Plossl or Orth EP?

[steve_bham]

But in the end you may come back to a set of Orthos as they let more light through with their design than many lenses with more lenses 6,7+.....So even though you might be able to move your eye away from the lens with a flashy wide angle seven lens system and see a wide field of view there may be something missing..yes that very faint galaxy might not be visible at all....

BUT you may not be a galaxy fiend like me..

Mark

The only thing that puts me off the orthos is the very small eye relief. I dont normally wear glasses to observe but if ive had a long week at work then i have to wear my specs to look through the EP

[albedo0.39]

Sorry - Ortho every time:- Colour neutrality, image contrast, image clarity. Trouble is, nobody has found a way to make them with a 80deg FOV !

I've got a 9mm Ortho (up for sale) and it's stunning but just too narrow for my 'scope but it performs very well.

[John]

Sorry - Ortho every time:- Colour neutrality, image contrast, image clarity. Trouble is, nobody has found a way to make them with a 80deg FOV !

Well I think the Nagler T6's are pretty close - can't see much difference between my Nagler T6 7mm and the Baader Genuine Ortho 7mm I've borrowed for a while TBH.

[brianb]

The only thing that puts me off the orthos is the very small eye relief.

0.85f - sure 0.85x6 isn't much but 0.85x18 is very reasonable unless you really must wear glasses .... and Barlow lenses were invented to get out of having to have very short eyepieces.

The popular Plossl design has slightly less eye relief than the Abbe design orthoscopic - only 0.8f. Doesn't stop people using them.

[albedo0.39]

If you want to know all there is to know about EP design, but were afraid to ask, take a look here

http://www.astrosurf.com/re/evolution_of_eyepieces.pdf

It's pretty deep and contains some very interesting calcs and basics of lens design. Page 41 has some pretty interesting information about "which is best"

John, my experience of the T6 is close to yours except I found the Ortho a touch crisper in detail and brightness (of course, the FOV is another matter)

[part timer]

Just to throw in my 2 pence worth.

I have a some older Televue plossls and had a small set of Baader ortho's previously.

The lowest focal length I can use in either design is 10mm. Any smaller and I just get so uncomfortable that I can't use it for more than a few seconds. The ortho's may have a bit more eye relief but only a meaningless fraction more in my opinion.

Optically, there isn't much between the two designs when they are good quality. The TV Plossls and the Baader's really are an improvement on cheaper eyepieces. I find that the extra field makes the TV's just a bit more versatile as I'm a general observer.

For the highest powers I use the TS planetary's which sacrifice almost nothing in performance over the plossls and ortho's but give really comfortable views. This comfort means I can see finer details as I can observe as long as I like.

Hope this helps.

[Andrew*]

Just to throw in my 2 pence worth.

I have a some older Televue plossls and had a small set of Baader ortho's previously.

The lowest focal length I can use in either design is 10mm. Any smaller and I just get so uncomfortable that I can't use it for more than a few seconds. The ortho's may have a bit more eye relief but only a meaningless fraction more in my opinion.

Optically, there isn't much between the two designs when they are good quality. The TV Plossls and the Baader's really are an improvement on cheaper eyepieces. I find that the extra field makes the TV's just a bit more versatile as I'm a general observer.

For the highest powers I use the TS planetary's which sacrifice almost nothing in performance over the plossls and ortho's but give really comfortable views. This comfort means I can see finer details as I can observe as long as I like.

Hope this helps.

Great post. I too love the TS Planetary's

[Moonshane]

sorry to resurrect an old thread (it's amusing how we all ask the same questions eventually!!).

despite my previous 'guarantee' to 'only' own six EPs, the recently appalling seeing conditions have made me realise that even if the field of view is well covered, the seeing conditions affect the magnifications possible massively and if you have fewer EPs then you have fewer choices, especially at the higher magnification end (eg 100x upwards).

therefore, although I do love my wide field EPs, and will use them where possible for the comfort they give, I am considering some cheaper options as 'fillers' for planetary, lunar and doubles work with my 6" dob which is really designed and bought specifically for this purpose.

I love my 11mm TV plossl and am thinking of adding a couple of Baader GOs (probably the 9mm and the 12.5mm) and also a TV 15mm Plossl as the seeing really does prevent magnifications above the 105x that this gives in my two scopes - shocking! I don't think I need a 8mm TV Plossl as my 8mm Radian covers this nicely (although I hope to be comparing an 8mm TV Plossl with the Radian soon) I don't think I need anything else as the Nagler zoom covers 6-3mm well enough. if only TV did a Nagler 14-7mm zoom!

I was thinking of getting a 10mm Ethos but in reality, I can buy all of the above plus a 10mm Radian new for about the same price.

I'll be going slowly and buying things as they seem required but based on my current experiences, this seems a sensible way to generate two sets of EPs which will cover both of my current scopes and serve the wide field preferred in the 12" and the narrower sharper field in the 6". After all the whole idea of getting the 6" was to squeeze every last bit of contrast out of the planets that I can. OK so now it's a no more than 10 EP, but they must all fit in one case, guarantee......

[glowjet]

I do not see any problem in adding a couple of Baader Otho's to your kit, for just observing the Planets looking at variables and splitting doubles, they are excellent.

[Moonshane]

cheers Glowjet

I am going to try the 12.5mm first I reckon and then go from there.

[pvaz]

In a direct comparison between my Baader Ortho 9mm and my Ethos 10mm, on some tiny details on planets/moon the BGO gives that slight extra contrast needed to see those details. My experience with plossls is limited to the Orion Sirius plossl range and the BGO wins that comparison for sure.

I would recommend a BGO for long, detailed observations of planets/moon. In fact I plan to get a few more of them when possible (read "when SWMBO" allows). Otherwise you may want something more comfortable to use.

[Kef9]

cheers Glowjet

I am going to try the 12.5mm first I reckon and then go from there.

Tell me all about the 12.5mm BGO! How does it compare to the 13mm ethos. Also we need to test the 8mm radian against the plossl soon.

[Kef9]

In a direct comparison between my Baader Ortho 9mm and my Ethos 10mm, on some tiny details on planets/moon the BGO gives that slight extra contrast needed to see those details. My experience with plossls is limited to the Orion Sirius plossl range and the BGO wins that comparison for sure.

I would recommend a BGO for long, detailed observations of planets/moon. In fact I plan to get a few more of them when possible (read "when SWMBO" allows). Otherwise you may want something more comfortable to use.

This is interesting and I am coming to the same conclusion. I want a set of orthos / plossl's for planetary. Wide fields are good for longer focal lengths but when doing high power I feel that light throughput is essential. It comes down to whether you can handle the eye relief.

[russ]

I've ditched all my widefields in the 4mm to 12mm range. Replaced them with a range of good quality plossls and orthos. Although i have to admit the credit crunch is partly behind the move. I could have 4 Plossls and Orthos for what i sold the Pentax XF for.

No Baader GO's though, too pricey (even secondhand) for me to consider. Better deals to be had with other branded Orthos. Picked up a UO HD Ortho 9mm for £25 and an Antares HD Ortho 7mm for even less. My current favourite for planets though is a Vixen 6.3mm Plossl. Sharpness and contrast are spot on. The TV 7.4mm and 8mm Plossls were lovely but worth too much for me to keep.

[Moonshane]

Tell me all about the 12.5mm BGO! How does it compare to the 13mm ethos. Also we need to test the 8mm radian against the plossl soon.

I have had one chance to use it very briefly and since then it's been cloudy! my initial impressions were that it is slightly sharper than the 13mm Ethos and comfortable to use. The field of view is clearly smaller than the Ethos (!!) but even with a manual dob, perfectly acceptable on planets.

I'll do a proper report when I get a decent night. Yep, we should get together at some point and try the 8mm Radian against the Plossl.

I reckon I'll be buying a 10mm Radian rather than a 10mm Ethos on this basis.

[Moonshane]

This is interesting and I am coming to the same conclusion. I want a set of orthos / plossl's for planetary. Wide fields are good for longer focal lengths but when doing high power I feel that light throughput is essential. It comes down to whether you can handle the eye relief.

I think this is right. I too plan a planetary/lunar/doubles set mainly for my 6" f11. This is likely to be 15mm TV Plossl, 12.5mm BGO, 11mm TV Plossl, 10mm Radian, 9mm BGO, 8mm Radian, 7mm BGO, 6-3mm Nagler. The ones I don't have can be bought (almost) for the price of one new 10mm Ethos!

[Moonshane]

I've ditched all my widefields in the 4mm to 12mm range. Replaced them with a range of good quality plossls and orthos. Although i have to admit the credit crunch is partly behind the move. I could have 4 Plossls and Orthos for what i sold the Pentax XF for.

No Baader GO's though, too pricey (even secondhand) for me to consider. Better deals to be had with other branded Orthos. Picked up a UO HD Ortho 9mm for £25 and an Antares HD Ortho 7mm for even less. My current favourite for planets though is a Vixen 6.3mm Plossl. Sharpness and contrast are spot on. The TV 7.4mm and 8mm Plossls were lovely but worth too much for me to keep.

this is a good plan Russ and I know you've been impressed with the quality of the 'cheaper' options; the quality is definitely not noticeably worse in most cases I bet with the seeing we get here.

do you manage the 6.3mm on your dob? I have been struggling with anything more than 145x (11mm plossl) with my two scopes on Jupiter.

[lunator]

I have a full range of the japanese ortho's for the money they are unbeatable

Cheers

Ian

[Kef9]

I have had one chance to use it very briefly and since then it's been cloudy! my initial impressions were that it is slightly sharper than the 13mm Ethos and comfortable to use. The field of view is clearly smaller than the Ethos (!!) but even with a manual dob, perfectly acceptable on planets.

I'll do a proper report when I get a decent night. Yep, we should get together at some point and try the 8mm Radian against the Plossl.

I reckon I'll be buying a 10mm Radian rather than a 10mm Ethos on this basis.

Yep

Tell me about it. I want to test my TV plossls in my C100ED where I think the view of Jupiter should be even better. I also want to try out my new Baader Skysurfer V.

Even with my undriven CG5 mount I'm not finding the small FoV's provided by these eps a problem. If anything it helps you to concentrate on the target.

Next time we get a clear night we should get together to compare the 8mm plossl to the radian. It would be good to compare them to an 8mm ethos too but that is just wishful thinking

[Revs]

I've not had chance to try my BGO 12.5mm more then a couple of times, and only in the Mak. It does bring out the most detail, but it can be a pain with spec's on. But every planetary observer should have one, regardless, as they're great EP's

EDIT: The 8mm Hyperion does dim things down a bit, but it's so comfortable. Superb in the dob!

EDIT2: No good if you've had a pint