7 replies to this topic

[sw196060]

I am interested in the Siebert Ultra, the 15mm or 17mm for now.  They look attractive with 70deg AFOV and good eye relief.

However, how do they perform?   

I will use them in my f/7 TV85 so, not a fast scope.

I also like their light weight.

 

Any user reviews?

 

Thx

[SeattleScott]

Whenever this question comes up, it seems like it is easy to get feedback on how the Seiberts perform. Very well apparently.

The hard part is seeing how they perform relative to other quality options. Not many people are buying Seiberts and comparing them to Delos.

If you want a solid performer for a reasonable price that is very light, Seiberts will do the job nicely.

If you are a discriminating observer looking for the best eyepiece performance, or best performance available at a particular price point, you might have trouble finding the information you are looking for. Maybe this time will be different?

P.S. the Nikon SW series is particularly small and light for 72 AFOV with good ER, and has a 14mm and a 17.5. There is a good deal of information about how they compare to Televue and other premium brands. That being said, they are considerably more expensive and heavier than the Ultras. The SWs are light for modern premium eyepieces with 70+ AFOV and good ER. The Ultras are probably more in a class by themselves in terms of how light they are for having 70 AFOV with good ER. So if weight is a primary driver, and just being lighter than Delos isn’t good enough, then I don’t know if there are really any viable alternatives to Seiberts.

Edited by SeattleScott, 25 June 2025 - 12:10 AM.

[betacygni]

I’ve not used the 15mm or 17mm, but the 24mm are very very good. It does look like the specs vary a bit amongst the line, particularly in element count, so might be hard to extrapolate performance.

In general Siebert makes some very good eyepieces that can rival top end options in the right circumstances. That said they are as Scott mentions fairly under reviewed, so in that sense a bit of a riskier option than the standard options, but I think they are worth the risk. I’ve owned a few Siebert eyepieces over the years and haven’t been disappointed.

[dregan]

The 13mm and 17mm Ultras are very good eyepieces with great light through put. As for contrast and sharpness, the Siebert Ultras will hold with the top dogs. The 24mm is a great eyepiece for f/7 and slower focal length scopes. At the old observatory we used the 13mm and 17mm Ultras with a bino-viewer in the 6" APO. The 24mm Ultras we have used in 7" Mac and 10" to 16" SCT's. I liked them so much I bought pairs of the 13mm, 17mm and the 24mm Ultras. My scopes are a 6" f/12.5 Mac, 7" f/15 Mac, 6" f/7 APO and a 185mm f/7 Askar APO on the way. 

 

How does the 17mm Ultra stack up to a 17.3mm Delos? Well, what you notice first off is that the looks and build quality of the TV are second to none. I see nothing wrong with the build or looks of the Siebert, I care more about the contrast, sharpness, light throughput and if there is any ghosting. It's not an eyepiece beauty contest, and yes build quality and the glass used matters more than the color of the barrel. The build quality of the Siebert Ultra series is very very good and the glass used is very very good. When viewing Jupiter with the TV 17.3mm Delos the views are outstanding as it is with the 17mm Seirbert Ultra in a 6" APO. The Delos may be a hair sharper but not enough to pay the extra money  in my opinion. Contrast I see no big difference between the two, and I see no ghosting in the TV Delos or the Siebert Ultra. I have not used the TV or the Siebert in fast scopes so I don't how good they are in slow fl scopes.     

The Ultras that I have I bought back in 2012 and I do not know if Siebert is using the same glass today in 2025.

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[izar187]

I am interested in the Siebert Ultra, the 15mm or 17mm for now.  They look attractive with 70deg AFOV and good eye relief.

However, how do they perform?   

I will use them in my f/7 TV85 so, not a fast scope.

I also like their light weight.

 

Any user reviews?

 

Thx

I have a 15mm Siebert Ultra. It spec's as stated on the website.

My direct comparison of it was to a 16mm UO König ll,15mm Carton plössl, and 15mm RKE. All VT type design FWIW

It was equal to all 3 in on axis sharpness(as expected) and in transparency/contrast.

Superior to them in eye relief, field in view, and off axis astigmatism correction.

Simple easy to use up/down folding eye cup, for glasses on or off relaxed viewing. IME

This was in my f/4(tiny) thru f/5 newts. It's a keeper IMHO.

But I have not done direct comparisons to all the different 70º(+/-) x 20(+/-)mm eye relief options on the market nowadays.

If interested, then call him before ordering.

[CollinofAlabama]

Can't add a whole lot here, but kind of second what everyone else has written.  I own the now-no-longer-sold Siebert SS III 3.9mm eyepiece.  I know for a fact that it puts up a better image than the AstroTech UWA 4mm, which I did compare it with, and which it won, hands down.  And the AT 4mm is an 82 degree ocular, but that didn't matter.  On axis, the Siebert was better.  Now the AT UWA 4mm is no DeLite/Nagler/Delos eyepiece, for sure, so this doesn't help much concerning how the Siebert's compare to the high end, but in this instance, very, very well.  In fact, I prefer the Siebert III 3.9 to my Nagler 3.5mm T6 not because it's necessarily better, but rather that my turbulent skies rarely permit me to even use the SS III 3.9mm, and the 3.5 T6?  Well, that one can only perform once in a blue moon.  And of course, neither can be used as often as my 5mm T6.  All that says a lot more about my wind current bedeviled skies, however, than how Siebert's perform relative to the Nagler T6 line, but I can vouch that I've never put the SS III 3.9mm into my focuser and, when weather conditions permit, haven't been very impressed with its performance.  That I can say with confidence.  Harry Siebert builds nice eyepieces.  I also own one of his 1.5x Siebert barlows.  Not much of a fan of barlows, personally, but it's very lightweight and does a good job when a person needs that extra umph a barlow provides.  Another quality optic product from Harry Siebert.

 

Sorry I can't comment about anything current.  Got my Sieberts over six years ago, so not recently.  I like them and see no reason to move on to other things, and, in fact, sold my AT 4mm UWA after comparing the views to the Siebert.  BTW, I own a LOT of different telescopes, and have used my Sieberts in 8" & 6" F/6 newtonians and F/10 to F/7 refractors.  They've performed well in all of them.  Good luck.

Edited by CollinofAlabama, 04 July 2025 - 02:45 PM.

[izar187]

  I have a 3.9mm SS3, and a 1.5x as well, and I agree regarding both.  : )

[CollinofAlabama]

sw196060,

 

Did you get the 13mm Ultra?  I'd be interested in knowing your thoughts on it, because I'm considering it as well.

 

Thanks,

 

Collin

Edited by CollinofAlabama, Yesterday, 06:14 PM.