What's the difference between

[Essex Stargazer]

A Barlow

A powermate

and

A tele extender

got me a bit confused

[faulksy]

a barlow doubles your magnification thats if its a 2x barlow not many like them.a power mate does the same as the barlow but is opyicaly perfect doesnt alter eyerelief like the barlow and retains same field of view. a telextender i think does the opposite to the barlow but some one else will correct me in less than 5 mins. hope this helps

[John]

The TeleXtender seems, apart from other things, to be Meades answer to a Powermate. The one I had worked in a very similar way and did not alter either the focal position or the eye relief. The Powermates are superb devices though - they just seem to "get out of the way" leaving only the increased magnification.

[Cornelius Varley]

There is some useful information on the Televue website Tele Vue Optics: Powermates

Peter

[newman]

Two main differences between a barlow and a powermate are:

1) A powermate won't alter eye relief. A barlow will. The effect is more noticable on longer f.l. eyepieces.

2) A powermate will be parfocal or almost parfocal with an eyepiece. Meaning you won't have to refocus (other than a possible minor tweak) when switching from eyepiece only to ep + powermate.

Of course, a powermate is a premium quality piece of glass, while a barlow's quality will depend largely on the manufacturer - that's not to say that there aren't excellent barlows out there; there just aren't crappy powermates

In case you were wondering, your field of view with a given eyepiece will be the same whether you use, for example, a 2x powermate or a 2x barlow. Neither will alter the eyepiece's AFOV, and both will "simulate" a longer focal length of your scope, so the formula to calculate your TFOV is pretty much the same using a powermate or a barlow.

[michael.h.f.wilkinson]

My two TeleXtenders work just like PowerMates, they get out of the way. I mainly use them for planetary imaging. The barlow the kids have in their scope requires substantial refocusing, unlike the TeleXtender.

[John]

...In case you were wondering, your field of view with a given eyepiece will be the same whether you use, for example, a 2x powermate or a 2x barlow. Neither will alter the eyepiece's AFOV, and both will "simulate" a longer focal length of your scope, so the formula to calculate your TFOV is pretty much the same using a powermate or a barlow.

In theory this is correct but I've found some barlows vignette with some eyepieces, eg: the Celestron Ultima 2x used with a 16mm Nagler.

[newman]

Interesting, John. I guess I lucked out and never ran into such a combo, but good to know.

[Essex Stargazer]

I purchased a Meade 3x TeleXtender

not sure if I should take it back and get a Tele vue Powermate ?

[michael.h.f.wilkinson]

I purchased a Meade 3x TeleXtender

not sure if I should take it back and get a Tele vue Powermate ?

I have both the 2x and 3x TeleXtenders, and they are great quality pieces of kit. I combine them with all my 1.25" EPs to great effect. I do not believe the PowerMates would be better.

[faulksy]

I have both the 2x and 3x TeleXtenders, and they are great quality pieces of kit. I combine them with all my 1.25" EPs to great effect. I do not believe the PowerMates would be better.

worth considering then, thanks for that