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aser hisham

underwhelming observing

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I recently bought a 6 mm eyepiece , I have a 2x barlow , my telescope is a 6 inch f5 reflector . I was looking forward to viewing Saturn with my new eyepiece and when I did I didn't really see any detail , I could barely see the gap between the planet and the rings . my telescope is a low quality one so is that the reason ? I saw Jupiter once with a celestron 8 inch sct and the detail was stunning so is the quality the reason or the mirror diameter ?

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I'll let some others weigh in, but it seems to me you're pushing your scope too hard. Theoretical max magnification for you is around 300x. Realistically it's going to be about half that, maybe a little more. You're trying to push it beyond that to so it's not surprising to me that you're not seeing much detail.

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Can you let us know the make and model of the telescope, eyepiece and barlow lens ?

Seeing conditions, scope collimation (the accurate alignment of the mirrors) and observer experience will also play a major part in the quality of the views.

With all the factors favourable and the scope optics being of good quality, a 6" scope should be able to show the sort of detail shown below at around 200x-250x:

 

sat.JPG

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Aser, your scope is relatively fast so collimation will be more critical for seeing good detail at high power. Have you checked the collimation? Cooling, or at least acclimatising to the outside temperature is also important and takes around 30 to 45 mins.

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@Stu the telescope is new so it should be well collimated , I leave it for sometime before observing and I also take a long time when viewing the planets

 

Edited by aser hisham

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36 minutes ago, aser hisham said:

@Buzzard75 even without the barlow lens there isn't much detail

 

But with less than exceptional seeing conditions, the higher you push the magnification the worse the image will get. There are a lot of other factors potentially at play as well as the others have suggested. A little more information about your setup and location may help shed some light and get you on the right track.

Just because it's new doesn't mean it's collimated. It could be put way out of alignment during shipping or just moving it from inside to outside for setup.

Edited by Buzzard75
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When I had my 6" Skywatcher I used a 8 mm eyepiece and could see the Cassini division, being a fast scope I.E F5 i had to tweak collimation every time I used it.

Edited by wookie1965

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I would check the collimation. Even if set correctly at the factory it is the bumpy journey to you that is likely to knock it out of collimation. 

The atmospheric conditions also play a big role. Try to observe the planet when it is at its highest in the sky so you are looking through the least amount of atmosphere. If possible have your telescope set up so that you are observing over vegetation rather than man made structures that release heat long into the night. 

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7 minutes ago, aser hisham said:

@Stu the telescope is new so it should be well collimated , I leave it for sometime before observing and I also take a long time when viewing the planets

 

As buzzard75 says, being new doesn't mean it is collimated. Certainly do a star test with it to check.

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I will try to observe Saturn when it's at it's highest , as for the collimation , I have always been kind of afraid because collimation can ruin everything so is it that dangerous ? and how do I collimate it ?

 

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Lot of good info here. It's not dangerous at all and it's extremely unlikely that you will do anything irreparable. It's just a matter of adjusting a few screws and knobs.

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6", f/5 that means 750mm focal length, forget the barlow and use just the 6mm eyepiece for 125x.

If the scope is decently set up - guessing it is a reflector - then that should give a reasonable view. BUT Saturn will always be small, do not go expecting to fill the eyepiece with an image.

Suspect that the magnification is too much (forget the claims made, they are generally way over the top) and that the barlow could be poor. Not sure what 6mm eyepiece it is that you have.

If it is a reflector then the sceondary will also be causing the image to be a little "soft". That is simply a property of have a central obstruction.

In quick response to your latest reply, you make a collimation cap, generally people use an old 35mm film caniister with a 1mm hole drilled centrally. There is "better" but not sure if they would post to Egypt - maybe email astroboot and enquire about shipping. Astroboot sell what they call Poshplugs and most but maybe not all have a suitable hole through them under the AE sticker. Peel off the sticker and you have a really nice collimation cap.

Edited by ronin

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A star test is a very good way to check and adjust the collimation of a scope.

 

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Before touching anything I would do a star test to see if a defocused star shows a concentric pattern when centred on the field of view.

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I will begin collimating it now , I will use Polaris but I don't know which of the screws are the ones for collimating , can anyone help me ? thanks

IMG-20171024-WA0001.jpg

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Difficult to say, not knowing the brand of scope. I'd guess that the outer ones (with large washers ?) could be the collimation bolts and the smaller ones inside them are locking bolts. As Stu said though, do the star test first before adjusting anything. If you get nice concentric rings either side of sharp focus and they look similar either side of focus, the collimation is good and no adjustments are needed.

Polaris is the best star to pick because it does not move.

 

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