Vixen Slv 5mm fuzzy image?

[lunartic]

After much deliberation I decided to buy a 5mm slv for some planetary viewing after plumping for a very nice 28mm MV last month. I'd read some good reviews for the 6mm slv and was unsure whether to go for that or the 5 from FLO but since the 5 had 20% off and would give me a hopefully top end of useable 240x mag in my 250px, that's what I went for. Anyway, I had my first light with Jupiter the other night. The view was quite disappointingly low on detail but I knew seeing conditions were bad that night and it was rather windy and unsettled. I took it out again tonight and looked at some doubles, the trapezium and a thin crescent moon. Again I was disappointed. I just couldn't reach a sharp focus at all. The scope had plenty of time to cool down. I believe my scope is reasonably well collimated, certainly the stars look fabulous in my MV but would this be super pronounced at 240x mag? Anyone think I should contact FLO? 

Any help or thoughts appreciated. Would be useful to try the EP in another stargazer's scope perhaps... 

[Stu]

I doubt there is anything wrong with the eyepiece, I'm sure it's just that it is too much power for the conditions. The crescent moon was quite low, so you are looking through a lot of atmosphere. M42 is also fairly low, did you try any targets towards the zenith?

[Chris]

It might simply be that 240x is too much mag 90% percent of the time. It may only deliver the goods on nights of exceptional seeing. I tend to get my best planetary views sub 200x for sure. 

If you've only just bought the eyepiece, maybe email FLO and see if you can exchange it for something around the 7mm mark (172x) perhaps?

Only my view mind, it would be good to get a consensus  

[jkwhinfrey]

I've got and use the 5mm SLV and it's clean and sharp in my 150PDS although that's only at 150x. What you're experiencing isn't typical of this eyepiece IMO.

Poor collimation will have a much more serious effect on performance at high magnification, so that could be the problem. Pointing your scope at Polaris and defocusing with the SLV and checking the rings of the pattern you see are concentric will tell you if the collimation's OK.

James

[John]

I agree with the other posters - it's likely to be the seeing conditions, the target and the amount of magnification that were the cause of the poor image rather than the eyepiece. With Jupiter I usually use around 200x even with my 12" scope for the best views. Sometimes 250x is still good but often the lower figure works better on teasing the details out.

 

[michael.h.f.wilkinson]

I have a little SLV 5mm and it is very nice. I also have a Pentax XW5, and when conditions are good the main difference between these to EPs is field of view.

[Mr Spock]

UK seeing conditions are often poor. We can thank the jetstream for that. Part of it is currently across the south of the country.

[jkwhinfrey]

True. In my scopes 150–180x tends to give the best results on Jupiter. The OP has more aperture, but that's not likely to help much in this case.

Jupiter was nice last night but only up to 150x for me, then mushy. I like the idea of a 7mm in your scope.

James

[alan potts]

Like the others I feel this is seeing and maybe for me at least a bit too much power, for me less is more on Jupiter, about X180 is my sweet spot. Yes I do and have gone higher in the 18 inch but even then only to about x250. I viewed the Moon only last night with the 12 inch Meade and even at X190, which is nothing on the Moon, I could bearly make out a crater.

[lunartic]

Sound advice! Fortunately for me FLO accepted the slv back without any fuss, so the quest is now on to select a more suitable EP for the 250px which hopefully will give me some good views but be useable most of the time. 

Back to the drawing board with my 50 - 100 squid budget.

Any suggestions? Seems to be plenty of choice. Although just over a hundred I has considered the ES 82 degree range after reading an excellent review on this site. They have 6.7 mm but maybe 8.8 would be safer? For a bit less there's the x-cel lx 7mm too. 

Andy

 

[LukeSkywatcher]

Something in the 8-9mm range would be good.

[Moonshane]

Pentax 8.5mm XF (141x) fits the bill and is sold by FLO. This magnification will regularly give excellent views.

If you have a 2x barlow, unscrew the element and then screw onto the eyepiece to get a 5.7mm eyepiece to give 210x.