Barlow & T6 Nagler's ?

[spaceboy]

SORRY! A little late I know as I see from your signature that you already went with the 6mm Radian.

The skies cleared earlier than forecast last night and I was able to give the 13mm and x2 barlow a go on Jupiter to better advise the pros and cons for you. Going between the barlowed x184 and none barlowed x92.3 I couldn't see much in it if I'm honest. The view of Jupiter obviously got bigger but there was no loss in the quality of the image and I was able to clearly see the usual 4 moons and 4 other stars B-V: 0.32, B-V: 0.41, B-V: 0.57 & B-V 1.17. Jupiter seemed really bright last night and I wouldn't have said the image darkened any more than you would expect given the additional magnification. At x184 the 82' FOV roughly allowed 40-50 seconds before I felt the need to nudge Jupiter to the opposite side of view again. Needless to say I was able to concentrate on picking out more detail on Jupiter's bands and with less fuss than experienced while using the zoom. The only niggle I did have with the barlowed nag and as previously mentioned is that there is an occasional ghosting in the view. I'm not talking about the reflection you some times get as a result of retina reflection (similar to red eye in photos) but an almost life of it's own flicker. I have come to the conclusion I think it is a tiny bit of air trapped between the lens (or in this case the barlow and the EP as it doesn't do it in the 7mm Nag) that is either condensation or fogging as the temperature changes. The bright light of planets merely catches this fogging and the result is a ghostly flicker. I'm thinking the ep is handled out of a warmish padded flight case into the cold and then my face and eye is radiating some more heat into the mix. It is not uncommon for the eye lens of a cold EP to steam up when looking through it so who's saying the other several lens won't react in a similar way. I'm guessing this is the reason behind ES purging their EP's with nitrogen. Most rifle sights are purged for the same reason. Making the scopes waterproof it also prevents fogging. I have come to the theory as I have noticed the same ghosting in TMB clones the high power radians and barlowed EP's. The common thing is that all have is relatively large eye lens and so more surface glass and air space. I've never noticed this issue with the usually all small lens plossls, BGO's or the nagler zoom (except when barlowing the zoom).

I don't know if this is a common issue for all or it's just me but if anyone else has experienced similar issues my guess is this ghosting would be permanently resolved with use of a dew band keeping the EP or EP barlow combination at a consistent temperature. I'd be happy to recommend a short FL Nagler / TV barlow combination to those looking for a high power wide field solution. Even if you don't use a dew band to heat the EP the shimmering is not constant and on occasions doesn't happen at all.

While the Nagler / barlow combination works, it's never going to offer the comfort of a radian (or DELOS ) The large lens, eye relief and easily seen 60' FOV (72' in a DELOS) may to some be the winning factor (Hmm DELOS) in choosing which works best for an individual (6mm DELOS) and I hope it works for you Damo. Should you choose to go a barlowed Nag (and not a DELOS) in the future I hope this report gives you a little more insight than my last post did. That or someone else can better explain to what causing this ghosting for those of us who do experience it?

[Damo636]

Some very useful info there Nick. In the end i decided not to go with the Barlowed option as it was going to cost me as much as the Radian did for a decent one. I haven't had a chance to try it out yet with the never ending cloud cover but fingers crossed for the weekend. I had the 13mm Nagler and a 14mm Radian in my possession for a short time and had a couple of opportunities to compare them side by side. To my eyes at least the Radian matched the Nagler in every respect other than fov and i was mightily impressed with it. Obviously i had to let one of them go and kept the Nagler for its superior fov. I have read some users, yourself included have had problems with ghosting and reflections with the 6mm Radian but i'm hoping fingers crossed that i get on ok with it. The 6mm Delos would have been my prefered weapon of choice but just to expensive new for the amount of use it would see. I won't rule one out in the future though when they start to appear on the 2nd hand market