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Best filter to bring out white ovals?

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#1 jeffmac

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Posted 29 June 2021 - 10:33 AM

For visual, what is the best filter(s) for bringing out Jupiter's white ovals? I know more aperture will reveal more but most of my planetary observing is done with a 4" apo.



#2 MisterDan

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Posted 29 June 2021 - 01:06 PM

Useful info here:

http://alpo-astronom...es/FILTERS1.HTM

 

Magenta (Wratten 30) is recommended for "brightening" white ovals.  However, the "background" hue(s) (the belt or zone a particular white oval is "riding") is key.  Is the brown tone reddish? yellowish? greyish?. There's no reason to refrain from trying other filters (i.e. yellow (12 or 15), green (56, 57, or even 58), and deep blue (47)).  If the oval is situated within a brown/brownish belt or zone, work with that brown background... try to darken it.

 

When I used filters for Jupiter, years ago, I found my greens (56 & 58) improved overall belt contrast (but not necessarily white ovals, themselves).  I also felt they improved seeing, even in my little 75mm refractor.  Red and/or orange filters are touted as better "seeing filters" than green, but I felt that green did better (for me) than did my 21 orange (I did not have a red filter).

 

As with many factors and variables in human vision, there are likely no "absolutes," and - as they say - "your own mileage may vary").

 

Best wishes and luck.

Dan


Edited by MisterDan, 29 June 2021 - 01:08 PM.

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#3 Special Ed

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Posted 29 June 2021 - 01:50 PM

jeffmac,

 

Good advice from MisterDan.  Just experiment with different filters and see what is working.  A W30 (magenta) is a good filter to have in your collection.

 

If you are talking about the small ovals in the south temperate regions, you need good seeing, too.  I just observed Oval BA (the mothership of ovals) the other night and I found that my W11 (yellow-green) worked best for improving the contrast enough to see this low contrast feature.  The seeing was very good.  My sketch and details are here:

 

https://www.cloudyni...021/?p=11196366


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#4 JHub

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Posted 30 June 2021 - 10:21 PM

I've been using a #11 yellow-green as my main Jupiter filter since the 90s. After trying others, I found that one best (for me) to bring out the belt features. Like MisterDan, I've also felt it tended to improve the effects of seeing. I suspect it has to do with limiting the spread of visual spectrum (color blurring) as the light passes through different densities of air in the atmosphere. Other green filters would have similar effects. As to white ovals, I've seen plenty but I can't swear it's really because of the filter.

 

Try different ones and see what works best for you.

 

John


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#5 Matt Looby

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Posted 01 July 2021 - 10:26 AM

None are good.

 

It's a gimmick.



#6 Redbetter

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Posted 03 July 2021 - 02:03 AM

For visual, what is the best filter(s) for bringing out Jupiter's white ovals? I know more aperture will reveal more but most of my planetary observing is done with a 4" apo.

 

I have not done much testing of filters for the white ovals.  I have used a #25 red filter for the pale Oval BA--but this was in order to darken the brow of belt that partially surrounds it while keeping the spot bright.  This has worked at times.  I caught Jupiter last night in the 20", still low in the sky, but with conditions just sufficient to detect two (possibly three) white ovals in the better moments at 278 and 357x.  Seeing has been poor this year so I have been waiting for the distance to Jupiter to close somewhat.  The white ovals are of only modest contrast with the belts they are embedded in. 

 

I remembered this question, so I made a few passes at the ovals last night with a few filters as quick checks:  Red #25, Blue 80A, Yellow/orange #15, Deep Blue #38A, and a Farpoint UHF (narrowband around the H-beta and OIII lines.)  None really helped.  The W30 Magenta filter mentioned up thread might work for this, since it works to keep both ends while cutting out the middle of the visual.  However, I suspect that is more problematic when Jupiter is still in the 20 plus degree elevation range, because atmospheric chromatic dispersion will have an even larger impact when when both ends are present and the middle is missing.  I don't have Magenta filter since compared to color filters they are spendy for a filter that requires an adapter just to use.

 

When I have observed the white ovals with my 110ED and 127Mak it has been when Jupiter was closer and the seeing was good.  I begin to see the largest ones at around 190 to 220x which is where these scopes top out with respect to planetary detail for my eye.  Even then the oval are marginal, but readily confirmed with a larger scope (8, 10 or 20".)  If you have a good 4" apo, it probably somewhat outperforms the 110ED which has some noticeable visual color.  


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#7 nibiru711

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Posted 03 July 2021 - 02:25 PM

It might depend on the conditions on which filter to use but the lighter one's are going to do better with smaller scopes. I have been using mostly yellow and light blue to view Jupiter and Saturn but last night using an 8 inch reflector a green filter worked best on Jupiter for helping with the glare. I seen up to four festoons and I think the red spot plus more in the middle than my maksutov but one thing maksutov 127mm is better at is showing the polar regions of Jupiter at the same time without a filter. it was an up and and down night with Jupiter as it would show at times details across the width of a 7mm wide field eyepiece better at some places than others.



#8 RLK1

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Posted 04 July 2021 - 11:49 AM

I tried my baader contrast booster on Jupiter and Saturn last night (7-3), and although it's my preferred filter for Mars, I wouldn't recommend it for either of the aforementioned planets. With my 16", even in light polluted skies, I tend to view the planets sparingly as they do a number on my night vision since I'm more of a DSO observer. I happened to catch a moon *just* coming off the limb of Jupiter's equatorial region last night at round 12:35. I always like those chance encounters when observing Jupiter with it moons. If there's any consensus on optimum filters for viewing Jupiter, I haven't seen it yet...




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