ES 20mm 100 First DAY Light

[Scooot]

I set up an hour ago facing a church steeple, principally to check I could focus, to see how the scope coped with the weight, to see what the eye relief was like and because it was a new toy I wanted to play with!

I stand on the left of the 4.8f 10" dob and use my left eye, mainly because my right eye is too weak, even with specs.

First the bad news: I am a bit disappointed with the eye relief, I thought 14.5mm would be fine, but I couldn't see much of the field of view with my glasses on. I had the eye guard down, with it up was pointless. However, when I removed my glasses I could see the field stop to the left and top but not to the right without peering inside the eyepiece. This was also with the eye guard down, with it up, without my specs on, it still seemed I wanted to get my eye closer to the lens. So I think I'm going to have to wear my contact lenses if I want decent views with this eyepiece. So Ed looks like your suspicions were well founded.

I had to tighten my focuser with an Allen key, initially the tube was having trouble rising due to the weight, but once I'd done this it focussed well in the normal way. A brass cockerel was perched on top of the weather vain on top of the steeple about 600 yards away. I had a crystal clear view of its date, 1820, or 1850, as it was the wrong way round I couldn't be sure.

I currently have a 40mm spacer that sits in my focus tube, without this my existing eyepieces wouldn't focus. I recently purchased a 2" self centre adapter http://www.altairast...&cat=261&page=1

If I use this, the ES 20mm 100deg won't focus unless I attach my GSO coma corrector.

So if I want to use the new eyepiece in the new adapter, without the coma corrector, I'd have to remove the 40mm spacer. That would be a pain because I'd have to put it back in to use my other eyepieces. So basically, if I don't want to use the coma corrector with it, I won't be using the new adapter. Looking at the steeple there was no noticeable difference in the view so I probably will be using the corrector and adapter, but we'll see.

The OTA coped with the weight of the eyepiece quite well considering I didn't make any adjustments for it. The scope was almost horizontal whilst looking at the steeple but the friction brake held it quite well. I had to have it quite tight though so I probably should rebalance the OTA slightly.

So hopefully, now I know how to set up to use it, I've saved myself some time when I go live so to speak. Just waiting for clear skies now.

[John]

Interesting. I have heard of others who wear glasses having problems with the ES 100 series - their eye relief in practice is a little shorter than 14.5mm because thats measured from the centre of the concave eyelens and the eyelens is recessed a few mm into the top of the eyepiece. I don't wear glasses to observe and find I need the rubber eyecup rolled down to see the whole FoV. Apart from that I'm very impressed with my ES 20 / 100 so hopefully you will find it very enjoyable when you get it under the stars.

[Scooot]

Thanks for that John. I'm sitting outside watching the clouds disperse so I'm hoping for a clear patch, although I think it will be brief. Will be using my contacts although the prescription isn't quite accurate enough. Been looking into the dioptrx today. Took the eye guard off my Delos and the new ES to compare and it looks exactly the same so I'm hoping it'll fit. More expense though!

[Scooot]

I've now had first star light so to speak, 1.5 nights actually as I had a good session last night and an hour early on tonight. To be honest I'm feeling decidedly down beat about it.

After realising the eye relief wasn't good enough to wear my glasses I put my contacts in last night. I've never liked wearing contacts to look through the scope because they have a habit of swivelling slightly.This causes a focussed star to suddenly become a mini airy disc, which is quite off putting to say the least. So I spent the evening looking at a variety of things starting with the double cluster as it was a fairly wide field object. I could easily frame it in a true field of 1.67 deg and once I'd fiddled with the spacing of the coma corrector I was able to focus both clusters in the same FOV . I had some memorable views during the evening due to the wide fields. One of which was seeing the ring nebula to one side, opposite sheliak and its surrounding cluster the other. To my eyes the contrast wasn't as good as the Delos, and the views did not seem as sharp, but the delos was slightly more powerful so perhaps this wasn't a fair comparison.

Today, the dioptrx I'd ordered Monday arrived and I was hopeful this would improve the viewing experience. It certainly did with the Delos. I wish I'd bought it before now. Viewing through the televues without glasses was much better in every way. Removing and attaching the dioptrx to change eyepieces was easy as well. The good news was it did fit ES 20mm as well. The bad news was it made the eye relief much worse. Viewing through the delos I had the dioptrx eye guard comfortably up. Viewing through the ES I had it down and felt as if I wanted to climb into the eyepiece to get a better view.

The seeing tonight wasn't that good and it wasn't that dark, but with the dioptrx on, the FOV didn't seem a lot better than the 17.3mm Delos and the views seemed a little wishy washy to me in comparison.

So the long and the short of it is, I'm very disappointed to say that I haven't got on very well with the ES 20 mm 100 deg.

[John]

Sorry to hear this Richard. Eyepiece choice can be a very personal thing though. The Delos has lots more eye relief than the ES 20 / 100 so it's going to be easier for you to use I think.

[Andy_E]

Sorry to hear that Richard. Really hope your views through it improve as you get to know the eyepiece a little better.

[Pig]

Richard thank you for the review it will certainly help others in the forum with decision making

[Mark in Macc]

Yes, thanks for your comments. I have read similar comments about eye relief with Ethos eyepieces as well. Maybe not ideal if you have to wear glasses. I don't, and I get on fine with my ES 20mm 100 deg.

[crashtestdummy]

As above,I'm loving my es 20mm but if I had to wear glasses I wouldnt.I wear glasses sometimes when reading star maps but not when looking through the eyepiece

[mert]

It is a quality eyepiece<, I had a look at m57 through part clouds and its stunning

[Scooot]

It is a quality eyepiece<, I had a look at m57 through part clouds and its stunning

Hi Mert, no I wasn't intending to knock the eyepiece, it clearly is an impressive piece which will perform excellently in the right hands and circumstances. Unfortunately my circumstances are a poor match.

[Scooot]

Thanks for all the comments. No one likes to admit they've made a mistake, but I thought I'd post my views whilst fresh in my mind and before I changed my mind. I do indeed hope they might prevent others from going down the same route if they have an astigmatism and wear glasses.

I've decided to return the eyepiece (or look into other disposal options) . The invoice is dated 5th August and I have 30 days. I've also found out I can get a return of all the duty from customs so it will end up costing me the shipping. Interestly I checked with the post office at lunch time and its only £15.50 (fully insured) going back to the states.

Live and learn, no point sulking

[crashtestdummy]

Ther was one for £300 on abs a while ago so maybe it would be cheaper to do that and you won't lose any money.

[Mark in Macc]

If it was a 14mm I would bite your hand off. . I suspect you might shift this fairly easily on ABS or the classifieds. This happened to a friend of mine who bought a 28mm Nirvana and can't use it because of his astigmatism/glasses. Try before you buy is the best option, but sometimes it just isn't possible.