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D Med

Question about Barlows and filters

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So I recently read somewhere that big light buckets need barlows or filters to see better detail on Jupiter and Saturn. Is this correct? If so, which is better to use, a barlow or a color filter? I appreciate any help or clarification anyone can provide. 

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The two are not mutually exclusive. You would use a barlow if you need to increase the magnification beyond the level that your eyepieces alone allow. You use a filter if you want to increase contrast. In my experience the one filter you want for planetary is a neodymium filter. 

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Thing with light buckets is that they tend to be fast scopes - often as fast as F/4. Maximum supported magnification with such scope (in excellent seeing, so not seeing limited) is with eyepieces in 2mm to 4mm range (half of F/ration to F/ratio, depending on who you ask :D ). There aren't many eyepieces out there in these focal lengths - this is why barlow is often a must to reach very high magnifications with such scopes. How usable those magnifications will be (due to atmosphere) that is another matter.

Filters on the other hand do have a place in observer's arsenal, but most are usable for same purpose in smaller scopes as well - and two are not directly related (filters/barlows, nor filters/light buckets for that matter). Only thing that one must take care of, and this is more related to nebula filters rather than planetary - is if filter blocks too much light and therefore is not recommended for very small scopes (below 4" or so).

Here is good overview of usability of simple color planetary filters:

https://agenaastro.com/choosing-a-color-planetary-filter.html

 

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Awesome! Thanks for the great responses! Definitely helps! 

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I’m going to go with #38A dark blue filter. That seems to cover what I’m looking for in a filter. Thanks again!

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Never mind, my aperture isn’t big enough for that filter. I’ll get the #80A blue filter

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14 hours ago, D Med said:

So I recently read somewhere that big light buckets need barlows or filters to see better detail on Jupiter and Saturn. Is this correct? If so, which is better to use, a barlow or a color filter? I appreciate any help or clarification anyone can provide. 

I have a 6" f/5 Newtonian.  I assume the "big light bucket" that you're wondering about is at least an 8".  Jupiter is generally bright, so much so that through my 6" f/5 the planet appeared as a brilliant white, washed-out sphere, and practically devoid of any detail.  I then attached one of these to my eyepiece, then the eyepiece into the barlow as before: a variable-polariser...

https://agenaastro.com/gso-1-25-polarizing-filter.html

NOTE: You must have two of them, then to screw them together and adjust for a brightness range from 1% to 40%, and in allow those percentages of light through to the eyepiece.  Also note what is stated there in the listing, "Buy 2 for $12.50 each and save 8%".  AA offers that discount, and for making a variable-polariser out of the two.

This is an image of my variable-polariser, and illustrating the different levels of light passing through...

2107233330_variablepolariser7.jpg.279dc729ddd485d77f2ea2eb30048eb6.jpg

Jupiter, before I went into the house to get my unit(left), and after the unit was integrated(right)...

variable-polariser.jpg.45db282cb725cb4f8a74f7e9c24e4e23.jpg

The unit also dimmed down the flaring caused by the secondary-spider vanes; eliminated them even.  The view made my jaw drop.  I could then see the whorls and festoons within the planet's equatorial bands, and almost sharp as a tack.  I say "almost" because I was near to the magnification limit per the atmosphere, high power whilst using a 3x barlow, at the time of the observation.

You'll see what I mean when you eventually point a larger aperture at Jupiter.

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8 hours ago, Alan64 said:

I have a 6" f/5 Newtonian.  I assume the "big light bucket" that you're wondering about is at least an 8".  Jupiter is generally bright, so much so that through my 6" f/5 the planet appeared as a brilliant white, washed-out sphere, and practically devoid of any detail.  I then attached one of these to my eyepiece, then the eyepiece into the barlow as before: a variable-polariser...

https://agenaastro.com/gso-1-25-polarizing-filter.html

NOTE: You must have two of them, then to screw them together and adjust for a brightness range from 1% to 40%, and in allow those percentages of light through to the eyepiece.  Also note what is stated there in the listing, "Buy 2 for $12.50 each and save 8%".  AA offers that discount, and for making a variable-polariser out of the two.

This is an image of my variable-polariser, and illustrating the different levels of light passing through...

2107233330_variablepolariser7.jpg.279dc729ddd485d77f2ea2eb30048eb6.jpg

Jupiter, before I went into the house to get my unit(left), and after the unit was integrated(right)...

variable-polariser.jpg.45db282cb725cb4f8a74f7e9c24e4e23.jpg

The unit also dimmed down the flaring caused by the secondary-spider vanes; eliminated them even.  The view made my jaw drop.  I could then see the whorls and festoons within the planet's equatorial bands, and almost sharp as a tack.  I say "almost" because I was near to the magnification limit per the atmosphere, high power whilst using a 3x barlow, at the time of the observation.

You'll see what I mean when you eventually point a larger aperture at Jupiter.

Alan, thanks. I am wanting a more natural color when I look at the gas giants. I think I will go with this filter instead of the color filters!

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5 hours ago, D Med said:

Alan, thanks. I am wanting a more natural color when I look at the gas giants. I think I will go with this filter instead of the color filters!

When I saw that incredible amount of detail, it was only for a brief time, then it went back a step or two down in sharpness.  That was the atmosphere's doing; the "seeing".  Patience is required in waiting for moments of good seeing during a night of average-to-poor seeing conditions, as we can never know when it will occur. 

When observing the Moon, the variable-polariser will enable you to dim it down, if it irritates your eyes, especially during a full phase.  Of course, during a full Moon there's very little contrasting detail to be seen, but I look at it anyway with my telescopes...

092615b-16mm-30x2a.jpg.c4b90a6d065e9f80fdc163cdbd2014df.jpg

The variable-polariser can also be used to discern the phases of Venus; phases just like those of the Moon.  You may come to find that Saturn does not really need to be dimmed, depending.

Colour filters?  Back in 2012, I went ahead and cobbled a set together, and after researching them...

1936818202_colourfilters2a.jpg.0a4599b39f1d252a3b270f2edb497bd3.jpg

The dark ones are for much larger "Dobsonians", 12", 16", and up.  I wanted those anyway, if only as curiosities.  The lighter colours can be useful: the #80A and #82A blues.  The lighter yellows can be used with fast-achromats to reduce the effects of false-colour when viewing brighter objects, although the detrimental effects(blurring, smearing) upon an image due to the chromatic aberration remain.  They also impart a yellowish cast to the images.  Still, I rarely, if ever, have used or will use any of those filters.

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