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[Chicago Astronomer - Astro Joe]

Zhumell 8-24mm Zoom 1.25" Eyepiece

Tis the season for taking inventory of our astronomical equipment and notice the small voids here and there....be it filters, eyepieces or other accessories that make urban astronomy better.

I once used a zoom barlow tube when starting out with my Montgomery Wards 60mm refractor - a very very long time ago. Still have it and it worked...but in a .096 format, it was limited.

C.A. Steve has a zoom eyepiece, a Televue one at that and I like it when we slip it in our scopes, especially the C11. I figured it's about time to include one in my arsenal as well.

"But wait Joe, you going back to 1.25"s?" I hear.

Well, yea and no.

I'm a fan of the 2" format of eyepieces- opens up a new vista from the 1.25", but after a certain mm - oh maybe 12mm and less - they are all basically a 1.25" eyepiece in a 2" tube. Granted, variations in solid and very expensive small mm 2 inchers exist - but out of my price range.

This is my compromise without feeling guilty...and it's priced very well...

Using a promo, it's well under 50 bucks and with free shipping...how could I not?

I have a 2" to 1.25" adapter with my 2" Barlow, enabling to mate the two formats together nicely...and I can still use my 2" filters attached to the the right diagonal.

I read the reviews on this particular zoom eyepiece and overwhelmingly positive. Let's see how it performs.

Sorry for the clouds kids...

[Chicago Astronomer - Astro Joe]

The Zoom came in this evening....

Packed nicely, both ends of the eyepiece are capped and it comes in not a eyepiece bolt case, but in a semi-conical holder...

The bottom of the eyepiece fits into the top cap of the holder. Not snugly, there is some play, but it keeps the eyepiece from banging around in the holder. A line of felt/velcro would take care of the looseness...

The glass surfaces are mutli-coated - lending the purple-ish/green-ish tint we are all used to in quality optics....

The bottom of the eyepiece is threaded for filters...but really only about two turns of the thread to screw on a filter. Not a big deal, but almost like hanging on with fingernails. Luckily, I will be using 2" filters on the adapted right diagonal with this.

The zoom action is smooth but not velvet-like. There is some friction felt when turning the knurled grip...

The "mm" markings are etched into the barrel - but are upside down - as when the eyepiece is used at the scope...

The rubber eyecup is thicker than most and is foldable. When removed, there is a threaded end for adapters and T-mounts...

Of course, it's heavier and longer that most 1.25" eyepieces, but lighter and shorter than a 2" one and should not be an issue. I'm thinking about getting another zoom and using them in the binoviewer, but I have still to test this eyepiece out on a scope.

And...it's cloudy.

Updates when they occur, but so far - I like it.

[patrickm]

Moon & Jupiter were up clear as a bell when I left work at 7:45. By home, totally cloudy. Weird times.

Steve has a zoom, no? What kind. Will be interesting to compare. Curious how you grade your, both up and down sides.
p

[Chicago Astronomer - Astro Joe]

Initial loose test of the Zhumell Zoom Eyepiece -

It's been rather cloudy since the Zoom eyepiece arrived, with some breaks, but for the most part...cloudy.

Looking out the window, I see that the skies have cleared somewhat and really anxious to try out the eyepiece, I donned winter gear - and fighting a cough from a throat cold....I venture to the garage observation site.

A nice Moon and Jupiter presented themselves for testing.

I did not want to set up the C11, but instead grabbed the portable tripod and set up the C5...

I did not power it up for this quick and manual test.

It was decent....

At the 24mm position, the full orb of the Moon was easily within the FOV with plenty of space around it. Popping in a 25mm Celestron Plossel, the views were identical. Sharp and detailed.

I slowly turned the knurled ring and increased the magnification thru the range up to 8mm. This zoom is not parfocal throughout the range, as I had to stop twice to refocus while twisting...

At 8mm, it's maximum setting, the view was good. But by this time some upper atmospheric haze had crept overhead and made testing tough. But when I did get a clear steady patch, the view was good. A bit of fuzziness was observed, but without clear conditions, hard to tell from where it was coming from.

I then slewed over to Jupiter, in close proximity. Returning the eyepiece back to the 24mm setting, all five satellites were easily observed. Cranking up the power, the Jovian bands came into view with good detail...but again - with the haze, fuzzy.

I dismounted the C5 and brought out the trusty 90mm refractor...

Here I used the 2" right diagonal and with the 1.25" adapter on the refractor. as opposed to the all 1.25" set-up on the C5.

Still on Jupiter, the views were similar to the C5, perhaps a bit sharper, (The C5 does need a collimation). And as I turned the ring, Jupiter grew in size, bringing the banding into view. And again a bit fuzzy - so it isn't the scope but could the the air or the eyepiece. A clearer night will determine this.

Primary Evaluation:

In comparison with straight dedicated mm eyepieces, it held it's own - with close/equal sharpness and detail. Turning action was smooth, even in the mid 20's temperature of the evening.

I examined the lunar terminator with the Zhumell, and found that I got sharp contrasts and defined details - best at 24mm and good at 8mm.

I attempted to take some images, but without power to the mount, the pics would not be presentable. And also, my Canon Powershot S3 adapter, (which normally fits all 1.25" eyepieces), was too small to fit over the this Zoom eyepiece, ....even with the eyecup removed. Another approach will be found.

Good and worth the purchase. For those who would like several eyepieces, this Zhumell zoom would fit nicely in an Astronomer's accessory case. It fills the gap of 16 eyepieces and saves the cost of purchasing several or just for plain convenience. Of course, a dedicated stand alone mm eyepiece is superior, but this is nice to have and just about as good.

I may have this as a permanent eyepiece in the ride-along 90mm refractor finder scope to the C11 or get another one for use in the Binoviewer.

A more in-depth evaluation soon - on a clear night.

Side note:

I tried out the new 2" skyglow filter on this night as well.

Highly recommeded.

A full narrative on it's own thread, but briefly - it does darken the sky with wide mm eyepieces and removes the ghastly orange wash we all experience in our FOVs....

[erikruud]

Dec 8, 2011 0:13:34 GMT -6 Chicago Astronomer - Astro Joe said:

I slowly turned the knurled ring and increased the magnification thru the range up to 8mm. This zoom is not parfocal throughout the range, as I had to stop twice to refocus while twisting...

Really? I thought that was part of why you would want a zoom EP.