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Another Leica zoom question...

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#51 j.gardavsky

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Posted 25 November 2021 - 05:36 AM

Pay attention to whether the EOFB appears more obvious at low power or at high power.  If this is the case, it's appearance or severity might be affected by exit pupil, rather than the act of zooming itself.

 

When I first acquired a Leica Zoom, I recall comparing it with my set of XW's.  On nights of poor transparency, the XW's would show slight EOFB, while it was much more apparent in the Leica.  The transparency had to be excellent for me not to see any EOFB in the Leica.  That doesn't happen very often around here. 

 

Mike

Hello Mike,

 

this EOFB observation sounds to me like marginal rays of scattered light entering the eyepiece, and generating the edge of field brightening.

 

The spotting eyepieces don't have the insert tube properly protected (with the buffles, rills, etc.) like most of the astronomy eyepieces, and especially not when you are not using the original adapter bayonet-to-1.25" or -2" of the manufacturer.

The baffle(s) to cut the marginal scatterd rays are is in the spotting scope.

 

That's the reason why I have added at least one baffle in the diagonal mirrorrs and prism houses for my 6" F/5 achro

 

What also helps on the nights of lower transparency are the oversized lens hoods. I have them on my 6" F/5 achro, on the Leica 82mm APO Televid, and on my astronomy binoculars.

In fact, I mount these lens hoods always.

 

Best,

JG
 


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#52 Sarkikos

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Posted 25 November 2021 - 08:04 AM

Hello Mike,

 

this EOFB observation sounds to me like marginal rays of scattered light entering the eyepiece, and generating the edge of field brightening.

 

The spotting eyepieces don't have the insert tube properly protected (with the buffles, rills, etc.) like most of the astronomy eyepieces, and especially not when you are not using the original adapter bayonet-to-1.25" or -2" of the manufacturer.

The baffle(s) to cut the marginal scatterd rays are is in the spotting scope.

 

That's the reason why I have added at least one baffle in the diagonal mirrorrs and prism houses for my 6" F/5 achro

 

What also helps on the nights of lower transparency are the oversized lens hoods. I have them on my 6" F/5 achro, on the Leica 82mm APO Televid, and on my astronomy binoculars.

In fact, I mount these lens hoods always.

 

Best,

JG
 

Yes, I always attach extension light hoods on my refractors and Cats.  I even use them sometimes on my Newtonians.  I made one especially for my 10" Dob.  They also help keep dew from forming on the objective/corrector, or in the case of a Newtonian, on the secondary mirror.

 

But how do you add a baffle to the diagonal mirror/prism body?

 

Mike


Edited by Sarkikos, 25 November 2021 - 08:06 AM.

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#53 j.gardavsky

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Posted 25 November 2021 - 10:34 AM

Yes, I always attach extension light hoods on my refractors and Cats.  I even use them sometimes on my Newtonians.  I made one especially for my 10" Dob.  They also help keep dew from forming on the objective/corrector, or in the case of a Newtonian, on the secondary mirror.

 

But how do you add a baffle to the diagonal mirror/prism body?

 

Mike

Hello Mike,

 

tomorrow during the daylight, I will take a pic of a baffle in the 2" tube on the zenith diagonal.

 

In another forum, I have written about the marginal rays scattering in the refracor OTA, and about the difference to how this is suppressed in the Leica 82mm APO Televid.

Here is a picture,

Marginal rays scattering in OTA.jpg

 

Myself, I am particularly sensitive to the scatterd light in the optics,

as my favourite observing program has been the galactic molecular clouds, IFN, large diffuse HII regions, and the recently discovered SNR. And on a side line, I have visually retrieved a few of those forgotten Gaze Shajn (1955) nebulae, which are not in the current catalogs.

 

Best,

JG


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#54 StarAlert

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Posted 25 November 2021 - 02:16 PM

Unsurprisingly, this thread has gotten way off topic. 
 

I keep going back and forth on trying one of these. My current EPs include the 14mm and 10mm Nikon NAVs, 7mm XW, 6mm Delos and 5mm Vixen SLV.  My question is what are people looking at with this zoom where they need the 80o AFOV at the high powers?

 

If I were to buy this zoom, I’d probably use it mostly for doubles and planetary observing in an f/7 refractor mounted on a tracking mount. I certainly don’t need the wide FOV for these kinds of targets with a tracking mount. 

 

It sure would be nice to stick one EP in the diagonal and be done for the night, though. 


Edited by StarAlert, 25 November 2021 - 04:05 PM.


#55 areyoukiddingme

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Posted 25 November 2021 - 02:24 PM

Hello Mike,

 

tomorrow during the daylight, I will take a pic of a baffle in the 2" tube on the zenith diagonal.

 

In another forum, I have written about the marginal rays scattering in the refracor OTA, and about the difference to how this is suppressed in the Leica 82mm APO Televid.

Here is a picture,

attachicon.gifMarginal rays scattering in OTA.jpg

 

Myself, I am particularly sensitive to the scatterd light in the optics,

as my favourite observing program has been the galactic molecular clouds, IFN, large diffuse HII regions, and the recently discovered SNR. And on a side line, I have visually retrieved a few of those forgotten Gaze Shajn (1955) nebulae, which are not in the current catalogs.

 

Best,

JG

I remember someone relieving EOFB in the Swarovski zoom by improving the baffling. My vague recollection was that it involve some surgery on the eyepiece.

 

It's not clear to me how the Leica might be improved by an end user on that, but I'd be interested to hear what people have come up with.
 


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#56 Sarkikos

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Posted 25 November 2021 - 04:02 PM

Unsurprisingly, this thread has gotten way off topic. 
 

I keep going back and forth on trying one of these. My current EPs include the 14mm and 10mm Nikon NAVs, 7mm XW, 6mm Delos and 5mm Vixen SLV.  My question is what are people looking at with this zoom where they need the 80o FOV at the high powers?

 

If I were to buy this zoom, I’d probably use it mostly for doubles and planetary observing in an f/7 refractor mounted on a tracking mount. I certainly don’t need the wide FOV for these kinds of targets with a tracking mount. 

 

It sure would be nice to stick one EP in the diagonal and be done for the night, though. 

What are people looking at with this zoom at 80 degrees AFOV?  Everything!  lol.gif

 

You seem to imply that zoom eyepieces have been purposefully designed to have a wider AFOV of view at high power than at low power.  That's not the case.  Apparently, the only ways that zooms can be designed is to have a 3x range of magnifications with an AFOV which widens from low to high power, a 2x range with an AFOV which also widens from low to high power but is somewhat wider along the entire range, or to have a 2x range with a constant AFOV.  I don't think there is a way to design a zoom with a wider AFOV at low power which narrows at high power.  I wouldn't want one. 

 

Keep in mind that not everyone has a mount that tracks.  Most larger Dobs don't have tracking mounts.  None of my mounts - at least the ones that I use anymore - track.  So I appreciate the 80 degree AFOV at high power.  I nudge the mount so the planet or doubles or whatever is at the following edge of the field and observe the object as it drifts completely across the field.  Then I nudge it back.  At high power, I actually prefer my 110 degree 3.7 and 4.7 Ethos-SX.

 

Mike


Edited by Sarkikos, 26 November 2021 - 01:47 PM.

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#57 areyoukiddingme

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Posted 25 November 2021 - 04:27 PM

While I see foibles of the Leica discussed quite often (I also bring them up), I've not yet heard anyone say:  Gee, this 80 degrees at highest power, with nice sharp views and good eye relief, if only the field were more narrow!


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#58 StarAlert

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Posted 25 November 2021 - 04:33 PM

What are people looking at with this zoom at 80 degrees AFOV?  Everything!  lol.gif

 

You seem to imply that zoom eyepieces have been purposefully designed to have a wider AFOV of view at high power than at low power.  That's not the case.  Apparently, the only way that zooms can be designed is to have a 3x range of magnifications with a wider AFOV at high power, or to have a 2x range with a constant AFOV.

 

Keep in mind that not everyone has a mount that tracks.  Most larger Dobs don't have tracking mounts.  None of my mounts - at least the ones that I use anymore - track.  So I appreciate the 80 degree AFOV at high power.  I nudge the mount so the planet or doubles or whatever is at the following edge of the field and observe the object as it drifts completely across the field.  Then I nudge it back.  At high power, I actually prefer my 110 degree 3.7 and 4.7 Ethos-SX.

 

Mike

Now, I’m confused. Isn’t the Leica a 2x zoom with an increasing AFOV (from 60o to 80o).

 

I understand that the increasing AFOV isn’t a design choice. I think you answered my question, though. If it’s because you want the extra FOV to allow for drift in a non-tracking mount, that makes sense.

 

But is there a reason why you should buy the Leica vs., say, a Baader Mark IV if you’re using a tracking mount? Are there high-powered targets people are looking at with a tracking mount that requires the extra AFOV that the Leica offers over a Baader?

 

If it’s not the wide AFOV the Leica offers that is the main selling point, then is it the comfort (long eye relief), superior optics, or convenience of not having to swap eyepieces? 
 

I should just buy myself one for Christmas and find out for myself. smile.gif


Edited by StarAlert, 25 November 2021 - 04:55 PM.

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#59 j.gardavsky

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Posted 25 November 2021 - 05:04 PM

Matt,

 

I can't answer your question why I am using the Leica zoom

And can't explain you why I am also using three fix focus Leica spotting eyepieces, and three Leica microscope eyepieces, to cover the focus lengths up to 32mm.

And one Leica "monocentric" triplet at 42mm.

They came over the times somehow together. That's the life.

 

Best,

JG


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#60 sixela

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Posted 25 November 2021 - 05:10 PM

 

But is there a reason why you should buy the Leica vs., say, a Baader Mark IV if you’re using a tracking mount? 

The Leica just is a much better eyepiece. It can rival the views in an ortho (so much so that it's become my monoculair planetary eyepiece). But you do have to barlow it in fast scopes if you want clean edges.


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#61 StarAlert

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Posted 26 November 2021 - 11:28 AM

APM is running a nice sale today on the Leica Zoom. With the 4% off coupon, I can get one with the 1 1/4” eyepiece adapter delivered to CA for about $805. 


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#62 Sarkikos

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Posted 26 November 2021 - 01:39 PM

Now, I’m confused. Isn’t the Leica a 2x zoom with an increasing AFOV (from 60o to 80o).

 

I understand that the increasing AFOV isn’t a design choice. I think you answered my question, though. If it’s because you want the extra FOV to allow for drift in a non-tracking mount, that makes sense.

 

But is there a reason why you should buy the Leica vs., say, a Baader Mark IV if you’re using a tracking mount? Are there high-powered targets people are looking at with a tracking mount that requires the extra AFOV that the Leica offers over a Baader?

 

If it’s not the wide AFOV the Leica offers that is the main selling point, then is it the comfort (long eye relief), superior optics, or convenience of not having to swap eyepieces? 
 

I should just buy myself one for Christmas and find out for myself. smile.gif

Yes, you are correct.  Don't be confused! 

 

The Leica does have a 2x zoom range - about 19mm to 8mm - and an increasing AFOV from about 60 degrees to 80 degrees, with the wider AFOV at 8mm.  But most zooms, such as the Baader and others, have a 3x range with increasing AFOV.   Maybe the Leica was limited in its zoom range in order to increase the overall AFOV?

 

A few zooms, such as both Nagler Zooms, have a constant AFOV and a 2x zoom range.  This is apparently the design plan of the new APM Zoom.  But instead of a constant 50 degree AFOV as in the case of the Nagler Zooms, it will have 75 degrees!

 

I don't use a tracking mount.  But I don't think whether or not the observer has a tracking mount should affect choice of a zoom eyepiece.  Why should it?  Even if the mount tracks, don't you still look at the entire field of view sometimes?

 

Here are the reasons I value the Leica Zoom over the Baader Zooms:

 

1) Improved optical performance.  I would judge the Leica Zoom to be equivalent to the XW's in optical performance - some say better - with the exception of intermittent EOFB in the Leica.

 

2) Parfocality.  I don't have to refocus the Leica Zoom when I zoom from high to low power, or vice versa.  I do with the Baader Zooms.  The Baader Mark IV Zoom is even less parfocal than the Mark III.  This is a big deal to me.  For me, having to refocus diminishes much of the convenience of a zoom eyepiece.  If I have to refocus a zoom, that is a deal breaker for me.  However, using the Baader Zooms with a Barlow, or using them in a slower telescope, will eliminate or make less obvious the nonparfocality.  But do I always want to put a Barlow on the zoom, or always use it in a slower telescope?  No, I do not.

 

3) The larger AFOV.  

 

Mike


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#63 RAKing

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Posted 26 November 2021 - 04:32 PM

The Leica does have a 2x zoom range - about 19mm to 8mm - and an increasing AFOV from about 60 degrees to 80 degrees, with the wider AFOV at 8mm.  But most zooms, such as the Baader and others, have a 3x range with increasing AFOV.   Maybe the Leica was limited in its zoom range in order to increase the overall AFOV?

 

I think Leica limited its zoom range to 2x in order to maintain its higher optical standards while keeping the eyepiece price as low as possible. 

 

The optical quality of the Leica sets it apart from the Baader.  There are some of us who use it in place of high-quality orthoscopic eyepieces (like ZAO-II).  The cost of the Leica is more than double the Baader, even with that discount coupon.  Just think how much it would cost if this zoom had a 3x range. 

 

For my purposes, the 2x range is fine and I love the wider AFOV at the "high mag" end.  I would be even happier if the AFOV started at 65 and went up to 85-degrees, but once again I realize just how much bigger and more expensive that eyepiece would be.

 

Ron


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#64 Sarkikos

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Posted 26 November 2021 - 05:23 PM

The Leica just is a much better eyepiece. It can rival the views in an ortho (so much so that it's become my monoculair planetary eyepiece). But you do have to barlow it in fast scopes if you want clean edges.

A Paracorr can also clean up the outer field of a Lecia Zoom in a Newtonian.

 

Mike


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#65 sixela

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Posted 26 November 2021 - 06:10 PM

A Paracorr was already a given in my advice ;-).


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#66 Astronome66

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Posted 27 November 2021 - 01:56 PM

Very cool to read this post. I’ve been exploring all kinds of options for an eyepiece collection to go with my new XT8+. Lots to learn and so many options. I’ve ordered a 30mm APM UFF and a 2” APM barlow with the intent of adding their 7.7-15.4mm super zoom, pending favourable reviews once it’s finally released.

 

Same idea as what BDS316 initiated this topic with: two lenses and one barlow which cover a very wide range of magnification. My Plan B, if the APM zoom fails to live up to the hype, is the Leica which I’d prefer to the Baader based on what I’ve read here and my own past experiences in photography, but it’s challenging to justify the added cost. Plan C is either the Baader zoom, or more likely a few wider field single focal length lenses to get me from 15mm to 5mm and maybe even down to 3mm for those rare nights of perfect viewing for the moon and planets.

 

In any case, I really like this minimalist approach. There’s something to be said about the simplicity of it and that barlow gives a lot of flexibility, much like Baader’s version. It’s like an astronomical swiss army knife. The appeal of a collection like this for travelling is obvious now that several members have mentioned it. I’m curious as to how many people would use a collection like this as their principal every night set. Cheers!


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#67 Voyager 3

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Posted 28 November 2021 - 03:38 AM

I'm too in for the same set provided the APM lives upto expectations . 




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