Super Plossls in fast F5 Frac?

[parallaxerr]

Does anyone have any experience of 70 degree super plossls in a fast scope, specifically an F5 frac?

Buying these would purely be an exercise in seeing what FOV & FL works best in my scope for certain targets, during this winter season. Ultimately I want to move on to ES 82 degree EP's but funds are going into the caravan pot at the mo.

Found these AA EP's: http://www.altairastro.com/altair-20mm-wide-field-70-fov-super-plossl-eyepiece.html

They look the same as these GSO's and Antares items advertised on the TS website:

http://www.teleskop-express.de/shop/product_info.php/language/en/info/p2643_GSO-SuperView-20-mm---1-25--WA-eyepiece---70--FoV.html

http://www.teleskop-express.de/shop/product_info.php/info/p2717_Antares-25-mm-70--wide-angle-eyepiece--1-25-.html

[Dude_with_the_tube]

I will answer very short:

4 elements,70 degree and F5=recepie for a disaster.Stay away and buy a round of beer for friends

[Roy Challen]

Hmm, whilst I don't have experience of the ep you linked to, 4 elements+

2 minutes ago, Dude_with_the_tube said:

I will answer very short:

4 elements,70 degree and F5=recepie for a disaster.Stay away and buy a round of beer for friends

I was gonna say that! Add in the £30 cost, ain't gonna be good!

[John]

They will give you a general idea of what a wide field looks like but expect the outer 50% of the field of view (or so) to be pretty distorted in an F/5 scope. Even at F/6.5 they struggle in the outer areas of the field to be honest.

Low cost + wide field + fast scopes don't mix well I'm afraid.

 

 

[billyharris72]

I've never used these, but eight elements in four groups is quite a bit of glass and ought to be more than capable of producing a well corrected field. Quite inexpensive so you never know, but I would think worth a try- I suspect you'll get some distortion at the edges, but that it'll be perffectly usable. Let us know if do do go for one.

What I really want to know is how an eyepiece with that much glass can be described as a Plossl, Super or otherwise. Another one to file with FMC, BAK4 prisms and diffraction limited optics?

[Stu]

1 minute ago, billyharris72 said:

I've never used these, but eight elements in four groups is quite a bit of glass and ought to be more than capable of producing a well corrected field. Quite inexpensive so you never know, but I would think worth a try- I suspect you'll get some distortion at the edges, but that it'll be perffectly usable. Let us know if do do go for one.

What I really want to know is how an eyepiece with that much glass can be described as a Plossl, Super or otherwise. Another one to file with FMC, BAK4 prisms and diffraction limited optics?

4 elements Billy, it says 8 optical surfaces...

[parallaxerr]

OK, pretty obvious where this is going. Not suprised really at the price point, it was just a thought.

Looks like I'll hang on a bit longer until I can get the ES pieces onboard!

[andrew63]

These change the equation, in my F5 refractor the 20mm ticks all 3 boxes !  They are sold out in most places now but RV optics might still have them.

http://www.rothervalleyoptics.co.uk/0215220.html

 

andrew

 

[parallaxerr]

1 minute ago, andrew63 said:

These change the equation, in my F5 refractor the 20mm ticks all 3 boxes !  They are sold out in most places now but RV optics might still have them.

http://www.rothervalleyoptics.co.uk/0215220.html

 

andrew

 

Funnily enough I've just been reading about these being ex-Meade 5000 series and that they perform well. I thinkI'll be going for ES82's though so I can use shorter FL's for larger image scale.

[Knighty2112]

I'll second that. The ES68 20mm EP works a treat in my f5 frac, and even better in my f11 frac. 

[John]

I use a 24mm 68 degree Maxvision eyepiece with my 12" F/5.3 dob quite often and it's really pretty good. I bought the eyepiece used for less than £50. 

[YKSE]

I agree with Adrew, this 20mm is among the best of 68° meade clones. The optical tests I have read says that it works very well in F4 too, not many 68° SWA does that.

[Dude_with_the_tube]

3 hours ago, billyharris72 said:

I've never used these, but eight elements in four groups is quite a bit of glass and ought to be more than capable of producing a well corrected field. Quite inexpensive so you never know, but I would think worth a try- I suspect you'll get some distortion at the edges, but that it'll be perffectly usable. Let us know if do do go for one.

What I really want to know is how an eyepiece with that much glass can be described as a Plossl, Super or otherwise. Another one to file with FMC, BAK4 prisms and diffraction limited optics?

plossl or super plossl is only 4 elements,each element 2 surfaces,makes it 8 surfaces in total.Are they all multi coated as they advertise? i really doubt,unless it is some cheap rubbish varnish of some sort what doesnt make any difference if its coated or not lol.

[billyharris72]

5 hours ago, Stu said:

4 elements Billy, it says 8 optical surfaces...

Don't know how I managed to misread that. Definitely moves these from "interesting" to "Danger Will Robinson!" territory.