Is a 1.5x Barlow just a tube

[jweaver]

I have been looking at my Barlow and as I understand it, with the lens attached its 2x.. But if I remove it, its 1.5x..

But with no lens, its just a tube.. Is that all a 1.5x Barlow is? Or am I missing something?

Jon

[Merlin66]

I think they mean remove the lens from the Barlow tube and screw it directly onto the eyepiece, like a normal filter.....

[RobH]

No, it's not just a tube....I can understand why you'd ask though.

The amount of magnification is dependant on the distance of the lens in the barlow from the chip/eyepiece, so what Merlin 66 says is probably correct.

Rob.

[Si W]

I think they mean remove the lens from the Barlow tube and screw it directly onto the eyepiece, like a normal filter.....

thats correct. But as Rob has also pointed out, it's also the distance as well, that why when the lens is screwed back onto the tube, because of the distance it turns into a x2 balow.

[brianb]

There's more to it than that: the back focus projection distance does determine the magnification, but it also affects the spherical & chromatic aberration, which can be correct for only one magnification / back focus projection distance. Within a reasonable range the aberrations will be reasonable but with a large change the performance will fall off considerably.