Eyepiece and Barlow configuration

[GasGiant]

Hi folks

Can you have a look at the images please and give me some advice ?

Pic 1, 9mm Plossl & 2x Barlow

Pic 2, Ive unscrewed the barlow lens

Pic 3, Ive attached it to the 9mm barrel

Will I get two times like this, or does the distance from one lens to another need to be specific length ? 

 

Thank you

 

Carl

[Cornelius Varley]

11 minutes ago, GasGiant said:

Will I get two times like this, or does the distance from one lens to another need to be specific length ? 

 

With that configuration the magnification will be about 1.4x.  2x magnification will only be achieved using the barlow lens as supplied. 

[PeterC65]

The magnification of a Barlow Lens depends on the distance between the Barlow lens and the lowest lens in the eyepiece barrel. So where the Barlow Lens is located with respect to the eyepiece matters. The location of the lowest lens also varies between eyepieces, so the quoted magnification of a Barlow Lens is not generally exact. Some Barlow Lenses are designed for use with particular eyepieces and only then will you get the specified magnification.

 

[GasGiant]

Ok thanks guys.

I'm not sure how I can use it then as it doesn't seem to 'stack' on anything else 

[bosun21]

1 hour ago, GasGiant said:

Ok thanks guys.

I'm not sure how I can use it then as it doesn't seem to 'stack' on anything else 

What do you mean when referring to “stacking”?

[Elp]

What are you trying to achieve, the Barlow lens stays on the bottom of the Barlow, the Barlow goes into your diagonal and then an eyepiece into the Barlow. Are you trying to do something completely different?

[Louis D]

6 hours ago, PeterC65 said:

The magnification of a Barlow Lens depends on the distance between the Barlow lens and the lowest lens in the eyepiece barrel. So where the Barlow Lens is located with respect to the eyepiece matters. The location of the lowest lens also varies between eyepieces, so the quoted magnification of a Barlow Lens is not generally exact. Some Barlow Lenses are designed for use with particular eyepieces and only then will you get the specified magnification.

 

Actually, its the distance to the focal plane of the eyepiece that matters, not the location of the lower lens.  This is particularly true for eyepieces with internal field stops due to the use of a Smyth lens group.

[Mr Spock]

A x2 Barlow will only be x2 when the focal length of the Barlow coincides with the focal plane of the eyepiece. 

I have a Meade 140 which averages around x2.4 and not the x2 it's supposed to be. I took the nosepiece out and attached it to a SvBony extension tube to get closer to x2.

[Albir phil]

Hi you put the Barlow lens into the diagonal,as a complete unit, then your eyepiece fits into the Barlow lens 👍

[GasGiant]

20 hours ago, bosun21 said:

What do you mean when referring to “stacking”?

Sorry. I meant putting in the correct place, ie stack it on the 9mm. Wrong terminology 

[GasGiant]

19 hours ago, Elp said:

What are you trying to achieve, the Barlow lens stays on the bottom of the Barlow, the Barlow goes into your diagonal and then an eyepiece into the Barlow. Are you trying to do something completely different?

What confused me was the threaded portion on the barlow

 

so the barlow into the telescope and the eyepiece into the barlow. But whats that threaded section for ? Thats what confused me LOL

Edited January 8 by GasGiant

[GasGiant]

Forget this thread. Ive been an idiot ! 

I just remembered, I bought this to go with an adaptor for my camera ! Thats what the thread is for lol 

Stand at ease 😂

[Louis D]

Yep, T-thread/mount for camera adapters.  It's M42x0.75.  Not to be confused with the M42 mount which is M42x1mm and was also used for camera lenses.