Variable Polarising filter???

[Elio_C]

Hi SGL, 

I recently found out about variable polarising filters from a thread on this forum but I'm a bit confused, I'll explain. 

In the past, all I have been able to use for my astronomy has been a measly 76mm national geographic dobsonian, rather below average views and etc. 

One of my main gripes about it is that I have never been able to get detail on anything other than the moon, not even the planets! All I've been able to see them as has been just coloured bright stars, with the exception of Jupiter's moons. 

I will be upgrading to the heratige 150p dobsonian telescope from skywatcher soon, and I'm quite excited.

However reading about the polarising filter has made me very worried! When I get the new scope, will all I will be able to see be just larger bright coloured objects because the planets are still too bright? Because that would be quite the disappointment. 

I have seen many videos of this scope producing great views without a polarising filter, so I would be quite confused if I had the same problem of getting no detail because of the brightness on this new scope. 

Any help would be greatly appreciated, thanks for your time. 

Elio. 

[cloudsweeper]

Elio - you should easily see a couple of belts on Jupiter, and Saturn's rings - although more detail is harder right now because they are quite low.  Mars has been good recently, but detail on that planet is not as dramatic as the previous two.  You don't need a filter to view these objects with a 150 'scope.  It might be better used with the Moon, when it is getting full.

Have fun!

Doug.

[Carbon Brush]

Good advice from @cloudsweeper.
Be patient for the best views of Saturn & Jupiter when they are higher in the sky. It is worth the wait.
But this winter, there are many other objects that will be well presented in your '150.

If you video the (very bright) moon without a polarising filter, you will present a bright image to the camera and help with image quality and frame rate.
But if you eyeball view the moon without dimming, you might not see much else for a few minutes until your eyes recover dark vision.

Enjoy your new scope. It should be a huge leap forward. Perhaps your first exposure to 'aperture fever'😁

David.

[Alan64]

1 hour ago, Elio_C said:

Hi SGL, 

I recently found out about variable polarising filters from a thread on this forum but I'm a bit confused, I'll explain. 

In the past, all I have been able to use for my astronomy has been a measly 76mm national geographic dobsonian, rather below average views and etc. 

One of my main gripes about it is that I have never been able to get detail on anything other than the moon, not even the planets! All I've been able to see them as has been just coloured bright stars, with the exception of Jupiter's moons. 

I will be upgrading to the heratige 150p dobsonian telescope from skywatcher soon, and I'm quite excited.

However reading about the polarising filter has made me very worried! When I get the new scope, will all I will be able to see be just larger bright coloured objects because the planets are still too bright? Because that would be quite the disappointment. 

I have seen many videos of this scope producing great views without a polarising filter, so I would be quite confused if I had the same problem of getting no detail because of the brightness on this new scope. 

Any help would be greatly appreciated, thanks for your time. 

Elio. 

I have a 150mm f/5 Newtonian, albeit not a collapsible... 

I spent practically all of 2015 observing the sky; once I relocated the telescope itself to a tripod-mount that is -- such freedom.

One night, I observed Jupiter, the event recorded via this shot I took through the eyepiece at a lower power...

Note the flaring caused by the secondary spider-vanes.

Not long afterwards I inserted a 12mm combined with a 2.8x barlow, and for a higher power of 175x.  Now, as you go up in magnification, the images will dim.  True enough, the flares round the planet were more or less gone.  But Jupiter was still a washed-out, white orb, devoid of any detail.  I went inside and retrieved my variable-polariser.  What a difference upon its integration.  I could then see many details on the planet's surface, and the subtle colourings.  During a few moments of exceptional seeing(you have be patient and wait for those to occur), the features suddenly became practically tack-sharp -- the festoons and whorls within the equatorial bands were a sight to behold. 

The planet appeared as though I was watching a NASA broadcast, albeit on an old CRT colour-television...

  

Again, what a sight to behold, and for only this much...

https://www.rothervalleyoptics.co.uk/antares-variable-polarising-filter-125.html

Mars may also benefit, particularly when at opposition...

Venus, too, and in discerning its Moon-like phases more easily.

Brightness is not always our friend when observing the night sky.

Edited November 12, 2020 by Alan64

[Elio_C]

Thanks for the help!

As Christmas is approaching I will hopefully be able to purchase a cheap one anyway, thanks everyone! 

[Ricochet]

If you want a filter for planetary and lunar then my first choice would be the neodymium. This filter tends to increase contrast a bit rather than just dimming the object. The Baader is the best but the cheap Chinese version is very good for a very small price. 

In my experience there seems to be a loss of detail when using polarising filters and you can also get extra reflections so I would only consider one for the moon. 

[Elio_C]

14 minutes ago, Ricochet said:

If you want a filter for planetary and lunar then my first choice would be the neodymium. This filter tends to increase contrast a bit rather than just dimming the object. The Baader is the best but the cheap Chinese version is very good for a very small price. 

In my experience there seems to be a loss of detail when using polarising filters and you can also get extra reflections so I would only consider one for the moon. 

Thanks for the advice, I'll see what I can find within budget but that sounds like a good idea.