Televue 8-24mm zoom

[dweller25]

After reading Andrews (AstroPhethean) excellent review of the Hyperion 8-24mm zoom I decided to buy the Televue equivalent as the idea of being able to find exactly the right power for the seeing conditions without swapping eyepieces sounded great.

I really wasn't expecting too much as zooms must be a compromise on many levels and certainly when I first started using it the Kidney beaning Andrew mentioned appeared straight away at the 24mm setting. However this did not put me off as I only use that setting to get a planet in the FOV and then increase magnification straight away - I am foremost a planetary observer only occasionally looking at the Moon and Messiers.

The Televue performs almost exactly as Andrews Hyperion with three slight differences :-

1. Kidney beaning at the 8mm is not a problem.

2. The eyepiece does not fog up at all.

3. There is some internal ghosting when observing bright objects.

The big surprise to me was the optical quality - it is very good and last night I saw the best ever image of Mars with this zoom in over 20 years of observing.

In conclusion with a long f-ratio scope and used in the 8-16mm range this eyepiece is great - ideal in my C925 for planetary viewing.

[MartinB]

Thanks for the report Dweller, very interesting

how did you find the FOV with the zoom? My understanding is that that is the biggest compromise with the zoom. Certainly not an issue for planetary observing. Does the EP have an adjustable eyecup? If you move your eye away from the EP at 24mm to stop the kidney beaning can you still see the full view?

I was looking at Mars as well last night and the seeing was as good as I've ever had. Definetly a good night for high powered planetary views where I was.

[dweller25]

Thanks for the report Dweller, very interesting

how did you find the FOV with the zoom? My understanding is that that is the biggest compromise with the zoom. Certainly not an issue for planetary observing. Does the EP have an adjustable eyecup? If you move your eye away from the EP at 24mm to stop the kidney beaning can you still see the full view?

I was looking at Mars as well last night and the seeing was as good as I've ever had. Definetly a good night for high powered planetary views where I was.

Hello Martin.

1. FOV is small - but as you say that's not an issue for a planetary observer.

2. I think the eyepice just has a fold down rubber cup but I will double check tonight.

3. If you move your eye backwards to avoid kidney beaning you cannot see the full view, however if you get your eye dead central to the axis you do not get kidney beaning and then you get the full view.

4. This is not an eyepiece for low power wide field viewing in my opinion.

HTH.

[MartinB]

Thanks dweller

[Andrew*]

Very interesting, Dweller,

thanks for sharing that. Do you know offhand the exact AFOV range?

Andrew

[dweller25]

Very interesting, Dweller,

thanks for sharing that. Do you know offhand the exact AFOV range?

Andrew

According to the specs the AFOV at 8mm is 55' with 15mm eye relief.

At the 24mm seting AFOV is 40' with 19mm eye relief.

Regards.

[James]

According to the specs the AFOV at 8mm is 55' with 15mm eye relief.

At the 24mm seting AFOV is 40' with 19mm eye relief.

40 degrees at 24mm? Ouch. The Baader Zoom offers a greater field of view at those settings. I'd love to know what the edge of field performance is like (as Andrew and others have seen at faster focal ratio's there's a certain amount of field curvature).

James

[John]

Thanks for that review - very interesting.

One zoom I would like to try is the Speers-Waler 5-8mm - that one's supposed to have an 80 degree field of view thoughout it's range but it's huge - about 7 inches long !.

John