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Equipment Discussions >> Eyepieces

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RAKing
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Reged: 12/28/07

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Re: Leica ASPH Zoom in a Fast Newtonian new [Re: johnnyha]
      #5480061 - 10/20/12 09:10 AM

Quote:

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.

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.

Cheers,

Ron


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Bob S.
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Re: Leica ASPH Zoom in a Fast Newtonian new [Re: RAKing]
      #5480081 - 10/20/12 09:33 AM

Quote:

Quote:

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.

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.

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.


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RAKing
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Re: Leica ASPH Zoom in a Fast Newtonian new [Re: Bob S.]
      #5480137 - 10/20/12 10:26 AM

Quote:

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.




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".

Ron


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Gord
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Re: Leica ASPH Zoom in a Fast Newtonian new [Re: RAKing]
      #5480282 - 10/20/12 12:09 PM

Quote:

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,


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RAKing
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Re: Leica ASPH Zoom in a Fast Newtonian new [Re: Gord]
      #5480416 - 10/20/12 01:41 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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pbsastro
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Re: Leica ASPH Zoom in a Fast Newtonian new [Re: RAKing]
      #5480615 - 10/20/12 03:48 PM

I would say someone who pays the price of the ASPH wants just the best, and therefore will only be happy with the barlow permanent on it That is my case anyway.
On axis it is good without barlow, but on-axis is usually used for planets, and planet mags usually go from 10mm to 3.5mm.
Also I find a zoom is more important in the high mag range to dial mag according to seeing.
So I use the ASPH permanmently barlowed. The unbarlowed low mag vignetting just sucks and the high mag edge is not pefect. Barlowed all is perfect. As simple as that.

Please note I don't use it with fast scopes, only f/7 to f/10.

Edited by pbsastro (10/20/12 03:50 PM)


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Bob S.
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Re: Leica ASPH Zoom in a Fast Newtonian new [Re: pbsastro]
      #5481491 - 10/21/12 06:59 AM

Quote:

I would say someone who pays the price of the ASPH wants just the best, and therefore will only be happy with the barlow permanent on it That is my case anyway.
On axis it is good without barlow, but on-axis is usually used for planets, and planet mags usually go from 10mm to 3.5mm.
Also I find a zoom is more important in the high mag range to dial mag according to seeing.
So I use the ASPH permanmently barlowed. The unbarlowed low mag vignetting just sucks and the high mag edge is not pefect. Barlowed all is perfect. As simple as that.

Please note I don't use it with fast scopes, only f/7 to f/10.




Pedro, You and Ron's suggestion concerning barlowing the Leica ASPH with a Paracorr II in a fast 16.5" f/3.65 Newtonian worked very well. I had been using the Leica with its 2" adapter in a Paracorr II and the views were very pleasant. However, when I placed the front element of a Astro-Physics Barcon on the Leica, the star points got tighter yet and I was seeing the I star (mag 15) and the G star(mag 14.5) periodically. I checked a chart or two to see what I was able to see and am quite freaked out by what the ASPH and my 16.5" were able to see. In my 11 years in the hobby having owned up to 28" scopes, I have never seen the I and G stars with a conventional eyepiece. I have seen them and the H1 and H2 stars just outside the Trapezium with my image intensifying eyepieces with good seeing once or twice but have NEVER, EVER, seen them visually before this morning. WOW!!!! The Barcon barlow added a very positive effect to the performance of the ASPH. Thanks for the suggestion from you and and Ron. I am totally blown away right now. I started viewing at 1 a.m EDT and the seeing went from spectacular to average then back to spectacular and then back to below average and then average by sunrise. I spent the entire night only viewing M42 and Jupiter. I would have to take breaks from Jupiter looking at the Orionids to get my night vision back. Bob

Edited by Bob S. (10/21/12 07:43 AM)


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RAKing
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Reged: 12/28/07

Loc: West of the D.C. Nebula
Re: Leica ASPH Zoom in a Fast Newtonian new [Re: Bob S.]
      #5481526 - 10/21/12 08:01 AM

Great report, Bob! Wow - G and I in the Trap, I can only dream about those in my little scopes.

My Barcon will never leave the Leica. I need good edge performance in order to do accurate VSO estimates. With the Barcon, I was able to zoom in on some 12+ mag comp stars the other night and still see them clearly. I consider that to be excellent performance with my little 5 inch refractor.

My next order of business is to use this setup in my C8 SCT and see if that fixes my original issues.

Cheers,

Ron


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johnnyha
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Re: Leica ASPH Zoom in a Fast Newtonian new [Re: RAKing]
      #5481537 - 10/21/12 08:15 AM

Thanks for the answers on the Barcon. I am still a little confused as to what magnification is being achieved by people. Ron said even with a 7mm spacer it's still only 1.2x - so was this enough to clean up the edge? And Ron you stacked some spacers to achieve 1.5X, which would be perfect for my scopes - what is the length between the Leica's 2" adapter and the Barcon element for 1.5X?

Also, Alexis, it is not entirely clear to me how you are screwing the Baader Zeiss barlow (I assume you are talking about the familiar 1.25" Baader Zeiss barlow) onto the 2" adapter, and what magnification that would achieve?

I am very seriously considering getting this eyepiece and streamlining my kit down to a 31T5, Leica Zoom, and then my MkV binos and collection of ortho pairs.


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RAKing
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Reged: 12/28/07

Loc: West of the D.C. Nebula
Re: Leica ASPH Zoom in a Fast Newtonian new [Re: johnnyha]
      #5481571 - 10/21/12 09:04 AM

Johnny,

Lots of questions - let's see if I can provide some answers.

To start, I used Andreas' formula and worked the numbers backward to come up with a 97mm focal length for my Barcon. (The Barcon is advertised to be 1.7x with the standard eyepiece holder.) Then you can just go on and use his formula to compute any magnification you wish, given your available spacers.

For me to hit 1.5x, I add three A-P CCD spacers to the Leica's two inch adapter. It comes up to 1.52x.

My personal preference is to use two A-P spacers and one empty filter ring for 1.46x.

I have not tried the Barcon with just the filter ring, yet. That only gives me 1.2x and it's not enough in my refractor. I'll try that combo in the SCT next time out and see if it clears up the vignetting and soft edges.

The Barcon will screw right on to the Leica two inch adapter, but mine hits the lens just before the end. You could slide the two inch adapter out a millimeter or so and use it that way. My calculations show that achieves 1.14x magnification increase.

Cheers,

Ron


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johnnyha
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Re: Leica ASPH Zoom in a Fast Newtonian new [Re: RAKing]
      #5481589 - 10/21/12 09:13 AM

Thanks Ron. I have a Televue 2" barrel extension (1.25" long) and I am thinking that might work perfectly with the Leica Zoom and Barcon for pretty close to 1.5X. At an effective fl of 12mm to 6mm that would be absolutely perfect for my two scopes and my viewing habits. Wow - two eyepieces to cover my full range of monoviewing. Very enticing.

Update: In stock. Paypal sent.


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RAKing
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Re: Leica ASPH Zoom in a Fast Newtonian new [Re: johnnyha]
      #5481729 - 10/21/12 10:58 AM

I think that will work out to the same length I'm using. 12mm to 6mm is also my sweet spot and I think you will enjoy that, too.

Cheers,

Ron


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sixela
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Re: Leica ASPH Zoom in a Fast Newtonian new [Re: johnnyha]
      #5481749 - 10/21/12 11:12 AM

I screw in the Baader Zeiss in a zero height M48x0.75 to T2 adapter and then screw that into the 2" adapter (Markus's adapter has 2" filter threads over its entire length, but the smallest barlow factor is around 1.95x since the element of the Zeiss is at the end of a fairly long 1.25" barrel.

The Baader VIP element can be put a lot closer (in a Baader T2-#12 with a T2->M48x0.75 adapter), but that still yields a factor of 1.6x (1.5x is possible but the edge then suffers from astigmatism).


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ThomasM
sage


Reged: 04/19/09

Re: Leica ASPH Zoom in a Fast Newtonian new [Re: sixela]
      #5481932 - 10/21/12 01:21 PM

Quote:

..

The Baader VIP element can be put a lot closer (in a Baader T2-#12 with a T2->M48x0.75 adapter), but that still yields a factor of 1.6x (1.5x is possible but the edge then suffers from astigmatism).




I am using the TMB 1.8 ED barlow in a special housing. Thanks to its long focal lenght I can get 1.5 x without astigmatism at the edge. It is a great combination,
for details see here:

http://www.cloudynights.com/ubbthreads/showflat.php/Cat/1,2,3,4,5,6,7,8,9,10,11/Number/5329647/Main/5325399

best regards

Thomas


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andydj5xp
Pooh-Bah


Reged: 05/27/04

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Re: Leica ASPH Zoom in a Fast Newtonian new [Re: sixela]
      #5482006 - 10/21/12 02:05 PM

Quote:

The Baader VIP element can be put a lot closer (in a Baader T2-#12 with a T2->M48x0.75 adapter), but that still yields a factor of 1.6x (1.5x is possible but the edge then suffers from astigmatism).



That's my experience as well.

For serious 1.5x barlowing of the Leica I've already suggested (in the review) using the Barcon:
"The Baader VIP barlow lens has a focal length of approximately -64mm. Using it in the 1.5x configuration places it quite near to the field lens of the zoom which introduces slight astigmatism near the edge of the field. If this barlow factor is very important a longer focal length barlow lens like the Antares 1.6x or the AP Barcon should be considered to reduce the astigmatism. On the other hand, for me the 1.5x with its up to 43' true field of view (framing nicely the double cluster at 83x) is too useful to reject it for some edge astigmatism. And zooming in up to 165x and still maintaining a true field of view of 30' (framing one or the other of both clusters) with even less astigmatism is very attractive."

Andreas


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sixela
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Re: Leica ASPH Zoom in a Fast Newtonian new [Re: andydj5xp]
      #5482198 - 10/21/12 04:13 PM

What I'm missing is which adapter people are using to get such small barlow factors with a Barcon or Baradv, given those can't actually go inside a 2" adapter's barrel.

My adapter from Markus is 42.5mm long beyond the shoulder of the Leica, and if I'd use a Baradv at the end of it (-102mm focal length, principal plane 12mm inside the housing) I'd get a factor of 1.58x.

Are you using the StarLight Instruments adapter, and is it that much shorter?


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andydj5xp
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Re: Leica ASPH Zoom in a Fast Newtonian new [Re: sixela]
      #5482240 - 10/21/12 04:35 PM Attachment (6 downloads)

Quote:

What I'm missing is which adapter people are using to get small barlow factors with a Barconor Baradv.

My adapter from Markus is 42.5mm long beyond the shoulder of the Leica, and if I'd use a Baradv at the end of it (-102mm focal length, principal plane 12mm inside the housing) I'd get a factor of 1.58x.

Are you using the StarLight Instruments adapter, and is it that much shorter?




My DIY-adapter made from a Baader T2 #16 is only 28mm long from the zoom's shoulder (including the 2"/T2-thread adapter #29, see pic) thus enabling barlow factors as low as 1.5x with the VIP barlow.

Andreas


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sixela
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Re: Leica ASPH Zoom in a Fast Newtonian new [Re: andydj5xp]
      #5482284 - 10/21/12 04:52 PM

Yes, I know about yours, but even that will yield a factor of 1.43x with a BarAdv (4,5mm from focal plane to shoulder, 28mm for your adapter, and 12mm from the threads of the BarAdv to its principal plane, the sum divided by 102mm, and then +1).

And yours is shorter than the commercial ones I know. I'm simply puzzled by what RAKing and Bob S. are doing.

If I remember the Barcon element well, it doesn't fit inside a 2" barrel, so it's bound to end up a lot further from the eyepiece's focal plane. Or does it have different housings, one of which is more narrow than a 2" barrel andallows it to go into Markus's 2" adapter?


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RAKing
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Re: Leica ASPH Zoom in a Fast Newtonian new [Re: sixela]
      #5482326 - 10/21/12 05:04 PM

The adapter I got from Markus is only 25mm long overall and the field lens of the Leica is less than 10mm from the bottom.

My math might not be correct, but the views I'm getting seem to indicate my Barlow factors with the Barcon are close to what I think they should be. If nothing else, I can stick the regular holder onto the Barcon and start at 1.7. I know if I go shorter, I am going down in magnification.

Cheers,

Ron


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johnnyha
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Re: Leica ASPH Zoom in a Fast Newtonian new [Re: sixela]
      #5482345 - 10/21/12 05:13 PM

If the Barcon *just barely*contacts the Leica field lens when screwing it into the 2" adapter, there is obviously no way it could go inside the adapter. So Alexis your Leica has a longer adapter? Sorry I'm a bit confused here.

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