Barlow Lens

[rizzi]

Hello, this might be a very stupid question but why do I see everything all hazy with a barlow 2x?

The focuser is twisted to the max and still the view is really out of focus but it does magnify.

Are my barlow lens of the worst quality or am I doing something stupidly wrong?

Also, would it be better to buy a barlow lens or separate high power eyepieces for magnification?

Thanks

[Peter Drew]

Hello Rizzi.

Forgive me if I'm wrong, but is there just a chance that you are using just the Barlow without an eyepiece?, it has happened before . Even poor Barlows usually give a reasonable focus. A mention of what telescope you are useing would be helpfull.

[Qualia]

Hello, this might be a very stupid question but why do I see everything all hazy with a barlow 2x?

Not a stupid question at all! Maybe transparency and seeing conditions aren't that good to be upping the magnification twofold, or again, maybe you're upping that magnification just a little too much by using the barlow, it would also depend on what exactly you're looking at when you're using the barlow.

[E621Keith]

Hi Rizzi, can you tell us about the scope and eyepieces you were using?

It may be caused by:

1. Too much magnification

2. Insufficient focuser travel

3. Collimation problem with the scope

4. Insufficiently cooled scope

etc...

[cosmological]

And also what barlow lens are you using?

[brantuk]

The thing most newbies don't realise is that being land based we are looking through a lot of atmosphere whenever we peer at an object in the night sky. The atmosphere has a lot of imperfections and it is constantly moving. When we magnify an object we also magnify these imperfections.

By imperfections we mean cloud, moisture, heat haze, light bounce (from Earth), dust particles, wind or breeze and I dare say a few more. Shine a torch in a dark room and you'll see loads of bits floating around in the beam if you look closely. To get through the crud can be a miracle at times, but the atmosphere is usually at it's clearest on a cold, dark night with good transparency.

Pick objects when they are high in the sky, you'll be looking through least and thinnest atmosphere, if you look at an object near the horizon you'll be peering through much more and much denser atmosphere. Choosing a good dark site at new moon (ie when the moon isn't around) will help immensely, bringing out all those faint fuzzies.

Choose sensible magnifications - too high and the object will become faint and grainy at high powers - too little and you can hardly make it out. For some objects low power is better. Somewhere in between you can achieve good clarity and definition. In UK "seeing" conditions I find most good viewing is done around 150x to 200x mag - subject to the limit of the telescope. On odd ocassions you can go a bit higher than 200x but seeing needs to be good. Of course - better quality eyepieces help as well - those supplied with the scope can be "just enough" to get you going - the difference with even a modest cost eyepiece can transform your viewing.

In my experience of India (Calcutta) the atmosphere is pretty hot, humid, and dusty most of the time - you're not far from there so you have your work cut out for you. Hth

[cotterless45]

Yep,seeing conditions are king.

I think folk would be surorised at the amount of detail at x100-x120 on planets and the Moon compared to difficult viewing at increased magnification. There are very few nights when a x2 Barlow gives a pleasing view at higher magnifications here in Middle Earth.

You might like to unscrew the end of the Barlow and screw it into the bottom of your ep. This'll give you x1.6 instead of x2.

Nick.

[rizzi]

Thanks for so many feedbacks guys

Well I'm using a Skywatcher Heritage 130p (baby dob 5" 650mm focal length) which shipped with a 25mm and a 10mm eyepiece. I ordered a cheap barlow 2x with it which was about 12 quid (sorry im writing quid coz my keyboard is an american :@ ) .

When I put the barlow and the 25mm eyepiece, the moon just looks really really out of focus so no need to mention about the 10mm lol... (moon looks superb and crystal clear with the 10mm itself, even crispier but smaller with my 25mm)

The skies have been fog free but there is a lot of light pollution which I think shouldn't interfere in the clarity of the moon.

[brantuk]

With the moon you should be ok because it's close (only 1/4 million miles away) and big. Light pollution tends to affect your view of the faint distant objects like galaxies which are thousands of light years away. You can barely see any of them when the full moon is up or if you have a lot of street lights and lights from buildings.

Looking at your eyepieces - the 25mm is not brilliant but should be ok, the 10mm will magnify on a clear night but imho is not very good, the barlow can be used with the 25mm though it also is not the best. If you barlow the 10mm I doubt you'll have any success at all - it's a combo I chose not to use when I had mine.

You'll be pleasantly surprised how much better the views will be with a modest cost eyepiece. You could pick up a nice s/h low power wide angle Meade or Celestron eyepiece for around £30-£40. Someone may suggest some good planetary eyepieces for you - but try not to magnify more than about 80% of your scope's practical limit. Hth

[E621Keith]

It sounds like a focuser travel problem. A balow moves the focal point further out.

Turn the focuser until it's fully extended, then undo the set screw holding the barlow. Look through the eyepiece and barlow and slowly pull them out of the focuser, see if the focus improve. If it does then it means your focuser doesn't have enough travel and this can be fixed by getting an extension tube like this one

http://compare.ebay.co.uk/like/160842048603?var=lv&ltyp=AllFixedPriceItemTypes&var=sbar&adtype=pla&crdt=0

[rizzi]

n it means your focuser doesn't have enough travel and this can be fixed by getting an extension tube like this one

http://compare.ebay....type=pla&crdt=0

Yep I think one of these because I've tried everything and nothing works. This may just solve it!

[rizzi]

You might like to unscrew the end of the Barlow and screw it into the bottom of your ep. This'll give you x1.6 instead of x2.

Nick.

Tried this today and it does up the magnification. Both Jupiter and the Moon appeared a bit larger this way. Well it doesn't screw on my EPs so I used a bit of sellotape to stick it underneath my EPs lol

With the normal barlow setup of putting the EP in the barlow tube, the image just appears as if im looking through a frosted glass for both the 25 and the 10 EPs.

Thank you so much for this brilliant little idea!

[rizzi]

This what I am doing right now to the Barlow. It does increase the magnification slightly, although the clarity of objects decrease a bit, esp the Moon since its the closest and brightest thing.