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Planetary filters


Paul Manuell

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2 minutes ago, Phillyterp85 said:

Thank you so much for the tip on focus!  Im assuming that focusing strategy works on any object im trying to get a focus on?

 

Mostly on round objects that are small - like bright stars or planets.

Moon is often too big and you'll see just a part of circle in the eyepiece (depending on magnification - you might not see whole moon even when in focus). It won't help in daytime either if you want to observe ships on horizon or maybe bird or wild life (just be careful not to point the scope near the sun when you observe during the day).

But don't worry, you only need a bit of practice with your scope and you'll instinctively know how to move focuser and get in correct focus regardless of the object in question.

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13 minutes ago, vlaiv said:

Mostly on round objects that are small - like bright stars or planets.

Moon is often too big and you'll see just a part of circle in the eyepiece (depending on magnification - you might not see whole moon even when in focus). It won't help in daytime either if you want to observe ships on horizon or maybe bird or wild life (just be careful not to point the scope near the sun when you observe during the day).

But don't worry, you only need a bit of practice with your scope and you'll instinctively know how to move focuser and get in correct focus regardless of the object in question.

Thanks so much!  I have had some success with getting a decent shot of the moon.  Was able to play with the focus until I was able to clearly see some detail. Here’s one I got the other night with my 9mm eyepiece (78x magnification) and I had a moon filter on.

 

 

D1A52AFE-BFB9-45F2-819C-A575139634A4.jpeg

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1 minute ago, Phillyterp85 said:

Thanks so much!  I have had some success with getting a decent shot of the moon.  Was able to play with the focus until I was able to clearly see some detail. Here’s one I got the other night with my 9mm eyepiece (78x magnification) and I had a moon filter on.

 

 

D1A52AFE-BFB9-45F2-819C-A575139634A4.jpeg

Magnificent!  

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  • 7 months later...
On 30/01/2023 at 15:34, vlaiv said:

It is very hard to depict what is seen at the eyepiece when looking at computer screen image.

First - you need to be at exactly "prescribed" distance from computer screen in order to make Jupiter image on the screen appear the same size in the eyepiece - and that will depend on pixel pitch of the screen used.

Second - there are various cognitive effects that come into play. When looking at the eyepiece - one just sees patch of the sky and a planet. There are no reference points to be able to judge size.

You are correct - 9mm eyepiece with 700mm FL gives about x78 magnification.

That is actually plenty of magnification for target like Jupiter. If current apparent diameter of Jupiter is ~36" - then x78 magnification will make it about x1.5 larger than the full moon when viewed with naked eye.

We can see some features on the full moon - and yes, you should be able to see some features on Jovian disk at x78 as well. At least main belts.

Here is handy way of knowing if you have focus right - you already know that Jupiter will look like large circle when out of focus. You can use that circle to roughly judge where is correct focus position. As you change focus (rotate focuser knob) - diameter of that circle will change - it will either grow or shrink - you should go in direction of shrinking the circle.

At some point - circle will be the smallest and if you continue rotating knob in same direction - it will start to grow again.

This point where circle is the smallest is place of actual focus. Once you reach it - pay attention to the detail on the planet and try to tease out detail - tweak the focus as needed to make features on planet sharp. Do be careful - there is spot just before perfect focus that focuses on disturbance in our atmosphere rather than planet itself - if you focus on that - you will see actual air - much like warm air over fire - distorting the planet. You don't want to focus on that - try to focus on actual planet, but do understand that atmosphere will make it difficult as everything will dance around more or less (depends how calm the atmosphere is).

I know this post was months ago, but just wanted to reply and say thank you!  I took a few months off and brought the telescope back out this weekend.  I used this technique, and was able to get a great viewing of Jupiter and 5 of its moons.  I then used this same approach for Saturn and was able to see Saturn and its rings!  It was amazing.   Unfortunately couldn’t get a picture as the phone adapter was being finicky.  But just seeing it was so cool!

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