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Planetary filters


Paul Manuell
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3 hours ago, Paul Manuell said:

Recommendations, please,  for best filters for bringing details out on Jupiter, whose brightness often overwhelms them.

First recommendation for planetary observation is not to get dark adapted.

As soon as you get dark adapted - changes happen to your vision and what is very faint starts to look very bright (think car headlights during night and during the day).

For filter performance and usability - check this:

https://www.firstlightoptics.com/flo-guides-colour-filters-to-improve-lunar-and-planetary-visual-observing.html

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Baader contrast booster can help on Mars. Televue used to make special Mars filters but you’d only find them 2nd hand now I think. Baader Neodymium is meant to help in general with contrast. I’ve been observing without filters so far this season but plan to give these filters a go again if the skies ever clear…

Mark

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Perhaps the best filtration, is to observe when there is thin haze enveloping the surface. Equally, becoming patient, comfortable and relaxed taking full advantage of steady seeing periods, that may often be sporadic and at fairly short interludes. Applying differing magnifications to ascertain which 'pops'; to gain the most satisfying and crisp image on a given evening.

Recently I started to use a filter again for planetary observing (having not done so for several years). Baader Neodymium, 2" version thus permanently attached to light path in focuser, for frequent switching between eyepieces. It provided pleasing impressions of Jupiter, accentuating subtle surface features a touch and some initial time spent on Mars; hopefully more so later next week with improved conditions. The contrast is slight which I quite like, retaining a still bright naturalist impression.

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10 hours ago, vlaiv said:

First recommendation for planetary observation is not to get dark adapted.

As soon as you get dark adapted - changes happen to your vision and what is very faint starts to look very bright (think car headlights during night and during the day).

For filter performance and usability - check this:

https://www.firstlightoptics.com/flo-guides-colour-filters-to-improve-lunar-and-planetary-visual-observing.html

Must be impossible to not get get dark adapted when observing at night, surely? 

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35 minutes ago, Paul Manuell said:

Must be impossible to not get get dark adapted when observing at night, surely? 

Observe next to a bright light - like under street lamp or on your balcony with the lights turned on.

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I’ve found the Baader Neodymium filter to be pretty handy for improving contrast. It works well on Jupiter and Mars at powers up to say x200, but I found at very high powers in my 8” (x300 or more on Mars), going without the filter was best. Jupiter is normally better at around x150 to x180 anyway.

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If you do try out some of the Wratten colour filters, go for the lighter ones, #8 light yellow, #82 light blue, #11 light green (yellow/green) and #21 orange are usable without dimming too much. They do have an effect though it is quite subtle. As others have said above, Neodymium and Contrast Booster from Baader work as well, the latter is the more aggressive. A lot depends on the size of the scope being used. Best thing to do is pick a few up secondhand and experiment, I used a filter wheel for quick comparisons when I was on the filter path. Nowadays the only filters that I use are the Baader Neodymium (for general contrast enhancement), Neutral Density 0.9 (for very bright objects), UHC-S and OIII (for deep-sky contrast enhancement) and Solar Continuum (for use with the Lunt solar wedge).

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On 04/12/2022 at 08:38, Stu said:

I’ve found the Baader Neodymium filter to be pretty handy for improving contrast. It works well on Jupiter and Mars at powers up to say x200, but I found at very high powers in my 8” (x300 or more on Mars), going without the filter was best. Jupiter is normally better at around x150 to x180 anyway.

Perfect, my telescope/eyepiece combo's maximum power is 153x :)

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On 04/12/2022 at 09:21, Franklin said:

If you do try out some of the Wratten colour filters, go for the lighter ones, #8 light yellow, #82 light blue, #11 light green (yellow/green) and #21 orange are usable without dimming too much. They do have an effect though it is quite subtle. As others have said above, Neodymium and Contrast Booster from Baader work as well, the latter is the more aggressive. A lot depends on the size of the scope being used. Best thing to do is pick a few up secondhand and experiment, I used a filter wheel for quick comparisons when I was on the filter path. Nowadays the only filters that I use are the Baader Neodymium (for general contrast enhancement), Neutral Density 0.9 (for very bright objects), UHC-S and OIII (for deep-sky contrast enhancement) and Solar Continuum (for use with the Lunt solar wedge).

For 'very bright objects', do you mean the Moon or the likes of Jupiter and Venus as well?

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30 minutes ago, Paul Manuell said:

do you mean the Moon or the likes of Jupiter and Venus as well

The Moon mainly but Venus, Mars and Jupiter can all be very bright, and a ND filter can subdue that brightness which can help in revealing more contrast. Also, as @vlaivmentions above, NOT getting dark adapted, as you would when viewing faint objects, can help. Some people also use a variable polarizing filter which, by turning, allows you to increase/decrease the amount of filtration.

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2 hours ago, Paul Manuell said:

That's really strange,  I've always assumed astronomy's best when done in as dark conditions as possible. 

Only if you want to observe very faint objects.

For planetary viewing you actually want to avoid getting dark adapted.

Dark adaptation reduces sharpness and color perception.

Have a look here for more detail:

 

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1 hour ago, vlaiv said:

Only if you want to observe very faint objects.

For planetary viewing you actually want to avoid getting dark adapted.

Dark adaptation reduces sharpness and color perception.

Have a look here for more detail:

 

Thank you, you learn something new every day :)

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Damn it, all your replies have convinced me I want one of those Baader Neodymium filters but it seems to be out of stock (which usually means discontinued) in most places except Amazon, which is charging an extortionate amount over the price that shops (which are out of stock) are  advertising it for

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15 minutes ago, Paul Manuell said:

Damn it, all your replies have convinced me I want one of those Baader Neodymium filters but it seems to be out of stock (which usually means discontinued) in most places except Amazon, which is charging an extortionate amount over the price that shops (which are out of stock) are  advertising it for

FLO lists it being in stock in two weeks:

https://www.firstlightoptics.com/baader-filters/baader-neodymium-filter.html

 

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29 minutes ago, Paul Manuell said:

Celestron Astromaster 90AZ

Your scope is an achromat so rather than a straight Neodymium filter it may be better to use a Baader Semi-Apo filter. It's essentially the same Neodymium filter but with an added minus violet element. This will control the chromatic aberration which is inherent in achromats like your Astromaster. The Semi-Apo filter will sharpen up the view through your scope on all objects, I have used this filter in achromatic scopes in the past and it definitely cleans up the view and makes focusing easier.

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Thinking again about this Paul, a much cheaper option for you would be to get a simple Wratten #8 light yellow filter, this will sharpen up the views in your scope, reduce chromatic aberration and increase contrast, and at a fraction of the cost of a Baader. You can get a #8 for a tenner.

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I've found that Baader Contrast Booster works best for achromats.

It is "cross" between Neodymium and Semi APO, and reduces CA nicely while boosting contrast.

https://www.firstlightoptics.com/baader-filters/baader-contrast-booster-filter.html

Here is interesting read for those Baader filters:

https://www.firstlightoptics.com/reviews/baader-contrast-filters_US-ATT_review_0414.pdf

I second use of Wratten #8 to reduce chromatic aberration - however, it does impart distinct yellow cast on the image.

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  • 2 weeks later...

If you search for moon and sky glow filter on ebay you can find some cheap generic filters “equivalent” to Baader Neodymium if you can’t find one of them. Maybe worth a try for a few quid. There’s not much difference apparently https://www.cloudynights.com/topic/533147-spectroscopic-analysis-comparison-of-planetary-filters/

Mark

Edited by markse68
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