21mm Ethos - exit pupil matters

[Sarah]

Whilst I have previously been impressed with our 35mm Panoptic, in our new f/4.4 dob it has been quite disappointing, with a distinct lack of contrast. After reading another thread on here, we realised that the exit pupil of the 35mm Panoptic, at 7.95mm, was really too high for our new dob.

So, after much deliberation, we decided to invest in 21mm Ethos, which gives us an exit pupil of 4.77mm in our dob. We were a bit nervous spending so much on one eyepiece, particularly as I seem to have quite fussy eyes when it comes to eyepieces.

Last night was the first opportunity we had to try the Ethos out in the dob. After some slightly disappointing views, we compared it to the 35mm panoptic and there was no comparison, the Ethos was much better. Not long after that we realised that the secondary was dewed up. So after clearing the mirror and returning to our first target of the evening, we realised the seeing was much better than we had initially thought! (The mirror must have dewed up whilst the scope was cooling down, which is a first for us.)

So after our first evening with the 21mm Ethos, all I can say is WOW!!!

Whilst it provides a very similar field of view to the 35mm Panoptic, there is such a huge difference in contrast between these two eyepieces, at f/4.4. This contrast difference is more than enough to convince me that the exit pupil is important!

[John]

Good result

The Ethos should deliver superb performance on a number of fronts as well as the much more reasonable exit pupil.

I agree - exit pupil is something that needs to be considered when selecting eyepieces for fast scopes. I'm moving from a 10" F/4.8 to an 12" F/5.3 newtonian so my Nagler 31mm should be a bit more effective in the latter as the exit pupil reduces from 6.5mm to 5.8mm. Still a touch large for a 50+ year old bloke but an improvement

[Damo636]

The 21 Ethos is rather special, isn't it! I find the boost in contrast, even from the 31 Nagler is quite remarkable.

[Sarah]

The Ethos should deliver superb performance on a number of fronts as well as the much more reasonable exit pupil.

Yes no doubt it will. Certainly in the dob it is impressive. I want to compare the two eyepieces in the refractor sometime to see the difference. I expect it will be much less of a difference but would still expect the Ethos to perform better. Will also see how we cope with the weight of the 21mm Ethos in the smaller scopes!

We also compared our new 14mm Delos with the 13mm T6 Nagler. I thought the Delos was slightly better contrast wise but vastly better in terms of comfort with the extra eye relief and lack of kidney beaning!

[Sarah]

The 21 Ethos is rather special, isn't it! I find the boost in contrast, even from the 31 Nagler is quite remarkable.

It certainly is special! The combination of the extra aperture of the new dob combined with the contrast of the 21 Ethos, gave us our best nights viewing ever. I now can't wait until the next star party, when we can try it out under darker skies!

[jabberwocky]

Is the one that was on eBay? Or did you buy new?

I've bought the 13mm and 10 mm on eBay in recent weeks and both are outstanding eyepieces although my dob isn't the most demanding scope. Have to say I'm hooked on them!

[Sarah]

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Is the one that was on eBay? Or did you buy new?

I've bought the 13mm and 10 mm on eBay in recent weeks and both are outstanding eyepieces although my dob isn't the most demanding scope. Have to say I'm hooked on them!

Didn't see the one on eBay. We ended up buying new.

You should add a 21mm to those! We looked through a 13mm at SGL in our 12" dob and that was very nice!

For me, the 21mm was about getting a wide field of view, with maximum contrast. It really delivers from what I have seen and in fact has already exceeded my expectations!

[John]

You missed this one too Sarah !:

http://www.astrobuys....php?view=62147

Unless it's sold and the seller has not updated the ad.

I think it may have been my 13mm Ethos you had a look with at the SGL Star Party. Sorry it that has got you hooked on them

[Damo636]

There's something dubious with that one John. I know of another member on here who expressed an interest in buying it, but the seller wouldn't provide a contact phone number, email address or bank details for transfer of funds? I personally would proceed with caution with that one!

[Sarah]

You missed this one too Sarah !:

http://www.astrobuys....php?view=62147

Unless it's sold and the seller has not updated the ad.

I think it may have been my 13mm Ethos you had a look with at the SGL Star Party. Sorry it that has got you hooked on them

I expect there will be lots popping up all over place now we have ours! But we did get an extra discount which helped!

No you are off the hook John, it was Astronut (Ian) and Lulu who are to blame! We are going to stick with just the one (at least for the foreseeable future!) as we have opted to go down the Delos route for other eyepieces.

[John]

I can have a clear conscience then Sarah

There's something dubious with that one John. I know of another member on here who expressed an interest in buying it, but the seller wouldn't provide a contact phone number, email address or bank details for transfer of funds? I personally would proceed with caution with that one!

That does sound dodgy Damo - as you say, treat with caution !

[alan potts]

Congratulations on the 21mm Ethos Sarah, I want one and will get one soon, but I also want a 4.5mm Delos. If spending was a Olympic event there would be some front runners from this site for the Gold.

Alan.

[Sarah]

Congratulations on the 21mm Ethos Sarah, I want one and will get one soon, but I also want a 4.5mm Delos. If spending was a Olympic event there would be some front runners from this site for the Gold.

Alan.

Thanks Alan. It is certainly an amazing eyepiece and the 100 degrees was easier to take in than I thought it might be. The Delos eyepieces are looking impressive too!

[Luke]

I really love the 13mm T6 Nagler, eye relief on it is fine for me and I haven't had the kidney beaning problem Sarah has experienced, and it's so compact and light. But it just doesn't work for the missus, and she's let me know about it!

I did get some blackout when trying the 14mm Delos, so I let Sarah know

Then she twisted the Delos and pulled up the barrel, and it was perfect!

What a sight we got of M82 the Cigar galaxy with both the Nagler and the Delos, with the Delos edging it for me showing a touch more detail. I've never seen so much detail on it before!

We also compared our new 14mm Delos with the 13mm T6 Nagler. I thought the Delos was slightly better contrast wise but vastly better in terms of comfort with the extra eye relief and lack of kidney beaning!

[Luke]

I'm really impressed with our new 21mm Ethos, my new favourite EP! It was as sharp and contrasty as I'd hoped from the reports we read. What suprised me was how comfy I found the wide view - I know some people don't take to it.

A quick thanks to SGL for helping us to understand exit pupil a bit better to make an informed choice on our new wide EP for our faster dob. It's not the first bit of kit SGL has helped us get right.

[Damo636]

I'm really impressed with our new 21mm Ethos, my new favourite EP! It was as sharp and contrasty as I'd hoped from the reports we read. What suprised me was how comfy I found the wide view - I know some people don't take to it.

I would have to agree with you on the comfort Luke. I also have the 13mm Ethos and previously owned the 8mm, but the 21mm is definitely the easiest of the three to look through. Although the eye relief is quoted at 15mm across the range, it felt tighter for me with the 8mm? (It wouldn't put me off buying another though!) The 21 Ethos replaced my 26 Nagler, itself a wonderful eyepiece, but I do feel the 21 Ethos is 2nd to none in the "low & wide" category.

[Luke]

I did a little test last night of the 35mm Panoptic (with the large exit pupil) versus the 21mm Ethos in our dob last night on NGC 1907, a little cluster that we can just catch in the same field of view as M38 at low power. The viewing conditions were not that great at the time.

With the Panoptic, with direction vision I could only see 1 star in NGC 1907 and no glow from the little cluster. I could see the glow with averted vision.

With the Ethos, I could see 7 stars and the glow with direct vision. Quite a difference! I'm guessing a lot of that was to do with the exit pupil.