Barlow or Plossl?

[sameer]

Hi,

I recently purchased a skywatcher telescope with this configuration Aperture 76mm Mirror Focal Length 700mm Focal Ratio f/9.2

It came with 25mm and 10mm Plossl eye pieces. It's supposed to have a maximum useful magnification of 150x.

Using a 4mm will give me 175x, so should I go with the Plossl or buy a good quality Barlow? Please help.

[hwsoderlund]

Hi,

I recently purchased a skywatcher telescope with this configuration Aperture 76mm Mirror Focal Length 700mm Focal Ratio f/9.2

It came with 25mm and 10mm Plossl eye pieces. It's supposed to have a maximum useful magnification of 150x.

Using a 4mm will give me 175x, so should I go with the Plossl or buy a good quality Barlow? Please help.

I would get a Barlow. A 4 mm Plossl is going to have very tight eye relief, which means you would have to literally press your eye against the eyepiece to get the full field of view. It is quite uncomfortable. With your existing eyepieces and the Barlow you would effectively have 25mm = 28x, 12.5mm = 56x, 10mm = 70x and 5mm = 140x. That should be plenty with your scope. After that you might think about following up with another Plossl in the 7-8mm range to give you something in between 70x and 140x.

[swamp thing]

This is one that will get mixed opinions. Some peolple dislike using Barlow lenses whilst others swear by them.

Some dislike the extra faff involved when using them, others have been put off by shoddy cheap optics.

Some like the cost effectiveness of not needing the extra eyepieces that a Barlow affords you, others like the smaller eyepiece case

Personally I love em. They mean every time I buy an eyepiece I get two for the price of one.

One piece of advice, if you do decide on going with a Barlow lens, buy the very best one you can (make sure it's a 2" one too). Your eyepiece case will see several different eyepieces throughout your observing life, but a good barloiw will serve you for life.

[Capricorn]

The might say a maximum magnification of 150x but I seriously suspect that you will not get that.

100x may be possible and if the scope is well set up and eyepiece works well with the scope then 120x.

I would not consider a 4mm plossl.

[hwsoderlund]

One piece of advice, if you do decide on going with a Barlow lens, buy the very best one you can (make sure it's a 2" one too).

Generally that is good advice, but I don't think Sameer's scope has a 2" focuser. @Sameer: I think you have this scope, am I right?

[Ganymede12]

I'd suggest a Barlow as it effectively doubles the amount of eyepieces you have.

I was lucky, my Mercury707 came with it's own Barlow!

[paul schofield]

I would go down the Barlow route personally, being that the use it will get with all your eyepieces will far outweigh buying a 4mm e.p. Good luck and make sure you get a good one.

[Fordos Moon]

Just checking if the EPs you have are inch and a quarter you need an inch and a quarter Barlow correct?

[cantharis]

Just checking if the EPs you have are inch and a quarter you need an inch and a quarter Barlow correct?

A two inch Barlow will probably come with a 2" to 1.25" adaptor, which you can use with your 1.25" eyepieces. But should you later get some 2" eps, you will need a 2" Barlow.

[LukeSkywatcher]

I may be wrong, but for this scope i think a 2x barlow would be the best bet. A 4mm EP is a struggle at the best of times and i think it would be even more of a struggle with 76mm aperture?

[earth titan]

TBH with the set up you have, I would go for a larger plossl rather than a barlow. Reasons for this:

The 10mm EP that ships with the scopes, is, regrettably, of very dubious quality. Doubling this to 5 mm would be pointless.

Doubling the 25 will get you to 12, so not far off the current 10mm.

The size of the scope won't allow massive amounts of magnification.

Personally I would go for something around the 35mm+ mark. Get some nice widefield views which will the scope will be best at.

Typed by me on my fone, using fumms... Excuse eny speling errurs.

[sameer]

Thank you all for the suggestion and replies. I did as the consensus said, buy a good quality barlow. Hence, I bought a 2x achromatic Barlow lens and it works like a charm.

Once again, thanks a lot people.

[sameer]

@Nebula Yes you are right! That is the same telescope that I have.