13% or 25% ND Moon filter?

[bytor666]

Resolution (the smallest detail that can be seen) is inversely proportional to telescope aperture: the wider the aperture, the more detail you can see.

I'm already well aware of this fact.....HOWEVER if you read what I said, it doesn't matter that much on the moon because it is so bright. You can throw all the math, etc you want at me, but the eyes do not lie.

I use the mask on the moon and Jupiter with excellent results.

[ZeroID (Brent)]

BTW you can stack filters, I have added a colour filter to my moon filiter to reduce the light even further. Useful also when doing white light solar through baader film and add a blue which seems to improve sunspot contrast or a yellow for a more natural look.

I know some people pooh pooh filters as being next to useless but I have a collection of camera filters that I'm growing. They are dirt cheap now ( 5 for $10 ) as DSLRs have made them redundant. Currently playing ariound with C80, light blue as it has a similar but far less dramatic profile to the Astronomik CLS. A test the other night with various colours and combinations gave me a much reduced LP effect for widefield work at home. Killed a lot of the red BG without showing too much blue and affecting exposure time by much.
I also have a pair of polarising filters that gives me a variable ND filter.
If I can get a clear night soon (Yeah Right!) I'll be testing a 2" Hoya C8 on the SONY at prime focus through either the Lunt or the Newt to see if it makes a significant difference.

Fun for $2 a pop, awesome !!
Who said astronomy was expensive ?

[astro744]

Originally Posted by bytor666

I'm already well aware of this fact.....HOWEVER if you read what I said, it doesn't matter that much on the moon because it is so bright. You can throw all the math, etc you want at me, but the eyes do not lie.

I use the mask on the moon and Jupiter with excellent results.

All I know is that I'm going to see (and have seen) smaller craters with my 10" telescope than with my 4" telescope. Brightness does affect resolution but so does contrast and probably more so. I would not consider Jupiter so bright that it requires an aperture stop and then expect to see the same amount of fine detail once stopped.

I see small craters simply disappear when using my Meade #905 variable polarising filter on my C9.25 or 10" Newtonian, (the latter with 2x Barlow to reach focus). It could be the optical quality of the filter but something is significantly affecting the resolution when darkening the image. I would think it is a function of crossing two polarising planes but I do not have another brand of filter to test this.

I did a search on the web for some info and came up with the following which I am yet to fully comprehend: http://www.houseofoutdoor.com/testra...ES_highres.pdf

I'm sure there's going to be a lot more to this debate.

[Astro_Bot]

Originally Posted by bytor666

I'm already well aware of this fact.....HOWEVER if you read what I said, it doesn't matter that much on the moon because it is so bright. You can throw all the math, etc you want at me, but the eyes do not lie.

I use the mask on the moon and Jupiter with excellent results.

Actually, I did carefully read what you said.

Resolution is not related to brightness - it's related to aperture width.

But how you use your telescope is up to you. I hope you enjoy using it, and if using aperture masks makes you happy, then great, because that's what it's all about.

Clear skies.

[Astro_Bot]

For completeness, what you "see" will be affected by a bunch of factors including the response of the human eye, which is affected by the brightness of the image. And the optical performance of your 'scope and/or filter plays a part. It is not right to call this resolution, though, especially in relation to aperture masks that have the opposite effect.

[sn1987a (Barry)]

Moon no filters,

16" "Hmmm!"

18" "Ooooh!"

28" with Binoviewers " Holy............................... ...me dead!"