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A little help needed


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Some newbie questions hope you can help,

Can't seem to get good focus when looking a say Jupiter, could this be due to collimating? (Scope is a skywatchers 130p)

Do the ep or mirrors mist up when outside?

Last one, when I do a tour of sky on goto and pick say M66 I can't see anything. I've tried using all ep's Barlow the lot.

Sorry if they are daft questions....total novice

Cheers

Carl

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Eyepieces will mist up sometimes, but I've been told not to wipe them, just to take them indoors for about 10 or 15 mins for them to clear up. Have u checked collimator by looking at a star out of focus? Still a newbie myself so not too clued up myself. Can't help with goto as don't have it. Best book to get that will help you loads is turn left at orion, well worth getting, will answer most of you questions. Good luck

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Welcome.

May be a collimation issue. Take a bright star out of focus quite a lot so it forms a big disc, and look to see if the curcles are equally concentric (google collimation star test or the like). If the "seeing" is bad, again look up "astronomical seeing" on google, then it is tricky to get a sharp image. If you yse an eyepiece with a low number, and you are trying to use too much magnification (maximum is about 30 times your apperture in inches, so if 10 inches the max usedul magnification would be about 300x); to calculate magnification, dicide the focal length of your telescope in mm, by the focal length of the eye piece you are using (also in mm). With a scope with small apperture, and shortish focal length, and keep the magnification within limits, the inage of the planet will be small, if you increase the magnification with a shorter focal length eye piece (lower number) the inage will get [removed word] but MuCH more blurry and impossible to correct this by trying the readjust the focus.

Mirrors and eye pieces can mist up outside. Keep eyepieces you are not using in a glove inside your pocket so they stay a bit warm. A home made dew shield (using a camping mat) may prolong the time you can use your kit before the insides of the scope mista up. If you do mist up, when you pack it away leave it open so air can circulate trough and it can dry out.

There are many reasons m66 won't be on view. Either you have done a poor star alignment (does it put bright named stars in the centre of the field of view when you use goto to say sitius, or arcturus, regulus eyc?). There may be some other reason goto is poor. The likely cause is that goto is good, but the target in question is just very faint and difficult to see. Most galaxies are hard to see with small scopes, especially if you have any light pollution.

James

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Are you viewing from a light polluted site ?

M66 and it's two galaxy companions ( the Leo triplet ) are not easy to see from town, more especially with the "clear" but hazy skies I've had this past several nights.

Best advice - Get out of town !

Try M94, a much easier to see galaxy.

Regards, Ed.

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Are you viewing from a light polluted site ?

M66 and it's two galaxy companions ( the Leo triplet ) are not easy to see from town, more especially with the "clear" but hazy skies I've had this past several nights.

Best advice - Get out of town !

Try M94, a much easier to see galaxy.

Regards, Ed.

Hi Ed,

Yeah its from my back garden, which is fairly dark, however street lights out front etc will cause light pollution.  I will have to go out with scope and see how I get on.  Ill try M94 see if I can find that.

cheers

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Reflectors do not mist up easily, so I think it is down to the optical quality of the supplied eyepieces. M66 and the Leo Triplet as the group is is called, is a difficult one as it is quite feint, you will be able to see it better with really dark skies and a fairly low power ep, say a 24mm or 25mm.

Edited by rwilkey
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When it comes to viewing Jupiter, good seeing conditions are very important and assuming your collimation is spot on, you'll find that on average Jupiter doesn't really need much more than 100x to begin observing some interesting detail. Of course, depending on the night's seeing you can up this magnification .

You've got a lovely scope, but recall, it is one typically used for wide views, rich star field observing. Obviously. there's no reason why you can't do planetary work with it but you may on occassion find you need quite high focal length eyepieces or the Barlow to gain the necessary magnification. If possible, make sure your collimation is good and start out with around 90x to 100x and see how Jupiter appears in your 5" f5 reaching out across the universe some 675,000,000 kilometers. If everything appears sharp and stead, up the magnification a little, see if you can tweak just a bit more detail. You'll probably find you won't be working over 160x to 180x on most nights.

However, If the stars are twinkling naked eye and you're confident with the collimation but still viewing a blurry mess of Jupiter, then depending how dark your skies, spend the night on some of the gorgeous Messier objecs about or some double stars and star fields and come back another night.

Both my 3" and 4" frac can make out the north and south equatorial belts, great red spot, the equatorial band and the north and south polar regions. If you stick with him, gradually, after 15 minutes or so, Jupiter reveals even more subtler markings especially in the north and south temperate belts and larger markings in the north and south tropical zones. So you really shouldn't have too much of a problem with your own scpoe.

Try to view Jupiter as close to the zenith or celestial meridian as possible and I'm sure with a little practice you will be able to see the Great Red Spot, those delicate reddish-brown belts, a darker, greyer hue to the Polar regions, and so on. You'll be able to trace the movement of the Jovian moons and observe their play of shadows over Jupiter in times of transit or of their eclipses by Jupiter's own shadow.

If you can, try to sit with Jupiter for a peaceful twenty or thirty minutes or so on your next observation session, ask yourself questions about what you are seeing, try to identify features as if you were showing someone by your side, perhaps make a little sketch which also helps train the eye to see more.

Regarding DSOs like galaxies. Within reason, darker skies are more useful than aperture. The general problem you'll find with galaxies is that they are quite large and faint objects with a low surface brightness, making them tricky to pick out in the eyepiece. The other problem we have is that a low power eyepiece with a fast Dob under a light polluted sky may result in the view being too washed out. This is due to a large exit pupil larger than your dark adapted pupil.

To counter these issues, the first obvious statement is that practice will help. Galaxy hunting is quite tricky and it does take a while to learn to pick out those fainting whisperings of ghost-clouds. The next is to make the most of your finder scope, the main telescope and a low power eyepiece with something around 4mm to 5mm (max if your skies are not perfect) and working with these three instruments in conjunction, make sure you really know where you should be looking which implies having a decent star atlas by your side. Galaxies don't always jump out at you, and you may have to work the area quite bit. What you're looking for at the beginning is a faint, cloud like smudge.

Hope this helps a little and let us know how you get along :smiley:

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Thanks for the reply Rob. I'm not 100% on the collimation, I'm sure I have viewed Jupiter better than what I'm seeing now. The EP's I have are 25mm & 10mm with a 2x barlow. When the 10mm and barlow are together I get a larger image of Jupiter but its not as sharp as I think it should be? Think I defo need to check the collimation.

Cheers

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Thanks for the reply Rob. I'm not 100% on the collimation, I'm sure I have viewed Jupiter better than what I'm seeing now. The EP's I have are 25mm & 10mm with a 2x barlow. When the 10mm and barlow are together I get a larger image of Jupiter but its not as sharp as I think it should be? Think I defo need to check the collimation.

Cheers

Hi again Carl.

It never hurts to check collimation, and could perhaps be why Jupiter is not as sharp as you would like.

However, less than sharp views have other causes, the main one being the steadyness of the atmosphere ( the 'seeing' as it's often called ).

Also, focus very carefully, and don't over magnify, smaller but sharper trumps larger but fuzzier...

Regards, Ed.

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Thanks for the reply Rob. I'm not 100% on the collimation, I'm sure I have viewed Jupiter better than what I'm seeing now. The EP's I have are 25mm & 10mm with a 2x barlow. When the 10mm and barlow are together I get a larger image of Jupiter but its not as sharp as I think it should be? Think I defo need to check the collimation.

There are just so many variables when it comes to viewing that the only thing we can do is the best possible :smiley: It's like running through a little list: collimation - check, seeing - check, transparency - check, fatigue - check :grin:

But there's also something else worth pointing out at this junction. An 5" f/5 is not an ideal high-mag, or planetary scope. Being of such a short focal length, it relies on very short focal length (FL) eyepieces to gain significant magnification. A longer FL telescope allows one to use longer FL eyepieces, which in turn would give one more eye relief making viewing a more comfortable possibility.

To get around 90x to begin viewing Jupiter's details, for example, you're going to need a 7mm to 8mm EP and unless it has decent eye-relief, you may find it a little uncomfortable to use. As you'll appreciate, magnification is equal to the telescope's FL divided by the EP's FL. So, if I wanted to enjoy Jupiter, for example, at around an average night's viewing of 140x, say, I'd need an eyepiece of around 4.5mm.

So, just looking at the numbers, I figure that if you want to do some serious high magnification viewing, you will be pushing your system. You have a beautifully crafted wide-field scope, it's going to be amazing on so many gorgeous objects and these telescopes can look at planets all the time but I think it is helpful to also have reasonable expectations of what is realistically possible from our gear :smiley:

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Thanks for the reply Rob.  I was not really wanting to do high magnification viewing (although it would be nice) I was just trying to get an idea if its likely that my scope needs the collimation looking at.  Being a total novice I'm not sure how clear these planets etc should look on a clear night.  I think its been better than what I'm seeing at the moment in terms of sharpness if that makes sense. 

If when I look at Jupiter I've seen a nice sharp image albeit small, however lately it has become blurred round edges even on clear nights?

Cheers

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