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Eyepiece question for APM 100mm APos

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#76 Mr. Bill

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Posted 11 February 2016 - 06:13 PM

My 20mm ES eps seem to work well (as well as 19mm Pans)

No vignetting, a decent fov and most important a exit pupil that seems to be the "sweet spot"

providing maximum contrast in my backyard with green/blue skies.

I save the 24mm Pans for darkest skies where the exit pupil can be used to best effect...

For my main observing interest (bright/dark nebulae), contrast trumps all including max fov.

#77 Allardk

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Posted 11 February 2016 - 06:19 PM

Sure, but then you end up in the borderzone of the APM. Some are ok with the performance there, but you seem not too happy.

For these kind of objects you might wanna use another kind of scope.

 

The APM shines on open clusters, double stars, the Moon and planets.


Edited by Allardk, 11 February 2016 - 06:21 PM.


#78 GamesForOne

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Posted 11 February 2016 - 06:31 PM

Sure, but then you end up in the borderzone of the APM. Some are ok with the performance there, but you seem not too happy.

For these kind of objects you might wanna use another kind of scope.

 

The APM shines on open clusters, double stars, the Moon and planets.

 

My Lunt APO 45 deg bino with Pentax XW20 pair eats up the Double Cluster, Rosette, M31, and then moves on to dark nebulae for late night dessert. I don't agree that you must have another kind of scope for those targets, but of course a larger aperture with 2" eyepiece can provide better views.

 

I think most would argue that the Moon and planets warrant another kind of scope, although I do have success at 137x with my bino on those targets when I just don't want to take the time to setup that other scope.

 

---

Michael Mc



#79 Mr. Bill

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Posted 11 February 2016 - 06:32 PM

I've lived in the "borderzone" for a long time.... :grin: 

In spite of the ghosting issues, the Lunt/APM APOs give me low power views with maximum contrast at the right image scale.

 

IMO, they are currently the best choice in binocular price/performance in the 100mm class.

If portability is not an issue, the 127mm BinoBox using mirrors instead of prisms is my "go to."


Edited by Mr. Bill, 11 February 2016 - 06:33 PM.

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#80 Allardk

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Posted 12 February 2016 - 02:37 AM

 

Sure, but then you end up in the borderzone of the APM. Some are ok with the performance there, but you seem not too happy.

For these kind of objects you might wanna use another kind of scope.

 

The APM shines on open clusters, double stars, the Moon and planets.

 

My Lunt APO 45 deg bino with Pentax XW20 pair eats up the Double Cluster, Rosette, M31, and then moves on to dark nebulae for late night dessert. I don't agree that you must have another kind of scope for those targets, but of course a larger aperture with 2" eyepiece can provide better views.

 

I think most would argue that the Moon and planets warrant another kind of scope, although I do have success at 137x with my bino on those targets when I just don't want to take the time to setup that other scope.

 

---

Michael Mc

 

I agree, I use the XW 20 as well. I have no problem. 

I compared the KOWA to the APM on planets. The KOWA is slightly, but only slightly better there. On the Moon the APM has a hint of CA, but it is very useful. Overall the idea of a BT. Grab and go. Minimum cooldown time.

 

It seems Janapier is very unhappy using the "borderzone". In that case I recommend something else. Don't get mad, try something else :-)

 

Probably most APM users are ok with the performance in that area. Could be better but for me not a dealbreaker.


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#81 Mad Matt

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Posted 12 February 2016 - 03:14 AM

<snip>

I compared the KOWA to the APM on planets. The KOWA is slightly, but only slightly better there. On the Moon the APM has a hint of CA, but it is very useful. Overall the idea of a BT. Grab and go. Minimum cooldown time.
 
<snip>


Just out of curiosity (and only if it interests you too), could you try comparing both on the planets and moon with the APM stopped down to 80mm. also a comparison with the APM at 90mm would be cool!

 

-M@


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#82 janapier

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Posted 12 February 2016 - 08:01 AM

...

 

It seems Janapier is very unhappy using the "borderzone". In that case I recommend something else. Don't get mad, try something else :-)

 

Probably most APM users are ok with the performance in that area. Could be better but for me not a dealbreaker.

 

What else, Allardk?



#83 Allardk

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Posted 12 February 2016 - 08:19 AM

Mr. Bill's binobox :-)

Ask him about the good and the bad....

 

Kowa Highlander with the 21x giving you a FOV of 3 degrees. The light transmission of the KOWA is very good. Very good contrast. Just the edge is less sharp from 70-80 %. Some reflections looking at bright objects (Moon, Sirius). 



#84 Allardk

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Posted 12 February 2016 - 11:54 AM

 

<snip>

I compared the KOWA to the APM on planets. The KOWA is slightly, but only slightly better there. On the Moon the APM has a hint of CA, but it is very useful. Overall the idea of a BT. Grab and go. Minimum cooldown time.
 
<snip>


Just out of curiosity (and only if it interests you too), could you try comparing both on the planets and moon with the APM stopped down to 80mm. also a comparison with the APM at 90mm would be cool!

 

-M@

 

I will put it on the list :-)

 

Yesterday compared the two on several double stars, open clusters, M42, planets and the Moon. First with similar magnification (32x), then I gave the APM a boost with the Docter 12.5 mm. A bit like the test Milton Wilcox did.



#85 astrofan007

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Posted 14 May 2019 - 02:17 PM

Hello, has anyone here used the Explore Scientific 9mm 100 degree EP in their BT100?  If so, how does it compare to similar 9mm EPs?

 

James



#86 astrofan007

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Posted 14 May 2019 - 08:17 PM

It was brought to my attention that the ES has a 2" barrel and thus would not be a candidate for the 100-90.  



#87 astrofan007

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Posted 16 May 2019 - 06:48 AM

Does anyone know if it is a reliable and effective way to evaluate EPs by just using one (instead of a pair) in a 100-90 BT?  


Edited by astrofan007, 16 May 2019 - 06:50 AM.



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