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Best 25mm eyepieces ever!

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#76 rfr66

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Posted 11 August 2012 - 07:39 PM

I have a pair of the E-PL 10x/20 that are made in China and can say that they perform amazingly well just as everyone described. Maybe you had a defective one. They are my favorite eyepieces and the only ones I am using for binoviewing. I tried a pair of the ridiculously expensive, $1400 each, E-PL 10x/25s but returned them. The extra wide angle on those was achieved with an additional screw on glass element that made the image much softer and fuzzier as if it stretched everything wider.

#77 chrisg

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Posted 17 November 2012 - 11:54 AM

Anybody know what is the difference between KPL, EPL, and plain PL? How does this effect their astronomical use? Does "W" mean "wide"? And for a 10x eyepiece, how far can you push these with a barlow before the image degrades? Do these eyepieces take barlowing particularly well??

#78 Astrojensen

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Posted 17 November 2012 - 02:58 PM

Hi Chris

"PL" means "planokular", which means flat field eyepiece. "KPL" = Compensating flat field eyepiece (an eyepiece that compensates for the last spherochromatism in apochromatic microscope objectives). "EPL" = Episcopic flat field eyepiece (I think! Not sure). The PL or flat field eyepieces can safely be used for astronomical telescopes. W does indeed mean wide. Wide is usually around 50° AFOV in the microscope world...

My own 10x (25mm focal length) microscope eyepieces can be barlowed in the extreme. I usually stack Baader GPCs to reach short effective focal lengths with them. 3x - 4x barlow effect is no problem at all. I believe Erik Bakker, who has identical eyepieces, also barlows his into very high magnification. Microscope eyepieces are usually designed with very long f/ratios in mind (with a high magnification objective, f/ratios can go into the hundreds!), which explains why they work so extremely well with barlows.


Clear skies!
Thomas, Denmark

#79 chrisg

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Posted 17 November 2012 - 03:06 PM

Thanks Thomas -

Just to be totally clear - you're not recommending the KPL or EPL eyepieces for astronomical use?
Thanks for the info!

Best,

Chris

#80 Astrojensen

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Posted 17 November 2012 - 04:44 PM

Just to be totally clear - you're not recommending the KPL or EPL eyepieces for astronomical use?


I can't say for sure, that they'll work without issues, as I don't have any experience with them at all. I've only used normal PL eyepieces and these have been spectacular.


Clear skies!
Thomas, Denmark

#81 Heavens Above

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Posted 18 November 2012 - 03:55 PM

I use the EPL and have been told this is the highest quality version. I love mine. I buy other eyepieces but always come back to these.

#82 chrisg

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Posted 20 November 2012 - 10:21 PM

Does anybody have a source where these can be converted to 1.25" relatively cheaply?

#83 Stellarfire

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Posted 23 November 2012 - 01:45 PM

I recently tried a pair of the current Zeiss 16mm eps and they were not of the same performance level. But that is another story....

Mark



Hi Mark,

I am interested in your experience with the current Zeiss 16mm. Are you referring to that one?

Stephan

#84 Space Dragon

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Posted 23 November 2012 - 01:58 PM

Does anybody have a source where these can be converted to 1.25" relatively cheaply?


APM- 50 Euro each
Precise Parts- $35 each
35mm Film cannister-Free

#85 chrisg

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Posted 23 November 2012 - 04:16 PM

Thanks - as I found, using the 35mm canister is easy and totally works. I don't feel like I'm missing any precision by using these. What I didn't realize - the lip of the canister is just wide enough to catch around the 1.25" hole, so height isn't too important. Very nice, just purchased the PL 10x/18's..

#86 Space Dragon

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Posted 23 November 2012 - 05:58 PM

Thanks - as I found, using the 35mm canister is easy and totally works. I don't feel like I'm missing any precision by using these. What I didn't realize - the lip of the canister is just wide enough to catch around the 1.25" hole, so height isn't too important. Very nice, just purchased the PL 10x/18's..

I have the PL 10x/18 as well. Mine came with a reticle crosshair pointer which sat across the field stop in the plastic barrel.
I decided to remove this glass and then also took out the fieldstop to the ID of the barrel, which is 25mm.
The edge performance isn't perfect but I prefer the wider field and no vignetting in my Earthwins.
Mileage may vary, of course.
I like the fit of the 35mm film cans as well, no movement or rotation, with a length of electrical tape around the barrel.

#87 Stellarfire

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Posted 24 November 2012 - 11:34 AM

Hi Thomas,

The webpage of APM-Telescopes lists 9 different Zeiss Astro Eyepieces 1 1/4".
According Markus Ludes, all are made in China now.

7 of them are 25mm eyepieces. Depending on the model, they are priced EUR 215.00 - EUR 1,539.00 each. Wow, that is an impressive price range. Choosing the right one is a hard task.

Thomas, could you provide me with any suggestions on the best suited 25mm e.p. model for observations with a 150mm f/7.3 APO refractor / Baader FFC / Baader Mark V binoviewer combination?

Stephan

#88 suburbanskies

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Posted 24 November 2012 - 01:19 PM


I recently tried a pair of the current Zeiss 16mm eps and they were not of the same performance level. But that is another story....

Mark



Hi Mark,

I am interested in your experience with the current Zeiss 16mm. Are you referring to that one?

Stephan


Dear Stephan,

Yes, I was referring to this eyepiece. I had a pair for binoviewer (Baader Mark V) use with a Baader FFC, prism and f/9 refractor operating at ~f/36. The problem I had was that on Mars, there were sharp reflections radiating from the planet. However, the seller did not experience this issue and kindly agreed to take the eyepieces back. It is a shame because these eyepieces were very well manufactured, with smooth diopter adjustment.

The other issue that may be important to some users (not for me because I mostly use for planetary at f/36) was that edge of field was very bad at f/9. Lots of aberrations starting at 50% from the center. At f/11, it was much better and good enough for me, but probably not good enough for some people.

Mark

#89 Stellarfire

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Posted 24 November 2012 - 02:23 PM

Hi Mark,

Thank you very much for your feedback, highly appreciated.
Too bad that the 16mm's did not work well for you, and great that the seller was kind enough to take them back.

I am a strictly binoviewer observer, using a 6" f/7.3 APO refractor in combination with a Baader Mark V and the FFC set at ~f/33. Our equipment is quite similar, so I would expect to see the same reflection issue as experienced by you with the 16mm.
Too bad, because the 16mm focal length looked very atractive to me, but the reported reflection issue on Mars makes them a no-go to me.

Stephan

#90 Astrojensen

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Posted 24 November 2012 - 04:05 PM

Hi Stephan

The webpage of APM-Telescopes lists 9 different Zeiss Astro Eyepieces 1 1/4".
According Markus Ludes, all are made in China now.

7 of them are 25mm eyepieces. Depending on the model, they are priced EUR 215.00 - EUR 1,539.00 each. Wow, that is an impressive price range. Choosing the right one is a hard task.

Thomas, could you provide me with any suggestions on the best suited 25mm e.p. model for observations with a 150mm f/7.3 APO refractor / Baader FFC / Baader Mark V binoviewer combination?



Not an easy question to answer, since I haven't tried any of the eyepieces shown. The ones I use, and can highly recommend, are these:

http://www.bw-optik....oberknochen.jpg

I can guarantee that they are in a class all by themselves. Totally outstanding. There's an error in the ad page shown, where they are listed as 27mm focal length, but they are 25mm.


Clear skies!
Thomas, Denmark

#91 Stellarfire

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Posted 24 November 2012 - 04:40 PM

Hi Stephan

The webpage of APM-Telescopes lists 9 different Zeiss Astro Eyepieces 1 1/4".
According Markus Ludes, all are made in China now.

7 of them are 25mm eyepieces. Depending on the model, they are priced EUR 215.00 - EUR 1,539.00 each. Wow, that is an impressive price range. Choosing the right one is a hard task.

Thomas, could you provide me with any suggestions on the best suited 25mm e.p. model for observations with a 150mm f/7.3 APO refractor / Baader FFC / Baader Mark V binoviewer combination?



Not an easy question to answer, since I haven't tried any of the eyepieces shown. The ones I use, and can highly recommend, are these:

http://www.bw-optik....oberknochen.jpg

I can guarantee that they are in a class all by themselves. Totally outstanding. There's an error in the ad page shown, where they are listed as 27mm focal length, but they are 25mm.


Clear skies!
Thomas, Denmark



Ok, thank you, Thomas!

Stephan

#92 johnnyha

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Posted 24 November 2012 - 09:34 PM

Thomas do you know where those can be purchased?

#93 chrisg

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Posted 10 December 2012 - 01:25 PM

Astrojensen - Are you using a barlow to achieve higher magnification with these rather than using your short focal length eyepieces? If so, which barlow are you using and could you describe how these perform better than your shorter length lenses?

#94 Astrojensen

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Posted 10 December 2012 - 02:31 PM

Hi Chris

When I use my 25mm Zeiss'es on my Maxbright binoviewer, I use the Baader GPCs to achieve higher magnifications. I have the 1.25x, 1.5x and 2.6x GPC and the 1.7x coma correcting GPC for newtonians. I can stack them and use extension tubes (not with the CC-GPC) to get higher magnfications. I also have a normal 2x GSO barlow, but it is not of the same quality as the Baader GPCs.

The advantage of using a rather long focal length eyepiece on a binoviewer combined with a barlow lens for high magnifications, compared to short focal length eyepieces, are manyfold. The chief advantage is that the collimation tolerances of a 25mm eyepiece with a 5x barlow in front of the binoviewer is five times less than a 5mm eyepiece and no barlow. This makes for relaxed viewing and easy merging. The longer eye relief and large eye lenses (28mm wide!) of the long focal length eyepieces also makes viewing very relaxed. It feels like looking out a window. The longer f/ratio of the light path that goes through the binoviewer prisms also introduce much less spherical aberration and false color than a faster f/ratio. The longer the better. Long focal length eyepieces are also inherently much easier to make with great precision than short focal length ones, so there are big advantages here as well.

All of this boils down to very relaxed, ultra high quality views. Sometimes I check the seeing with a pair of shorter focal length eyepieces, such as my 10mm GSO Superviews, but if the seeing is good and merit a longer view, out comes the 2.6x GPC, which turns the 25mm's into a pair of 9.6mm eyepieces with great eye relief. Of maybe the 1.5x GPC and extension tube, turning them into 13.1mm eyepieces, if the seeing can't support higher magnifications. I've got lots and lots of options with the GPCs.


Clear skies!
Thomas, Denmark

#95 chrisg

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Posted 10 December 2012 - 11:05 PM

Thanks Thomas!
I was thinking of using a 1.7gpc (because I only have this one) with either a 4x or 5x powermate to catch a view of Jupiter. Would you say these eyepieces could support such a set up or am I pushing it? I'm asking because I just purchased a set of these lenses and I could clearly see that they're extremely sharp and contrasty! Or maybe I'm better off with a set of 16mm Brandons and barlowing my way down from there! :rainbow:

#96 Astrojensen

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Posted 11 December 2012 - 03:39 AM

The eyepieces can take any amount of barlowing you can throw at them! It's the scope that'll give up first! Remember that with a 120mm scope, you only have so much light. I usually stop my 6" refractor down to 125mm when observing Jupiter and I find that a magnification of 120x is usually the best. A 4x Powermate and 25mm eyepieces will give 144x and by then Jupiter is starting to get a bit dim. But do try it and see what you find. It will be excellent for objects with high surface brightness, such as the Jovian satellites and the Moon. Saturn will also be superb.

The best way to find wisdom in these matters is to do a lot of experiments.


Clear skies!
Thomas, Denmark

#97 Sarkikos

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Posted 11 December 2012 - 08:21 AM

I've pushed my Burgess Binoviewer and a pair of SA LER 6mm eyepieces on my 10" f/4.8 Dob up to 600x with good results. This was for Mars when it was at about 7 arcsec and smaller last Spring. But for Jupiter I usually keep the power down to about 300x or less.

Mike

#98 Sarkikos

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Posted 11 December 2012 - 08:33 AM

Thomas,

I usually stop my 6" refractor down to 125mm when observing Jupiter and I find that a magnification of 120x is usually the best. A 4x Powermate and 25mm eyepieces will give 144x and by then Jupiter is starting to get a bit dim. But do try it and see what you find. It will be excellent for objects with high surface brightness, such as the Jovian satellites and the Moon. Saturn will also be superb.


Why stop down the 6" refractor? Does it have edge aberrations? If Jupiter seems too bright, there are better ways to solve that problem than stopping down the aperture. I would never give up aperture unless it's to cover up some defect at the edge of the mirror or objective, such as a turned edge. If Jupiter appears bright in a 6" telescope, I really think that the observer's eyes are not properly adjusted for observing planets.

Mike

#99 Astrojensen

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Posted 11 December 2012 - 09:48 AM

Why stop down the 6" refractor? Does it have edge aberrations?



Yes. It has quite a bad case of turned down edge. :( 125mm is the max before it shows up, determined with a ronchi grating.

If Jupiter seems too bright, there are better ways to solve that problem than stopping down the aperture. I would never give up aperture unless it's to cover up some defect at the edge of the mirror or objective, such as a turned edge. If Jupiter appears bright in a 6" telescope, I really think that the observer's eyes are not properly adjusted for observing planets.



I agree and you're going to be happy when I tell you that I now usually observe Jupiter with a 12" dob, not stopped down. :grin: I really like the big, bright images. I am usually at 160x with it, via a 2.6x GPC and my 25mm Zeiss'es.


Thomas, Denmark

#100 denis0007dl

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Posted 23 May 2013 - 08:34 AM

Here are my 25mm Zeiss Aspherics E-PL eyepieces 10x/20, cant wait to test them :)

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