Eyepiece Preferences - Why do you like it?

[Dennis]

Originally Posted by janoskiss

John, I read it on the Baader Hyperion brochure or "data" (uhm advertising) sheet:
http://www.alpineastro.com/Eyepieces.../Hyperion2.pdf
which says that if you remove the barlow bit, the negative achromatic doublet, you end up with a 6-element Erfle.

Last night, with the 21mm Hyperion in the WO 80mm, the FOV was pleasantly sharp all over. When I unscrewed the (1 ¼”) Barlow, making the 21mm Hyperion it a (2”) 42mm, the view was only sharp in the central half of the FOV. Outside that circle, the stars were quite fuzzy. This was all through a WO 2" Dielectric diagonal.

Its worth noting that I am not a visual observer by nature, so my review of eyepieces would tend to be relatively unsophisticated and not supported by lots of hard experience.

Cheers

Dennis

[janoskiss (Steve H)]

Thanks John. Yes, that Erfle looks very different to the Hyperion.

[ballaratdragons (Ken)]

Originally Posted by janoskiss

How does your Erfle go in the 2" barlow, Ken? I just found out that LVWs and the clones (hyperion/stratus) are nothing more than barlowed Erfles!

It works quite well Steve. It's like having a 'head in space' view at 16mm. No distortions or seagulls.

The thing to remember with Erfles though is 'black-spot'. That alone often turns people off them. Doesn't bother me. Only takes about 1 minute to learn how to get rid of black-spot, and then the views are great!

And good 2" 32mm Erfles are still relatively cheap.

[cahullian]

ATM I put cost as my main reason. I have seen ep's worth more than my scope and the view is fantastic, but the view through my ep is always the best as it's the one I'm most used to and the one I get the most enjoyment with. I have a $400.00 Dob and $40.00 ep's and still see the same things as everyone with all their mega bucks gear. The money I save on ep's goes on my kids education and with one in year 12, one in year 11 and one in year 9 it's money well saved at least for the next three years.

Gazz

[janoskiss (Steve H)]

Originally Posted by cahullian

I have a $400.00 Dob abd $40.00 ep's and still see the same things as everyone with all their mega bucks gear.

Well said Gazz! Indeed $40 spent wisely these days buys a very capable EP that shows everything a $400 EP does. Anything beyond good but inexpensive FMC plossls is a luxury. But if you buy 2nd hand and at good prices, you could at least temporarily enjoy a premium EP collection that would be the education fund for your kids.

[cahullian]

LOL Steve you are a very bad man trying to tempt me...

[jjjnettie (Jeanette)]

I chose Cost, Sharpness, Eye Relief and Field of View.

[johnno]

Originally Posted by ausastronomer

Here is a link showing two of the Erfle variants, including the original.

http://www.quadibloc.com/science/opt04.htm

You can see that they are clearly different to the configuration of the Hyperion, shown in the link you provided.

I also checked the Erfle configuration in Telescope Optics, Rutten and Van Venrooij and it is consistent.

CS-John B

Very Good info John,
Thanks for the link.

Regards.
John

[Merlin66 (Ken)]

For high mag work, this has to be the best!! Tight focus, hi contrast and great image.

[stephenmcnelley]

Compromises abound with this sort of priority indexing.
I am willing to give away a little field curvature and outer field 20-30% for pin sharp mid axis viewing with 65-80 degree EP's at F5 in a Newt.
But then the only Nagler's i use are borrowed.

[stephenmcnelley]

Then my most favourite EP's are 6mm and 9mm UO Orthoscopics, bugger all fov but they make up for it by giving you everything else.
Not a lot of fun in a manual scope though..

Gotta have;
Contrast
Minimum field curvature,
Good light transmission, not a heap of elements,
As few white birds around the field stop as is possible
contrast,
Decent threads in the barrel extension, unlike my 8mm Stratus which droped a UHC into the OTA on its first night out Wasnt impressed with its optics either, it was a dud that was replaced pronto.
Just my 2 cents worth, again..

[glenc (Glen)]

I go for contrast, sharpness on axis, wide field of view, cost and light transmission. I like looking at nebulae and for them contrast is important and a large field of view especially for things like NGC 1499 and 7000. On globulars, galaxies and planetary nebulae sharpness, high power and transmisssion are more important.

[Don Pensack]

I'm surprised focal length was not a criterion listed separately.
First I choose the appropriate focal length (=/- a mm), then I look for
the other characteristics. I don't care how good any 3mm eyepiece is, because I can't use it, as a simple example.

[wavelandscott (Scott)]

Originally Posted by Don Pensack

I'm surprised focal length was not a criterion listed separately.
First I choose the appropriate focal length (=/- a mm), then I look for
the other characteristics. I don't care how good any 3mm eyepiece is, because I can't use it, as a simple example.

An interesting comment...when I developed the poll I just took the focal length as a given (any focal length) and for that focal length what characteristics do you look for...as in, for a 12mm focal length I prefer/desire...eye relief etc.

I do normally pick the focal length first and then move into the characteristics...

[Kevnool (Kev)]

Originally Posted by Ric

I only have the one eyepiece at the moment, a Meade 5000 26mm Plossl which I find to be a very capable eyepiece. My main criteria is field of view.
I am currently saving for another two of the Meade Ultra Wides though which two is yet to be determined.

cheers

My sentiments I love this eyepiece.

I just swap between the 26mm and the 2x barlow.

Next will be a 13 or 14mm with apparant 82`field of view.

Also this 7mm Orthoscopic cause i got told to get it.

Like aperture i like field of view for my very casual observing.

[GrahamL]

Very old thread I know ... DESIGN is a good starter

Useing an f 6 scope as a gauge slower /faster examples would greatly influence your eyepiece choices before considering other factors imo?