Using the barlow lens.

[Jupiter_19]

Hello, Im using a Celestron AstroMaster 90az telescope, i have the standard 20 and 10 mm eyepieces. After deciding that its not enough i got today a Celestron barlow lens X2 and a couple of eyepieces( 6mm and 15mm).

What is the right way to place the barlow lens, before or after the diagonal?
It says on the manual that it should be placed before the diagonal, though i get focus only when its placed after the diagonal.

[Pleiades M45]

Not totally sure what you are trying to say but using a Barlow you would be using it after the diagonal. 

The Barlow would be placed in the star diagonal once it has been properly place into your scope.

[Laurie61]

Barlows are used with an eyepiece fitted, this produces the rated magnification factor shown on the barlow. If you move the barlow further back along the optical train it will increase the magnification factor, although this is not necessarily a problem as long as you are aware of the effect.   

[Jupiter_19]

On the manual it says :  first the barlow then diagonal and then the eyepiece. Though im able to focus only when i do it by that order : diagonal then barlow and then the eyepiece.

[Pleiades M45]

On the manual it says :  first the barlow then diagonal and then the eyepiece. Though im able to focus only when i do it by that order : diagonal then barlow and then the eyepiece.

 

The order that you have configured is correct.

1. Diagonal

2. Barlow

3. Eyepiece

[LukeSkywatcher]

Hi. You place the EP you want to use into the open end of the barlow and then insert the closed end of barlow (with the glass lens) into the end of the diagonal which is sticking out of the telescope tube. Tighten all the screws also.

[Cornelius Varley]

Normally the barlow is placed between the diagonal and eyepiece. if the the barlow is in front of the diagonal you will get an increase in the effective magnification power of the barlow,

[Pleiades M45]

Can you show a picture of what it says in your manual?

This is odd.

[RT65CB-SWL]

Shalom 'Jupiter_19' and welcome to SGL.

Oddily enough I asked the same question last year or the year before.

It is strange why some manufacturers say 'before...' and others say 'after...'

It got me confused too!

I now always use my Barlow lens after the star-diagonal.

[LukeSkywatcher]

Shalom 'Jupiter_19' and welcome to SGL.

Oddily enough I asked the same question last year or the year before.

It is strange why some manufacturers say 'before...' and others say 'after...'

It got me confused too!

I now always use my Barlow lens after the star-diagonal.

I suppose its down to which way you look at it. If you are talking from the EP end, then the barlow goes "before" the diagonal. If you are talking from the diagonal end, then the barlow goes "after" the diagonal. In both cases, the barlow is in the same place, its just a case of which end you consider starting from.

scope>diagonal>barlow>eyepiece

OR

eyepiece>barlow>diagonal>scope

Both of the above are the same and correct.

[Pleiades M45]

I suppose its down to which way you look at it. If you are talking from the EP end, then the barlow goes "before" the diagonal. If you are talking from the diagonal end, then the barlow goes "after" the diagonal. In both cases, the barlow is in the same place, its just a case of which end you consider starting from.

scope>diagonal>barlow>eyepiece

OR

eyepiece>barlow>diagonal>scope

Both of the above are the same and correct.

Well you found out everyone's confusion. There you go.

[LukeSkywatcher]

Well you found out everyone's confusion. There you go.

Have i de-confused the situation or just made it more confusing.

LOL.

I normally chuck manuals away and wing it. Yrs of putting together flat pack furniture has taught me never to rely on manuals.  

[Jupiter_19]

Thank you for the help guys.

'LukSkywatcher' u got pretty cool name lol.