Seben 31.7mm 1.25" Zoom 8-24mm FMC Telescope Eyepiece

[Raga]

Hi folks.

Does anyone know if the Seben range of eyepieces are any good, in particular this zoom piece?

Has anyone got one? Are they any good?? Are they worth the money or would I be better off standing in the road trying to catch passing cars with my teeth????

Thanks to anyone who replies.

[Spec-Chum]

I've got one, it's not too bad at F6. For the price.

I'd be reluctant to use it on anything faster tho. Saying that, it's contrast is rather good and it is rather convenient; I still use it quite often despite my ever growing EP selection.

I found the sharpness, colour and contrast as good as my old 8mm BST on axis. Fell apart a bit towards the edges tho.

If you can get one second hand (£30 or so) I'd say give it a go.

[keithatrochdale]

A surprising good for the money eyepiece, great for use in Ha scopes. Worth the £47 e-bay price.

[Raga]

Cheers guys.

MIGHT might just give it a whirl.

[Spec-Chum]

The biggest recommendation I can give is the EPs in my signature have swapped and changed all over but the Seben, one of the first I bought, remains.

It must be doing something right

[sunshine185]

I don't know wether to get 2 of these for my bv or save a bit longer and get 2 made zooms.

[Eastridge]

Spec-chum have you tried it on anything faster?

Like sunshine I have a 250 f4.7 dob. and was wondering about getting it, at the least it would allow me to see how I like a zoom and to establish which focal lenghs I use it at to inform which mid range EP's to get later.

Am I mad? How horrid will things look?

By comparison I use the 10mm hyperion and 32mm GSO in my scope which people say are rubbish in fast scopes but I have to really look for the issues to see them. I guess either my eyes or my experinece are not good enough to see the things that so annoy others.

I have noted the Meade but seems to be pricy unless I grey import from the states.

The Hyp zoom is even pricier and I am assuming not great in fast scopes just like the fixed ones.

[Spec-Chum]

Hmm, I really wouldn't be too sure in lower than F6.

[Peter Drew]

+1 for the Seben for F6+, OK at F5 but no better than that, great at F10 for the price.

[cantharis]

Am also looking at the Telescop Services 7 - 21mm - also good value apparently.

[fredster]

+1 for the Seben for F6+, OK at F5 but no better than that, great at F10 for the price.

I have the Celestron 8-24, identical to the Seben. Its awesome in my 102 Skymax for holidays, when minimum kit and space are the priority. In the F5 Skytravel its still a very serviceable eyepiece, as Peter says, its OK but not spectacular like in a slower scope.

With the 7-21, i always thought that was the poor relation and to steer clear? Don't quote me on that though.

[keithatrochdale]

Am also looking at the Telescop Services 7 - 21mm - also good value apparently.

I have one of these too, nice but I would say save your money.

[rwilkey]

The Seben 8-24 zoom is exactly the same as the Sky Watcher one, with the following identification letters on the case: MZT8-24. The 7-21 zoom offered by Sky's the Limit is also the Sky Watcher one and marketed as StarGuider, good for the price here: http://www.skystheli... eyepieces.html

[John]

I've been looking at the specs of some zooms. The 7-21mm ones, ie: Skywatcher, TS and other clones have a field of view range of just 30-43 degrees, the 30 being at the 21mm focal length wheras you would want it the other way around really !. Given that the sharp field of view with an F/6 or faster scope is going to be somewhat less than the whole 30 or 43 degrees (quite a lot less in an F/4.7 I reckon) any scope that you have to track manually, eg: dobsonain is going to create a real challenge in keeping the object under observation centered in the sharp area of the field.

I've never really "got" zoom eyepieces I'm afraid. Even the Hyperion zoom (better performing and much more expensive than the ones being discussed here) was not quite as good as the fixed focal length Hyperions when I had both for a while and could compare them closely. The performance of the fixed focal length Hyperions themselves suffer when the scope focal ratio dips below F/6-ish, the zoom a bit more so.

My choice every time would be to invest in a few decent plossls as a low cost upgrade to the eyepieces that come supplied with the scope. I'm not convinced that using low cost zooms with medium-to-fast scopes is doing the scope or the observer any favours in terms of performance.

Sorry if this is a contrary view point but there we are

[Raga]

It's always helpful to have contrasting views John so thanks for the reply. I prefer to have an opinion from both sides of the fence, that way I can make a better informed decision about parting with my hard earned cash.

Thanks to everyone who replied btw.

[sunshine185]

As cost is the main issue for me, I could get 2 zooms for under £100 but, at around £30 I would only be able to get 2 plossls. I am still unsure as to what high mags will be best in the bv and 250px, so using the zooms I can at least find out what mags will be best, then I can save up and get 2 plossls based on my findings with the zooms.

[Spec-Chum]

I tend to only use the zoom from about 16x down, the fov is only 40 degrees at the 24mm end. It's 60 at 8 and 50 at 16 I don't like limited fov, but that's just me.

Personally, I'd grab the zoom and a couple of low power 2nd hand plossls.

[Eastridge]

I think sunshine185 and I are thinking along the same lines , have it as a low cost 'trial' before spending more on the focal length that we setlle on.

If I didn't go zoom I 'm looking at things like 15mm ( TV Possl not sure what eye relief it has) and 18mm X-cel LX (16 mm eye relief may be a lttle tight for me & my glasses) so having a zoom might help answer that Q

[Raga]

That's not a bad idea. Spend the £40-50 on the zoom and see what focal length I use most and in the mean time save like a squirrel before winter so as to buy the fixed length ep.

And from what most of y'all are saying I could do worse than buy the seben.

Cheers guys.

[Naemeth]

I think sunshine185 and I are thinking along the same lines , have it as a low cost 'trial' before spending more on the focal length that we setlle on.

If I didn't go zoom I 'm looking at things like 15mm ( TV Possl not sure what eye relief it has) and 18mm X-cel LX (16 mm eye relief may be a lttle tight for me & my glasses) so having a zoom might help answer that Q

15mm Plossl will have 12mm eye relief, and I find 16mm is fine for glasses, but 20mm would probably be much more comfortable.

[Eastridge]

15mm Plossl will have 12mm eye relief, and I find 16mm is fine for glasses, but 20mm would probably be much more comfortable.

Thanks, that rules the Possl out then - so looks like 18mm Ex-cel LX is favourite. Maybe I should just go for that & probably would if one came up here 2nd hand but I am sure tempted by the zoom as a trial and cos with a manual scope when changing EP's and not around to nudge I often find on return the object has often gone out of view and I need to refind .

[Naemeth]

Thanks, that rules the Possl out then - so looks like 18mm Ex-cel LX is favourite. Maybe I should just go for that & probably would if one came up here 2nd hand but I am sure tempted by the zoom as a trial and cos with a manual scope when changing EP's and not around to nudge I often find on return the object has often gone out of view and I need to refind .

Trick is to unscrew but leave the eyepiece in, and have the eyepiece you are changing into, then you can just quickly swap. Of course, I've only done this with Plössls (~130g), not heavier eyepieces.

[Eastridge]

Ta yeah you are right of course , but you still have to turn away from the scope and get the EP you are changing to ready at some point ? I don't always loose the object completely & luckily as there are often 2 of us viewing one can keep the object in view whilst the other preps the EP. Maybe I just need practice if a McLaren pit crew can change 4 tyres in 2.3 secs an EP should be a dodle