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Greenspring

Absolute Beginner With A Question

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I got my first telescope today and I dived straight into it and actually managed to find a star, I was so excited until I zoomed in on the star and most of it was blocked by what I'm led to beleive is the secondary mirror. My view of the star looks something like this:

 92aac65f780769cc7438b4b417bc7476.png

How can I stop this from blocking my view?? Thank you

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It appears your new scope is doing just fine. That is what you should be seeing if you de-focus a star. All you need to do now is adjust the focuser until the star becomes a sharp point of light.

You're doing fine,

Dave

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You cannot zoom in on a star.

You drop an eyepiece in and focus with that eyepiece, there is no zoom.

If you want a bigger image you change eyepieces and refocus for that eyepiece.

As Dave says you have an out of focus image.

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When I twist the focus knob I get this:

efba1a86c1268d5f630d34c712e105dc.png

Can I not get a closer view without seeing the black circle?

No, a star is a point source of light (except the sun), you won't ever see them as anything else, well they will appear as a tiny disk with a diffraction ring or two perhaps, but essentially they are points of light.

There is plenty to see though, star clusters, both open and globular, planets, the moon, planetary nebulae, galaxies etc

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When I twist the focus knob I get this:

efba1a86c1268d5f630d34c712e105dc.png

Can I not get a closer view without seeing the black circle?

The focus knob DOES NOT make the image bigger or smaller it just focuses what is there, I think you are not quite understanding what the focus knob does, the only was to Zoom in on an object, as you seem to want to try and do, is to put a much more powerful eyepiece in the scope, and refocus.

You need to try on the moon next time it is around, and you will,see better what we mean, but by turning the focus knob the image will go out of focus and you will get the doughnut picture as on the first picture you posted, and then into focus as on the last picture you posted, it will not zoom in and out....

By the way on your first image of the doughnut, the star is not blocked from view from the secondary mirror, the circle you can see around that IS THE STAR but way out of focus, because it is way out of focus, you can see a shadow of your secondary mirror, which is normal, the star is certainly not behind that, it is all around it......... But out of focus

Hope that makes some sense and helps a bit, and sorry if I have repeated myself, just trying to stress to you what you are doing wrong, or you wil not find this hobby enjoyable at all.

Regards

AB

Edited by Astroboffin

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To increase magnification you need to use different eye pieces. Ones with smaller numbers give bigger magnification but there will be an limit as to how high you can go dependant on your scope and seeing conditions.

Zoom eyepieces do exist but good ones cost a lot of money, cheap ones are a waste of money.

Stars themselves don't magnify to give detail but higher magnification can allow you to split two close stars to see double stars. Sometimes they can even be different colours.

Solar system objects respond well to higher magnification and can give great detail.

Sent from my iPad using Tapatalk

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Hello again all.

Tonight I went out again and I actually found Jupiter! It was a great moment for me as I actually saw the moons around it as well as very faintly, lines going across the planet (the pattern). I feel like I need some new eyepeices as I couldn't quite see it in enough detail. I have a celestron 76eq and I'm using the default eyepeices (20mm and 10mm) What kind of eyepiece should I invest in? Cheaper if possible. I'm very interested in seeing planets like Jupiter!

Thanks for all the effort you all put into replying, I now have an understanding on the focus!

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Your scope is a F/9.21. This means that you use this simple formula. Aperture (diameter of primary mirror) is 76mm. Multiply 76 X 9.21 = 699.96mm. Call it 700mm. To find the magnification of an eyepiece: 700 / 10 = 70X for the 10mm eyepiece that came with the scope. You can double that on nights of good 'seeing.' 700 / 5mm = 140X. So either a 5mm eyepiece (the '5' being the focal-length, or F.L., of the eyepiece.

So either a 2X Barlow lens, or a 5mm eyepiece would be good ideas for your shopping list.

Clear Skies,

Dave

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Tonight I went out again and I actually found Jupiter! It was a great moment for me as I actually saw the moons around it as well as very faintly, lines going across the planet (the pattern). I feel like I need some new eyepeices as I couldn't quite see it in enough detail. ...

Okay, I'm going to advise "Don't rush". Seeing conditions can be quite variable - take a little time, and try again over the next few months, perhaps get up early and look at Saturn - but learn to distinguish between bad nights, good nights, and great nights.

"Seeing", to astronomers, is the stability of the air in the atmosphere. On a really stable night (not necessarily the clearest!) is when you'll get your best views of planets. My best views of Jupiter have been through a faintly hazy sky - but under really stable skies. If the stars are twinkling lots, though, the air is unstable - and planetary viewing is harder. I've found that sometimes when the jet stream is overhead you can't get any worthwhile view.

Also, I find that lower magnification can be better for seeing detail. Sometimes less is more. A common mistake is to try too high a magnification, and then you just get a fuzzy mess.

Personally, I think a 5mm might be a bit pushy, and would be inclined to go for a 6-7mm, but like I say, I prefer small but sharp images.

Oh, and do check out the Moon first too.

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