3.5mm in a 250px dob

[Philk_80]

Hi

I was fortunate enough to be bought a 3.5mm 70 SWA Skywatcher eyepiece for Christmas but think it is too much for my scope!

Is it worth trying out or should I see if I can swap for a 5mm?

I have a 250px dob flex tube with a f4.7

Help please

Thanks

Phil

[Pig]

Phil,

It all depends on the magnification the eyepiece gives in your scope  ( focal length of your scope / focal length of eyepiece = magnification )

The UK is restricted to around 200 X magnification due to our atmosphere, Jupiter is best for me around 170 X and the moon can easy take 350 X.

The planets vary between around 100 X and about 225 X dependant on the seeing conditions and the planet.

[emadmoussa]

I've got a similar combination: 250mm GSO Dob and SWA 3.5mm. For lunar observing this eyepiece works brilliantly, but it's difficult to get Jupiter for instance to come into a prime focus. It seems to work better in my 4" apo and 6" achro though.

I also use a Hyperion 5mm. And to be honest, the same thing...works better in refractors.. While the 5mm works better on planets than the 3.5mm, the 6mm Delos is slightly better on Jupiter  and bright nebulae such as M42. 

[emadmoussa]

Phil,

It all depends on the magnification the eyepiece gives in your scope  ( focal length of your scope / focal length of eyepiece = magnification )

The UK is restricted to around 200 X magnification due to our atmosphere, Jupiter is best for me around170 X and the moon can easy take 350 X.

The planets vary between around 170 X and about 225 X dependant on the seeing conditions.

Absolutely.

[Moonshane]

personally as you have been bought it as a present I'd keep it as it will be useful on moon and double stars and as suggested above, scopes of a shorter focal length. sure a 5mm would be useful more often but you can eventually buy one of those too. there will be nights when whichever one you choose, you'll wish you had the other one.

[Bart]

Depends on who bought it for you and how they would mind you changing it. The 5mm would definitely be more useful.maybe if you're a lunar type of guy, keep it, but if you're not, try to change it

Barry

[Pig]

Its pointless keeping something you wont use, especially if was a present.

Sell it and put the money toward something you will use, I am sure the person who bought you it would prefer that

[Philk_80]

Thanks for the advice.

If you guys think its worth keeping then I will.

Can you give advice or pictures on how it fits in my scope as it has a screw as part of it that I am unsure about etc.

[emadmoussa]

Thanks for the advice.

If you guys think its worth keeping then I will.

Can you give advice or pictures on how it fits in my scope as it has a screw as part of it that I am unsure about etc.

I'd personally unscrew the 1.25" bit and use it as a 2" eyepiece. It'll be gripped more tightly this way. I however use it as it is in my Dob and it seems fine.

[Moonshane]

be careful http://stargazerslounge.com/topic/203118-ruined-brand-new-eyepiece/?p=2150134

[Rustysplit]

I would keep it.  At 335x mag, Lunar detail will be stunning on good nights, and with the 70 deg fov, the amount of nudging required will be less. You may not use it a lot, but as a gift you have bagged a nice high power ep.

[swamp thing]

The UK is restricted to around 200 X magnification due to our atmosphere, Jupiter is best for me around 170 X and the moon can easy take 350 X..

But of contradiction here. First you say the UK is restricted to 200x then the moon can take 350x!!!! Or is that when observing from the moon

Planetary observing is perhaps what your basing the first statement on?

Double stars, globular clusters, small planetary nebulae etc can easily take more power than 200x.

[emadmoussa]

But of contradiction here. First you say the UK is restricted to 200x then the moon can take 350x!!!! Or is that when observing from the moon

Planetary observing is perhaps what your basing the first statement on?

Double stars, globular clusters, small planetary nebulae etc can easily take more power than 200x.

Well, planetary nebulae don't necessarily show more noticeable details whether 200x or 250x..at least in 10" Dob or 6" achro. But globular clusters do show subtle details upon more magnification...this is my experience - I stand corrected

[swamp thing]

I use higher mag on planetary nebulae in my 10" Dob when looking for central or associated stars. The higher mag can help pin point them. It can also make some of the stellar appearing ones easier to detect.