Explore Scientific 20mm 100 degree eyepiece

[gooseholla]

Tonight I tried my latest eyepiece buy. I purchased it from bresser.de in their ex-display section for 250 euros plus 10 euros shipping. With paypal's exchange rate this came to £193 posted - a huge saving over UK prices. If you are interested they still have it listed so they may have more?http://www.bresser.de/en/Sale/Display-Items/0218420-1.html (31/10/2015). It showed no sign of use and for an ex-display looked remarkably new.

The eyepiece was listed as Argon but a Nitrogen version came. Not too worried - the eyepiece performance is the most important thing. I can confirm nitrogen purging does absolutely nothing to stop it dewing up. A few times I thought cloud had rolled in only to find the eyepiece lens dripping in water. On the flip side however, the Argon 6.7mm that I had the other night didn't seem affected by the dew, so maybe there is good reason they changed to Argon over Nitrogen.

I only tested it on a couple of objects. Andromeda quickly and more thoroughly on the moon. Having a Nagler T5 20mm I was keen to compare the two.

Andromeda

The galaxy looks wonderful in 100 degree AFOV. With my setup this gives 1.09 degrees compared to 0.9 degrees of the Nagler. Performance wise, on axis I could see little if any difference between the two. Both showed the same level of detail and both were about as sharp as each other. I'd say the Nagler won it as star HIP 3293 near M32 was a bit sharper. Also the faint stars imposed on Andromeda's core appeared sharper and a bit whiter to my eyes in the Nagler. But I wasn't disappointed with the ES 100. It showed exactly the same level of detail in Andromeda as the Nagler did.

The Moon

I started off by comparing the two on the Moon. To my eyes they were equally as sharp and again neither showed more detail. However, the ES 100 seemed to show a better range of tone, with certain greys appearing darker to my eyes.

The sharpness of the picture matched the Nagler T5, and even the Nagler 12mm T2 I viewed with the other night. So you would be buying a very capable lunar eyepiece. I used it all night and was most satisfied with the view and how relaxed my eye was. At the end of the viewing session I put the T5 back in and could find no extra detail or differences in the craters and objects I had observed over the past 3 hours.

Off-axis

Off-axis performance goes to the Nagler. Coma is more controlled and less noticeable. The ES 100 starts suffering quite a bit near the edge of field, but this is a very long way out. Coma appears before this, although more noticeable than the Nagler it certainly isn't annoying in my opinion.

When I first put the eyepiece in I thought this isn't much bigger AFOV than the Nagler. The fact it didn't seem much bigger to me suggests that 100 degrees doesn't require much eye movement to see the whole FOV. The difference against 82 degrees is noticeable side-by-side. I put the Nagler back in and wow the difference was amazing. It would be like going back to something like a plossl after using a Nagler. The extra AFOV the ES showed was a welcome bonus and I didn't find it annoying or distracting to have a bit more sky when viewing an object.

As the Moon drifted to the edge of the field the image was still reasonably sharp. A slight tweak was needed to keep it in focus and I noticed that around white features such as Aristarchus a purple false colour appeared. This happened with the Nagler off-axis as well but it was far less noticeable.

Other factors

The eyepiece is huge and weighs quite a bit. I had no balance issues but it did feel like if you weren't careful when moving the dob about it could tip towards you as there is no counter weight opposite the focuser, it is all to one side of the upper cage. I tried barlowing it for a bit of fun just to see what the 14mm and 9mm would be like and I must say I may trade in my 82 degree eyepieces for 100 degree in the next year. I won't be doing this often as it does put the eyepiece quite a long way out and feels like a slight tug of the dob towards you and it might start tipping.

The rubber eyecup is a bit annoying to me. If you press your eye up to it then the top part folds down. I couldn't stop this happening and just had to keep rolling it back up.

As mentioned the Nitrogen purging doesn't stop dewing.

It focuses quite a bit further in than the Nagler 20mm. I had to chop 1cm off of my poles to get it to even focus. The focus, as I have found with all ES eyepieces I have had is quite soft. There is no real moment when it goes from out of focus to in focus. It is sometimes a bit of guesswork and fine tweaking. A Nagler, on the other hand just seems to snap in to focus and you know it is focused.

I had no problems seeing the whole field of view. It wasn't an extreme movement of the eye needed to see the very edges and it certainly wasn't uncomfortable to view through. I experienced no black outs or other such effects. In fact it was a very comfortable eyepiece to use.

Conclusion

I would be happy to recommend this eyepiece to anyone. It has Nagler like performance on-axis but suffers a bit in my fast scope off-axis. The Nagler wins in terms of off-axis performance but in terms of detail and sharpness, the ES is right up there with the Nagler. For such a larger AFOV, I didn't find the off-axis coma annoying. I suspect if you used a coma corrector you'd end up with a very nice stunning view indeed.

I cannot say how it performs against a 21mm Ethos. Also, the price of a Nagler 20mm and this eyepiece are about the same so careful consideration is required about what you want to do with your eyepiece and what you want out of your viewing experience.

Really happy with it for £193, but I would not be unhappy even if I paid £360 for it. In fact I would be ecstatic if I had this eyepiece at full price. It is hard to see me keeping the Nagler T5 now that I have this eyepiece and that is a very strange thing to say in the eyepiece world!

John

[Lorne]

You have just twisted my arm..............     Just ordered one at that price. I think its time I moved on my 28mm Nirvana (the unthinkable has happened) to make some room in my EP case! 

[John]

Great review John

I've owned the 20mm ES 100 and the 20mm Nagler T5 (before that a 22mm Nagler T4) and now a 21mm Ethos.

Your performance assessment seems spot on to me

I found the ES 20 / 100 more immersive and the full field easier to access with the eyecup rolled down even though I don't wear glasses when observing.

[gooseholla]

You have just twisted my arm..............     Just ordered one at that price. I think its time I moved on my 28mm Nirvana (the unthinkable has happened) to make some room in my EP case! 

Shame I don't get commission  You won't be disappointed and at that price, if you don't get on with it, instant profit on resale

Great review John

I've owned the 20mm ES 100 and the 20mm Nagler T5 (before that a 22mm Nagler T4) and now a 21mm Ethos.

Your performance assessment seems spot on to me

I found the ES 20 / 100 more immersive and the full field easier to access with the eyecup rolled down even though I don't wear glasses when observing.

Good to know I wasn't dreaming it or having that initial excitement of ownership which clouds judgement on true performance!

John

[John]

..... if you don't get on with it, instant profit on resale

Except that we know what it cost to buy ......

[Lorne]

Shame I don't get commission  You won't be disappointed and at that price, if you don't get on with it, instant profit on resale

I've already had the pleasure of looking through the 20mm, I'm not anticipating moving this one on...... although, I did say that  about my 28mm Nirvana!! 

[gooseholla]

Except that we know what it cost to buy ......

Yeah but good luck getting one that cheap once Bresser.de stop selling it so ridiculously cheap  I must admit, whatever money it cost me, I am not selling it on even if someone offered me £250.

John

[John]

Yeah but good luck getting one that cheap once Bresser.de stop selling it so ridiculously cheap  I must admit, whatever money it cost me, I am not selling it on even if someone offered me £250.

John

I sold mine for £190 a year or so back.

Thats the double edged sword of lower cost importing - it hits the used prices too.

[Paul73]

Back to €479 now. Grrrr.

Well done on grabbing a real bargain chaps.

Paul

[gooseholla]

That link is still showing it as 250 Euro?

John

 

[Lorne]

That link is still showing it as 250 Euro?

John

Yeh I just checked too, I hope you haven't bought the last one and they've forgotten to update the website.... I've just sold my 28mm and now have a big gaping hole to fill in my EP case! 

[gooseholla]

Well I did buy it over a week ago... they've added and removed a bit since then! I suspect by ex-demo they mean they have a few nitrogen ones lying about, so they probably do have more than 1 in stock.  Did you get an email confirmation of your order Lorne?

[Lorne]

Yeah I got the confirmation, no details of a delivery date mind you. I'm sure it will be OK, though I do know it will signal the start of a run of clear nights until it arrives on my doorstep! 

[gooseholla]

Hopefully they'll do the 14, 9 and 5.5mm at some point cheap too

[laudropb]

Very readable review. Thanks for posting.

[Lorne]

Well, I now have the EP - after picking it up at the UPS depot - missed the delivery yesterday.  It is the same N2 purging as you got Dave so I guess they were offloading whatever stock they had left, if you click the link in the top post they are showing out of stock, discontinued. 

It came out the packaging in a black box - not the "star chart" design of the latest Argon purged version and after a quick inspection, as you mentioned above, there were absolutely no signs of being a demo/ display eyepiece, basically brand new!

Hopefully I'll get a chance soon to add my review (I'm sure the price paid wont "cloud" my judgement) but from using my 14mm and my previous looks through a 20, I'm sure I wont be disappointed. 

L.

[gooseholla]

Who's Dave?!

JOHN

Glad you got one. I suspected when it was N2 that turned up that they were a last few lying about. Still, performance is going to be the same for a lot less.

[John]

The whole gas purging thing is a bit of a gimmick IMHO anyway so it does not really matter whether it's argon or nitrogen. Tele Vue eyepieces seem to have managed OK with air inside them.

I hope you both enjoy your ES 100's

[gooseholla]

I agree - as the review stated the eyepiece fogged up anyway! I notice a lot of high end binoculars use nitrogen purging and say it is to stop the inside fogging up... We'll I've never had the inside of any eyepiece fog up!

John
 

[Paul73]

Boulder the fact that they are completely sealed (waterproof) make them prone to internal fogging?

Paul

[YKSE]

Boulder the fact that they are completely sealed (waterproof) make them prone to internal fogging?

Paul

I don't think this is the case. Given the fact that most spotting scopes have waterproof eyepieces, and these scopes are meant to use in more difficult conditions than telescopes, prone to internal fogging should not an appreciated feature.

My experience is that 95% of the time, this waterproof eyepiece don't have any benefit, while in those few more dewy and cold weather nights, they do withstand dew better than non-water proof ones. Maybe I should add, that all Pentax owners don't know that XWs are water-proof too.

[Lorne]

Who's Dave?!

JOHN

Glad you got one. I suspected when it was N2 that turned up that they were a last few lying about. Still, performance is going to be the same for a lot less.

Sorry JOHN 

Grrrrr too late for the edit funtion...... I can't even blame this on predictive text this time 

[swamp thing]

After comparing my Nagler T5 20 to Dan K's 20ES 100˚ I'd agree with your findings too John. Just do't let Calvin near your scope with that Ethos 21.

The blokes a darn nuisance  

[estwing]

...ahhh another victim...I mean wallet to dent

[gooseholla]

You can try denting my wallet, it is like Fort Knox and has rusty padlocks on it... it rarely opens

Well I purchased two little extension rings so I can screw the 1.5x element of my barlow on to it. That will give me around 15mm which will fit nicely with my other eyepieces!

John