Is it me, the moon or my scope? - Page 2

OzStarGazer · #21 06-05-2015, 05:15 PM

Quote:

Originally Posted by BilliGoatsGruff

What brand would you recommend for eyepieces? Celestron?

I bought the 8mm one from the UK. It is a Starguider ED. And I bought the 6mm on Aliexpress. It is a TMB II. TMB is cheaper than the Starguider. They are also cheap on eBay, but postage was free from China.
Of course now that the AUD has fallen everything is a bit more expensive...

For high magnifications you also need really clear nights with no turbulences, which unfortunately have become very rare here!

BilliGoatsGruff (Billi) · #22 06-05-2015, 05:19 PM

So you think the 10mm Super Plossl? I haven't had a chance to use my scope because of yucky weather and then this whole mix up so I'm not too worried about a new eyepiece yet. It would be good for future reference though. Maybe I'll shout myself a birthday present

inertia8 (Australia) · #23 06-05-2015, 05:59 PM

Do you wear eyeglasses in general and/or when using the scope?

BilliGoatsGruff (Billi) · #24 06-05-2015, 06:06 PM

Quote:

Originally Posted by inertia8

Do you wear eyeglasses in general and/or when using the scope?

I have to wear glasses all the time.. That made it even worse with the 10mm. At least the 25mm has heaps of eye relief. I'm guessing that would determine what eyepieces to get?

inertia8 (Australia) · #25 06-05-2015, 07:11 PM

That's correct, I suffer astigmatism and find it easier to keep my glasses on all the time and through trialing different eyepieces have found 15mm eye relief to be the absolute minimum for me.

Remember that you will need to get 1.25" eyepieces and advice for this little scope is to keep them under 250g.

I began with a Bintel/GSO superview 15mm for $49, which is good for the price (aFoV is 68deg and ER is 15mm). To get it to come to focus in the little 130p I have to loosen the strut tubes and retract them by about 1cm or so.

The BST Starguider/Explorer (also sold under Astrotech Paradigm and Agena Dual ED) range, as suggested above, has a pretty good eye relief and gets reasonably favourable reviews. The 8mm one has 60deg apparent field of view (aFoV) and 16.5mm eye relief (ER) and might be a suitable replacement for your 10mm.

Good Luck

Sato (Dom) · #26 06-05-2015, 07:33 PM

Hiya. I've had the SW 130P Heritage for 6 months now. The 25 & 10 eps work just fine for me...ok, maybe not the greatest but I've seen the bands of Jupiter from inner Sydney so they can't be that bad?

BilliGoatsGruff (Billi) · #27 06-05-2015, 07:56 PM

Quote:

Originally Posted by Sato

Hiya. I've had the SW 130P Heritage for 6 months now. The 25 & 10 eps work just fine for me...ok, maybe not the greatest but I've seen the bands of Jupiter from inner Sydney so they can't be that bad?

Ive only had mine for a week, so I still have a lot to figure out

BilliGoatsGruff (Billi) · #28 06-05-2015, 08:09 PM

Quote:

Originally Posted by inertia8

That's correct, I suffer astigmatism and find it easier to keep my glasses on all the time and through trialing different eyepieces have found 15mm eye relief to be the absolute minimum for me

My daughter has astigmatism so I understand completely where you're coming from

My left eye is lazy and it turns out slightly so the 10mm is almost useless as it's so hard for me to focus. I have to cover my left eye (my right eye is dominant so it is pretty much impossible for me to use my left) or all I end up seeing is a fuzzy mix of the ground and the sky haha.
I think I'll just stick to the 25mm wide relief until I can get a new eyepiece.

BilliGoatsGruff (Billi) · #29 06-05-2015, 09:02 PM

Would it be worth getting a barlow to go with the 25mm or should I just get another eyepiece?

Sato (Dom) · #30 06-05-2015, 10:04 PM

Quote:

Originally Posted by BilliGoatsGruff

Ive only had mine for a week, so I still have a lot to figure out

Oh sure, but look at my post count...I'm still crawling

.

My point was simply not to race out & throw money at eps until you're sure it will help

.

inertia8 (Australia) · #31 06-05-2015, 10:42 PM

I can use the 10mm if I take my eyeglasses off and am careful not to hit the lense with my lashes, give that a go first?

AstralTraveller (David) · #32 07-05-2015, 10:25 AM

If you are only long sighted or short sighted you shouldn't need to use glasses. You can compensate with the focusser. That's what my wife does. If you have astigmatism you may need to use glasses. Generally the larger the scope's exit pupil the more effect the astigmatism will have.

Exit pupil is the size of the beam of light coming out of the ep. It is can be calculated as either Exit pupil = aperture of scope / magnification OR Exit pupil = focal length of eyepiece / focal ratio of the scope. Focal ratio = focal length of scope / aperture. Don't do calculations in inches. Measure everything in mm.

The problem you are having is nothing to do with the quality of the ep. It's true that the cheapest upgrade you can do now is better eps but wait for a fair while before you do. My recommendation is to make a plan (remembering that one day you -will- get a bigger scope!) for your whole collection and then buy eps as the budget allows. Otherwise you risk winding up with an ep box that looks like the proverbial committee's camel.

BilliGoatsGruff (Billi) · #33 07-05-2015, 11:20 AM

Quote:

Originally Posted by AstralTraveller

If you are only long sighted or short sighted you shouldn't need to use glasses. You can compensate with the focusser. That's what my wife does. If you have astigmatism you may need to use glasses. Generally the larger the scope's exit pupil the more effect the astigmatism will have

I did try taking my glasses off and I think it made the image fuzz out a bit.

Weather conditions have been terrible which means I haven't had a chance to test it all out again. Fingers crossed we will get clear skies tonight!

OzStarGazer · #34 07-05-2015, 11:39 AM

Quote:

Originally Posted by BilliGoatsGruff

I did try taking my glasses off and I think it made the image fuzz out a bit.

Weather conditions have been terrible which means I haven't had a chance to test it all out again. Fingers crossed we will get clear skies tonight!

Focus is different with or without glasses, as well as with different people so you will just have to refocus after taking them off.
I hope the weather will improve where you are. It just did here. Hopefully it will last.

OzStarGazer · #35 07-05-2015, 11:56 AM

Quote:

Originally Posted by BilliGoatsGruff

Would it be worth getting a barlow to go with the 25mm or should I just get another eyepiece?

In general people seem to think that it is better to have more eyepieces than using a Barlow. I find the Barlow to work OK (and I have a cheap one), for a beginner at least (although I agree that more eyepieces would be better).
PS: I have only used the Barlow for the moon.
PPS: The "long" 3x Barlow won't work well with our scope. I made the mistake of buying one and then had to buy a short one (incredibly cheap, but it still does an OK job on clear nights). (Luckily I also have another scope I can use the long one with.)

Nikolas (Nik) · #36 07-05-2015, 03:02 PM

If you have focus lock screws, make sure they are loose enough to allow focus travel, sometimes you can turn the focusing knobs and the barrel doesn't move so nothing happens. Iv'e been caught out once or twice like that in the past.

AstralTraveller (David) · #37 07-05-2015, 03:35 PM

Quote:

Originally Posted by Nikolas

If you have focus lock screws, make sure they are loose enough to allow focus travel, sometimes you can turn the focusing knobs and the barrel doesn't move so nothing happens. Iv'e been caught out once or twice like that in the past.

I don't think this is relevant on a helical focusser, but check anyway.

BilliGoatsGruff (Billi) · #38 10-05-2015, 07:59 AM

So I finally scored a break in the seemingly endless clouds today and got to try my scope again. This time I made sure the 25mm was fitted instead of the 10mm (haha silly me) and I made sure that it was fully extended. It was just on dawn, which meant no stars, but I got the most glorious view of the moon! I really wasn't expecting it to be so crystal clear.

However, after a bit of ogling I decided to pop in the 10mm for a squizz. What are those things supposed to be used for? The moon went as fuzzy as the clouds that were drifting around and no matter how much I tried to focus, it didn't get any better!

OzStarGazer · #39 10-05-2015, 08:54 AM

Quote:

Originally Posted by BilliGoatsGruff

However, after a bit of ogling I decided to pop in the 10mm for a squizz. What are those things supposed to be used for? The moon went as fuzzy as the clouds that were drifting around and no matter how much I tried to focus, it didn't get any better!

If there is an astronomy club near you maybe you could join so you can have a look with somebody else? The SW is easy to carry, so you could go to a meeting with your scope.
I don't know, I am not happy with the 10mm eyepiece, as I said before, but I can still focus, so I am not sure why you can't. It is also possible that even if you didn't notice any turbulences with the 25mm eyepiece you noticed them with the 10mm eyepiece, so the lack of focus were the turbulences. Turbulences are also present when the sky is clear. Sometimes I look at the moon in the afternoon (no clouds) and the moon literally floats in front of my eyes!

barx1963 (Malcolm) · #40 10-05-2015, 09:27 AM

When I still used my old 130mm scope, I almost never used the 10mm EP that came with it. I still have it in my kit, occasionally pop it in a scope to remind myself how hard to use these things are!
They are designed to be used for higher power, but applying the principle of TANSTASFL ("there ain't no such thing as a free lunch" for anyone not familiar with the works of Robert Heinlein), everything has a cost, and the price of higher magnification is a much tighter focus point, increasing visibility of poor seeing (atmospheric distortion) and tighter eye relief.

It is probably nothing wrong with the scope or eyepiece, simply a consequence of the laws of optics! So relax, use the 25mm and enjoy the views.

Malcolm