ES 100 degree

[JJDOBBER79 (Jas)]

Hi all,
I have been having a look on various online stores for a ES 100 degree 20mm and I noticed that there was a big price variation. I found that there are 2 of these. 1 seems to be nitrogen purged and the other argon purged. Prices are US $299 for nitrogen and $399 for argon. What exactly is the difference and does it warrant paying an extra 100. I read that these are waterproof eyepieces so i presume dew resistant is more to the point (unless I want to use my scope underwater). Does anyone know if it is just a higher level of waterproofing or something visual?

[MattT]

My 68º ES's are Argon purged and my former 100º ES 's were Nitrogen purged. The difference at the eyepiece is zero. The good thing, being water proof they are dead easy to clean. No cleaning fluid/spray should seep down between the lenses, but doesn't change the resistance to dewing up on the outside.
I'm guessing the Argon types are more to do with the increase in price than anything 'scientific' about them.
Matt

[JJDOBBER79 (Jas)]

yeah. thanks matt. thats what I thought. I figured if I was going to be missing out on something visual it might be worth it.

[killswitch (Edison)]

They purge and seal the eps with an inert gas to prevent fungus and lifeforms growing internally. They switched to Argon because its less reactive and more stable than Nitrogen.

No difference to image quality.

[David Niven (David Niven)]

The 100D is just overhyped and IMHO not worth the extra money.
I would just go for the 82D and they are really, really good.

[MattT]

Originally Posted by killswitch

They purge and seal the eps with an inert gas to prevent fungus and lifeforms growing internally. They switched to Argon because its less reactive and more stable than Nitrogen.

No difference to image quality.

Ahh there is something in it then!

Totally agree with David on the 100's…had a few of the 82's in the past. I'm now using the ES coma corrector with the 68's... wouldn't use a Newt without one.

[AG Hybrid (Adrian)]

100 degree apparent field of view is definitely worth the money. Otherwise Televue would never had bothered or they would be discontinued. Deciding if the price difference between a TV 100 and a ES 100 is a different matter though.

It's a personal choice, not everyone want's 100 degree eyepieces for multiple reasons. Some people just don't want to see a field stop, while others like framing objects in their eyepiece. As my dob is undrivien I enjoy the 100 degree line as it allows me extra time where I don't have to nudge the scope as often to keep up with the object.

I also like being lost in a huge view. But, the 82 degree line is very good a fantastic value for money also. It's not that I would ever recommend 100 degree eyepieces to newer people to the hobby. They just look through my scope and decide they want them themselves.

[Camelopardalis (Dunk)]

All of the above

Personally I love my 100 degree FOV and the ES range are great eyepieces for the money. But they are big and relatively heavy. Like Adrian, I can't fault the 82 range either, much smaller and lighter. And cheaper

As for why they changed from nitrogen to argon? Only they really know. Maybe they noticed some corrosion/reaction with one of the other elements used in their construction, as while nitrogen isn't quite as inert as argon, 79% of our atmosphere is diatomic nitrogen which is pretty stable

[JJDOBBER79 (Jas)]

looks like I will give the 82's a go.

[nebulosity. (Jo)]

Originally Posted by JJDOBBER79

looks like I will give the 82's a go.

Good idea, I especially like the 14mm.

[David Niven (David Niven)]

I prefer the 6.7 and the 18 mm.
It seem the 14mm has a bit of field curvature.

[GraemeT (Graeme)]

I decided to standardise on the ES 82 degree series and have never regretted it. OPT in the US had several months where the ES eps were heavily discounted and I filled a gap in my range from the IceTrade classifieds.