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APM 4.7mm and 3.5mm vs 4.7 & 3.7 Ethos

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#1 Augustus

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Posted 03 September 2020 - 09:11 PM

Looking at upgrading.... I can really only afford one Ethos but the APMs look pretty tempting. Would I be losing much going for them vs an Ethos? Would I be sacrificing much ditching my 3.5mm Delos and 5.5mm UWA? Planning on using with a 24" f/3.5, 14.7" f/2.89 and Paracorr II, and occasionally with a 13.1" Coulter, C9.25 and 127mm apo.



#2 havasman

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Posted 03 September 2020 - 11:06 PM

I've not used the short APM HDC's. But I've had the 20, 13 & 9mm's and like fl ES100's and Ethos. It's likely the HDC short fl's performance versus the Ethos is like the others - closer in performance than in price.

 

But what are you trying to solve? Both your 3.5 and 5.5 are high performance ep's. And the amateur I probably listen most closely to says the short Delos are just better than everything else in their fl range.

 

Chasing a chimera is a dodge-y proposition.


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#3 Augustus

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Posted 03 September 2020 - 11:13 PM

I've not used the short APM HDC's. But I've had the 20, 13 & 9mm's and like fl ES100's and Ethos. It's likely the HDC short fl's performance versus the Ethos is like the others - closer in performance than in price.

 

But what are you trying to solve? Both your 3.5 and 5.5 are high performance ep's. And the amateur I probably listen most closely to says the short Delos are just better than everything else in their fl range.

 

Chasing a chimera is a dodge-y proposition.

Tracking by hand with the 3.5mm Delos in the 14.7" already sucks; the 24" is double the focal length. Having a wide-field eyepiece where I at least don't constantly lose the target (even if I have to recenter) would help a lot with smaller DSOs.


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#4 junomike

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Posted 04 September 2020 - 07:57 AM

The longer F/L APM's I tried were excellent however I don't like the fact there's no listings for the Field Stop sizes. 

With the Ethos you know you're getting 110°.



#5 hoof

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Posted 04 September 2020 - 12:42 PM

I own both the 3.7mm and 4.7mm, as well as three Ethos (8/13/21).  Those APM's are every bit the equal to my Ethos eyepieces in terms of sharpness and contrast, in everything but the moon, as far as I can tell.  Pinpoint stars to the edge, flat field, contrasty, everything you want in an eyepiece like this.

 

However ...

 

The glare control in these eyepieces is not so good.  What I mean is that when looking at a bright extended object that is beyond the field stop, there is light reflected off of the internals of the eyepiece.  If you do not position your eye's pupil to mask off that light, you get a glare effect over the view. This only affects the views of the Moon, from my experience.

 

This is why I'm considering replacing mine with the Ethos.  I primarily use mine on the moon, and with my telescopes, the moon extends well beyond the field stop.  Thus the glare issue has really started to bug me, as it requires careful eye placement to avoid the glare, especially on the 3.7mm eyepiece.

 

Don't get me wrong, the views of the moon are fantastic, sharp, contrasty, and *wide*.  However, if my pupil catches some of that stray internal reflected light, I will get a glare across the view.  The 3.7mm seems worse in this regards to the 4.7mm

 

So if you primarily intend to use this for non-Lunar things, or are able to tolerate having to place your pupil just right, these are excellent, excellent choices.  If not, the Ethos might be the way to go.

 

The one caveat with what I've said is I haven't actually used the 3.7/4.7 Ethos on the moon, they might have a similar issue.  I'm hoping the strong internal light control of the 8mm/13mm/21mm Ethos carries through to the 3.7/4.7.  Otherwise I might be spending $600 for something that doesn't help me with the moon smile.gif  

 

Also, I thought I'd add, I've only used mine in F/4 and slower telescopes (sharp to the edge), with a Paracorr II.  It's possible the Ethos are optically better in the ultra-fast telescopes you are using.  That's something else to consider.


Edited by hoof, 04 September 2020 - 12:46 PM.

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#6 hoof

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Posted 04 September 2020 - 12:44 PM

The longer F/L APM's I tried were excellent however I don't like the fact there's no listings for the Field Stop sizes. 

With the Ethos you know you're getting 110°.

My Lunt (APM) 3.7 and 4.7mm eyepieces are noticeably wider than my Ethos eyepieces (8mm, 13mm, 21mm).  Somehow the Ethos looks like a Plossl in field of view after using one of those :)  So whatever the AFoV is, it's noticably wider than my Ethos eyepieces.  It also seems less wide than my Explore Scientific 9mm 120deg eyepiece.  110 is probably about right.


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#7 Augustus

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Posted 04 September 2020 - 01:06 PM

I own both the 3.7mm and 4.7mm, as well as three Ethos (8/13/21).  Those APM's are every bit the equal to my Ethos eyepieces in terms of sharpness and contrast, in everything but the moon, as far as I can tell.  Pinpoint stars to the edge, flat field, contrasty, everything you want in an eyepiece like this.

 

However ...

 

The glare control in these eyepieces is not so good.  What I mean is that when looking at a bright extended object that is beyond the field stop, there is light reflected off of the internals of the eyepiece.  If you do not position your eye's pupil to mask off that light, you get a glare effect over the view. This only affects the views of the Moon, from my experience.

 

This is why I'm considering replacing mine with the Ethos.  I primarily use mine on the moon, and with my telescopes, the moon extends well beyond the field stop.  Thus the glare issue has really started to bug me, as it requires careful eye placement to avoid the glare, especially on the 3.7mm eyepiece.

 

Don't get me wrong, the views of the moon are fantastic, sharp, contrasty, and *wide*.  However, if my pupil catches some of that stray internal reflected light, I will get a glare across the view.  The 3.7mm seems worse in this regards to the 4.7mm

 

So if you primarily intend to use this for non-Lunar things, or are able to tolerate having to place your pupil just right, these are excellent, excellent choices.  If not, the Ethos might be the way to go.

 

The one caveat with what I've said is I haven't actually used the 3.7/4.7 Ethos on the moon, they might have a similar issue.  I'm hoping the strong internal light control of the 8mm/13mm/21mm Ethos carries through to the 3.7/4.7.  Otherwise I might be spending $600 for something that doesn't help me with the moon smile.gif  

 

Also, I thought I'd add, I've only used mine in F/4 and slower telescopes (sharp to the edge), with a Paracorr II.  It's possible the Ethos are optically better in the ultra-fast telescopes you are using.  That's something else to consider.

My Lunt (APM) 3.7 and 4.7mm eyepieces are noticeably wider than my Ethos eyepieces (8mm, 13mm, 21mm).  Somehow the Ethos looks like a Plossl in field of view after using one of those smile.gif  So whatever the AFoV is, it's noticably wider than my Ethos eyepieces.  It also seems less wide than my Explore Scientific 9mm 120deg eyepiece.  110 is probably about right.

Hmm. What if I got the 3.7 Ethos and 4.7 Lunt/APM? How bad is the glare really on the 4.7?

 

Also how is the 9mm 120? Don't think I'll ever buy one but I'm curious nonetheless.



#8 hoof

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Posted 04 September 2020 - 01:18 PM

Hmm. What if I got the 3.7 Ethos and 4.7 Lunt/APM? How bad is the glare really on the 4.7?

 

Also how is the 9mm 120? Don't think I'll ever buy one but I'm curious nonetheless.

If I had to do it over, and couldn't afford Ethos for both, that's what I would do.  But that's because I mostly use these on the moon (and on Globs, which they are awesome for)

 

The 9mm 120mm is awesome.  But it is not a Moon eyepiece (I've definitely tried).  On bright scenes (daylight, the moon) it has a nasty Orange Ring Of Fire effect if your eye isn't positioned well.  And the view has a yellowish tint to it.  My 8mm Ethos is a much better experience in that focal length range on the moon.

 

For everything else, the 9mm is really a lot of fun.  Every other eyepiece I have feels narrow (even my Lunts) after using it.  It's main drawback is its weight, and the fact the eye lens reflects environmental light (this was more of a problem when I was in the Seattle suburbs, now I live in a rural area on a large property this is no longer a problem).

 

What impresses me with the 9mm is that it's so good in terms of star dot quality right to the edge.  A very impressive eyepiece.


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#9 hoof

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Posted 04 September 2020 - 01:22 PM

To directly answer your question :)  for my setups and 'scopes, the 4.7mm isn't bad in the glare department (which is why I gambled on the 3.7mm).  Much easier to mask out the stray light.  The 3.7mm has a smaller exit pupil (and thus the glare rings are smaller too) thus was noticeably more sensitive, becoming more annoying to me.  To me, the 4.7mm is fine, just annoying if my eye drifts too far to the glare side.  Though if I end up replacing my 3.7mm (and it works out), I'll probably upgrade the 4.7mm too.


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#10 Augustus

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Posted 04 September 2020 - 01:51 PM

To directly answer your question smile.gif  for my setups and 'scopes, the 4.7mm isn't bad in the glare department (which is why I gambled on the 3.7mm).  Much easier to mask out the stray light.  The 3.7mm has a smaller exit pupil (and thus the glare rings are smaller too) thus was noticeably more sensitive, becoming more annoying to me.  To me, the 4.7mm is fine, just annoying if my eye drifts too far to the glare side.  Though if I end up replacing my 3.7mm (and it works out), I'll probably upgrade the 4.7mm too.

Hm, what exit pupils are you getting with these? 



#11 hoof

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Posted 04 September 2020 - 02:48 PM

On my F/6 Mak Newt the 3.7mm is 0.6mm and on my 5” apo its about 0.5mm.

#12 Augustus

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Posted 04 September 2020 - 02:51 PM

On my F/6 Mak Newt the 3.7mm is 0.6mm and on my 5” apo its about 0.5mm.

I'd be getting at least 0.85mm with my fast scopes, so do you think the APM 3.5 would be more forgiving in my case?


Edited by Augustus, 04 September 2020 - 02:51 PM.


#13 rowdy388

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Posted 04 September 2020 - 03:08 PM

I have a Lunt 4.7 110 and view under a dark sky at home almost always when the moon

isn't out. I haven't noticed any glaring but that may just be due to my conditions. The 4.7 

gets as much use as my 6 Ethos and the view is equally as good, just with a wider apparent

field which is nice for such a high power eyepiece.  I also happen to have a 9mm ES120.

That eyepiece hasn't grown on me so much. I prefer an 8 or 10 Ethos.



#14 CeleNoptic

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Posted 04 September 2020 - 03:17 PM


The longer F/L APM's I tried were excellent however I don't like the fact there's no listings for the Field Stop sizes. 

With the Ethos you know you're getting 110°.

 

Ernest has tested 3 of them (3.5, 5 and 9mm) labelled as Sky Rover/APM HDC and found that the 5mm (aka 4.7) has FS of 9mm and exit FOV of 111.2°. Pretty much like 4.7mm Ethos with its FS of 8.94mm and 110°.  The other two while harder to compare due to difference in FL still showed very close numbers to appropriate Ethoi, IMO. 


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#15 Augustus

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Posted 04 September 2020 - 03:28 PM

Thanks guys. I just bought both APMs and maybe I can upgrade to an Ethos 3.7 later.


Edited by Augustus, 04 September 2020 - 03:31 PM.

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#16 Voyager 3

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Posted 06 September 2020 - 10:46 PM

I have read in CN (guess Don said ) once that these APMs and lunts decrease in their quality as the FL increases i.e the order of their quality is 4.7mm >9mm>13mm>20mm and not sure about the 3.5mm APM. So you made a wise move I guess
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#17 Starman1

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Posted 07 September 2020 - 11:34 AM

The differences are subtle, and how often with 4.7mm and 3.5mm eyepieces be used?

It's sometimes difficult to justify a high price for an eyepiece that sits in the case 95% of the time.

 

Of course, this year we have a once in 400 year conjunction experience (Dec.21)with Jupiter and Saturn and a close approach of Mars.

They'll probably get a bit of use in the next few months.


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#18 Augustus

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Posted 07 September 2020 - 11:41 AM

The differences are subtle, and how often with 4.7mm and 3.5mm eyepieces be used?

It's sometimes difficult to justify a high price for an eyepiece that sits in the case 95% of the time.

 

Of course, this year we have a once in 400 year conjunction experience (Dec.21)with Jupiter and Saturn and a close approach of Mars.

They'll probably get a bit of use in the next few months.

I use my 5.5mm, which this is replacing, a fair amount with the 14.7". The 3.5 Delos not so much, but that was more because of the tiny true field rather than a lack of usefulness for that magnification.

 

With the 14.7" these two will yield only 253x and 365x, which aren't particularly pushing the limits of the telescope, so I expect to get a fair amount of use out of at least the 4.7mm.

 

With the 24", I don't expect to use 501x let alone 722x very often.....



#19 Voyager 3

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Posted 08 September 2020 - 08:20 AM

This can also depend on what you are planning to observe mainly . If this is more often used will be used to observe small DSOs then APM would be a big bang for the buck . But if planets will be the focus then you will need a bit more contrast and a better scatter control which the ethos SXs give . ( Well this isn't a fair statement ... Who would have different EPs for planets and PNs and that too when they cost +600$!? Surely I would use those FL EPs for both of em ) and at last this all burns down to your budget and observing conditions.

P.S : I'm just a utter newbie with lack of experience and not in a position to suggest you , so take my suggestions as a single crystal of salt .
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#20 Augustus

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Posted 08 September 2020 - 09:04 PM

Tried both out tonight with the 14.7". The 3.5mm has a little bit of annoying glare but so did my 3.5 Delos honestly, and I have a polarizing filter on the way. Both eyepieces are splendid! Jupiter, GRS and Io transit looked tack sharp. M13's Propeller looked wide enough to drive a truck through. Planetary nebulae look splendid with all sorts of fine details. I'm quite satisfied with my purchase!


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#21 russell23

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Posted 10 September 2020 - 04:43 PM

Based upon my use of the following:

 

APM 20mm, 13mm, 9mm, and 4.7mm XWA

Ethos 8mm and 6mm

 

I think the APM and the Ethos work seamlessly together.  My 4.7m APM is incredibly sharp and contrasty as is the 8mm Ethos. 

 

Dave



#22 sanbai

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Posted 08 October 2020 - 12:02 PM

Augustus, which is your opinion after one month? I guess (hope) you have used them quite often with the planets.


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#23 Voyager 3

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Posted 09 October 2020 - 07:40 AM

Augustus, which is your opinion after one month? I guess (hope) you have used them quite often with the planets.

+1 ? 😀
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#24 RickM.

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Posted 09 October 2020 - 08:03 AM

Does anyone make a 3mm eyepiece with a 100* AFOV?



#25 hoof

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Posted 09 October 2020 - 11:29 AM

Does anyone make a 3mm eyepiece with a 100* AFOV?


Sure, Televue does :) It’s a 6mm Ethos with a 2x Powermate =)

In all seriousness, that’s one if several reasons I’m planning on getting a 6mm Ethos in the next few weeks (the other is to fill the gap betwrrn my Lunt 4.7mm and 8mm Ethos)


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