133x (4.5mm Delos and TV-85) under urban skies?

[GCab]

Hello

This is more a general magnification query rather than about this particular EP I guess, but is 133x realistic for planetary viewing in a suburban garden setting? (as well as atmospheric seeing, it's a small garden and there's plenty of heat rising from surrounding houses etc. so things tend to be on the wobbly side).

If you were buying a premium lens would you settle for a more modest 100x (6mm EP) for maximum crispness under a wider range of conditions, or is this selling the scope a bit short? 

To be honest this is a luxury purchase and aimed mainly for sharing views with friends and neighbours, as I already have a 3-6mm zoom but I thought the Delos would be super-sharp for me plus with eye relief would allow others to enjoy the view more reliably.  Nudging things along manually with an alt-az mount limited the 'friends and family' sharing before too, but I am getting a motorised mount and wanted a "just right" high-magnification EP to go with it.

So I guess my question is, with a good scope and mount but with seeing conditions that are a long way from a crisp mountain top, if you had to choose one or the other, would you go for 133x or a more conservative 100x?  (or should I even go for a 3.5mm)?).

Quite possibly you'll ask why I'm wasting money getting a Delos that is bang in the middle of my 3-6mm TV zoom range anyway, and I have no good answer for this ...

Thanks!

[GCab]

Incidentally the other obvious question is, I know, why don't I just try viewing at 4.5 and 6 with the zoom first and see, but previously I found the alt-az a bit limiting for higher magnification viewing (cack-handedness no doubt) so I have't played enough to get a good idea, and I'm in shopping mood at the moment and fancy trying the Delos, and I tend not to get much free viewing time, so I'd rather have the right EP already by the time next opportunity arises.  So any advice appreciated!

[John]

Hi and welcome to the forum

Personally I find that I need somewhat more power than 100x on the planets to make observing really rewarding and most often I'm using 150x - 200x with my 4" refractor up to 200x - 300x with my 12" dobsonian.

Having tried a number of zooms, including the superb Nagler 3-6mm my personal preference is for fixed focal length eyepieces however a zoom can be very useful to see what the scope / seeing conditions will stand and what you prefer yourself.

The TV 85 is excellent optically and I would have thought 150x - 180x a realistic target for planetary viewing and sometimes more if the conditions are steady.

[DirkSteele]

As John wrote, 133x is pretty low for planetary observing, even from an area suffering a reasonable amount of turbulence.  I also prefer the fixed focal length EPs vs zooms (even one of the quality of the Nagler Zoom – though when travelling, the space saving of that one is very important) and I believe the Delos are among the very best eyepieces available.  Perhaps it might be worth considering the 3.5mm Delos as that will give 170x?

I think the utility of the zoom comes not only from the travel convenience as already mentioned, but as each focal length click stop position is parfocal, there is no refocusing needed so when the atmosphere suddenly settles for a few moments, it takes no time at all to take the magnification up to higher powers.

[alan potts]

I tend to agree with the last two posters here, X133 is a bit low and the 3.5mm that Dirksteele mentioned is a superb eyepiece as is the same 3.5mm from Pentax. Jupiter should be outstanding at this magnification, I rarely use more than around that though on other planets I up the anti.

Alan.

[GavStar]

I've got a tv85, delos 4.5 and 6 and pentax xw 3.5,5 and 7 and view in South west London, so very similar to you.

Generally I find that 4.5mm is high enough magnification for me. When I use the 3.5, for me the exit pupil is too small and the view has too many floaters and is too dark. However, I'm sure it varies from person to person. Incidentally I like the eye relief that the delos and xw have but find I'm changing eyepieces quite often to get a preferred view. So I've just got a Leica zoom which I will barlow to give a nice Range of about 4.5 to 10 with good eye relief. Looking forward to trying it out on Jupiter in the next few months.

[Stu]

I find 3.5mm about the max in the TV85. This gives an exit pupil of 0.5mm which is as high as I like to go for planetary viewing. As Gavster says floaters become a problem at this level but I like the magnification (x171) so am prepared to look around the floaters.

If this is for sharing though it might be wise to back off a little. The 4mm Radian is very nice, good eye relief and 60 degree fov giving x150.

I have used a 3.7mm Ethos SX before but would not recommend this for casual observers. The eye relief feels tighter than the spec and seeing the field stop is challenging.

Don't forget that smaller scopes cut through seeing conditions better than larger ones, although heating flues etc are a pain. I tend to get two good steady views of the planets each clear night as they pass over the gaps between houses. The views improve noticeably during these periods, something to look out for.

It's a tough call as conditions change and you could easily find yourself usefully using a 3.5, 4 and 4.5mm on different occasions.

I'd be tempted to get a 3.5mm Delos, or 4mm Radian and use the Nag zoom to fill in the gaps when lower power is all you can use.

Stu

Sent from my iPhone using Tapatalk

[GCab]

Thank you very much for the welcome and for all the replies! This is very helpful. I think I'll go with the 3.5mm Delos and see how it goes - crystal clear daytime skies in London this morning and it's clouded over as soon as I decided to pop into the Widescreen Centre this afternoon and see if I could try it out this evening, inevitably :-)

[GCab]

Well, that was worthwhile - went with the 3.5mm and got my first look at Uranus today - took me a while to convince myself I was seeing a planet and not an out of focus star: any lower magnification and I'd still be wondering :-)

Only had time for a quick look (moon too, of course) but very rewarding - thanks again for the advice!

[John]

Glad it's worked out well

It should be good for binary stars too.

[alan potts]

Nice to hear that you got the eyepiece, Uranus may well look better when the Moon is not so close. I too looked last night with the 190mm and it didn't look anything like it normally does.

Alan