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Leica ASPH Zoom in a Fast Newtonian

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#1 Bob S.

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Posted 11 October 2012 - 10:56 PM

I am totally beat as this is my second observing session today. The morning session was dedicated to playing with my Baader Mark V's in my 16.5" f/3.65 Lockwood/Starmaster with tracking from 1:30a.m. until about 5:30a.m. Today, I received my Leica ASPH zoom with 2" adapter. It appears that Andreas, Bill P., Doug C., and others are really onto something quite interesting. I used both my Paracorr II and 2x Powermate to look at a bunch of objects tonight with the Leica. In the Paracorr II, the Leica prefers the "A" setting and requires just a bit more infocus than my 17mm Ethos. Objects of interest tonight were M22, M57, Double Double, October Salt/Pepper, M31, Alberio and a few others that I am too tired to remember.

The Leica zoom is without a doubt the finest zoom that I have ever used. In fact, it doesn't feel like a zoom in terms of the expected degraded images I have gotten in zooms so often. With the Paracorr II and/or TV 2x Powermate, the stars are extremely tight and very pleasing in terms of color/light transmission.

I was recently diagnosed with a form of cataracts known as cortical spokes and so there are some self-induced abberations that I have been able to compensate for but notice the spokes with a defocused intrafocal position and thus some of my observations are less reliable than someone without my current but soon to be remedied medical condition.

I tried to use the Leica with my 2x Powermate on the Ring Nebula to catch the central star and could not make it out tonight even though I kept zooming in and out. The double double was a hoot with the zoom and the 2x Powermate. Comparisons between the views with the Leica ASPH and my 17mm Ethos in the relatively same mag were somewhat equivocal with the Leica tending to show a darker background and slightly tighter star points.

I cannot wait to do some further testing both in my fast Newtonians and my slow refractor. I missed the VP debate tonight but figured that playing with a Leica ASPH zoom had to be more fun than listening to politicians :lol: Bob

#2 sixela

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Posted 12 October 2012 - 04:41 AM

What, you want _even more_ entertainment value from Joe Biden? Whatever you think of the man, I don't think you can accuse him of being 'no fun'.

Clouds here and I was back from a tango milonga, so I watched 'your' debate.

#3 Bob S.

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Posted 14 October 2012 - 03:16 PM

Just got back from the Peach State Star party at Deerlick observation field (what a great bunch of astronomers!) and have now had the Leica ASPH zoom which has a 60-80 FOV and zoom range of 8.9 to 17.8mm range in a 16.5" f/3.65 Lockwood/Starmaster; 16" f/4.5 Spooner/Home Built; and a 28" f/3.7 Kennedy/Webster. The eyepiece was placed in Paracorr I's for the homebuilt and Webster and a Paracorr II with the Starmaster.

The results were uniformally well received and wowed all who looked through it. In numerous comparos with 10mm and 13mm Ethos ep's, the Leica reliably showed tighter star points and darker backgrounds (more contrast) in all three scopes. The ability to zoom to the best magnification for a given seeing moment won great favor as well as the fact that you can set the zoom to frame the object that most aesthically pleases you.

Markus Ludes reported that another new zoom he will be selling seemed to be a bit sharper than the Leica (Meopta) in a f/5 Newtonian. I am not sure how this could be because the stars were pretty pinpoint to the edge in all three Newtonians. I am wondering if Ludes' recommendations are based on tests where the Leica was used exclusively in Newts with a Paracorr in place? Certainly, the scopes I tested it in really benefit from the use of a coma corrector. The stars were a bit more bloated in the 28" on M13 and I suspect that it was related to the owner using a Paracorr I rather than the newer Paracorr II that is designed for sub f/4 Newts. The 28" was also not tracking when we were doing the tests and the 16" homebuilt was also not a tracking telescope.

The ep is close to being parfocal when you zoom but you do have to fine focus when you stop at another zoom setting. It seems that when you zoom it to the highest mag (8.9mm),
the sharpness of the image may be slightly degraded at the end-stop and backing off the zoom with a slight twist of the rubber zoom ring seems to produce a slightly sharper image that stays that way all the way up to its least mag at 17.8mm). This phenomena was noted by another astronomer and has not been realiably tested to ascertain if this performance observation is accurate?

As I mentioned to Andreas, I have yet to compare the Leica ASPH with my ZAOII's, Baader GAO's fast Newts. I can say that it is one of the finest ep purchases I have made in the last decade in terms of its surprising and almost logic defying performance. I have yet to get it into my 6.2" Apo refractor and some other fast scopes. Bob

#4 Paraclete

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Posted 14 October 2012 - 04:21 PM

In numerous comparos with 10mm and 13mm Ethos ep's, the Leica reliably showed tighter star points and darker backgrounds (more contrast) in all three scopes.

I noticed the same thing in my friend's SCT. Stars in the Ethos were slightly bloated when compared to 2 other premium wide-field eyepieces.

The ep is close to being parfocal when you zoom but you do have to fine focus when you stop at another zoom setting.

I require two minor tweaks on the micro-focuser. Tweaking the main focus knob induces too much of a focus change...so the Leica is very nearly parfocal for me too. Thanks for your report.

#5 sixela

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Posted 14 October 2012 - 05:17 PM

Just got back from the Peach State Star party at Deerlick observation field (what a great bunch of astronomers!) and have now had the Leica ASPH zoom which has a 60-80 FOV and zoom range of 8.9 to 17.8mm range in a 16.5" f/3.65 Lockwood/Starmaster; 16" f/4.5 Spooner/Home Built; and a 28" f/3.7 Kennedy/Webster. The eyepiece was placed in Paracorr I's for the homebuilt and Webster and a Paracorr II with the Starmaster.

The results were uniformally well received and wowed all who looked through it.


I'm very surprised. Even in my 'mundane' f/4.5 scope with Paracorr II, the edge of field astigmatism that the Leica produces is hard to ignore until I use it with a 1.6x barlow.

#6 Bob S.

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Posted 14 October 2012 - 06:26 PM

Just got back from the Peach State Star party at Deerlick observation field (what a great bunch of astronomers!) and have now had the Leica ASPH zoom which has a 60-80 FOV and zoom range of 8.9 to 17.8mm range in a 16.5" f/3.65 Lockwood/Starmaster; 16" f/4.5 Spooner/Home Built; and a 28" f/3.7 Kennedy/Webster. The eyepiece was placed in Paracorr I's for the homebuilt and Webster and a Paracorr II with the Starmaster.

The results were uniformally well received and wowed all who looked through it.


I'm very surprised. Even in my 'mundane' f/4.5 scope with Paracorr II, the edge of field astigmatism that the Leica produces is hard to ignore until I use it with a 1.6x barlow.


That is kind of wild. I nor anybody else commented or was seeing astigmatic stars? Could it be that your scope is astigmatic? Or is it possible that your eye is producing some stig? We looked at globular clusters, planetary nebula, open clusters, nebula, planets and did not experience any stig? Bob

#7 sixela

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Posted 15 October 2012 - 03:19 AM

That is kind of wild. I nor anybody else commented or was seeing astigmatic stars?

Tangential/sagittal eyepiece astigmatism only in the edge of the eyepiece, and disappearing when you use other eyepieces? Not that likely, I think.

Plus I'm not the only one to have reported that. In addition to what Markus Ludes said in the thread in which he announced the Meopta zoom, Doug Culbertson, BWAZ, Bill Paolini and I think Andreas and Tammy all reported similar things - an edge of field which isn't as well corrected as the centre of the field.

Or is it possible that your eye is producing some stig?

At all exit pupils, and again only at the edge, with the orientation different at different parts of the edge?

and did not experience any stig? Bob


Uhm...I have yet to see _any_ eyepiece that does not produce at least some edge of field astigmatism (i.e. enough to make it obvious in a star out of focus, even though the best eyepieces tend to make it inobtrusive in focus). "Not any" is not in my vocabulary.

Now I do use the eyepiece unbarlowed in my f/5 travelscope, and bear it with a grin. I feel no need to rationalise away what is clearly there: the eyepiece is fine and is not perfect. Yes, it's a lot more practical than fixed focal length eyepieces and the centre of the field is so nice (and stays nice for a field that's so wide) that you'll excuse the defects at the outer edge.

I think what we're looking at, as far as our different appreciations are, is a difference in observing style: I quite frequently keep my scope pointed in the exact same point and look throughout the entire field; others don't tend to use the entire field as often and reposition their scopes more readily to look at another corner of an object or group.

Given many people ask me for an opinion about an eyepiece/scope combo, I've also developed the bad habit of instinctively star testing the entire field (including the edge) while focusing, i.e. being aware of the shape of the diffraction patterns throughout the field while I run through focus a couple of times to determine where I'll focus (it does help me to avoid too many problems with field curvature, since on some eyepieces I'll instinctively end up focusing something else than the centre).

But you've convinced me to give my barlowless Leica another chance, though.

#8 johnnyha

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Posted 15 October 2012 - 03:31 AM

Markus himself said the Leica ASPH zoom "sucks a bit" in newtonians. I'm pretty sure he was referring to just the edge of the field.

#9 Bob S.

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Posted 15 October 2012 - 04:46 AM

Alexis, I can see that you are analyzing the eyepiece at a level that I am not interested in paying attention to for several reasons. The first is that the Leica to me represents a very convenient package that presents stars as good at least as a TV Ethos (and likely Pentax XW's although I have not compared them yet) with a lot less hassle in terms of changing eyepieces to get different mags. Secondly, my aging eyes an some current medical eye challenges are causing me to be less critical in both my expectations and capabilities to discern some subtle aberrations. Thirdly, with the zooms capability, I and others were using it to frame the object of interest and so stars beyond the framed area have likely not been as critically analyzed as the framed area of interest which is where the zoom seems to "shine". Even with those caveats, there was still no significant noticeable astigmatism that caused my eye or others to comment or experience edges of the FOV that were problematic. I suspect that in playing with this new eyepiece, I and the others that were using it were not holding it up to the most critical of analyses.

When I see where you are coming from with the level of your analysis, I do not doubt that there are some minor aberrations that can be discerned if you are looking for them. Unlike tight FOV's like are presented in orthos, I guess my expectations for an overall presentation of tight stars in the FOV were adequately met and the sense that the edges presented astigmatic stars was not apparent to me or others at the relatively simplistic level that we were assessing the eyepiece. Bob

#10 sixela

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Posted 15 October 2012 - 07:04 AM

Oh, another point: how did you manage to get the eyepiece to focus when you weren't using a barlow?

In my scope with a SIPS Paracorr, there's simply no way to focus the eyepiece (with a SIPS in place there's really no way to focus anything that requires more than 3mm more focuser in-travel than a 17mm Ethos). I'm not missing much, but I am missing something (obviously, putting the SIPS a bit too close to the telescope would fix that, but at the expense of some of the coma correction).

I assume you were using a 'regular' Type 2 Paracorr with tunable top fully turned in and then still had to rack in the focuser some more?

#11 Bob S.

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Posted 15 October 2012 - 08:49 AM

Oh, another point: how did you manage to get the eyepiece to focus when you weren't using a barlow?

In my scope with a SIPS Paracorr, there's simply no way to focus the eyepiece (with a SIPS in place there's really no way to focus anything that requires more than 3mm more focuser in-travel than a 17mm Ethos). I'm not missing much, but I am missing something (obviously, putting the SIPS a bit too close to the telescope would fix that, but at the expense of some of the coma correction).

I assume you were using a 'regular' Type 2 Paracorr with tunable top fully turned in and then still had to rack in the focuser some more?


No problems focusing at all with either the Paracorr 1 or 2. They are both in the A or full-in position. I am using it with the 2" adapter supplied by APM and have no focus issues yet in anyone's Newt.

#12 Bob S.

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Posted 17 October 2012 - 10:12 PM

Oh, another point: how did you manage to get the eyepiece to focus when you weren't using a barlow?

In my scope with a SIPS Paracorr, there's simply no way to focus the eyepiece (with a SIPS in place there's really no way to focus anything that requires more than 3mm more focuser in-travel than a 17mm Ethos). I'm not missing much, but I am missing something (obviously, putting the SIPS a bit too close to the telescope would fix that, but at the expense of some of the coma correction).

I assume you were using a 'regular' Type 2 Paracorr with tunable top fully turned in and then still had to rack in the focuser some more?


No problems focusing at all with either the Paracorr 1 or 2. They are both in the A or full-in position. I am using it with the 2" adapter supplied by APM and have no focus issues yet in anyone's Newt.


I had a colleague over tonight with his two grandchildren and proceeded to show them a bunch of eye candy with a IIE image intensifier with and without an Ha filter (M22, M20, M8, M16, M17, M31, M57, Veil. They left and the night was full of promise with transparency about 8/10 and seeing about 7-8/10. I had my Pentax XW's out and also played with a 16mm Brandon, 16mm ZAO II, 18mm Baader GAO and the Leica ASPH zoom on Alberio. The ZAO II and the Leica showed the tightest star points in my 16.5" f/3.65 Lockwood/Starmaster with either a Paracorr II in the "A" setting or a 2x TV Powermate. I also tried the ASPH without anything other than the ep in the focuser and had absolutely no problem having everything come to focus.

It's funny but I slightly preferred the views for a while with the Leica ASPH over the Zeiss Abbe Ortho because I could zoom the mag to the exact place where I started to get some image softness. Both were absolutely beautiful. I also had to zoom around with the Leica to M15 and enjoyed that beautiful globular cluster while zooming at different mags. The 60-80 degree AFOV with the excellent eye relief makes this a wonder of an eyepiece. I had forgotten that I had it until about 2/3 of the way through viewing this evening. Sheesh, I didn't think it would fit into the lineup that quietly ;) As others have remarked, the Leica ASPH zoom is just an all around wonderful ep and it works very well in a fast Newtonian in spite of a brief negative remark by Markus Ludes who sells them but has possibly found and even better performing zoom with a 66 degree AFOV. Bob Schilling

#13 sixela

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Posted 19 October 2012 - 08:14 AM

I also tried the ASPH without anything other than the ep in the focuser and had absolutely no problem having everything come to focus.


Quite. As I said, the only note I wanted to make is that without a barlow, it wants slighly more focuser in-travel than a 17mm Ethos, which creates problems _for a SIPS Paracorr_ (and only that) so I'd advise people to get a regular Paracorr Type 2 instead if they want to use that zoom unbarlowed.

It's funny but I slightly preferred the views for a while with the Leica ASPH over the Zeiss Abbe Ortho because I could zoom the mag to the exact place where I started to get some image softness.


Mirrors my experience with the Leica vs. the Pentax XO. When the best view in the Leica is at an effective 5mm (with Zeiss barlow), the Pentax XO delivers a slightly cripsier view.

But if other focal lengths are required for the best view, that XO doesn't change focal length...

I'm sure I could tweak a longer ZAO-II plus a Zeiss barlow and variable length between the two to "always" beat the Leica, but I'd be spending my time screwing and unscrewing T2-rings instead of observing, and I'd hate to think of the moments of good seing missed...


#14 johnnyha

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Posted 19 October 2012 - 04:27 PM

The newer model Zeiss barlow does have maybe 1/2" "tweakability" built in to the 1.25" clicklock eyepiece holder. Not a lot but you can definitely get a bit more mag with the helical feature.

#15 sixela

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Posted 19 October 2012 - 04:31 PM

But that's extremely cumbersome --been there, done that-- and hardly makes a lot of difference, given the barlow focal length (measured from the principal plane, not the flange) is roughly 68mm. Even a 15mm T2-extension only changes the barlow factor by 0.22.

Now that shiny 40mm Baader T2-tube, _that_changes things ;-).

#16 johnnyha

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Posted 19 October 2012 - 04:33 PM

How about the Baader T2 helical variable length extension? 41-56mm and you won't have to screw it on and off like the T2 tube...

#17 sixela

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Posted 19 October 2012 - 04:47 PM

Actually, two Baader #24 "Schiebe-focussierer" are even better for that. Allow you to go from 55mm to 77mm very rapidly.

And there's the #25V 29-46 Varilock, and two of these go from 58mm to 92mm but they're more than a bit more difficult to handle rapidly.

If you're thinking 'helical', screwing on T2-rings is usually faster.

#18 johnnyha

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Posted 19 October 2012 - 04:51 PM

Oh that is cool thanks!

#19 johnnyha

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Posted 19 October 2012 - 06:32 PM

So as far as barlowing the Leica ASPH zoom can I just screw say a Barcon element onto the bottom of the 2" adapter or what? I have the short 1.6X Antares barlow but I'd prefer an even shorter overall length.

#20 sixela

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Posted 20 October 2012 - 05:37 AM

Yes, you can. I personally use a Baader Zeiss in that exact same manner you describe, and alternatively a Baader VIP in a Baader T2-#12 adapter screwed into the 2" barrel (since that allows me to place the element closer and get a smaller barlow factor).

#21 RAKing

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Posted 20 October 2012 - 08:10 AM

So as far as barlowing the Leica ASPH zoom can I just screw say a Barcon element onto the bottom of the 2" adapter or what? I have the short 1.6X Antares barlow but I'd prefer an even shorter overall length.


Johnny,

You can screw the Barcon directly to the two inch Leica adapter ---- But a word of WARNING: The top lens element of the Barcon will contact the bottom of the Leica with about 1/4 - 1/2 turn to go. :shocked:

Personally, this is way too close for me, so I inserted an empty filter ring between the two. This only adds a total of 7mm distance and your magnification will still be a puny 1.2x set up like this.

I am now using a couple of A-P CCD spacers between my Leica and the Barcon because I want a bit more magnification. These spacers are 0.5" each and you can stack them as needed. With my refractor, I have settled on a comfortable 1.45 - 1.5x setup and this allows me to use the full range of the Leica. My effective focal lengths go from a nominal 12mm to 6mm with the zoom. If I need more mag, I pop in the XW 5.

I have been using my Leica for a couple of weeks now. It performed poorly in my C8 Edge SCT with no barlow - but it works like a champ in my refractor with the Barcon.

I am not planning to sell my ZAO-II set, nor do I plan to sell my Pentax XW collection, yet. But after moving the Leica to my refractor, I definitely understand the enthusiasm for this eyepiece. I like to view double stars and I also do variable star estimates for AAVSO. The Leica is now an indispensible piece of gear for both activities. :cool:

Cheers,

Ron

#22 Bob S.

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Posted 20 October 2012 - 08:33 AM

So as far as barlowing the Leica ASPH zoom can I just screw say a Barcon element onto the bottom of the 2" adapter or what? I have the short 1.6X Antares barlow but I'd prefer an even shorter overall length.


Johnny,

You can screw the Barcon directly to the two inch Leica adapter ---- But a word of WARNING: The top lens element of the Barcon will contact the bottom of the Leica with about 1/4 - 1/2 turn to go. :shocked:

Personally, this is way too close for me, so I inserted an empty filter ring between the two. This only adds a total of 7mm distance and your magnification will still be a puny 1.2x set up like this.

I am now using a couple of A-P CCD spacers between my Leica and the Barcon because I want a bit more magnification. These spacers are 0.5" each and you can stack them as needed. With my refractor, I have settled on a comfortable 1.45 - 1.5x setup and this allows me to use the full range of the Leica. My effective focal lengths go from a nominal 12mm to 6mm with the zoom. If I need more mag, I pop in the XW 5.

I have been using my Leica for a couple of weeks now. It performed poorly in my C8 Edge SCT with no barlow - but it works like a champ in my refractor with the Barcon.

I am not planning to sell my ZAO-II set, nor do I plan to sell my Pentax XW collection, yet. But after moving the Leica to my refractor, I definitely understand the enthusiasm for this eyepiece. I like to view double stars and I also do variable star estimates for AAVSO. The Leica is now an indispensible piece of gear for both activities. :cool:

Cheers,

Ron


Ron,
I measured the depth of the Barcon barlow piece from the glass to the end of the threads and it measured just a hair under 5mm. I measured the APM supplied 2" adapter for the Leica and the threads extend down to the top of the bottom part of the eyepiece element 5mm. So your recommendation to not fully screw down the Barcon piece is warranted.

Like you, I do not plan to sell my ZAO II's, Pentax XW's, Brandons, TV Ethos or Baader GAO's anytime soon but the Leica is extremely versatile. This morning I used it placed in a TV 2" 2x Powermate in a 12.5" f/5 Newt with power ranging ranging from 178x-356x primarily on Jupiter. My most steady/reliable views were at slightly past the 30x marking at about 230x. In this scope the markings translated to 25x=178 30x=216, 40x=283 and50x=356x. The seeing really did not reliably allow more than the 40x seeting at 283x with the overall best views at 230x. The eyepiece is simply amazing in that you can precisely dial in the magnification that affords the absolutely best views. Can't do that with any of my fixed focal length ep's. :p

#23 RAKing

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Posted 20 October 2012 - 09:26 AM

Ron,
I measured the depth of the Barcon barlow piece from the glass to the end of the threads and it measured just a hair under 5mm. I measured the APM supplied 2" adapter for the Leica and the threads extend down to the top of the bottom part of the eyepiece element 5mm. So your recommendation to not fully screw down the Barcon piece is warranted.

Like you, I do not plan to sell my ZAO II's, Pentax XW's, Brandons, TV Ethos or Baader GAO's anytime soon but the Leica is extremely versatile. This morning I used it placed in a TV 2" 2x Powermate in a 12.5" f/5 Newt with power ranging ranging from 178x-356x primarily on Jupiter. My most steady/reliable views were at slightly past the 30x marking at about 230x. In this scope the markings translated to 25x=178 30x=216, 40x=283 and50x=356x. The seeing really did not reliably allow more than the 40x seeting at 283x with the overall best views at 230x. The eyepiece is simply amazing in that you can precisely dial in the magnification that affords the absolutely best views. Can't do that with any of my fixed focal length ep's. :p


Bob,

Thanks for confirming my fears! I measured these pieces several times and hoped I was wrong, but my math kept coming up, "too close for comfort." And my very gentle attempt to mate the two was halted by contact.

I want to be able to use as much of the Leica's range as possible and this is the reason for my experiments. I have my zoom set up so it's more in the sweet spot for my needs. I have the 12T4 Nagler (and others) for finding my target stars and I have the 5mm Pentax (and others) if I really need to get close. The Leica is performing perfectly in between these two.

It's way too cool to be able twist the Leica until the view is "just right". :bow:

Ron

#24 Gord

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Posted 20 October 2012 - 11:09 AM

I have been using my Leica for a couple of weeks now. It performed poorly in my C8 Edge SCT with no barlow - but it works like a champ in my refractor with the Barcon.


Ron, could you describe more on your experience with the zoom in the Edge? What aspect of performance wasn't good? Planetary, DSO, field performance?

The rave reviews I keep hearing about the zooms would suggest they should be as good as anything on axis (as good as the ZAO's I've heard commented...). Just wondering what would be different with the Edge.

Thanks,

#25 RAKing

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Posted 20 October 2012 - 12:41 PM

At the risk of hijacking this thread, the Leica vignetted badly in the C8 SCT from the 30x position down to the 25x position. Possibly the baffle tube? Going the other way, the exit pupil dropped too quickly for me and I couldn't use it much beyond the 40x position.

For those who don't own these, there is a tiny focal shift as you zoom in and I couldn't adjust in the C8 as I can in my refractor. So I was left with decent views from 30x to 40x and that's not good enough for me.

Caveat - I only had one opportunity with the C8 and will try again. I could also have been victimized by poor seeing at the higher end.

Another Caveat - These are my impressions through my eyes, with my scopes, under my skies. YMMV! :)

Cheers,

Ron






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