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MrCat

The moon is very bright!

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Hey folks,

Having just got my first ever glimpse of the moon last night through my new scope, I noticed that the darker edge was the best place to look as it had the most contrast and the craters looked amazing. But as the moon pans across the view (amazing to see it moving so fast!) I noticed that the middle and brighter edge of the moon are, well, very bright and consequently it's hard to make out much detail. I was wondering if there's a way round this to somehow bring out more contrast, some kind of special filter or something?

Cheers

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You can experiment with filters such as variable polarising filters or a Baader Neodymium filter which do help the contrast a bit.

The best bet though is just to observe at different phases of the moon. As the terminator moves across the surface, different craters and other features are highlighted so they are much easier to observe.

For example, this is the moon tonight

a6f7c6cf0f1db3854fd27f701feb2e82.jpg

This is the moon on 3rd Nov, totally different features highlighted

6b16d99b588a751934de3ed6c62a0ed4.jpg

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The best thing is to try to follow the Moon through a lunation. Then you will be amazed at the different views you get as the angle of illumination changes.

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BigSumorian did you get that info and those pictures from an app matey? Really interesting to see the different phases and the highlights of features.

Thanks

Rob

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Hi MrCat, the best Moon filter I have found is the ND96(0.9) or ND13 - they both give 13% (light) transmission and enable you to see great detail, best on 4" scopes and above, otherwise the ND25 (ND96(0.6)) for smaller apertures.

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BigSumorian did you get that info and those pictures from an app matey? Really interesting to see the different phases and the highlights of features.

Thanks

Rob

Hi, yes they are from an iOS app called Moon Phase Photo Maps which I think is excellent.

9f8a6495b52b8f3860ee34cc599a10e9.jpg

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A good way to demonstrate what's going on here is to get some mash potato.   A cottage pie is perfect.  And a torch.

Now, turn off the lights in the room and look down on the mash potato.  Shine the torch at the dish.  If you have the torch close to your head, you should notice that it's hard to see any detail in the surface of the mashed spud.

Now, move the torch out to arms length and shine in on the spud from the side.  It should be much easier to see the peaks and troughs in the surface of the pie.

This is what you see on the moon,  when we have a full moon, the sun is almost directly behind you, when it's a qtr moon, it's off to the side.  As the moon is a sphere and not a flat pie dish.  You'll find that the part that is side on to the sun is much easier to observe.

Enjoy the mash ;-)

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Nice Moon phase poster in November S@N mag, gives you views through all next year.

Dave

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Hi, yes they are from an iOS app called Moon Phase Photo Maps which I think is excellent.9f8a6495b52b8f3860ee34cc599a10e9.jpg

Cheers for the response mate, hope they have an android version. I'll have a look. Can go in my folder with about eight or nine or apps then!

Rob

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Cheers for the response mate, hope they have an android version. I'll have a look. Can go in my folder with about eight or nine or apps then!

Rob

If not Rob, I'm sure there are other similar apps on Android

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save money

wear your sunglasses when viewing the Moon, these will reduce the glare

(for other readers, never look at the Sun without the right solar filters on your telescope)

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You can experiment with filters such as variable polarising filters or a Baader Neodymium filter which do help the contrast a bit.

The best bet though is just to observe at different phases of the moon. As the terminator moves across the surface, different craters and other features are highlighted so they are much easier to observe.

For example, this is the moon tonighta6f7c6cf0f1db3854fd27f701feb2e82.jpg

This is the moon on 3rd Nov, totally different features highlighted6b16d99b588a751934de3ed6c62a0ed4.jpg

Need to get that app on my IPhone and IPad. Thanks! : )

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Ahhh of course, being tidally locked you should get to know it pretty quick I guess.

There's quite a few free apps out there too I just found, I've just got one called 'Lunar Phase calendar for the moon' which looks quite good, tho my phone is being a bit cheeky this morning so I can't tell you what it's like yet...

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Try increasing magnification, if you can - that will also make the image dimmer, which might help.

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Cool, thanks! But I think I'm maxed out on magnification with an 8mm eyepiece and 2x barlow with my scope, and I don't have anything smaller yet.

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MrCat

I just whipped up a little spreadsheet for you to help you understand the magnifications involved with your scope.

EyepieceCalculator.xlsx

Here's the vital stats for you...

Scope Diameter 76mm, Focal Length 700mm (I got these from the video from your first post)  Eyepieces that you have 20mm, 8mm and 2x Barlow.

So, here's the answers worked out....

Maximum magnification for that scope 152x anything above this is not likely to resolve, ever.  152x is the theoretical maximum limit, you are more likely to struggle to get anything over about 2/3 of this, so let's round that to 100x maximum practical.  This should be achievable on a good clear, still night when there is no scintillation (when the stars are not sparkling), on the perfect night, you may be able to get above 100x, maybe 110-120 if you are extremely lucky, so I'd stick with 100x.

With the eyepieces that you have, the 20mm works out to 35x magnification, and if you add the barlow this will double to 70x.  This is a good eyepiece for your setup, and should work well both with and without the barlow.

The 8mm worked out to 87.5x magnification.  With the barlow, it's 175x.  So the 8mm should work ok without the barlow, as it's below the 100x, and you should have no problems viewing the moon etc with it.  On a bad night it might result in fuzzy images, but on a good night, everything should be fine.    Don't bother trying to use the barlow with this lens.  that 175x is about the 152x theoretical maximum, so you'll never be able to get a sharp image from it even under the best skies.

Without a barlow, I think the most powerful lens that you'd probable be able to use is a 7mm without a barlow, that'll result in 100x magnification.  A 6mm (116x) might work on a perfect night, and a 5mm (140x) would really be pushing your optics.

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Awesome, thank you so much :)

Well I still haven't looked at anything apart from the moon yet, but I was able to get what I thought was a good image with the 8mm and the barlow 2x combined.

I did just get a bracket to clamp on so I can try and take some photo's too, I'll post some if I manage to make it work ok :)

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The moon is a very bright object, so if anything is going to be able to break the rule of thumb on the maximum magnification that you can get from the moon, it'll be a gibbous moon.  Just don't expect that to work all the time.

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What scope do you have? With my Newt, the dust cover has a little cap in it which you remove to reveal a small aperture. It reduces the brightness. I can't look at the Moon without it!

Alexxx

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A whole in the dust cap acts as an aperture mask, reducing the brightness and increasing contrast, but reducing resolution (the level of detail that you can make out at high magnifications).

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A whole in the dust cap acts as an aperture mask, reducing the brightness and increasing contrast, but reducing resolution (the level of detail that you can make out at high magnifications).

Oooh, I didn't know that! Have to use full aperture when imaging next time!

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