Seben Zoom 8-24mm, Cheap Zoom Eyepiece

[Peter Drew]

I have both the 7.5 - 21 and 8 - 24 units. The former does work and was about half the price of the latter but the 8 - 24 was more than twice as good. The dismantled images supplied by Dave show the cheapness of the build quality. The 8 - 24 is a good budget zoom.   

[John]

3 minutes ago, Peter Drew said:

I have both the 7.5 - 21 and 8 - 24 units. The former does work and was about half the price of the latter but the 8 - 24 was more than twice as good. The dismantled images supplied by Dave show the cheapness of the build quality. The 8 - 24 is a good budget zoom.   

I posted the pics of the Seben zoom internals earlier in this thread Peter. Here is the full SGL thread that they originated in:

 

 

[Cosmic Geoff]

I have just taken delivery of the 8-24 zoom eyepiece sold by 'Sky's the Limit' under the Starguider brand. In the Ebay listing, it's claimed to be similar to the Celestron and Sky-watcher models, which it physically resembles.  But it was around half  the price.

http://www.ebay.co.uk/itm/Starguider-8-24mm-1-25-Zoom-Telescope-Eyepiece-/162523741115?hash=item25d72b7bbb:g:AOUAAOSw5cRZIVNn

I might have bought the Celestron, but was tempted by a similar product for a lower price. And I bought a binoviewer from the same company which despite being half the price of similar bodied binoviewers turned out to be quite a satisfactory product. 

Time will tell whether this zoom is any good. It's raining now.

[davyludo]

2 minutes ago, Cosmic Geoff said:

I have just taken delivery of the 8-24 zoom eyepiece sold by 'Sky's the Limit' under the Starguider brand. In the Ebay listing, it's claimed to be similar to the Celestron and Sky-watcher models, which it physically resembles.  But it was around half  the price.

http://www.ebay.co.uk/itm/Starguider-8-24mm-1-25-Zoom-Telescope-Eyepiece-/162523741115?hash=item25d72b7bbb:g:AOUAAOSw5cRZIVNn

I might have bought the Celestron, but was tempted by a similar product for a lower price. And I bought a binoviewer from the same company which despite being half the price of similar bodied binoviewers turned out to be quite a satisfactory product. 

Time will tell whether this zoom is any good. It's raining now.

Good find! Let us know how it goes....because I've been thinking about it after reading this thread. 

[wookie1965]

I was just going to ask about the Starguider 8-24mm zoom as I have 8 other eyepieces, Zoom 7-21 and Barlow in the same range I will wait for more information. 

[Cosmic Geoff]

I have now been able to try out the Starguider 8-24mm zoom. The main issue I found is that the zoom twist mechanism is very stiff.  I will file a more detailed report under "Member Equipment Reviews".

[rwilkey]

The 'StarGuider' zoom is the GSO one rebranded, the GTZ8-24 on the container gives this away, and therefore the same as the 'Seben' one etc etc. 

[YKSE]

On ‎2017‎-‎08‎-‎05 at 12:17, Stub Mandrel said:

I know someone who imports machine tools from China.

Everything Dave says is true with respect to lathes, milling machines, grinders etc. etc. and all the tooling that goes with them.

There are some important points to know, though:

If you go to the good manufacturers (and they can be very good) you can specify the components and QC you want for your product. You might see what appears to be the same lathe from a dozen of more suppliers (yes this include many big US, Japanese and German brands) and each one is different in detail. Some of the differences (QC, circuit boards, bearings) are invisible to the average buyer. I'm sure this is exactly the situation with Vixen's special glass.

An upside of this is that the QC demanded by the bigger buyers can trickle down. While cheap EPs may not get expensive glass, the factory will use the same process to make all the focusers, for example.

It's also important to know that (for machines at least) there may be several factories making a similar product that has evolved from the same original design. These could be iMax B5 battery chargers or mini lathes. If you don't know the supplier and trust their  QC you could end up with anything.

BUT, and it's a big but, what about all the really cheap versions to be found? The Chinese factories never throw anything away - if a batch of parts/machines/eyepieces fail QC someone's cousin/friend etc. will pay a pittance for them and they get dumped on the market. Its not like Europe or the USA where they would get scrapped or trashed deliberately. there are even people who make machine tools by assembling overstocked spares - ones that may even be meant for different manufacturer's versions of the same basic design, sometimes creating strange hybrids or resulting in batches of total basket cases going on the 'low end' market.

Lots of very foolish people judge all Chinese manufacturing by the cheap crap on ebay "I'll never buy Chinese made rubbish" they tell someone over their iPhone... truth is , if you know what to look for and where to buy you will do OK.

Also, buy big items from reputable dealers. these days they are usually cheaper than eBay or Amazon (look at the prices of new scopes on eBay!) plus you get after sales service, a genuine warranty and backup spares.

Great summary of the look-alikes.

[Mangleworsle]

An update to my previous comments on the Seben 7.5-22.5 mm zoom eyepiece. I lent it to a birdwatcher friend who obviously used it with his scope (don't know what it is) he thought it was great for his application so much so he bought it off me, said it held it's focus very well whilst zooming and gave a good sharp view.

So maybe birdwatching is what it is really aimed at.

Jim

[andre2]

Hi, i buy the seben zoom for an Alpha- h scope. Its a good eyepiece, but not great. ( i think)  Maby i will buy one more zoom such as the vixen 8-24 or the pentax xf 19.5=6.5  both has lanthanium glass so i aspect they are noticeble better. the big question is , if lanthanium glass really do make you see details better....??? i am still  not convinced enough!

Thanks for the tip.

[Louis D]

12 hours ago, andre2 said:

Hi, i buy the seben zoom for an Alpha- h scope. Its a good eyepiece, but not great. ( i think)  Maby i will buy one more zoom such as the vixen 8-24 or the pentax xf 19.5=6.5  both has lanthanium glass so i aspect they are noticeble better. the big question is , if lanthanium glass really do make you see details better....??? i am still  not convinced enough!

Thanks for the tip.

The main thing I've noticed with Lanthanum optics is that they impart a slight coffee color to the image and slightly reduce perceived light throughput.  The same dimmest stars are visible, but they seem dimmer than in non-Lanthanum eyepieces, if that makes any sense.

The main use for rare earth glasses is to allow for more radical lens curves without introducing image destroying dispersion.  Those radical curves in turn allow for a smaller number of elements to achieve higher levels of edge correction in super/ultra wide eyepiece designs.  However, due to China cornering the market on rare earths and inflating their prices for non-Chinese owned companies, designs employing them have become too expensive to continue producing.  The most famous example is the Televue Radians which employed rare earth glasses and were discontinued in favor of the cheaper to produce DeLites which have no rare earth glasses and yet produce at least a good of an image, but probably with at least one more element.

[andre2]

So, iT depends on whether you are gonne find " litlle better" worth the extra money?  And for what you gonne use iT for?Then I will think about iT or stick with my decent China seben zoom.( maby if you want best of the best =even slightly- maby iT can be worth.....its still tempting.) however, these chinese products gonne rule the word if they do become  better and better and cheeper.

[John]

For use with an H-Alpha scope, I've found that simple, low cost eyepieces work very well.

I found this zoom works very well for this purpose and for nighttime viewing as well (no idea what glass types it uses though):

http://www.opticstar.com/Run/Astronomy/Astro-Accessories-Telescopes-Opticstar.asp?p=0_10_5_1_8_330

The same zoom is available under a number of different brandings including Lunt, Telescope Servies, Skywatcher and others. The one I have linked to is currently the lowerst priced version that I can find.

 

[andre2]

Hmmm.... looks like another good zoom for a  low price and lighter and good magnification settings for  a pst! find this also on a site: "the seben zoom is as good in alpha-H then the pentax xf zoom the xf has only better eye placement" . There you go.