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Comparing the 18mm UFFs and 17.5mm Morpheus eyepieces

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#1 Mr. Bill

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Posted 13 June 2018 - 02:52 PM

Another good night with SQM 21.5+ skies starting at 12:30 AM.

 

Spent two hours comparing views of same MW objects using first the 17.5mm Morpheus and then the 18mm UFFs in my Lunt/APM 100mm APOs.

 

Contrast and image sharpness was to my eyes the same which is to say excellent and same number of stars in each noted in open clusters, so they both get high points. No apparent coma or astigmatism noted in either. Eye relief and ease of eye placement similar with a nod to the UFFs for my eyes....YMMV.

 

Big difference was the apparent fov, 65 degrees for the UFFs and 76 degrees for the Morpheus.

 

In a nutshell, if you like big immersive views with a moderate amount of field curvature 80% out from on axis, the Morpheus are your choice.

 

OTOH, if you want a really flat field almost to the fieldstop with just a touch of field curvature at the edge and don't mind the smaller apparent fov, the UFFs are it.

 

Me, I can't decide....scratchhead2.gif


Edited by Mr. Bill, 13 June 2018 - 02:53 PM.

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#2 nicoledoula

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Posted 13 June 2018 - 04:00 PM

And if wider fields are ones thing, buying EP's that are better corrected than the Morpheus isn't out of the question.



#3 GamesForOne

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Posted 13 June 2018 - 04:11 PM

And if wider fields are ones thing, buying EP's that are better corrected than the Morpheus isn't out of the question.

What options would that include for 1.25" barrel size of > 17mm focal length?

 

I have a Pentax XW20 pair and it displays considerable field curvature in the binos at the field edges.

 

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#4 Mr. Bill

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Posted 13 June 2018 - 04:23 PM

And if wider fields are ones thing, buying EP's that are better corrected than the Morpheus isn't out of the question.

IMO, field curvature is inherent in the binocular objectives and the Morpheus' larger apparent fov shows it up more.

 

I believe that the APM UFFs were designed around the APM BTs to minimize field curvature at the eyepiece; that's why they are included with APM's BT binoculars.

 

Someone that has an APO telescope with a known flat field and the 17.5mm Morpheus would be able to test  the amount of field curvature in the ep.


Edited by Mr. Bill, 13 June 2018 - 08:40 PM.


#5 Nightfly

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Posted 13 June 2018 - 04:55 PM

I can attest to the small amount of FC with the 18mm UFF's and excellent on-axis performance in the Orion BT100.  Contrast is superb as well.

 

I was checking out Barnard 142/143 and these eyepieces framed it very well.  These dark nebulae filled the field with wonderful sharpness and contrast.  Surpassed the photos.

 

If these EP's were built around the binocular, the rest of the series should be grand as well.  The 24's are pending......



#6 starzonesteve

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Posted 13 June 2018 - 04:59 PM

If these EP's were built around the binocular, the rest of the series should be grand as well.  The 24's are pending......

The 24’s are spectacular in my APM 120mm



#7 duck2k

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Posted 13 June 2018 - 05:05 PM

I enjoyed the wider field of the Morpheus 17.5

the 18 UFF have a narrower field, but the targets are 

no less beautiful.

 

while I have many eyepieces for my APM’s (and they are all good), the

17.5, 12.5 Morpheus, and my APM 24 mm UFF remain in my eyepiece

tray. I am sticking to my story.smile.gif


Edited by duck2k, 13 June 2018 - 05:07 PM.

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#8 GrahamDFyffe

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Posted 13 June 2018 - 11:19 PM

I love the APM 24’s in my new Oberwerk BT 100 XL’s. Did I hear some rumor about APM bringing out a 90° eyepiece?


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#9 wargentin

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Posted 25 June 2018 - 06:54 PM

I've received a pair of APM UFFs 18mm. With my APM 100 ED APO, I can see easily field curvature. In fact, the last 20 or 25% of the field are blurry. It is possible to focus stars near the fieldstop, but then the center of the field is blurry.
In this regard, they are clearly inferior to my Televue eyepieces (24 Pans, 13T6) which are sharp almost to the fieldstop, with zero field curvature.

On the other hand, for terrestrial observations, the 24 Pans have way too much distortion, and I don't like them for daytime. The APM UFFs 18 have only a hint of pincushion distortion, and I find them much more enjoyable for daytime.

Apart from the fact that they are NOT ultra-flat, I think these APM eyepieces are excellent.



#10 GamesForOne

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Posted 25 June 2018 - 08:12 PM

I've received a pair of APM UFFs 18mm. With my APM 100 ED APO, I can see easily field curvature. In fact, the last 20 or 25% of the field are blurry.

Blurry in the last 25%? Wow, everyone's eyes are different. I sure don't see that in my APM 100 90-deg APOs.

 

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#11 Mr. Bill

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Posted 25 June 2018 - 08:35 PM

Blurry in the last 25%? Wow, everyone's eyes are different. I sure don't see that in my APM 100 90-deg APOs.

 

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Michael Mc

+1......I see mild field curvature the last 10-15% in my Lunt/APM 100 APOs


Edited by Mr. Bill, 25 June 2018 - 08:37 PM.


#12 wargentin

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Posted 27 June 2018 - 05:50 PM

I should have said "slightly blurry", or "not as perfect as the Panoptics". smile.gif

Last night I tried the APM UFF on my 120/900 ED refractor: the field curvature was barely perceptible at the edge.
Then I tested the APM on my XT10g with a Paracorr Type I: there was a slight astigmatism near the fieldstop, but I can't say I saw field curvature. So it has probably a flat field.

With the 24 Pan on the same scope, I could detect a slight field curvature, but the curvature is inverted: the focuser must be moved outwards to achieve the best image near the fieldstop. I had never noticed that before!
My guess is that the 24 Pan has field curvature, whose convexity points towards the eyepiece, and which matches perfectly the field curvature of the APM binoculars.
I am more and more impressed by the 24 Pan…




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