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APM MS ED APO 16X80mm vs 20x80mm

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#1 Noumenon

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Posted 25 November 2021 - 05:51 PM

Hi all! I'm torn between these two. The 20x will get me everything I care about in my view, closer, but the 16x will be wider in general maybe allowing slightly easier finding of objects, etc.

Weight, size, etc seems the same between the two, "subjective field of view" is stated the same at 66deg. So it seems to me the only real difference is just the EPs affecting the zoom.

So this is more of a, "in your experience, what would you prefer"?

I suppose there's also a question around how at the same Aperture but different zoom, will one provide a brighter or crisper view vs the other? If so, that will help determine my course, also.

#2 DeanD

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Posted 25 November 2021 - 07:16 PM

I think your second sentence says it all "The 20x will get me everything I care about in my view...". Problem solved. wink.gif

 

The 20x will give a slightly darker background sky with a little bit more detail but a slightly reduced FOV. The 3.3° FOV will still allow finding of objects to be relatively easy, so I don't see that as a major factor. Both binos will require a mount of some sort, and I would use a red-dot finder as well. I love my 22x60 Taks, which have an even smaller FOV but give a lot of detail in the view, and I have mounted a RDF on their mount attachment (I am using the Farpoint mount which is terrific: https://farpointastr...mounting-system ). (FWIW I also have the 15x70 Orion Resolux and they are excellent; but I generally prefer the view given by the higher magnification of the Taks, despite the smaller FOV.)

 

I would expect that both magnifications will give an equally crisp view, so I don't think that is an issue.

 

Having said that, I think you would benefit from getting two binoculars: something that can be hand-held to complement the large ones and give you the ability to do a general sweep and then "zoom in" with the larger ones. I often do this to ascertain the correct position that I want to investigate, or simply to enjoy the view. A "standard" 10x50, or 8x40 would be a great addition to your herd. You don't have to spend a fortune on these: many people swear by the Nikon AE series, and they will last a lifetime. The 8x40's have an 8.2° FOV, while the 10x50's are 6.5° : both giving great wide field views.

 

Good luck, and happy viewing!

 

- Dean


Edited by DeanD, 25 November 2021 - 07:18 PM.

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#3 sevenofnine

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Posted 25 November 2021 - 07:21 PM

Choosing the right binocular for astronomy requires a lot of thought on how you plan to use them. Thinking through the whole process will help you determine what's right for you. My mistake was thinking large straight through 20x80's would be easy to use on a heavy duty professional tripod. I find them very difficult to use at angles above 60 degrees. Guess where most objects are? So, if your planning on either the 16x or 20x then plan on investing in a heavy duty parallelogram mount is my advice. Otherwise, you should consider the types that have 45-90 degree interchangeable eyepieces. On a H/D tripod, those work great from all reports that I've read.

 

Maybe the best advice would be to start a binocular collection with the most recommended type on this forum. That would be the 10x50 porro prism. My Nikon AE 10x50's are great and get used a lot. Best of luck to you and your decisions! waytogo.gif


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#4 Noumenon

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Posted 25 November 2021 - 08:57 PM

Dean, thank you, yes, that pretty much settles it. 20x80 it is, then! It's good to know I don't have to worry about any other variables between the two, really. The smaller binocular idea is a good one... I'll look into that, also. I'm thinking as low-power (under 10x), higher-Aperture (though 50mm max) mix as possible.

Sevenofnine, yeah, I thought about this, and I really, really wish there was a market for fixed EP binoculars with at least 45deg EP... Unfortunately, the ones that do have the 45/90deg are *significantly* more than I want to spend, let alone having to buy multiple EPs, etc...

Anyway, my thought was to accommodate the silliness of using the straight through binos for astronomy, that I'd be reclining back in a lawn chair for the most part.
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#5 sevenofnine

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Posted 25 November 2021 - 11:27 PM

Oberwerk.com is another highly recommended source for excellent binoculars. If I didn't feel comfortable spending APM $$$ then I'd look at this one...worth checking out anyway waytogo.gif

 

https://oberwerk.com...ar-telescope/. 



#6 ECP M42

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Posted 26 November 2021 - 12:25 PM

So this is more of a, "in your experience, what would you prefer"? 

I would prefer the 20x70, for two reasons.

The first, very important, is the lightest weight ... if you intend to hold it in your hand when you are lying in the chair.
And the second is that at 20x, a 3.5mm exit pupil is far too "bright", for my eyes under the Bortle 4 sky that I could reach (when I can). 

 

If you don't have a problem with weight, then I would prefer 20x80, because in any case (or at least 98% of cases), under the stars, a higher magnification is more effective than a wider pupil.
I believe that with your telescope you normally will use a pupil between 0.5 and 4mm at the most, or am I wrong?


Edited by ECP M42, 26 November 2021 - 12:26 PM.

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#7 Noumenon

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Posted 26 November 2021 - 01:06 PM

I would prefer the 20x70, for two reasons.

The first, very important, is the lightest weight ... if you intend to hold it in your hand when you are lying in the chair.
And the second is that at 20x, a 3.5mm exit pupil is far too "bright", for my eyes under the Bortle 4 sky that I could reach (when I can). 

 

If you don't have a problem with weight, then I would prefer 20x80, because in any case (or at least 98% of cases), under the stars, a higher magnification is more effective than a wider pupil.
I believe that with your telescope you normally will use a pupil between 0.5 and 4mm at the most, or am I wrong?

I don't have a problem with weight, no. Thank you for further solidifying my increasingly stronger lean toward the 20x80mm. 

 

Yes, the lowest power eyepiece I have is a 42mm, so 4.2mm exit pupil (though I've considered picking up a 50mm).

 

Hrmmm... in another thread I inquired about an issue I'm having with the 42mm eyepiece in that I am picking up on a very distracting double-image/overlapping "shadow" of objects like Jupiter and Saturn, and can't get stars pinpoint, even though a much larger object like the Moon looks spectacular and my 26mm and higher power eyepieces give no such aberrations... I bring this up, now, because some are figuring it's due to some astigmatism in my eye(s) showing up at this large an exit pupil (I'm 38, btw) -- considering this, assuming they're right and it's not an issue with the 42mm eyepiece, should I expect to experience the same issues, even with the APM binocs?


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#8 Rich V.

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Posted 26 November 2021 - 02:46 PM

Anyway, my thought was to accommodate the silliness of using the straight through binos for astronomy, that I'd be reclining back in a lawn chair for the most part.

 

 

I don't have a problem with weight, no. Thank you for further solidifying my increasingly stronger lean toward the 20x80mm. 

Holding a 20x bino steady enough to enjoy isn't about the weight as much as it is the magnification.  70mm and 80mm binos do get heavy over time, though.  Even in a recliner, it will be virtually impossible to hold the binos steady enough to see all the detail that the binocular has to offer.  Every shake and wiggle you make will be amplified 20x as well.  Unfortunately, a good quality tripod/head setup, or better, a parallelogram, can cost as much or more than the binos themselves.  You'll still have to deal with the uncomfortable neck angles with the tripod, but not with the right p-gram for reclined use. 

 

IME, mounting becomes essential at 20x and even 16x is difficult without; you'll likely find 16x easier to hand hold in a recliner, whether the 16x80 or the lighter 16x70.  FWIW, if you need longer eye relief for eyeglasses, deep set eyes or whatever, both the APM 16x models use the same "20mm eye relief" 18mm eyepieces rather than the "16mm ER" 15mm eyepieces of the 20x models.

 

Rich


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#9 ECP M42

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Posted 27 November 2021 - 07:29 AM

the lowest power eyepiece I have is a 42mm, so 4.2mm exit pupil (though I've considered picking up a 50mm).

A larger exit pupil tends to trigger internal reflexes more often or more easily.
What you describe about the 42mm eyepiece appears to be a ghost reflection, which is most likely triggered by a lower quality of the anti-reflection coatings. But if the cause is too large a pupil, this could be due to the telescope being unable to accept such low power. Therefore, using a 50mm eyepiece should be another failure. Try high quality eyepieces.


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#10 tmichaelbanks

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Posted 27 November 2021 - 04:30 PM

I have the APM 20x80ED and use it mounted and handheld about 50/50. They are not much heavier than the OB 15x70 Ultra I used to have, and if you are looking at targets overhead in a zero-g chair you can keep them fairly steady. But as Sevenofnine and Rich recommended a parallelogram mount will get the most out of them and save your neck. Any mount though adds setup time and fuss. I’m in southern New England and I’m always conscious that clear skies can haze up in the time it takes to set up my mount.

 

The extra aperture adds some pop to OCs, but I find that brighter targets like Jupiter and Vega get a little spikey.


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#11 Noumenon

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Posted 27 November 2021 - 07:07 PM

Holding a 20x bino steady enough to enjoy isn't about the weight as much as it is the magnification.  70mm and 80mm binos do get heavy over time, though.  Even in a recliner, it will be virtually impossible to hold the binos steady enough to see all the detail that the binocular has to offer.  Every shake and wiggle you make will be amplified 20x as well.  Unfortunately, a good quality tripod/head setup, or better, a parallelogram, can cost as much or more than the binos themselves.  You'll still have to deal with the uncomfortable neck angles with the tripod, but not with the right p-gram for reclined use.

 

IME, mounting becomes essential at 20x and even 16x is difficult without; you'll likely find 16x easier to hand hold in a recliner, whether the 16x80 or the lighter 16x70.  FWIW, if you need longer eye relief for eyeglasses, deep set eyes or whatever, both the APM 16x models use the same "20mm eye relief" 18mm eyepieces rather than the "16mm ER" 15mm eyepieces of the 20x models.

 

Rich

Thank you -- I'm actually glad you took the extra step here to really note the shakiness being the real issue over the weight. It seems like everyone is implying the need for mounts based on the weight (whether that's their point or my ignorance perception of their point), and mention stability maybe as a side note -- and while I could see 5.5 lbs or so after a while get tiring by holding with my hands, since I'll be in a lawn recliner it's less of a concern -- but this more forcefully clarifies the real issue I could experience with the 20x80s.



#12 Noumenon

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Posted 27 November 2021 - 07:16 PM

A larger exit pupil tends to trigger internal reflexes more often or more easily.
What you describe about the 42mm eyepiece appears to be a ghost reflection, which is most likely triggered by a lower quality of the anti-reflection coatings. But if the cause is too large a pupil, this could be due to the telescope being unable to accept such low power. Therefore, using a 50mm eyepiece should be another failure. Try high quality eyepieces.

It seems like it could be so many different reasons for the issue I'm having with that eyepiece and some feel pretty confident the cause is this or that reason. I don't want to invest in a more expensive eyepiece if it turns out it has do with with my eye(s), even though this seems like a reasonable explanation... luckily I plan on going to a local astronomy group meetup with the eyepiece to talk about it, maybe look at it through others' scopes, look at their eyepieces, etc.

 

Okay, so let me ask it this way... if I get this 20x80 binocular in, and look through it and don't have the same issue, since they will be roughly the same exit pupil (4.2mm vs 4mm), is it safe to say that it is likely either the particular eyepiece or the quality of the eyepiece with my f/10 scope (necessitating a more expensive eyepiece)? Will that effectively rule out the astigmatism reason?



#13 ECP M42

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Posted 28 November 2021 - 02:15 AM

Will that effectively rule out the astigmatism reason?

Astigmatism does not produce ghost images or shadow reflections (which look like "beans"). And if astigmatism is in your eye, you'll pretty much always have it with any tool (more or less). The use of corrected glasses becomes mandatory, to eliminate or at least to minimize this defect. 

 

If that defect you see at the telescope with the 42mm, you do not see it with the 20x80 it seems obvious to me that it is caused by the telescope. Most likely from the eyepiece, perhaps because of the quality or perhaps too low magnification = too large field of view for your telescope.

 

 


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#14 DeanD

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Posted 28 November 2021 - 05:44 AM

WRT the eyepiece issue, I wonder whether the elements in the eyepiece itself are seated properly: if one is not quite right then you could well get a "shadow" effect. My astigmatism is manifested more in spikes around bright objects, which are reduced or removed with eyeglasses. 

 

In terms of holding binos steady: the higher the power the harder this is, and I find that even if I am lying back with everything as solid as I can make it, my heartbeat will induce some vibration even at 8x. A good mount is the answer for long sessions: and you can pull binos on a parallelogram mount across to your lying down position in a chair.

 

The ultimate for me was when I used a motorised "Starchair" at the Arkaroola reserve in South Australia (see the discussion on these here: https://www.cloudyni...starchair-3000/ - with some piccies from post #16. ). When you had the binos properly adjusted it was magical, and you felt like you were in space. They had 3 of them at Arkaroola, and I was fortunate to be able to make them operational and play with them. Unfortunately Chris doesn't make these anymore...
 

All the best,

 

Dean


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#15 Rich V.

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Posted 28 November 2021 - 12:18 PM

Hrmmm... in another thread I inquired about an issue I'm having with the 42mm eyepiece in that I am picking up on a very distracting double-image/overlapping "shadow" of objects like Jupiter and Saturn, and can't get stars pinpoint, even though a much larger object like the Moon looks spectacular and my 26mm and higher power eyepieces give no such aberrations... I bring this up, now, because some are figuring it's due to some astigmatism in my eye(s) showing up at this large an exit pupil (I'm 38, btw) -- considering this, assuming they're right and it's not an issue with the 42mm eyepiece, should I expect to experience the same issues, even with the APM binocs?

 

It seems like it could be so many different reasons for the issue I'm having with that eyepiece and some feel pretty confident the cause is this or that reason. I don't want to invest in a more expensive eyepiece if it turns out it has do with with my eye(s), even though this seems like a reasonable explanation... luckily I plan on going to a local astronomy group meetup with the eyepiece to talk about it, maybe look at it through others' scopes, look at their eyepieces, etc.

 

Okay, so let me ask it this way... if I get this 20x80 binocular in, and look through it and don't have the same issue, since they will be roughly the same exit pupil (4.2mm vs 4mm), is it safe to say that it is likely either the particular eyepiece or the quality of the eyepiece with my f/10 scope (necessitating a more expensive eyepiece)? Will that effectively rule out the astigmatism reason?

Here's a CN thread about astigmatism severity and exit pupil size.  Perhaps it will be helpful to you.

 

https://www.cloudyni...out-glasses-on/

 

As I've aged (and I'm a lot older than you), bright star points and even too brightly set red LED points in my reflex sights become irregularly bloated when my eyes are dilated larger than around 4mms any more.  Bright stars and planets can stretch out downward to look like "peanuts" as if there's a glare reflected below them.  More so in my right eye than the left so far.  Sometimes these things just sneak up on you.

 

Your suggestion of trying different eyepieces/exit pupils at an astronomy group meeting would be telling if it's your eyes or not, I'd think.  It sure wouldn't hurt to see if there's a difference for you.

 

Rich




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