views of planets
without filters, as the filters will not perform any magic making a poor view all of a sudden good
with many details......."

So no "magic bullets" then.

 

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Excellent report. 👍🏻

Although I tried the contrast booster was never that impressed with it but perhaps I should give it another try.🤔

The #30 magneta filter is certainly hard to find at a reasonable price. The Brandon one is readily available but needs the Brandon to standard 1.25” thread adapter. There is a #30 filter in the Orion 20pc filter set but don’t need any of the other filters.

And yes agree that the right filter can help add a little bit of detail when seeing is good.

Found this filter guide from Orion that could be useful.

ABD0DAF0-1408-4AB4-ABEB-94D3DCA3DFAA.png

Edited by johninderby

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Great report - thanks for posting!

I've been getting some good glimpses of Mars recently and have been keen to get some filters to see if that helps tease out some detail - looks like quite a few of the ones I've ordered won't be that useful after all :icon_scratch:. Shame you didn't post it 2 days ago 😄.

8 minutes ago, johninderby said:

...the contrast booster was never that impressed with it ...

I'll give it a new home if you still aren't impressed John 😇

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Just now, globular said:

Great report - thanks for posting!

I've been getting some good glimpses of Mars recently and have been keen to get some filters to see if that helps tease out some detail - looks like quite a few of the ones I've ordered won't be that useful after all :icon_scratch:. Shame you didn't post it 2 days ago 😄.

I'll give it a new home if you still aren't impressed John 😇

It was sent to a new home with an SGL member a while ago. 😁

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Thanks Bill for an excellent detailed report on filters. Some years ago I undertook a review using a filter slide. Can't remember the coloured filters now but of the two slots remaining one had nothing and the other I used a Neodymium Moon and Skyglow filter. The best result came from the Neodymium followed by no filter at all.

I particularly appreciate your statement on exit pupil. Certainly on my 12" Dob using my 10mm Baader Ortho + Baader 2.25x barlow (exit pupil 0.88) gave very good views last night observing Jupiter, Saturn and Mars.

Finally, thanks for the overall conclusion that the Baader Contrast Booster gave the best results. It certainly appears to be the 'Jack of all trades'.

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John,

Hi.  Yes I saw that Orion guide as well as oodles of others.  Also the ALPO guide.  But vast majority of what they showed did not pan out for me.  Indeed when working at <1mm exit pupil to get to descent planetary magnifications, many of the filters recommended in guides are just too dark and excessively dimming.  I think that for descent image scale of a planet one needs at least 150x.  The aperture needed to be at 150x and say a 2mm exit pupil so the planet and features are bright enough to work with many of the darker filters would be 300mm.  Larger than what most folks have.  So IMO the common guides one finds on the internet for what filters help what I feel are basically unrealistic.  But I put the caution in my write up that things may change with larger apertures when one can get to planetary magnifications with larger and brighter exit pupils.  So I think what I saw is probably extensible to apertures as large as 200mm.  Larger than 200mm and one is getting enough extra light that more color filters might start to become a little more useful, and by the time you get to 300mm aperture probably a whole different ballgame as long as observing at 2mm exit pupil and larger.  If the seeing is good enough that one can get to a .75mm exit pupil with a 200-300mm scope, then I the filter field will be limited to the useful ones I discovered.

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Great report - thanks for sharing it!

I´m waiting for the C. Booster, while from time to time I use the color ones I have (not that good quality they have...)

So I´m looking forward to check it with my own eyes, for planets and moon soon...

 

Regards,

 

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I have played around with filters on planets myself in the past although not to the depth that you have gone Bill and your efforts are to be commended.

I played around with a basic set of R.G.B.Y filters on Jupiter and the Moon, nothing else. I did find results to be improved by filters.

I also tried using a Baader UHC-S on Jupiter which has a relatively broad band pass compared to other filters, much more so than other premium UHC filters and I noticed a considerable increase in contrast when viewing Jupiter. The bands and GRS stood out much easier as it seemed to darken/enrich reds more than the other colours although everything was a little darker.  However I was using a 12" dob so with such a light grab the darkening was not an issue.

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I've used various colour filters and dimming filters over time and have found some to be beneficial.

However the higher the magnification gets the more marginal any benefits become as the dimming of a filter becomes a hindrance.

Often a benefit I have found is that colour filters just bring  different features to my attention that I go back to looking at without a filter. Looking at a full moon through various colour filters is a good example of this.

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