Jump to content


Photo

Leica ASPH Zoom in a Fast Newtonian

  • Please log in to reply
91 replies to this topic

#76 Sarkikos

Sarkikos

    Hubble

  • *****
  • Posts: 16681
  • Joined: 18 Dec 2007
  • Loc: Per sylvam ad astra

Posted 28 October 2012 - 02:51 PM

I've mastered collimation in Newts - if anyone can legitimately say that :grin: - and binoviewing is a walk in the park. The Paracorr is still a bit of a challenge, but only because I don't use it constantly like some observers.

But to make a long story - or a long thread - short, I have a fast Newtonian, so IF I go for the Leica ASPH, what do I really need to make it work optimally in my setup? It's a Celestron 10NGT OTA, a 10" f/4.8 Newt with an after-market Dob mount and a Crayford focuser, but not a low-profile.

Like most Newts, if I stack a filter wheel or binoviewer or eyepiece turret between the focuser and the eyepiece, I will need an OCA or Barlow to allow enough in-focus. A Leica ASPH would take the place of my Baader Hyperion Zoom, which I often use stacked with a filter wheel of DSO filters at a dark site. So having to screw on an OCA or Barlow lens cell would be par for the course whether or not I use a Leica Zoom.

Often when I stack my Baader Zoom with a filter wheel, I just screw a Burgess OCA onto the neck of the wheel. This gives me about 100-300x, which I find to be a nice range for many DSO, including galaxies, planetaries and moderately-sized bright nebulae.

Would something as humble as a Burgess OCA give me decent results in the Leica ASPH?

Mike

#77 johnnyha

johnnyha

    Fly Me to the Moon

  • *****
  • Posts: 6500
  • Joined: 12 Nov 2006
  • Loc: Sherman Oaks, CA

Posted 28 October 2012 - 05:04 PM

Would something as humble as a Burgess OCA give me decent results in the Leica ASPH?

I think so Mike. I had a chance to check my new Leica ASPH Zoom out last night in my f8 APO refractor with average seeing in suberbia. As reported, the edge correction of the Zoom in native mode is not so good, in fact there was quite a bit of CA in my setup in the outer, say, 15% or so. Other than the edge CA, the views of the full Moon were, however, phenomenal. As for the different barlow combinations well, that's half the fun Mike! :grin: I tried the Leica zoom with my 1.6X Antares, my 1.7X Barcon, my 2X Baader/Zeiss Abbe Barlow, and also in different combinations with the Barcon element and spacers. The Moon was exquisite with the barlows attached, extremely sharp and clear. There was still a tiny amount of CA on the very edge even using the barlows but this could be my setup.

My only negative to report was that this zoom has some internal reflections on very bright Jupiter. I compared this to my 13 Ethos and the 13E also had a lot of internal reflections on Jupiter, and my XWs had some internal reflection but not as much as the Leica zoom. Anyway, I checked and ALL my eyepieces had internal reflections on Jupiter last night, even a small amount on the Brandons and ZAO-IIs, so the internal reflections I saw in the zoom were not unique. I panned over to the Double Cluster and the Leica Zoom presented a beautiful view with pinpoint stars that went on and on.

The performance of the Leica ASPH zoom was similar with all the barlows, with the 2X Abbe barlow being my favorite. There was no vignetting on any of the barlows, even with the 1.25" Abbe barlow attached directly to the bottom of the Leica zoom. I did not see any of the vignetting at the 17.9mm setting either as some have reported, the field stop was sharp all the way from 17.9mm to 8.8mm with or without a barlow.

Those are some of my initial impressions, I hope I get a chance to use this in better seeing conditions and with darker skies soon. I will also check it out in my f4.5 dob soon. This is a very crisp, sharp eyepiece that has terrific apparent contrast, and performance on the Moon was pretty spectacular. I suspect performance on globs, DSO's and doubles should be spectacular as well. Used with a barlow, the entire field was crisp and sharp at every setting. The zoom was not parfocal, I did need to tweak the focuser whenever changing the zoom power. Fit and finish was beautiful with excellent mechanical performance, it was a pleasure to use the zoom feature.

The only real surprise I got was the amount of CA on the edge in native mode - I am curious to see if my dob gives the same results.

#78 sixela

sixela

    Voyager 1

  • *****
  • Posts: 14318
  • Joined: 23 Dec 2004
  • Loc: Boechout, Belgium

Posted 28 October 2012 - 05:39 PM

Yes, an OCA will work. But particularly the small factor ones are sometimes also meant to compensate for the chromatic error introduced by some length of BK7 glass in the converging beams, so a regular barlow with an element you can unscrew from its holder should be better.

If you don't have a Paracorr, you don't care that much. Even the unbarlowed Leica needs only 3-4mm more focuser in-travel than a 17mm Ethos.

If you have a regular Type 2 Paracorr, it's also not a problem unless you insist you want the Paracorr placed optimally (where it corrects coma best). If you don't, you can just rack in those few millimeters while using the Leica.

With a Type 1 Paracorr, though, you'd better have some focuser in-travel left for 'regular' eyepieces since even the 17mm Ethos wants some and the Leica will want more.

With a SIPS you do want a barlow, because the setup is intolerant of eyepieces that want more focuser in-travel than a 17mm Ethos. The focal plane is 56mm from the Paracorr lens top and 10mm above the fully racked in focuser, and you just run out of focuser in-travel, although Andreas's self-hacked adapter might just work (since it allows you to insert the Leica deeper).

The Leica's not alone with that issue with the SIPS, some Speers-Walers and anything in the TV 2"-1.25" adapter in a TMB 1.8x barlow are even worse. But you don't have a SIPS, so you don't care.

For you, that leaves the barlow mainly to get a clean edge in a fast scope, or to get the magnification range you want. There's no magic recipe for someone else to decide what's right in your stead with respect to those two, of course.

The Baader VIP works quite well and can be screwed in very close to the Leica (or further, so you can pick the range fairly easily).

The Baader/Zeiss also works very well, but the barlow factor is always fairly large.

The Barcon also works well and cleanly but its long focal length means you're not going to make it Paracorr-perfect (or SIPS-friendly), because if you place it close it wont't really have a large barlow factor and if you place it further it'll stick out so much that you'll have to watch out for hitting the Paracorr. Unless you simply use it as a regular barlow (with its holder) and stick with that barlow factor.

Same for the Antares 1.6x barlow; that should just about work even with Paracorrs, with the top set low.

The BarAdv (with a focal length of -102mm instead of -127mm) is a bit better if you want to use it as a screw-on barlow, be able to tweak the focal lemgth range and still make it Paracorr-friendly.

#79 sixela

sixela

    Voyager 1

  • *****
  • Posts: 14318
  • Joined: 23 Dec 2004
  • Loc: Boechout, Belgium

Posted 28 October 2012 - 05:45 PM

By the way, for me the zoom is parfocal.

But whether it is for you depends on whether you are short- or nearsighted and even on what distance you find natural to focus your eyes on when looking through an eyepiece and focusing the scope (not everyone sets the focuser for an afocal scope plus eyepiece system and then looks at infinity with his eyes).

It's impossible to make it exactly parfocal for everyone.

#80 RAKing

RAKing

    Fly Me to the Moon

  • *****
  • Posts: 6241
  • Joined: 28 Dec 2007
  • Loc: West of the D.C. Nebula

Posted 28 October 2012 - 05:49 PM

By the way, for me the zoom is parfocal.

But whether it is for you depends on whether you are short- or nearsighted and even on what distance you find natural to focus your eyes on when looking through an eyepiece and focusing the scope (not everyone sets the focuser for an afocal scope plus eyepiece system and then looks at infinity with his eyes).

It's impossible to make it exactly parfocal for everyone.


Thanks for that info. I generally have to tweak the fine focus knob a little as I zoom in, but sometimes the focus stays good all the way in. Now I know it's my eyes and not the zoom. :)

Cheers,

Ron

#81 sixela

sixela

    Voyager 1

  • *****
  • Posts: 14318
  • Joined: 23 Dec 2004
  • Loc: Boechout, Belgium

Posted 28 October 2012 - 05:57 PM

By the way, for me the zoom is parfocal.

But whether it is for you depends on whether you are short- or nearsighted and even on what distance you find natural to focus your eyes on when looking through an eyepiece and focusing the scope (not everyone fouses the eyepiece for an afocal scope plus eyepiece system and then look at infinity with their eyes).

It's impossible to make it exactly parfocal for everyone.

#82 sixela

sixela

    Voyager 1

  • *****
  • Posts: 14318
  • Joined: 23 Dec 2004
  • Loc: Boechout, Belgium

Posted 28 October 2012 - 05:57 PM

Yes, an OCA will work. But particularly the small factor ones are sometimes also meant to compensate for the chromatic error introduced by some length of BK7 glass in the converging beams, so a regular barlow with an element you can unscrew from its holder should be better.

If you don't have a Paracorr, you don't care that much. Even the unbarlowed Leica needs only 3-4mm more focuser in-travel than a 17mm Ethos.

If you have a regular Type 2 Paracorr, it's also not a problem unless you insist you want the Paracorr placed optimally (where it corrects coma best). If you don't, you can just rack in those few millimeters while using the Leica.

With a Type 1 Paracorr, though, you'd better have some focuser in-travel left for 'regular' eyepieces since even the 17mm Ethos wants some and the Leica will want more.

With a SIPS you do want a barlow, because the setup is intolerant of eyepieces that want more focuser in-travel than a 17mm Ethos. The focal plane is 56mm from the Paracorr lens top and 10mm above the fully racked in focuser, and you just run out of focuser in-travel, although Andreas's self-hacked adapter might just work (since it allows you to insert the Leica deeper).

The Leica's not alone with that issue with the SIPS, some Speers-Walers and anything in the TV 2"-1.25" adapter in a TMB 1.8x barlow are even worse. But you don't have a SIPS, so you don't care.

For you, that leaves the barlow mainly to get a clean edge in a fast scope, or to get the magnification range you want. There's no magic recipe for someone else to decide what's right in your stead with respect to those two, of course.

The Baader VIP works quite well and can be screwed in very close to the Leica (or further, so you can pick the range fairly easily).

The Baader/Zeiss also works very well, but the barlow factor is always fairly large.

The Barcon also works well and cleanly but its long focal length means you're not going to make it Paracorr-perfect (or SIPS-friendly), because if you place it close it wont't really have a large barlow factor and if you place it further it'll stick out so much that you'll have to watch out for hitting the Paracorr. Unless you simply use it as a regular barlow (with its holder) and stick with that barlow factor.

Same for the Antares 1.6x barlow; that should just about work even with Paracorrs, with the top set low.

The BarAdv (with a focal length of -102mm instead of -127mm) is a bit better if you want to use it as a screw-on barlow.

#83 johnnyha

johnnyha

    Fly Me to the Moon

  • *****
  • Posts: 6500
  • Joined: 12 Nov 2006
  • Loc: Sherman Oaks, CA

Posted 29 October 2012 - 06:59 PM

I had another short session with the Leica ASPH Zoom last night in the FS152, with the Moon and later Jupiter as the targets. I was able to confirm on Jupiter that yes, even the Brandons and ZAO-IIs showed a little internal reflection as I had also reported with the Leica Zoom, although the orthos show less. But jupiter is so bright and shiny now that it defies all of my eyepieces as far as that goes. However the good news - it was the best seeing conditions I have seen from my backyard in L.A. this year, Jupiter was stunning and looked like a photograph on up past 240X. I tried the Leica ASPH Zoom with the 1.7X Barcon which I estimate was around 120X-240X and the image was breathtaking, very very crisp and clear with loads of details seen in the belts and even near the poles, at all mags. I switched later to the binoviewers but I was very impressed with the performance of the Leica. :cool:

#84 johnnyha

johnnyha

    Fly Me to the Moon

  • *****
  • Posts: 6500
  • Joined: 12 Nov 2006
  • Loc: Sherman Oaks, CA

Posted 29 October 2012 - 10:38 PM

Oh and I did catch the very slight vignetting or whatever you might call it right at the very end of the lowest mag setting - it's very subtle. Its just a very slight softening of the field stop, right at the last little twist.

#85 Taeyoung

Taeyoung

    Sputnik

  • -----
  • Posts: 32
  • Joined: 26 Apr 2010

Posted 15 November 2012 - 01:31 AM

Hello Bob^^
Exept for FOV, this ASPH is better than old Leica 20x-60x zoom?
I'm considering to buy Leica's zoom now. My club member said that this ASPH has large FOV but the old one is better sharpness and contrast^^
Is it right?
For me, narrow FOV is not problem. I'm a sincere planet observer^^ My main target is Planet and Moon^^
I use ball lens eyepiece which made by myself and ultra narrow fov(about 10 degree) is no problem to me.
I want more sharp and more contrasty one^^
My precious line-up is this
Ball lens 4.4mm, 5.9mm, 7.3mm
XO 5mm
Circle V celestron 7mm ortho(this one is really sharp^^)
Brandon 8 & Televue Plossle 8


My plan is,
If old Leica is same quality with ASPH except FOV, buy 2 of it and use it with my Nikon binoviewer^^


Which one is suitable for me?

#86 sixela

sixela

    Voyager 1

  • *****
  • Posts: 14318
  • Joined: 23 Dec 2004
  • Loc: Boechout, Belgium

Posted 15 November 2012 - 02:58 AM

I wouldn't buy an ASPH if I already had the other one except for the FOV. You only 'gain' a more narrow range if you don't care about the AFOV.

But then, I don't think 'the old one is better with respect to sharpness and contrast' either.

#87 andydj5xp

andydj5xp

    Apollo

  • -----
  • Posts: 1409
  • Joined: 27 May 2004
  • Loc: 52.269 N/10.571 E

Posted 15 November 2012 - 03:16 AM

Hello Bob^^
Exept for FOV, this ASPH is better than old Leica 20x-60x zoom?
I'm considering to buy Leica's zoom now. My club member said that this ASPH has large FOV but the old one is better sharpness and contrast^^
Is it right?
For me, narrow FOV is not problem. I'm a sincere planet observer^^ My main target is Planet and Moon^^
I use ball lens eyepiece which made by myself and ultra narrow fov(about 10 degree) is no problem to me.
I want more sharp and more contrasty one^^
My precious line-up is this
Ball lens 4.4mm, 5.9mm, 7.3mm
XO 5mm
Circle V celestron 7mm ortho(this one is really sharp^^)
Brandon 8 & Televue Plossle 8


My plan is,
If old Leica is same quality with ASPH except FOV, buy 2 of it and use it with my Nikon binoviewer^^


Which one is suitable for me?


If you are intending binoviewing the 20x-60x Leica zoom definitely is the better choice. Only 53mm outer diameter as compared to the 59mm of the ASPH. Besides the narrower field of view the "old" zoom is optically as good as the ASPH.

Your club member's opinion ".... that this ASPH has large FOV but the old one is better sharpness and contrast" should be taken with a grain of salt. I've used the 22-7.3mm Leica for seven years and the ASPH zoom now for almost four years: as far as contrast, definition, and lack of stray light is concerned both are equal and equally top notch.

Andreas

#88 Bob S.

Bob S.

    Surveyor 1

  • *****
  • Posts: 1835
  • Joined: 14 Jul 2005

Posted 12 January 2013 - 11:38 AM

Andreas, I posted the performance of the Leica ASPH on the reflectors forum this morning pertaining to the Leica ASPH's phenomenal performance. "The coyotes were literally howling, the owls were hooting and a Leica ASPH vario zoom 8.9-17.8mm with 80-60 degree AFOV got an intense workout tonight in my 20" f/3 Lockwood/JP Astrocraft. The NELM was just under mag 6 tonight as measured by my Sky Quality Meter and the seeing was quite steady. Earlier experiments tonight with the fans on Jupiter and Rigel showed that the (Comprehensive Boundary Layer Mitigation System) is working superbly. I tuned the SIPS to perfection on Jupiter using a 5x magnifying loupe and checked collimation of the scope after it had been cooling with the CBLMS running at full speed for about 1.5 hours. I was looking at Jupiter with the Leica ASPH and was finding that 194x was not even making the eyepiece or the scope breathe deeply. I popped the Leica ASPH into my 2x TV powermate and now was running views of the planet between 194x-389x. Still the views were showing that I could use more power. In goes the 4x TV Powermate coupled to the Leica ASPH for views between 389x-777x. Predominantly, the views at about 389x to about 600x showed periods where the planet looked like a CCD image. The orb of Jupiter seemed suspended in black space. The contrast of atmospheric features against a jet black background was jaw dropping. Now, for the first time since this past years WSP in the Florida Keys, I was able to view comfortably at over 550x. With the ASPH in the 4x Powermate and a 2" OIII filter, I had the scope go over to the Eskimo Planetary Nebula in Gemini which is an object on good nights that can take a lot of power. The Eskimo was not to disappoint either then or hours later at ridiculously high mags. I am used to viewing it with my former 28" f/3.5 Lockwood/Starmaster and so noticed that the brightness was way down with the OIII filter and only 20" of aperture compared to the views I would get with the 28". Now, I had not had a chance to see the Horsehead and Flame Nebulas with my new scope. I put a 2" H-Beta filter into the bottom of my ASPH and was zooming in and out on the Horsehead and Flame Nebulas. I actually like the view better in my Leica at 17.8mm with 60 degree AFOV than my 21mm Ethos or 17mm Ethos with the h-b filter and their 100 degree AFOV.

Of course, in the high mag mode, I had to see the Pup in Sirius. Sirius was a superb pinpoint of a star and I used it for further high-mag testing of the primary mirror. I did a test of the fans on this object and each time I turned off the CBLMS, the star would get more flairs. The tightest views were with the CBLMS running and so it was left on all night. Back to Jupiter with the 389x-777x eyepiece arrangement and Jupiter was strutting the GRS along with beautiful festoons and white ovals and a dark barge or two in the NEB. The amount of different colors I was seeing in the GRS, festoons, ovals, barges and belts was very impressive. At between 550x-777x, I was able to make out reliable but faint albedo markings on Ganymede in what I think was the Southern half of the Jovian Moon. This is only the third time that I have been able to do that and it was best seen when I moved Jupiter out of the FOV. I forgot to mention that I used the ASPH with the 4x Powermate on M42 and was seeing the A-I stars (not the H-stars). The G and I stars were only intermittently seen with averted vision. This is only the second time that I have seen the I and G stars without my image intensifying eyepiece. BTW, I tried my Micro IIE Gen 3 image intensifier and was unable to get it to come to focus with the SIPS system in place. I was lacking just a bit of infocus. I finished off the session tonight first returning to the Eskimo and seeing his face briefly with a full parka surrounding his face and nose. I then went back for a last look at Jupiter and the seeing was getting a bit soft even at a lowly 389x. It was time to wrap it up and glow in the aftermath of my best viewing session to date with my new telescope. It also represented the best magnification I was able to successfully deploy in the past year here in North Florida. For some reason, obtaining 1000x plus nights like we used to get have been very difficult for the past two years. I did some high-power testing of the mirror on Sirius and Betelgeuse and the mirror is superb! Mike, I found that the Leica showed pinpoint stars to the edge with tighter star points when it was in either the 2x or 4x Powermates with those items behind the SIPS. Without a barlow, the stars were a bit less tight and not so uniform across the FOV with just the Leica ASPH and the SIPS. The views were not bad but just not perfect like they were with barlowing. I am including a picture of the setup. You will note that all focusing was done with my 3" Feathertouch optional focuser wheel which made focusing a dream. I cannot say enough good things about this 3" focuser wheel for critical focusing at high-mags. To say that I am pleased with the scope and the performance of the Leica ASPH with the TV Powermates would be an incredible understatement. I am frankly ecstatic! I am very much questioning if I need all of my fine Ethos ep's (I have the whole set). As some know, I had done comparisons of the Leica ASPH with my Zeiss Abbe Ortho II's along with a host of other orthos and ep's and the Leica was a good as or at times better than the Zeiss glass in a 6.3" f/7 fluorite Apo and this is no small accomplishment. It's performance on Jupiter was so convincing tonight and the fact that it was being used in a f/3 scope with a Starlight Instruments Paracorr System (SIPS) that made the AFOV perform like an f/12 scope leads me to wonder how much glass I need? I am forever indebted to John Pratte for making such a stout scope with an ultra-stout focuser board/UTA that easily handled all of the weight placed on it. This is without a doubt, the finest 20" scope I have ever been priviledged to be the steward of." Bob

#89 andydj5xp

andydj5xp

    Apollo

  • -----
  • Posts: 1409
  • Joined: 27 May 2004
  • Loc: 52.269 N/10.571 E

Posted 12 January 2013 - 02:06 PM

Bob, thanks for your enthusiastic report. I'm very glad my recommendation for the Leica ASPH zoom turned out being the right one for you. And remember: my main recommendation was for using it with your f/7 160FL. The better if it's also that powerful - in particular together with the powermates - in a fast Newtonion.

I've no affiliation whatsoever with Leica but as a German engineer I'm glad - may be proud even - that this famous name of German optics history has managed to survive into the 21st century. Unfortunately this is not the case for many other also famous names from the past.

Enjoy your fantastic gear.

Andreas

#90 Bob S.

Bob S.

    Surveyor 1

  • *****
  • Posts: 1835
  • Joined: 14 Jul 2005

Posted 12 January 2013 - 04:24 PM

Bob, thanks for your enthusiastic report. I'm very glad my recommendation for the Leica ASPH zoom turned out being the right one for you. And remember: my main recommendation was for using it with your f/7 160FL. The better if it's also that powerful - in particular together with the powermates - in a fast Newtonion.

I've no affiliation whatsoever with Leica but as a German engineer I'm glad - may be proud even - that this famous name of German optics history has managed to survive into the 21st century. Unfortunately this is not the case for many other also famous names from the past.

Enjoy your fantastic gear.

Andreas


Thanks Andreas. I updated my original post here and mentioned that the testing had been done with my TEC 160FL. It is a lot slower than my f/3 Newt. Thankfully, I think that the SIPS system mitigates the ultra-steep lightcone and the star images were exceptionally pleasing last night. Not as tight as with my refractor but the extra 14" of aperture minus the 5" secondary so actually 9", didn't hurt. Come to think of it, I did not have as high of expectations for the Leica zoom in my Newtonian but last night definetly proved that the Leica flat performs even in very fast scopes if properly tamed with the best coma correction that can be implemented. Bob

#91 johnnyha

johnnyha

    Fly Me to the Moon

  • *****
  • Posts: 6500
  • Joined: 12 Nov 2006
  • Loc: Sherman Oaks, CA

Posted 12 January 2013 - 05:29 PM

I actually like the view better in my Leica at 17.8mm with 80 degree AFOV than my 21mm Ethos or 17mm Ethos with the h-b filter and their 100 degree AFOV.

Remarkable especially since the Leica is actually 60 degrees at 17.8mm. Thanks for the great report Bob, I posted a few days ago in another thread I had excellent results with the Leica ASPH zoom unbarlowed in my f4.65 with a Paracorr 1.

#92 Bob S.

Bob S.

    Surveyor 1

  • *****
  • Posts: 1835
  • Joined: 14 Jul 2005

Posted 12 January 2013 - 08:06 PM

I actually like the view better in my Leica at 17.8mm with 80 degree AFOV than my 21mm Ethos or 17mm Ethos with the h-b filter and their 100 degree AFOV.

Remarkable especially since the Leica is actually 60 degrees at 17.8mm. Thanks for the great report Bob, I posted a few days ago in another thread I had excellent results with the Leica ASPH zoom unbarlowed in my f4.65 with a Paracorr 1.


Thanks Johnny, I always get the numbers backward on the AFOV of this thing :rainbow: Johnny, I had to take the Leica out with my Apo and get the FOV issues squared away empirically for myself. The reason is that when I zoom to higher powers, it appears that I am losing FOV which is sort of true based on increase mag but when I was looking through the ASPH tonight and zooming it, I did in fact notice maybe for the first time solidly that the zoom AFOV gets smaller at lower power and larger at the higher powers of the zoom. Quite counterintuitive but absolutely correct. Thanks for helping me to understand my zoom better. Bob






Cloudy Nights LLC
Cloudy Nights Sponsor: Astronomics