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Equipment Discussions >> Eyepieces

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Cames
sage


Reged: 08/04/08

Filters for Jupiter
      #5555328 - 12/05/12 09:14 AM

I noticed two new(?) Zhumell filters in the Hayneedle catalog.
They are the Zhumell 1.25 inch High Performance Urban Sky Filter and the Zhumell 1.25 Inch High Performance Filter

Have you had experience with either of these?

I'm looking for a filter of good optical quality that will enhance views of Jupiter which appears very bright in this apparition and I suspect that its glare may be obscuring some details.

I haven't been able to find specifics on these filters so your input and impressions after actually using one would be appreciated.

-----
Cames


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Sarkikos
Postmaster
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Reged: 12/18/07

Loc: Suburban Maryland, USA
Re: Filters for Jupiter new [Re: Cames]
      #5555428 - 12/05/12 10:29 AM

Cames,

I advise a Baader Moon & Sky Glow to increase perceived contrast.

Also, if Jupiter seems too bright, blame your eyes, don't blame the planet. When viewing bright planets, your eyes should be as close as possible to photopic (daylight) adaptation, the level at which they would have optimal visual acuity. Try looking at the reflection on a white piece of paper from a bright white flashlight every so often during the observing session. This will bring your eyes closer to photopic. If a planet appears too bright in the eyepiece, your eyes are stuck at the partially dark-adapted mesopic level.

Mike


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BSJ
Pooh-Bah
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Reged: 12/22/08

Loc: Grand Isle, VT
Re: Filters for Jupiter new [Re: Sarkikos]
      #5555465 - 12/05/12 10:52 AM

I find a Moon & Sky Glow stacked with a Finge Killer is the best for Jupiter, or any bright Solar System object.

I just got a Semi-Apo filter, but it's been too cloudy...

The Semi-Apo combines the M&SG and the FK into the same filter.


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Sarkikos
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Reged: 12/18/07

Loc: Suburban Maryland, USA
Re: Filters for Jupiter new [Re: BSJ]
      #5555475 - 12/05/12 10:58 AM

I've also tried the M&SG stacked with FK, and the Semi-Apo by itself. But usually I just put on the M&SG.

Mike


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mich_al
Carpal Tunnel
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Reged: 05/10/09

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Re: Filters for Jupiter new [Re: Sarkikos]
      #5555487 - 12/05/12 11:06 AM

I'm getting very good results using an 80A light blue filter.

Al


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demiles
professor emeritus
*****

Reged: 11/07/06

Re: Filters for Jupiter new [Re: mich_al]
      #5555575 - 12/05/12 12:21 PM

I use the M&SG filter as well but just recently started using a 25% ND filter with excellent results.

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jaddbd
professor emeritus


Reged: 05/18/05

Loc: Woodbine, MD
Re: Filters for Jupiter new [Re: mich_al]
      #5555596 - 12/05/12 12:33 PM

+1 on the 80A. It's a subtle, and does seem to enhance the contrast a bit.

JD


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SPO
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Reged: 12/03/10

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Re: Filters for Jupiter new [Re: jaddbd]
      #5555641 - 12/05/12 12:57 PM

The urban sky filter looks to be the same one I have from zhumell. I think they changed the name a few times.

It's similar to the Baader M&SG. I've had both and couldn't tell a difference in use and returned the Baader M&SG. Your results in your scope may differ. I think the Baader uses a different type of glass and when looking at it under light you can see a difference. I just couldn't see any improvement when using it over the zhumell.

The other filter looks like it might be a neutral density filter.


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Scanning4Comets
Markus
*****

Reged: 12/26/04

Re: Filters for Jupiter new [Re: SPO]
      #5555697 - 12/05/12 01:37 PM

I used to use the 80A and yellow / green with good results, but for all my planetary viewing, except for Saturn, I use a polarizing filter with excellent results. I just put one half in my 2" extension tube and the other half on the bottom of my Antares twist lock adapter and I turn the eyepiece to set the brightness.

Cheers,


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Sarkikos
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Reged: 12/18/07

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Re: Filters for Jupiter new [Re: Scanning4Comets]
      #5555726 - 12/05/12 01:54 PM

I only use filters to enhance contrast or emphasize specific features over others. To tone down the brightness, nothing works better than the "bright white light trick." The eyes are the problem, not the planet.

Mike


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JIMZ7
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Reged: 10/22/05

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Re: Filters for Jupiter new [Re: Sarkikos]
      #5555738 - 12/05/12 02:06 PM

Once with a Celestron 8" Star-Hopper, I looked at Jupiter with polarized sun glasses. At that time it was the only thing I had for glare-it worked!

Jim


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moynihan
Carpal Tunnel


Reged: 07/22/03

Loc: Lake Michigan Watershed
Re: Filters for Jupiter new [Re: Cames]
      #5555741 - 12/05/12 02:10 PM

A useful ALPO page on the subject.

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REC
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Reged: 10/20/10

Loc: NC
Re: Filters for Jupiter new [Re: Sarkikos]
      #5555744 - 12/05/12 02:10 PM

That's an interesting tip. I notice when I first go out my patio door from a lighted room to view Jupiter, at first it looks pretty good with dark sky around the moons and detail on the planet. After a little bit longer at the EP, the glow around Jupiter starts to increase and I loose surface detail. So I guess my photopic vision is then turning into night vision, that's why the glare then?

I will have to try the white paper trick:)

Bob


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Jaimo!
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Reged: 10/11/07

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Re: Filters for Jupiter new [Re: mich_al]
      #5555765 - 12/05/12 02:20 PM

Mike,
If you look into a flash light to stop down your pupil diameter, couldn't you accomplish the same thing with a smaller scope? I find my 12" dob a little much for Jupiter, but great for deep sky, and typically get my best views at 6-8"...

Jaimo!


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Starman1
Vendor (EyepiecesEtc.com)
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Reged: 06/24/03

Loc: Los Angeles
Re: Filters for Jupiter new [Re: Jaimo!]
      #5555842 - 12/05/12 03:20 PM

Quote:

Mike,
If you look into a flash light to stop down your pupil diameter, couldn't you accomplish the same thing with a smaller scope? I find my 12" dob a little much for Jupiter, but great for deep sky, and typically get my best views at 6-8"...

Jaimo!



But the smaller scope will lose resolution.
If dimming the image in a larger scope enables you to see more details (and sometimes it does), try a light #50 neutral density filter or a #82A light Blue. The ND won't change the color.

However, I've found coloration in bands and details to be greater in greater aperture. My best view of Jupiter in color was in a 28" scope with no filter.

And remember, double the power and the image is 1/4 as bright per unit area. My best views of Jupiter have all been over 300X.


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Sarkikos
Postmaster
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Reged: 12/18/07

Loc: Suburban Maryland, USA
Re: Filters for Jupiter new [Re: Jaimo!]
      #5555857 - 12/05/12 03:26 PM

Jaimo!

Quote:

Mike,
If you look into a flash light to stop down your pupil diameter, couldn't you accomplish the same thing with a smaller scope? I find my 12" dob a little much for Jupiter, but great for deep sky, and typically get my best views at 6-8"...




No, don't look directly into the light. That will give you an after-image. Not too good. You need to shine the bright white-light from the flashlight onto a piece of white paper, and look at the white paper. That should be enough to bring your eyes up toward the photopic level of adaptation.

And there is more to this effect than stopping down the iris of your eye. I'm sure that is part of it, but there are also changes going on in the retina.

I would not advise going to a smaller aperture scope just so Jupiter won't seem so bright! It's not about the scope or the brightness of Jupiter. What is important here is adjusting your eyes to the optimum adaptation for viewing planets.

I think a 12" Dob would be great for Jupiter. In fact I know it would be, since I've viewed planets in 12" and larger Dobs. The real problem with larger mirrors is thermal adjustment, not that the aperture is too big. My best scope for planets is a 10" Dob, better than my 8" Dob or my 6" Rumak. I have no problem with Jupiter being "too bright." It's all a matter of doing it right and making sure your eyes are prepared for planet observation, not for deep sky.

Mike


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Dick Jacobson
scholastic sledgehammer


Reged: 12/22/06

Loc: Plymouth, Minnesota, USA
Re: Filters for Jupiter new [Re: Sarkikos]
      #5555931 - 12/05/12 04:20 PM

A binoviewer is very helpful, if you're lucky enough to have one. Not only cuts glare, but makes it easier to see faint contrast and suppresses "floaters".

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Sarkikos
Postmaster
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Reged: 12/18/07

Loc: Suburban Maryland, USA
Re: Filters for Jupiter new [Re: Dick Jacobson]
      #5555942 - 12/05/12 04:25 PM

Yes, a binoviewer is excellent for Jupiter.

Mike


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and75
member


Reged: 08/31/10

Loc: Hungary
Re: Filters for Jupiter new [Re: mich_al]
      #5555945 - 12/05/12 04:27 PM

I came in just right now, it was a 1 hour observing window, and after that Jupiter disappeared behind the clouds. I tested my new Soligor HP eyepieces (almost the same as the Vixen LV series I think) with a Baader M&SG and a light blue filter (Made in Germany, but not for astronomical use, I think it was an accessory of a camera)
The main impression on the M&SG is that it's good, noticed some improvement... but not a big deal. The blue color filter did just the same performance (for free) I can't screw the blue filter into the eyepiece, perhaps I will invest into a real astro-filter, a Baader light blue.

I have never heard about that white paper trick, it sounds good, I'll try it asap.


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Sarkikos
Postmaster
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Reged: 12/18/07

Loc: Suburban Maryland, USA
Re: Filters for Jupiter new [Re: Sarkikos]
      #5555948 - 12/05/12 04:28 PM

I hate to belabor the point, but all this talk about Jupiter being too bright, too much glare, need to dim the image, are off the mark. Unless you're observing with a really big scope - maybe a 26" or bigger? - the problem isn't that Jupiter is too bright. The problem is that your eyes aren't properly prepared to observe Jupiter.

Mike


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Sarkikos
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Reged: 12/18/07

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Re: Filters for Jupiter new [Re: and75]
      #5555958 - 12/05/12 04:37 PM

Quote:

The main impression on the M&SG is that it's good, noticed some improvement... but not a big deal. The blue color filter did just the same performance (for free) I can't screw the blue filter into the eyepiece, perhaps I will invest into a real astro-filter, a Baader light blue.




Yep, no filter will perform miracles for planets or even show you anything that you couldn't see without it. But a good filter will make it easier for you to see what's there.

Quote:

I have never heard about that white paper trick, it sounds good, I'll try it asap.




It's nothing new. Planet observers have been keeping white light around themselves for a long time. But it does seem that it's a trick that's been forgotten or ignored. Otherwise you wouldn't hear all the complaints in these threads about how bright Jupiter is!

My preference, though, is to only expose my eyes to the white light - I mean a reflection of the light - every ten minutes or so, instead of having a constant light on near where I observe. It's too easy for a bright light that's constantly on to introduce glare - real glare - into the optics or your eyes while you're observing.


Mike


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Cames
sage


Reged: 08/04/08

Re: Filters for Jupiter new [Re: Dick Jacobson]
      #5555981 - 12/05/12 04:50 PM

Wow! Thank you all for the great hints. And, now that you mention it, I alternate eyes when one eye fatigues after prolonged gazing and I've noticed that Jupiter appears very washed out in the new eye at first but then gradually develops more contrast and detail. One reason why I was pursuing the filter route is that passing haze or thin clouds seemed to bring out detail that went unnoticed under more transparent conditions.

We're going to be socked in with clouds for the next few days. I'm going to implement your suggestions on the next clear night.


Again, many thanks

------
Cames


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StarStuff1
Post Laureate
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Reged: 04/01/07

Loc: South of the Mason-Dixon Line
Re: Filters for Jupiter new [Re: Cames]
      #5556002 - 12/05/12 05:00 PM

For grins try an OIII filter. You will get a psychedalic planet but there will be details that were not there before.

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GeneT
Ely Kid
*****

Reged: 11/07/08

Loc: South Texas
Re: Filters for Jupiter new [Re: Cames]
      #5556036 - 12/05/12 05:22 PM

Most who post on this issue will disagree with me. However, after years of using a variety of planetary filters, I finally decided I could see as much detail without any. I made a club member very happy when I gave my planetary filters to him--for free.

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Scanning4Comets
Markus
*****

Reged: 12/26/04

Re: Filters for Jupiter new [Re: GeneT]
      #5556085 - 12/05/12 05:58 PM

Quote:

I hate to belabor the point, but all this talk about Jupiter being too bright, too much glare, need to dim the image, are off the mark. Unless you're observing with a really big scope - maybe a 26" or bigger? - the problem isn't that Jupiter is too bright. The problem is that your eyes aren't properly prepared to observe Jupiter.

Mike




Well, the problem is not that Jupiter, (or Mars for that matter), is 'too bright", the problem many planetary observers, including myself, come across is NEEDING THE RIGHT CONTRAST.

Irradiation on bright areas and dark areas bleed over into each other, especially on Jupiter, and even more so for Mars. Dimming these planets to desirable levels makes observation of bright / dark areas a lot easier. This also makes it a lot easier and better to observe small detail when the atmosphere and telescope allows it. Color filters also help bring out detail as they reject / cancel certain wavelengths of light, making colors stand out more.

Cheers,


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Sarkikos
Postmaster
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Reged: 12/18/07

Loc: Suburban Maryland, USA
Re: Filters for Jupiter new [Re: Scanning4Comets]
      #5556192 - 12/05/12 06:53 PM

Yes, I agree that lack of contrast is a problem. There are a number ways to enhance perceived contrast for planets. Filters can help. So can an apodizing mask for Newts. Binoviewers are of benefit. Very close collimation is very important, and is often overlooked by observers. Thermal stabilization of the optics is necessary for a sharp image. We should also mention decent eyepieces.

But all these methods deal with the optical equipment. What about the observer's eyes?

If the observer says Jupiter is "too bright," that doesn't indicate the contrast in the image is too low but that the image appears too bright to their eyes. I'll take them at their word. IME, the best solution is not to dim the image but to improve the adaptation of the eyes.

Mike


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Scanning4Comets
Markus
*****

Reged: 12/26/04

Re: Filters for Jupiter new [Re: Sarkikos]
      #5556289 - 12/05/12 07:48 PM

The title of this thread is "filters". The rest is obvious, (collimation, etc, etc, etc). Contrast is the key to all observing being it planetary or deep sky.

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Sarkikos
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Reged: 12/18/07

Loc: Suburban Maryland, USA
Re: Filters for Jupiter new [Re: Scanning4Comets]
      #5556324 - 12/05/12 08:03 PM

The OP did mention that "Jupiter appears very bright." That raises a red flag for me. I am compelled to address it. The assumption was made that the cure for Jupiter's brightness is to use filters, but that isn't necessarily the only or the best solution.

Mike


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JIMZ7
Pooh-Bah
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Reged: 10/22/05

Loc: S.E.Michigan near DTW
Re: Filters for Jupiter new [Re: Sarkikos]
      #5556958 - 12/06/12 06:54 AM

My past experiences with different scopes from 80mm to 203mm-the filters I liked the most were #80A-blue**#11-green/yellow**& #ND of different percentages. On a Discovery 12.5" f/5 Dob. with no filters Jupiter's belts were nicely viewed at 511x.

Jim


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Jaimo!
Pooh-Bah
*****

Reged: 10/11/07

Loc: Exit 135 / 40° North
Re: Filters for Jupiter new [Re: Jaimo!]
      #5557125 - 12/06/12 09:24 AM

Quote:

Mike,
If you look into a flash light to stop down your pupil diameter, couldn't you accomplish the same thing with a smaller scope? I find my 12" dob a little much for Jupiter, but great for deep sky, and typically get my best views at 6-8"...

Jaimo!




Maybe I should be pushing the magnification... I am typically hovering around 200-250x, with the increased magnification I should also have a reduction in light throughput. I'm still a Dob novice...

Thanks,
Jaimo!


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Sarkikos
Postmaster
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Reged: 12/18/07

Loc: Suburban Maryland, USA
Re: Filters for Jupiter new [Re: Jaimo!]
      #5557159 - 12/06/12 09:47 AM

Jaimo!

In the experience of many observers - myself included - Jupiter doesn't take higher magnification as well as Mars or Saturn. When viewing Jupiter with my 10" f/4.8 Dob, I usually keep it at 250x or below. That's 25x per inch and 1mm exit pupil. If the eyes are kept near photopic - especially if other methods of enhancing contrast are used - very fine surface detail can be seen at this image scale. Don't let anyone tell you it can't be done, because I know for a fact that it can. (I think some folks just like to push the power.) For your 12" f/4.9, a comparable power would be 300x. Try for that if the seeing will allow.

But whatever you do, don't look directly into the flashlight! I have never said to do that. Just look at a reflection of the white light on a white piece of paper.

Mike


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dpwoos
Pooh-Bah
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Reged: 10/18/06

Loc: United States
Re: Filters for Jupiter new [Re: Sarkikos]
      #5557967 - 12/06/12 05:44 PM

Quote:

In the experience of many observers - myself included - Jupiter doesn't take higher magnification as well as Mars or Saturn.




I have no idea what it means for something to not "take" higher magnification. Sounds like an equipment problem to me. Care to elaborate?


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Peter Natscher
professor emeritus


Reged: 03/28/06

Loc: Central Coast California
Re: Filters for Jupiter new [Re: Starman1]
      #5558358 - 12/06/12 09:57 PM

Ditto on that technique! Jupiter through my 24" dob is too bright with one eyepiece, no filter and under 300X. Neutral density filters and especially binoviewing cut down enough light and glare to see the surface details. I usually stack 2" M&SG and 50% ND filters together front-side on the Mark V bino and use 350X-450X on good seeing nights to get the view I like.

Quote:

Quote:

Mike,
If you look into a flash light to stop down your pupil diameter, couldn't you accomplish the same thing with a smaller scope? I find my 12" dob a little much for Jupiter, but great for deep sky, and typically get my best views at 6-8"...

Jaimo!



But the smaller scope will lose resolution.
If dimming the image in a larger scope enables you to see more details (and sometimes it does), try a light #50 neutral density filter or a #82A light Blue. The ND won't change the color.

However, I've found coloration in bands and details to be greater in greater aperture. My best view of Jupiter in color was in a 28" scope with no filter.

And remember, double the power and the image is 1/4 as bright per unit area. My best views of Jupiter have all been over 300X.




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DeSoto Kid
super member


Reged: 08/24/07

Loc: DeSoto, Texas
Re: Filters for Jupiter new [Re: Peter Natscher]
      #5558714 - 12/07/12 06:40 AM

What about using a Kendrick focusing aid cover available for SCT,s etc.? The one for the C9.25 has 3 - 3" holes around the periphery of the scope entrance. Being close to the outer edge should not reduce resolution so much and being positioned on the outer half of the scope might reduce spherical abberation if present. The single equivilet in area of these 3 spheres would be a 5" sphere ... and all this with NO central obstruction. This would reduce quite a bit of the light coming in.

Bob (REC) mentioned that brightness of Jupiter was not so severe when he first beging observing. It my be a good idea to eliminate this phenomenon before it happens ...???

Wayne


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Sarkikos
Postmaster
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Reged: 12/18/07

Loc: Suburban Maryland, USA
Re: Filters for Jupiter new [Re: dpwoos]
      #5558739 - 12/07/12 07:11 AM

dpwoos,

Quote:

Quote:

In the experience of many observers - myself included - Jupiter doesn't take higher magnification as well as Mars or Saturn.




I have no idea what it means for something to not "take" higher magnification. Sounds like an equipment problem to me. Care to elaborate?




No, it is not an equipment problem.

Of course, any object can "take" any magnification you care to throw at it, in the sense that you can setup the equipment to have that magnification. But will the image show you any more surface detail than at a more moderate magnification? Some objects will, some won't. Jupiter is one of those that don't "take" high magnification well, as compared to Saturn or Mars or double stars, for instance. This is nothing new.

A largely ignored factor in the equation of how much magnification is needed to see a high level of fine detail is how well the observer's eyes have been prepared for observing planets. IME & IMO, many observers don't have a clue how to do this, or even that it will make a difference. If the eyes are properly prepared, the observer shouldn't have to push the magnification - with some exceptions, such as close double stars, subtle detail in Saturn's rings and Mars at a small apparent diameter. (I've pushed a 6 arcsec Mars up to 600x in my 10" Dob with good results.)

I'm not usually a big fan of huge image scale for its own sake, particulary since my best planet scopes don't track. What I'm after is finer detail. I can see that without crazy-high power when observing Jupiter.

Mike


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Sarkikos
Postmaster
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Reged: 12/18/07

Loc: Suburban Maryland, USA
Re: Filters for Jupiter new [Re: Peter Natscher]
      #5558768 - 12/07/12 07:48 AM

Peter,

Quote:

Ditto on that technique! Jupiter through my 24" dob is too bright with one eyepiece, no filter and under 300X. Neutral density filters and especially binoviewing cut down enough light and glare to see the surface details. I usually stack 2" M&SG and 50% ND filters together front-side on the Mark V bino and use 350X-450X on good seeing nights to get the view I like.

Quote:

Quote:

Mike,
If you look into a flash light to stop down your pupil diameter, couldn't you accomplish the same thing with a smaller scope? I find my 12" dob a little much for Jupiter, but great for deep sky, and typically get my best views at 6-8"...

Jaimo!



But the smaller scope will lose resolution.
If dimming the image in a larger scope enables you to see more details (and sometimes it does), try a light #50 neutral density filter or a #82A light Blue. The ND won't change the color.

However, I've found coloration in bands and details to be greater in greater aperture. My best view of Jupiter in color was in a 28" scope with no filter.

And remember, double the power and the image is 1/4 as bright per unit area. My best views of Jupiter have all been over 300X.







Please folks, stop copying Jaimo!'s incorrect description of the "Bright White Light" technique. It will do no one any good to look directly into a bright flashlight! Instead, look at the reflection of that light onto a white piece of paper!

Peter: I agree on binoviewing and the use of M&SG filters. Yep, at around 24" or so you might be hitting the threshold at which you actually do need to think about dimming Jupiter's image a bit.


Mike


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Sarkikos
Postmaster
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Reged: 12/18/07

Loc: Suburban Maryland, USA
Re: Filters for Jupiter new [Re: DeSoto Kid]
      #5558783 - 12/07/12 08:03 AM

Wayne,

Quote:

What about using a Kendrick focusing aid cover available for SCT,s etc.? The one for the C9.25 has 3 - 3" holes around the periphery of the scope entrance. Being close to the outer edge should not reduce resolution so much and being positioned on the outer half of the scope might reduce spherical abberation if present. The single equivilet in area of these 3 spheres would be a 5" sphere ... and all this with NO central obstruction. This would reduce quite a bit of the light coming in.

Bob (REC) mentioned that brightness of Jupiter was not so severe when he first beging observing. It my be a good idea to eliminate this phenomenon before it happens ...???




The brightness of Jupiter should not be a problem in a 9.25" aperture. If Jupiter appears too bright, your eyes are not prepared optimally for observing Jupiter. It is not a good idea to reduce the aperture in order to reduce the brightness of a planet. You will be decreasing the resolution while trying to solve a problem that doesn't really exist.

Placing a ring around the aperture might cover up optical errors. But reducing aperture because a planet appears "too bright" is not a good solution to the problem of "brightness" - which actually is not a problem at all in moderate-sized scopes.

Mike


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dpwoos
Pooh-Bah
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Reged: 10/18/06

Loc: United States
Re: Filters for Jupiter new [Re: Sarkikos]
      #5558790 - 12/07/12 08:09 AM

Quote:

dpwoos,

Quote:

Quote:

In the experience of many observers - myself included - Jupiter doesn't take higher magnification as well as Mars or Saturn.




I have no idea what it means for something to not "take" higher magnification. Sounds like an equipment problem to me. Care to elaborate?




No, it is not an equipment problem.

Of course, any object can "take" any magnification you care to throw at it, in the sense that you can setup the equipment to have that magnification. But will the image show you any more surface detail than at a more moderate magnification? Some objects will, some won't. Jupiter is one of those that don't "take" high magnification well, as compared to Saturn or Mars or double stars, for instance. This is nothing new.




You again state your claim that Jupiter (unlike Saturn, Mars, etc.) doesn't "take" high magnification, but still don't explain why you think that. I often view Jupiter (and other high mag targets) at 250x in my 10" because that seems to be what the seeing on good nights most often allows. However, I have also observed Jupiter in the same scope at 400x, and I am quite certain that I was able to see fine detail that was not visible at the lower mag, and as one would expect. Honestly, I have no idea how one can possibly maintain that there is some minimum exit pupil size (I take it around 1mm?) that shows all there is to see on this target specifically, especially given the seemingly infinite amount of detail visible?


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Re: Filters for Jupiter new [Re: dpwoos]
      #5558831 - 12/07/12 08:34 AM

dpwoos,

Quote:

You again state your claim that Jupiter (unlike Saturn, Mars, etc.) doesn't "take" high magnification, but still don't explain why you think that.




It's not a claim. It's an honest report of personal experience. An explanation of why it happens is another matter. Low contrast detail on Jupiter as opposed to high contrast detail on Saturn's rings? Larger image scale of Jupiter as opposed to the usually smaller image scale of Mars? I think those are good explanations.

Quote:

I often view Jupiter (and other high mag targets) at 250x in my 10" because that seems to be what the seeing on good nights most often allows. However, I have also observed Jupiter in the same scope at 400x, and I am quite certain that I was able to see fine detail that was not visible at the lower mag, and as one would expect. Honestly, I have no idea how one can possibly maintain that there is some minimum exit pupil size (I take it around 1mm?) that shows all there is to see on this target specifically, especially given the seemingly infinite amount of detail visible?




Well, good for you. Or maybe not so good, if you actually need higher magnification to see what I'm seeing at more moderate power. My scopes don't track, so I try to avoid higher power if I can. I don't need a substantially larger image scale for Jupiter in order to see fine surface detail. I know through experience how to avoid that. To each their own.

Mike


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Re: Filters for Jupiter new [Re: Sarkikos]
      #5558926 - 12/07/12 09:51 AM

i agree with Mike here

Jupiter is the planet for which higher magnification is generally not as useful as for other planets. the most useful mag is around 160-180. while i use much higher mags with Saturn and mars, when i use high mags pn Jupiter, i do not see more detail but i loose some.


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Re: Filters for Jupiter new [Re: coutleef]
      #5558959 - 12/07/12 10:09 AM

Saturn is an odd ball planet. It has very high contrast features - the rings - and very low contrast - the globe. So while higher power can help bring out subtle detail in the rings when the seeing is good, it won't help as much with surface features. But in general I try to push the power for Saturn.

Mike


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Re: Filters for Jupiter new [Re: Sarkikos]
      #5559058 - 12/07/12 10:59 AM

A little math.

Jupiter at its largest is 50" across. If you want to see a detail 1/50 the diameter of the disc, and you want to bring it up to the 8' apparent visual threshold, that requires a magnification of 480/1 = 480X
Saturn's disc maxes out about 20". To see a detail 1/50 the size of the disc, brought up to the same 8' apparent threshold would require a magnification of 480/.4 = 1200X.
Looking at the comparison, Saturn requires a magnification 2.5X as great to see details the same apparent size as you see on Jupiter.

Hence, if you see enough detail on Jupiter at 150X, you will need 375X to see details on Saturn at the same scale.

It's purely size as to why Saturn requires and takes higher magnifications than Jupiter, to see details that is.

That's without getting into relative contrast and albedo and coloration contrast, etc., all of which influence magnifications used.


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Re: Filters for Jupiter new [Re: Starman1]
      #5559139 - 12/07/12 11:46 AM

great answer Don! it explains a lot

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Re: Filters for Jupiter new [Re: Starman1]
      #5559150 - 12/07/12 11:50 AM

Don,

I always enjoy reading your posts and quite often learn something.

Can you explain why you chose 8' as the minimum size? If Jupiter is 50" at it's largest wouldn't that require a magnification of 576?

50"/60" = 0.833 of a degree
then
8' = 480"
so 480/0.833 = 576

My logic is probably wrong but thought I would ask even at the risk of looking stupid.


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Re: Filters for Jupiter new [Re: Dave Ittner]
      #5559165 - 12/07/12 11:56 AM

I know my logic is wrong but still am having a hard time wrapping my brain around this.

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Re: Filters for Jupiter new [Re: Dave Ittner]
      #5559219 - 12/07/12 12:26 PM

Many thanks Don!

Sorry Mike, You are the only source of "using a reflection a flashlight off of a piece of paper to reduce your pupil size" as an observing technique I have ever heard. I'm just not convinced that it is the best method, constantly re-adjusting you pupil size throughout an evening. I would think that being dark adapted and using a filter would yield more consistent results. That being said, I will try it out for myself...

Jaimo!


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Re: Filters for Jupiter new [Re: Dave Ittner]
      #5559246 - 12/07/12 12:46 PM

Quote:

Don,

I always enjoy reading your posts and quite often learn something.

Can you explain why you chose 8' as the minimum size? If Jupiter is 50" at it's largest wouldn't that require a magnification of 576?

50"/60" = 0.833 of a degree
then
8' = 480"
so 480/0.833 = 576

My logic is probably wrong but thought I would ask even at the risk of looking stupid.



Books I read when I was young said that the eye could easily differentiate one dot from another, with good vision, at a separation of 6' apparent. But 8' was a lot easier.
8' = 8x60" = 480"
A detail on the disc of Jupiter 1/50 of the disc in width would have a width of 1". To make 1" appear like 480" requires a magnification of 480X.
I don't know why you used degrees. I was talking minutes.

However, those of us with relatively acute vision can see distinct points with separations of 4'. Hence, 240X would suffice to see a feature 1/50 the width of Jupiter's disc.

Complicating the issue is that some features we look at are <1/50 the width of the disc, and if distinctly different colors, separations can be less than the apparent 4' and still appear separate. Small kids sometimes have vision that can separate details of 1' apparent separation, and a lot of adults (myself included) can see as distinct points features separated by 3' apparent. And if the points differ in brightness significantly, all bets are off as to what magnification will be required.

I was able to see dark blue-green festoons hanging out over the edge of an equatorial band that appeared quite ocher in color. The festoons were <1/50 the diameter of Jupiter in size. The detail was amazing at 228X. However, I could see the shadows of those festoons on the sides of the cloud bank below them at 456X, and I could not see those shadows at 228X. Sometimes, magnification is necessary.
I should note that on that night the seeing actually exceeded the resolution of my 12.5" at times, so the instrument was aperture limited. That is exceedingly rare, and the images from that night are burned into my brain. M15 was resolved all the way to the center at 228X and small triangles of faint stars covered the very center--a detail I'd never seen before and haven't since.


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Re: Filters for Jupiter new [Re: Jaimo!]
      #5559332 - 12/07/12 01:47 PM

Jaimo!,

Quote:

Sorry Mike, You are the only source of "using a reflection a flashlight off of a piece of paper to reduce your pupil size" as an observing technique I have ever heard. I'm just not convinced that it is the best method, constantly re-adjusting you pupil size throughout an evening. I would think that being dark adapted and using a filter would yield more consistent results. That being said, I will try it out for myself...




Again, please don't misinterpret this technique. It's not just about adjusting pupil size. When did I ever say that? There are also changes in the retina. Google "photopic mesopic scotopic" for more info.

Dark adaptation is the last thing you want for observing planets. Not that you would ever be deeply dark adapted when you view Jupiter, but you would tend to be at the mesopic level rather than closer to photopic. The photopic level is ideally where your eyes should be.

There are some threads on CN - mostly older threads, I think - that mention the importance of being around white light for planet work. I don't agree with all the old techniques and the theories of the old timers who used them, but they were on the right track.

For instance, there was the idea that twilight viewing of planets would increase the perceived contrast. Some thought this was due to do a contrast effect between the disk of the planet and the bright sky surrounding it in the FOV. I disagree. I think there is enhanced contrast because the eye is better adapted to viewing planets as a result of the brighter ambient light surrounding the observer. I don't deny, though, that the better image might also be due partly to better seeing at this time of day in many locales.

They also liked to have constant white light around them when viewing planets, particularly in observatories. I'm not sure this is such a good idea, because it is too easy for the light to become a source of glare in the optics or your eyes. You don't want to see a light in the corner of your eye or reflected off the eye lens while you're trying to discern fine surface details. (This is one reason I really don't like viewing planets at twilight. The "Bright White Light" trick will make the eyes function as if it is twilight at midnight, but without the glare.)

Observers can try the "Bright White Light" trick or not, as they wish. I have no horse in this race. It's just an interesting and - in my experience - worthwhile method of improving the perceived image of planets. Besides, it's very cheap! $3 will get you a great little bright white-light flashlight.


Mike


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Re: Filters for Jupiter new [Re: Starman1]
      #5559390 - 12/07/12 02:17 PM

Don,

Quote:

However, those of us with relatively acute vision can see distinct points with separations of 4'. Hence, 240X would suffice to see a feature 1/50 the width of Jupiter's disc.




Also, maintaining eye adaptation closer to photopic will help the eyes retain more of the visual acuity that they enjoy during daylight hours. This has helped me to see very fine details - such as structure within the GRS or "strings of black pearls" along the equatorial bands - without having to push the power above 250x. There is not much joy in trying to sketch Jupiter as it drifts by at 500x.

Quote:

Complicating the issue is that some features we look at are <1/50 the width of the disc, and if distinctly different colors, separations can be less than the apparent 4' and still appear separate. Small kids sometimes have vision that can separate details of 1' apparent separation, and a lot of adults (myself included) can see as distinct points features separated by 3' apparent. And if the points differ in brightness significantly, all bets are off as to what magnification will be required.




Another problem with allowing the eyes to fall into the mesopic level is that color range and contrast is diminished. As you comment here, contrast in color and brightness levels can allow our eyes to discern very small features, smaller than some would think possible. That ability is diminished if our eyes are not properly prepared for planet observation.

Owls' eyes are for deep sky. Hawks' eyes are for planets.

Mike


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Re: Filters for Jupiter new [Re: Sarkikos]
      #5559393 - 12/07/12 02:19 PM

Quote:

Again, please don't misinterpret this technique. It's not just about adjusting pupil size. When did I ever say that? There are also changes in the retina. Google "photopic mesopic scotopic" for more info.




I understand, but if you look at a white light your pupil will change size. You didn't have to say it, it's biology, it's how the eye works. However I don't understand the changes you are talking about with the retina. Photopic, mesopic & scotopic refer to the usage of rods & cones under different lighting conditions (and on a side note is a great explanation for averted vision, taking advantage of the cones). Is it that under photopic conditions, typical daylight conditions where the retina is using only rods, that planetary visual acuity increases?

Jaimo!


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Re: Filters for Jupiter new [Re: Starman1]
      #5559396 - 12/07/12 02:21 PM

Got it. I see where I went wrong.

Thanks.


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Re: Filters for Jupiter new [Re: Jaimo!]
      #5559424 - 12/07/12 02:42 PM

Jaimo!,

Quote:

Is it that under photopic conditions, typical daylight conditions where the retina is using only rods, that planetary visual acuity increases?




Yes. Why wouldn't that be the case? IMO, this is the main reason why planet observers often say they can see detail, color and contrast on planet surfaces better and more easily at twilight. Detail, color and contrast are exactly what photopic vision allows us to see better and more easily. All of these aspects of visual acuity are diminished at the mesopic level. Our ability to discern detail and contrast are greatly impaired at the scotopic level, and color perception is virtually nonexistant, though we have a much greater range for perception of dim objects.

One quick and easy way to simulate photopic conditions at night is the "Bright White Light" trick. Another is to have constant white lights around the observing site, but that can introduce glare. Neither of these methods is perfect, but I find a bright white-light flashlight does help when I'm observing planets.

Mike


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Re: Filters for Jupiter new [Re: Sarkikos]
      #5597551 - 12/31/12 09:03 AM

Quote:

(snip)
Observers can try the "Bright White Light" trick or not, as they wish. I have no horse in this race. It's just an interesting and - in my experience - worthwhile method of improving the perceived image of planets. Besides, it's very cheap! $3 will get you a great little bright white-light flashlight.


Mike




Just a thought... the brain make sure the eyes are adapted to whatever light is available (within the constrains of the "hardware"), right? So it stops down and opens up the aperture of the eyes (pupil size) to whatever suits the available light. And as I understand it, stopping down is faster than opening up (the evolutionary reason perhaps to prevent damage in case of a sudden bright light? sudden darkness doesn't damage the eyes so no hurry). Anyway, shouldn't it then stand to reason that if you are dark adapted and spend a few minutes looking at something bright (say, Jupiter) the brain will automatically stop down the eyes to whatever level is optimal? Hence making the exercise of looking at papers unnecessary?

I'm not making an argument here, just asking.


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Re: Filters for Jupiter new [Re: SteveTheSwede]
      #5597800 - 12/31/12 11:41 AM

Quote:

One quick and easy way to simulate photopic conditions at night is the "Bright White Light" trick. Another is to have constant white lights around the observing site, but that can introduce glare. Neither of these methods is perfect, but I find a bright white-light flashlight does help when I'm observing planets.

Mike




I've never done this myself, and I have seen incredible detail on Jupiter and Mars. Twilight observing is all about contrast. Everything you view has to do with contrast, be it twilight, or night time viewing.
You could go on & on 'till the cows come home, but I am not convinced in the least. The first time I saw incredible detail on Jupiter was in my backyard, in the dark with a 12.5" Orion reflector which had Discovery optics in it.

I can't recall, but if memory serves me well, I didn't use a filter and all we did was just keep on looking for what seemed like hours. Sam, (Plant Earth), was with me at the time and he had his 8" F/7.62 which he made himself and we were comparing scopes. The festoons, red spot, everything was showing up that night like never before. His home made scope, in which he ground the optics, was no slouch either and it kept right up with my scope which was quite a bit larger in aperture.

Neither of us had fans on our scopes from what I remember as well. It was a night I will always remember because it was my first time ever seeing such great detail on the big gas giant!

Cheers,


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Re: Filters for Jupiter new [Re: SteveTheSwede]
      #5597829 - 12/31/12 11:54 AM

Quote:

Quote:

(snip)
Observers can try the "Bright White Light" trick or not, as they wish. I have no horse in this race. It's just an interesting and - in my experience - worthwhile method of improving the perceived image of planets. Besides, it's very cheap! $3 will get you a great little bright white-light flashlight.


Mike




Just a thought... the brain make sure the eyes are adapted to whatever light is available (within the constrains of the "hardware"), right? So it stops down and opens up the aperture of the eyes (pupil size) to whatever suits the available light. And as I understand it, stopping down is faster than opening up (the evolutionary reason perhaps to prevent damage in case of a sudden bright light? sudden darkness doesn't damage the eyes so no hurry). Anyway, shouldn't it then stand to reason that if you are dark adapted and spend a few minutes looking at something bright (say, Jupiter) the brain will automatically stop down the eyes to whatever level is optimal? Hence making the exercise of looking at papers unnecessary?

I'm not making an argument here, just asking.



The size of the pupil is not relevant to this discussion. In dark adaptation, pupil diameter is only a tiny tiny percentage of the whole of dark adaptation.
The pupil opens up to about a 4X greater area, but the retina gains a sensitivity of about 90,000.
So when doing the white light trick, we are sacrificing our night vision entirely in order to use the cones in the eye in day vision mode so we can gain the superior resolution and color sensitivity that comes with photopic day vision.


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Re: Filters for Jupiter new [Re: Cames]
      #5597920 - 12/31/12 12:48 PM

I use color filters on occasion with Jupiter, usually a #38 or 80A blue filter, sometimes a #58 green, #15 yellow or #23 orange. They make specific features look brighter or darker, and can help reveal subtle, faint features in the atmosphere. Most of the time however I prefer the unfiltered view, even with my 15-inch which makes the planet very bright indeed.

Taras


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Re: Filters for Jupiter new [Re: Starman1]
      #5598009 - 12/31/12 01:42 PM

Quote:

Quote:

Quote:

(snip)
Observers can try the "Bright White Light" trick or not, as they wish. I have no horse in this race. It's just an interesting and - in my experience - worthwhile method of improving the perceived image of planets. Besides, it's very cheap! $3 will get you a great little bright white-light flashlight.


Mike




Just a thought... the brain make sure the eyes are adapted to whatever light is available (within the constrains of the "hardware"), right? So it stops down and opens up the aperture of the eyes (pupil size) to whatever suits the available light. And as I understand it, stopping down is faster than opening up (the evolutionary reason perhaps to prevent damage in case of a sudden bright light? sudden darkness doesn't damage the eyes so no hurry). Anyway, shouldn't it then stand to reason that if you are dark adapted and spend a few minutes looking at something bright (say, Jupiter) the brain will automatically stop down the eyes to whatever level is optimal? Hence making the exercise of looking at papers unnecessary?

I'm not making an argument here, just asking.



The size of the pupil is not relevant to this discussion. In dark adaptation, pupil diameter is only a tiny tiny percentage of the whole of dark adaptation.
The pupil opens up to about a 4X greater area, but the retina gains a sensitivity of about 90,000.
So when doing the white light trick, we are sacrificing our night vision entirely in order to use the cones in the eye in day vision mode so we can gain the superior resolution and color sensitivity that comes with photopic day vision.




I have done a decent amount of research on this stuff and figured I would add a bit. These guys are right when they say that pupil dialation is only a small part of night vision, or scotopic vision. When daytime level light hits the eyes, two things happen. One is pupil contraction, which is faster than pupil dilation (partial dilation is nearly instantaneous, but it takes around 7-10 mins for the pupil to fully dilate). To use a metaphor, it is much easier to close an umbrella than to open.

The other change in the eye that happens is what these guys are referring to on the back of the retina. Unlike pupil dilation/contraction, the changes on the retina aren't a reflex, but rather a simple chemical reaction. This reaction takes quite a bit more time than the pupil reflex (full transfer over from cone to rod usually takes 25-30 mins). These changes can actually be seen during the day. If you close your eyes for a few minutes, when you open them, you will notice that a) everything is brighter and b) colors look washed out. Those effects are mostly the switch from cone cells to rod cells. Another thing you will notice is that color does NOT completely go away. This is the "mesopic" vision Sarkikos referred to. You would need to close your eyes for about 30 mins to go totally scotopic.

When you do the white paper trick, you will need to do it for a decent amount of time, at least 3 mins I would think. A quick glance won't give your eyes enough time to switch over. Although the switch back to photopic from scotopic is faster than the reverse, it still takes much more time than it takes your pupils to contract. So be patient with it. Also note that you cannot easily go back to scotopic vision once you have done this. You will need to wait another 30 or so mins to go back to night adjusted vision. DSO's will be pretty dim if visible at all if you don't.


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Re: Filters for Jupiter new [Re: Starman1]
      #5598290 - 12/31/12 04:16 PM

Quote:

Quote:


Just a thought... the brain make sure the eyes are adapted to whatever light is available (within the constrains of the "hardware"), right? So it stops down and opens up the aperture of the eyes (pupil size) to whatever suits the available light. And as I understand it, stopping down is faster than opening up (the evolutionary reason perhaps to prevent damage in case of a sudden bright light? sudden darkness doesn't damage the eyes so no hurry). Anyway, shouldn't it then stand to reason that if you are dark adapted and spend a few minutes looking at something bright (say, Jupiter) the brain will automatically stop down the eyes to whatever level is optimal? Hence making the exercise of looking at papers unnecessary?

I'm not making an argument here, just asking.



The size of the pupil is not relevant to this discussion. In dark adaptation, pupil diameter is only a tiny tiny percentage of the whole of dark adaptation.
The pupil opens up to about a 4X greater area, but the retina gains a sensitivity of about 90,000.
So when doing the white light trick, we are sacrificing our night vision entirely in order to use the cones in the eye in day vision mode so we can gain the superior resolution and color sensitivity that comes with photopic day vision.




Ok, fair enough. But, regardless what the body does to adapt to brighter conditions, wouldn't this adaptation take place from looking at a bright object (such as Jupiter) just as well as looking at the paper?


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Re: Filters for Jupiter new [Re: SteveTheSwede]
      #5598347 - 12/31/12 04:51 PM

Quote:

Ok, fair enough. But, regardless what the body does to adapt to brighter conditions, wouldn't this adaptation take place from looking at a bright object (such as Jupiter) just as well as looking at the paper?




No, because the eye sees all that surrounding blackness which tells the eye to dark adapt. I'm another observer who leaves the lights on to binoview the Moon and planets. To me, it reveals a much greater degree of detail than trying to observe with dark-adapted eyes.


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Re: Filters for Jupiter new [Re: DaveJ]
      #5598698 - 12/31/12 08:18 PM

Quote:

Quote:

Ok, fair enough. But, regardless what the body does to adapt to brighter conditions, wouldn't this adaptation take place from looking at a bright object (such as Jupiter) just as well as looking at the paper?




No, because the eye sees all that surrounding blackness which tells the eye to dark adapt. I'm another observer who leaves the lights on to binoview the Moon and planets. To me, it reveals a much greater degree of detail than trying to observe with dark-adapted eyes.




This is also why point and shoot cameras' auto focus features usually overexpose the planet you are looking at. Fortunately, a good portion of cameras have manual exposure settings. Less fortunate is that our eyes do not... :/


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Re: Filters for Jupiter new [Re: SpaceRooster]
      #5599356 - 01/01/13 10:51 AM

Quote:

I must stop before I get into an area not allowed. Again I apologize for the intrusion...




Too late.

This is not the place for statements of religious points of view.

Edited by Boot (01/01/13 04:55 PM)


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Re: Filters for Jupiter new [Re: dag55]
      #5599382 - 01/01/13 11:08 AM

Moderator,
The posts that are trying to inject religious beliefs into this conversation, like the previous one, are a violation of the TOS and should be removed.
They are not relevant to the conversation, either.


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Re: Filters for Jupiter new [Re: Starman1]
      #5599446 - 01/01/13 11:55 AM

Filters are fun to play when it comes to Jupiter.

I tend to switch em, stack em, switch em some more, try this E.P, try that one.

One thing I like about planetary viewing is the ability to do it, even if skies are not the best or your neighbour has a few thousand watts of christmas lights and porch lights blaring at you.

I am partial to a green type No. 11 filter that I have. It works nicely for me.

jake


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Re: Filters for Jupiter new [Re: SpaceRooster]
      #5599464 - 01/01/13 12:08 PM

Don, that makes a lot of sense! Thanks!

I would like to clarify further that it is *apparent* size that is primarily responsible...Jupiter and Saturn are about the same actual size (Jupiter is slightly larger but not a ton), but Saturn is more far away, and thus appears smaller.

(Please correct me if I'm mistaken though -- I think that is correct, but I'm just a beginner at actual observing!)

Saturn also has more moons that are visible in a low-to-medium size amateur's telescope, I'm told -- although Jupiter's 4 largest moons require less aperture too see, I think I heard a rumor that with an 8" you can see more than 4 of Saturn's moons relatively easily, even in non-ideal skies. I have yet to look since getting my 8" for Christmas (mostly due to very cloudy skies), but don't forget the moons of Saturn.


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Re: Filters for Jupiter new [Re: butsam]
      #5599478 - 01/01/13 12:15 PM

Quote:

I am partial to a green type No. 11 filter that I have. It works nicely for me.

Jake




I used to use that one also with excellent results on Jupiter!


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Re: Filters for Jupiter new [Re: SteveTheSwede]
      #5599500 - 01/01/13 12:23 PM

StevetheSwede,

Quote:

Ok, fair enough. But, regardless what the body does to adapt to brighter conditions, wouldn't this adaptation take place from looking at a bright object (such as Jupiter) just as well as looking at the paper?




Yes it would, if Jupiter were bright enough to induce the shift toward photopic levels. Jupiter might appear bright through the telescope, but that is because the eye is partly dark-adapted. What is needed is a brighter source of light - such as a bright white-light flashlight - to produce the photopic effect. Otherwise, your eyes will be slipping down into the mesopic level.

Mike


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Re: Filters for Jupiter new [Re: northernontario]
      #5599505 - 01/01/13 12:26 PM

Jake,

Quote:

Filters are fun to play when it comes to Jupiter.

I tend to switch em, stack em, switch em some more, try this E.P, try that one.




It's even more fun if you can slip several filters into a filter wheel. Switching among the filters and seeing an immediate effect is very nice indeed!

Mike


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Re: Filters for Jupiter new [Re: SpaceRooster]
      #5599528 - 01/01/13 12:36 PM

SpaceRooster,

Quote:

I have done a decent amount of research on this stuff and figured I would add a bit. These guys are right when they say that pupil dialation is only a small part of night vision, or scotopic vision. When daytime level light hits the eyes, two things happen. One is pupil contraction, which is faster than pupil dilation (partial dilation is nearly instantaneous, but it takes around 7-10 mins for the pupil to fully dilate). To use a metaphor, it is much easier to close an umbrella than to open.

The other change in the eye that happens is what these guys are referring to on the back of the retina. Unlike pupil dilation/contraction, the changes on the retina aren't a reflex, but rather a simple chemical reaction. This reaction takes quite a bit more time than the pupil reflex (full transfer over from cone to rod usually takes 25-30 mins). These changes can actually be seen during the day. If you close your eyes for a few minutes, when you open them, you will notice that a) everything is brighter and b) colors look washed out. Those effects are mostly the switch from cone cells to rod cells. Another thing you will notice is that color does NOT completely go away. This is the "mesopic" vision Sarkikos referred to. You would need to close your eyes for about 30 mins to go totally scotopic.

When you do the white paper trick, you will need to do it for a decent amount of time, at least 3 mins I would think. A quick glance won't give your eyes enough time to switch over. Although the switch back to photopic from scotopic is faster than the reverse, it still takes much more time than it takes your pupils to contract. So be patient with it. Also note that you cannot easily go back to scotopic vision once you have done this. You will need to wait another 30 or so mins to go back to night adjusted vision. DSO's will be pretty dim if visible at all if you don't.




Thanks for your input. Much food for thought here, as well as opportunities for further research and experimentation.

For example, I'm not sure what would be the ideal amount of time to look at a reflection of the white light in order to optimize your eyes for planet observation. IME, a bit more than a quick glance is needed to "get there," but I'm not really sure if three minutes will do any better than 30 seconds.

Also, the brightness of the ambient light is probably a factor in determining how long you need to do the "White Light Trick" to maximize the effect.

There is also the question of how often you need to do this to keep your eyes sufficiently in the photopic to show an appreciable improvement in a planet's image. IME, it seems that every 10 to 15 minutes should be often enough.

In addition, will the optimum protocol be the best in terms of efficient use of time at the eyepiece?

A lot of questions. I wish I knew the answers!


Mike


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Re: Filters for Jupiter new [Re: Sarkikos]
      #5599536 - 01/01/13 12:40 PM

I have this little card with 8 colors of acetate color filters in little 1/2" circles.
By moving the card back and forth between my eye and the eyepiece, I can quickly get an idea which color enhances the particular features I want to view.

This card is labeled:
Chroma-Scan
Hemet, CA 92343

from Cole Enterprises
PO Box 3235
Hemet, CA 92343


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SteveTheSwede
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Re: Filters for Jupiter new [Re: dag55]
      #5599546 - 01/01/13 12:44 PM

Quote:

No need to quote / repeat a TOS violation.




I assume you refer to my post since I was the only one to mention evolution. I will not defend one of the best proven theories in science, nor will I comment on your religious ideas since they are completely off topic.


Feels a little like First Contact.

Steve

( Moderator Edit. Let's just leave it at that. )

Edited by Boot (01/01/13 04:36 PM)


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Re: Filters for Jupiter new [Re: Sarkikos]
      #5599549 - 01/01/13 12:44 PM

Quote:

Jake,

Quote:

Filters are fun to play when it comes to Jupiter.

I tend to switch em, stack em, switch em some more, try this E.P, try that one.




It's even more fun if you can slip several filters into a filter wheel. Switching among the filters and seeing an immediate effect is very nice indeed!

Mike




A filter wheel eh....you mean I've been fumbling with mitts, freezing my fingers, dropping stuff, when all this time...

I am definitely gonna look into this. Thanks Mike

jake


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Re: Filters for Jupiter new [Re: Starman1]
      #5599567 - 01/01/13 12:54 PM

Don,

Quote:

I have this little card with 8 colors of acetate color filters in little 1/2" circles.
By moving the card back and forth between my eye and the eyepiece, I can quickly get an idea which color enhances the particular features I want to view.

This card is labeled:
Chroma-Scan
Hemet, CA 92343

from Cole Enterprises
PO Box 3235
Hemet, CA 92343




Thanks, Don. I'm going to look into this - so to speak.


Mike


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rfr66
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Re: Filters for Jupiter new [Re: Starman1]
      #5599581 - 01/01/13 01:03 PM

Don,
I Googled Chroma-scan and Cole enterprises but nothing came up. How old is that card?


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Re: Filters for Jupiter new [Re: rfr66]
      #5599653 - 01/01/13 01:44 PM

Pretty old, unfortunately. There may be someone still doing a similar card.

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Re: Filters for Jupiter new [Re: SteveTheSwede]
      #5599669 - 01/01/13 01:55 PM

Quote:

Off-topic matter deleted by moderator.




We're not going to have a discussion concerning religious points of view on this forum.

This is a good thread. Let's keep it going within the confines of the TOS.

Thank you in advance for your cooperation. And thank you to all members who have resisted the temptation to add fuel to the fire. I appreciate it

Edited by Boot (01/01/13 04:41 PM)


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Re: Filters for Jupiter new [Re: butsam]
      #5599715 - 01/01/13 02:19 PM

Quote:

Saturn also has more moons that are visible in a low-to-medium size amateur's telescope, I'm told -- although Jupiter's 4 largest moons require less aperture too see, I think I heard a rumor that with an 8" you can see more than 4 of Saturn's moons relatively easily, even in non-ideal skies.




I don't know of any reports in my club of anyone seeing more than 5 moons in an 8" SCT. In my own excellent 6" f/8 dob I have observed Enceladus as well, but most other folks observing with me could not. I have never seen Mimas in any scope, but I can't say that I have spent much time trying in anything larger than my 10". I have no idea of the quality of your optics, your seeing, your visual acuity, etc. but I would discount claims that they will be "relatively easy" for you to see. Saturn is bright, and these moons are dim. I think you will be surprised as just how faint they are.

My advice is not to know where they are positioned ahead of time, and then see what you can see. Furthermore, expect to spend an hour or more at the eyepiece as you go from thinking you see one, to not being able to see it again, to seeing it in another location, etc. until you may be able to say with certainty where the moons are, and how bright they are, and identify them on a chart. After some practice you will know which one is which just by brightness and ease of viewing. I suggest 200x as a good power to try, and go up/down from there.


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Re: Filters for Jupiter new [Re: dag55]
      #5599725 - 01/01/13 02:25 PM

Quote:

No need to quote / repeat a TOS violation.



Trolling is when someone posts something not germane to the original discussion, knowing this will get a rise out of many of the participants.
And trolling is not a good thing in a forum of any kind.

Be aware that your statements are of a religious nature and both religion and politics are "hot button" issues that shouldn't be brought up specifically to avoid the issues associated with bringing them up.

Myself, I'm not offended and I would gladly debate you were the topics you bring up in any way shape or form related to the subject of planetary filters, but they are not.

Edited by Boot (01/01/13 04:28 PM)


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Re: Filters for Jupiter new [Re: dag55]
      #5599756 - 01/01/13 02:45 PM

Dane,

This is not the proper venue.

Mike


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Re: Filters for Jupiter new [Re: Sarkikos]
      #5599765 - 01/01/13 02:52 PM

Agreed. Other discussion rooms on the Internet for this topic.

Question, so of all the filters out there, if you had to limit it to just two filters that did the best on bringing out the most features on Jupiter, which two would it be? Seems like many feel one of the blue color filters would be one.


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Re: Filters for Jupiter new [Re: northernontario]
      #5599784 - 01/01/13 03:01 PM

Quote:

Quote:

Jake,

Quote:

Filters are fun to play when it comes to Jupiter.

I tend to switch em, stack em, switch em some more, try this E.P, try that one.




It's even more fun if you can slip several filters into a filter wheel. Switching among the filters and seeing an immediate effect is very nice indeed!

Mike




A filter wheel eh....you mean I've been fumbling with mitts, freezing my fingers, dropping stuff, when all this time...

I am definitely gonna look into this. Thanks Mike

jake




Also check out filter slides (Astrocrumb, lumicon, etc). Astrocrumbs can be used with binoviewers/incocus as well.


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Re: Filters for Jupiter new [Re: BillP]
      #5599939 - 01/01/13 04:44 PM

Quote:

Agreed. Other discussion rooms on the Internet for this topic.

Question, so of all the filters out there, if you had to limit it to just two filters that did the best on bringing out the most features on Jupiter, which two would it be? Seems like many feel one of the blue color filters would be one.




I have used a variety of filters on Jupiter, and find that a 82A light blue or 80A blue brings out the darker details best (maybe a #38 on a really big aperture). I have also found the #15 yellow (which means a #12 yellow would work also) to sharpen details and make white storms a little sharper and crisper. That's not too surprising since a yellow filter seems to work best on Saturn's rings, too. Something pure white is made sharper by a yellow filter because the blue is removed from the image (blue tends to cause a "haze") and because the deep red is also, enhancing contrast in the image.
Target shooters often use yellow sunglasses for the same reason--to enhance contrast.
Lunar viewers use yellow filters to enhance contrast, too. I can often see small details inside a crater with a yellow filter that are very difficult without the filter.

"Observing and Photographing the Solar System" recommends the following filters for Jupiter:
#80A/82A for boundaries between belts and zones
#12 or 21 for festoons, garlands, polar details (I found a #15 superior to the #21)
#80A/#82A for the GRS (or a #30 Magenta)

Some really hardcore filter users say this about filters and Jupiter:
Clouds
#11 Yellow-Green

Belts
#8 Light Yellow
#15 Deep Yellow
#21 Orange
#23A Light Red
#25 Red
#29 Deep Red
#38A Deep Blue
#56 Light Green
#80A Blue

Rilles
#80A Blue

Festoons
#80A Blue

Atmosphere
#56 Light Green

Red-Orange Features
#12 Yellow

Orange-Red Zonal
#8 Light Yellow

Red/Blue Contrast
#11 Yellow-Green

Blue/Light Contrast
#25 Red

Great Red Spot
#38A Deep Blue
#80A Blue

Galilean Moon Transits
#25 Red
#29 Deep Red

Red/Blue/Light Contrast
#56 Light Green
#58 Green

Polar Regions
#21 Orange
#23A Light Red

Disc
#38A Deep Blue

Low Contrast Features
#82A Light Blue

I don't agree with all of the above, but it does point out that Jupiter, like Mars, rewards experimentation.


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Re: Filters for Jupiter new [Re: Starman1]
      #5600008 - 01/01/13 05:29 PM

Thanks. Yes, I see things like this all the time...after reading them the basic come away is that ALL filters are what someone should use But reading into it...it seems that basically blue and yellow are the best for all features.

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Re: Filters for Jupiter new [Re: BillP]
      #5600067 - 01/01/13 06:10 PM

Bill,

Quote:

Question, so of all the filters out there, if you had to limit it to just two filters that did the best on bringing out the most features on Jupiter, which two would it be? Seems like many feel one of the blue color filters would be one.




Here are the filters I place in my filter wheel for Jupiter:

Medium Blue 80A - Festoons, GRS detail, white spots and ovals

Deep Yellow 15A - Belts, low contrast ST ovals, polar regions, blue festoons

Yellow Green 11 - Sharpens edge and rim of GRS, red/blue contrast

Light Violet 47H - Fine detail in zones, white ovals in ST bands and zones

I either leave the fifth slot empty or put in a Fringe Killer filter. Many times I'll use these filters combined with a Baader Moon & Sky Glow in the neck of the filter wheel or binoviewer.

If I had to pick only one filter, I'd choose the Baader M&SG. It is the best general purpose contrast filter I've ever used for viewing planets.

Mike


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Re: Filters for Jupiter new [Re: Jaimo!]
      #5600160 - 01/01/13 07:14 PM

To observe the Moon or other bright objects, I just install the scope on the sidewalk in front of the house, south from the street light but not far from it. The level of ambient light is pretty high. Either the Moon or Jupiter look great, there's plenty of detail visible, and there's no need to reduce the "glare" with neutral density filters - because there is no glare when your eyes are adapted to twilight-level ambient light.

The eye can see fine detail so much better when it's not adapted to full darkness.


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Re: Filters for Jupiter new [Re: FlorinAndrei]
      #5600268 - 01/01/13 08:21 PM

Florin,

Exactly right. But filters can still be useful to enhance contrast for various types of surface features to make them a bit more obvious and easier to see.

Mike


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Re: Filters for Jupiter new [Re: Sarkikos]
      #5600598 - 01/02/13 12:49 AM

It's not a matter of "glare". Neutral density and polarizing filters help cut down irradiation, which is light and dark areas "bleeding over" on each other.

If you have a thin layer of clouds, I find that it acts like a filter and I have had the best views of planets under a thin layer of cloud or haze. It really depends on the sky because I have had excellent views of the planets with no filters at all as well. My favorite color filter to use on Jupiter is #11 yellow-green I think it is as a color.

I would like to get another one of those!

Cheers,


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Re: Filters for Jupiter new [Re: Scanning4Comets]
      #5600774 - 01/02/13 07:04 AM

The fundamental meaning of "glare" is "an intense or blinding light." Glare When observers complain about "glare" from a planet, unless they say otherwise, I interpret "glare" to mean "an intense light." This is verified when I ask them if they mean that the planet appears too bright. In Florin's case, it's obvious from the context that when he says "glare" he means "intense light," or actually, light that only appears intense when the observer's eyes are not adapted correctly.

IIRC, none of them have ever complained of "irradiation," or light from brighter areas bleeding over into darker areas. What they want is a way to dim the light because the planet appears uncomfortably bright to them. That is why I explain to them that the planet only appears "too bright" because their eyes are not at an optimal level of adaptation. IME & IMO, filters are probably not the best solution to the problem of "glare." But that's OK. To each their own.

Mike


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Scanning4Comets
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Re: Filters for Jupiter new [Re: Sarkikos]
      #5600782 - 01/02/13 07:13 AM

Well, irradiation is a huge part in seeing details or seeing none because of bleeding from bright parts over to darker areas Mike.

I am just explaining another area where problems can arise in planetary observing. One minute you're saying that filters help and another they aren't? Hmmmm. OK.


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Re: Filters for Jupiter new [Re: Scanning4Comets]
      #5600784 - 01/02/13 07:15 AM

Contrast filters and various color filters can enhance the perceived contrast for planets. Maybe what they are actually doing is decreasing the effects of irradiation? I'm not sure. But when an observer says that there is "glare," in the sense of intense brightness, coming from a planet, the problem is in their eyes, not irradiation.

Mike


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Re: Filters for Jupiter new [Re: Sarkikos]
      #5602402 - 01/03/13 06:09 AM

Quote:

I only use filters to enhance contrast or emphasize specific features over others. To tone down the brightness, nothing works better than the "bright white light trick." The eyes are the problem, not the planet.

Mike




I could have saved allot of money on filters if I had learned this trick. I have tried the following filters with limited sucess.

1) Orion skyglow filter. Some good but changed the image
2) Polarizing filter. Works but not a miracle maker.
3) #80A Blue. More effective than 1 and 2 and allot less expensive
4) Bright light trick. Works better than all three filters and cost nothing!


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Re: Filters for Jupiter new [Re: Brent Campbell]
      #5602835 - 01/03/13 11:53 AM

A variation of this trick, which works well with Dobs, is to shine a not too bright flashlight down the tube while observing a planet to increase the brightness of the background field of view. By aiming the flashlight differently can control how bright the background becomes, and activates your color vision and makes the planet appear better.

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Re: Filters for Jupiter new [Re: BillP]
      #5603740 - 01/03/13 09:44 PM

Plug for myself...Just put up a set of 1.25" Orion color filters in the Classifieds...saw a few of the colors I have for sell I saw mentioned while perusing this thread.

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Scanning4Comets
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Re: Filters for Jupiter new [Re: drbyyz]
      #5604075 - 01/04/13 04:16 AM

Shine a flashlight down the tube? Now I've heard it all. Can't say I'll be doing that one. haha.

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Re: Filters for Jupiter new [Re: Scanning4Comets]
      #5604390 - 01/04/13 09:38 AM

Quote:

Shine a flashlight down the tube? Now I've heard it all. Can't say I'll be doing that one. haha.




It's a very old trick. And it works! basically you are illuminating the side walls of the Dob interior and the aim angle controls how much brightening of the background FOV occurs.


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Re: Filters for Jupiter new [Re: BillP]
      #5604454 - 01/04/13 10:17 AM

Bill,

Quote:

A variation of this trick, which works well with Dobs, is to shine a not too bright flashlight down the tube while observing a planet to increase the brightness of the background field of view. By aiming the flashlight differently can control how bright the background becomes, and activates your color vision and makes the planet appear better.




I've got to admit I've never heard this one either. So after all the trouble I've taken to fully flock the OTA, add a fully-flocked dew/light shield, touch up the exposed hardware with flat-black paint, paint over the bevels on both mirrors, flock the focuser and install a baffle in the focuser ... I'm going to point a flashlight done the OTA? Seems a little counterintuitive to me.

I think I'll try it!


Mike


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Re: Filters for Jupiter new [Re: Sarkikos]
      #5604469 - 01/04/13 10:23 AM

Bill,

Seriously, though, this sounds a lot like the old idea that a brighter background around a planet improves observation. This was the reasoning that many old-timers gave for why planet contrast and detail appeared better around twilight.

IME, a brighter background per se never did anything for me except maybe make my eye floaters more obvious. I think the reason that planet observation tends to be better at twilight with a bright background is that the eyes are closer to photopic, not because of any contrast effect.

But at least you are giving the correct reason - IME & IMO - for why shining a flashlight into the OTA could improve planet viewing. It's about the adaptation of your eyes, not about any contrast effect between the planet and background.

I can't help but think, though, that shining a light down the OTA would not only brighten the background but also introduce veiling glare over the image of the planet.

Mike


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Scanning4Comets
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Re: Filters for Jupiter new [Re: Sarkikos]
      #5604502 - 01/04/13 10:38 AM

Is it just me? or do posts here seem to be a little over the top lately? I dunno, but some of the things I am reading here leaves me shaking my head and closing up CN walking away in disbelief.

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Svezda
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Re: Filters for Jupiter new [Re: Starman1]
      #5605473 - 01/04/13 07:54 PM

Quote:

A little math.

Jupiter at its largest is 50" across. If you want to see a detail 1/50 the diameter of the disc, and you want to bring it up to the 8' apparent visual threshold, that requires a magnification of 480/1 = 480X
Saturn's disc maxes out about 20". To see a detail 1/50 the size of the disc, brought up to the same 8' apparent threshold would require a magnification of 480/.4 = 1200X.
Looking at the comparison, Saturn requires a magnification 2.5X as great to see details the same apparent size as you see on Jupiter.

Hence, if you see enough detail on Jupiter at 150X, you will need 375X to see details on Saturn at the same scale.

It's purely size as to why Saturn requires and takes higher magnifications than Jupiter, to see details that is.

That's without getting into relative contrast and albedo and coloration contrast, etc., all of which influence magnifications used.



I understand your reasoning here, but I always intuitively thought that this is more related to the physical characteristics of the planets or the Moon. For example, if you're looking at anything on the Moon, or /almost/ anything, the inherent contrast is just so high - the features are so clear-cut and so 'black and white' - that higher mags don't give you a 'washed out' or low contrast or fuzzy appearance. At that same power, say, 500x in a given scope, Jupiter may appear very bad aesthetically and may likely show /less/ detail to you than at lower mags, just because you are looking at a disk that is more like 'cream and golden cream on beige' rather than 'black and white on dark gray'.

Not only that, the lunar disk has a super hard edge with superb contrast, whereas Jupiter's edge can appear very fuzzy due to limb darkening or a slight phase effect.

Does this not make sense? It's what I've observed the last nearly four decades of observing. It may be more an 'impression' of the reason for Jupiter not 'taking' higher mags, but nevertheless I definitely use lower magnifications on Jupiter than I do on Saturn, Mars, Luna, etc.

I think the larger size of Jupiter and thus the larger size of its details has little to do with it not 'taking' or needing higher mags since, for example, you can hardly hope to see small details even /five/ arcseconds across on Saturn with /any/ magnification because they are just almost not there (you usually just see the faint brownish bands and no spots at all, no matter what mag you use).

The reason I use higher mags on Saturn is not that I hope to see one arcsecond details on Saturn the same size as I would see them on Jupiter at half the magnification - I use higher mags on Saturn because the physical characteristics of the disk and rings of Saturn allow it and give a pleasing appearance at higher mags. The much harder edge of the disk and the high contrast rings allow higher mags without the 'fuzzy' appearance that such mags would give on Jupiter.

That is my take on it...I am interested in all the opinions and experiences I've read and look forward to more since this is a pretty interesting topic for those of us who like to observe the Moon and planets.


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Re: Filters for Jupiter new [Re: Svezda]
      #5605512 - 01/04/13 08:22 PM

Well, if I look back, my all-time best view of Jupiter was at 456X, while my all-time best image of Saturn was at 1123X. 1123X = 456X times roughly 2.5, keeping with the 2.5X difference in feature sizes.

Whereas you may not see small storms on Saturn (at least not often), you can see similarly small features in the Rings (spokes, Keeler Gap, Cassini Division, "grooves" in the rings, and occasionally a star or moon passing through a gap), so the idea of Saturn needing more magnification holds.

You point out the difference in contrast of features, too. Spokes or grooves in Saturn's rings are definitely lower contrast features than, say, festoons on Jupiter against the EQ belts, for instance.


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Re: Filters for Jupiter new [Re: BillP]
      #5606049 - 01/05/13 05:47 AM

Quote:

A variation of this trick, which works well with Dobs, is to shine a not too bright flashlight down the tube while observing a planet to increase the brightness of the background field of view. By aiming the flashlight differently can control how bright the background becomes, and activates your color vision and makes the planet appear better.




Okay maybe this sounds strange but:
I've observed Jupiter through a light/moderate fog and found it helped bring out color and very fine detail. I don't understand why: Fog may be acting like a Apodizing mask or the mirror is being flooded by fog filtered skylight?
So yes the flashlight trick may deserve more investigation. Possible a flashlight with dimmer and the light passing through a material like fine frosted glass to possibly simulate observing Jupiter at twilight or a hazy summer night as many observers know a dark sky and a bright Planet isn't the best enviroment for observing. Twilight for me has always been the best, or in those still hazy nights of the summer. In the Winter I never observe Jupiter without some yard lights on.
Sam


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Sol Robbins
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Re: Filters for Jupiter new [Re: planet earth]
      #5606191 - 01/05/13 09:32 AM

Lately I have been using a dialectric variable neutral density filter.

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Sarkikos
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Re: Filters for Jupiter new [Re: Scanning4Comets]
      #5606674 - 01/05/13 01:55 PM

Mark,

Quote:

Is it just me? or do posts here seem to be a little over the top lately? I dunno, but some of the things I am reading here leaves me shaking my head and closing up CN walking away in disbelief.




Can you be specific?


Mike


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Sarkikos
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Re: Filters for Jupiter new [Re: planet earth]
      #5606717 - 01/05/13 02:18 PM

Sam,

Quote:

Okay maybe this sounds strange but:
I've observed Jupiter through a light/moderate fog and found it helped bring out color and very fine detail. I don't understand why: Fog may be acting like a Apodizing mask or the mirror is being flooded by fog filtered skylight?
So yes the flashlight trick may deserve more investigation. Possible a flashlight with dimmer and the light passing through a material like fine frosted glass to possibly simulate observing Jupiter at twilight or a hazy summer night as many observers know a dark sky and a bright Planet isn't the best enviroment for observing. Twilight for me has always been the best, or in those still hazy nights of the summer. In the Winter I never observe Jupiter without some yard lights on.




Two different image-enhancing effects might be taking place here.

I've also seen the image of planets improve when there is a fine layer of intervening cloud or mist . Yes, I think this effect works similarly to a contrast filter or maybe an apodizing mask.

But there is a separate type of image enhancing effect that is produced by white ambient light when observing planets. The white light improves the appearance of the image by changing the adaptation level of your eyes, bringing them closer to photopic.

IME, a bright background surrounding the image of a planet - such as seen at early twilight - only enhances the image by introducing a change in the adaptation level of the observer's eyes. It is not due to any contrast effect between the bright background and the image of the planet.

Personally, I prefer a dark background when observing planets. I have eye floaters which become more obvious with a bright background. Also, I like the aesthetic look of a planet in a dark sky.

It is entirely possible to have a dark background when observing planets and still have great contrast, color and detail. The "Bright White Light" trick or something similar can bring the eyes closer to photopic adaptation and allow improved visual acuity even on a dark night.

FWIW, though, I put a diffusing filter on all my flashlights, whether white or red. Actually, the "diffusing filter" is just a circular piece of parchment paper (used in cooking) that I place in front of the bulb. This paper diffuses the light, making a more even projection of light on reading material or atlases, without appreciably dimming the brightness.

Mike


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BillP
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Re: Filters for Jupiter new [Re: planet earth]
      #5606884 - 01/05/13 04:04 PM

Quote:

Okay maybe this sounds strange but:
I've observed Jupiter through a light/moderate fog and found it helped bring out color and very fine detail. I don't understand why: ...




This is a very common phenomenon. Many observers over the years have reported this. Not just fog, but on evenings when there is a thin transparent cloud deck high up (where the Moon makes that halo) are also wonderful times for planetary observing. My guess on why this is so is probably that the atmosphere is just more stable during these times. More stable the air is and more uniform the temperatures, then better details can come through.

btw, I don't usually use filters. However last night with Jupiter decided to experiment. To my eye, the light orange and light green filters were the best on Jupiter. Other colors I felt took away, rather than added to the view and experience. This was in a 4" scope so specific to that aperture.

Edited by BillP (01/05/13 04:07 PM)


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Sarkikos
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Re: Filters for Jupiter new [Re: BillP]
      #5606943 - 01/05/13 04:43 PM

Bill,

Quote:

This is a very common phenomenon. Many observers over the years have reported this. Not just fog, but on evenings when there is a thin transparent cloud deck high up (where the Moon makes that halo) are also wonderful times for planetary observing. My guess on why this is so is probably that the atmosphere is just more stable during these times. More stable the air is and more uniform the temperatures, then better details can come through.




So maybe the planet image appears better because the air is more stable, rather than because of any specific filtering effect caused by the thin clouds? Maybe. But I know that I've had some nights when Jupiter presents a better image - more contrast, easier to see surface features - when a thin layer of cloud temporarily passed over the planet. When the thin clouds had moved away, the image was not quite as good.

When the air is turbulent, and there are winds, the seeing is poor, though the sky may appear clear. On other nights there is a haze or thin clouds, and the seeing is good. Maybe just because there is no appreciable wind to blow away the haze and clouds?

Last night I was at my dark site. When I first arrived, there were some patchy clouds covering the sky, but soon a strong wind - up to 25 mph gusts, I believe - blew those clouds away. Intermittent gusts of wind continued for the rest of the night. The sky was very transparent, but the seeing was pretty bad. I bagged 35 more objects from the Herschel 400, mostly faint galaxies. Also, it was the first night that I was able to see the Horsehead Nebula (B33) in Orion.

Mike


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Re: Filters for Jupiter new [Re: Sarkikos]
      #5607746 - 01/06/13 03:47 AM

Bill P
Sarikos

Lots of interesting answers and ideas well worth trying.
So the quest goes on....
Clear Skies
Sam


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