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The perfect astronomical duo?

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#1 ERHAD

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Posted 19 January 2019 - 06:41 AM

Even though I arrived relatively late in life to this hobby of ours, I always had an interest in astronomy and stargazing. I remember at a young age when I started showing an interest, my father (who had been an avid observer in his youth) always said:

 

"Best way to stargaze is with binoculars. Buy a decent 50mm pair, 7 or 10 power and be done with it. A good quiet place to observe, a nice chair and some warm coffee. Feel free to add some Mahler or Bruckner or Brahms to the equation. Find a reference point on the horizon (mountain),  fix your binoculars and just let the sky roll... You'll be surprised how much you learn, about the constellations, the universe and yourself".

 

My father always embedded everything he did in a fascinating mix of pragmatical romanticism. I wish he was still around so I could tell him that he was right (again...).

 

I naturally dismissed his advice, as one does when youth, pompous opinions and vehemence take the best of oneself. I spent years observing (lugging around) through fairly big telescopes that proved as fascinating as impractical.

 

Last year I had an accident which resulted in some severe damage to my left hand. Though the hand is slowly recovering, I've had serious functional limitations and stationing my 9 inch Schmidt Cassegrain has been too much of a painful hassle, to the point where I reverted to binoculars to scratch my astronomical itch. And, oh boy, has it been a beautiful ride!

 

My observing routine has consisted of the simultaneous mount side by side, of a Vanguard Endeavour ED II 10x42  and an APM 20x80 ED (which is fantastic). I will go from one Bino to the other, scanning the sky for the usual suspects of each season. It has been a wonderful experience, the wider vistas for context (10x42) together with the complementary tighter "zoomed-in" views through the 20x80 have brought endless hours of pleasure in which it was as if dad had been next to me with a smile that meant one of those "I told you" that he was  kind and patient enough to never ever say...

 

I have always suspected, though, that as much as I like it, the weak link of this fantastic observational duo was the 10x42. Nice as it is, I have always felt that it was a little on the dim side. Last week I borrowed a friends Nikon Aculon 10x50 and placed it next to the 10x42 for testing. Aculon may not be the best bino around, but I was shocked at how much brighter and detailed it was, both day and night. It didn't really show a massive improvement in the number of stars it showed (even though it did show a little more), but the views were clearly brighter and  should I say, more vibrant...?

 

I have decided to buy something to replace the 10x42. I want something with at least 6.5 degrees of true FOV and with  high light transmission. I think I want to go for a 56mm bino for maximum light gathering a bigger EP. I don't want to collect Binos, but I want to have a really nice unit that gives pleasurable views and serves me well for the years to come. I'm looking into Zeiss Conquest and Swaro SLC, mainly for the AK prisms. No individual focusing, since I might use these for daytime use from time time.

 

I'm not so much interested in advice regarding specific models, my main doubt here, and I would love to hear your opinions, is whether to go for a 8X56 or a 10x56. These will mostly be used as my "wider" bino together with my 20x80, or for those casual quick observing sessions. it might serve as a daytime bino too, though my use will be 80% astro, 20% daytime. The bulk of my observations takes place under my urban sky, though living in the Canary Islands I do have access to very dark skies once or twice a month. My pupils still dilate slightly beyond the 7mm mark, so I am interested in the wider EP and FOV of the 8x, these could be my "dark sky" Binos. I also feel that some things come into life with a bit more magnification, and I also find Binos with wider AFOV more enjoyable, hence those would be the 10x bino strong points. these might also be a bit better under light-polluted skies.

 

I understand that this is a very personal thing, so instead of asking you for advice, I'm asking you to walk a mile in my shoes and tell me what YOU would do in my situatrion: 8x56 or 10x56?

 

Thanks for taking the time to read my longish rant, I eagerly await your opinions and/or experiences...

 

Clears skies,

 

Erik.


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#2 Erik Bakker

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Posted 19 January 2019 - 07:43 AM

Even though I arrived relatively late in life to this hobby of ours, I always had an interest in astronomy and stargazing. I remember at a young age when I started showing an interest, my father (who had been an avid observer in his youth) always said:

 

"Best way to stargaze is with binoculars. Buy a decent 50mm pair, 7 or 10 power and be done with it. A good quiet place to observe, a nice chair and some warm coffee. Feel free to add some Mahler or Bruckner or Brahms to the equation. Find a reference point on the horizon (mountain),  fix your binoculars and just let the sky roll... You'll be surprised how much you learn, about the constellations, the universe and yourself".

 

Erik,

 

Your father spoke words of wisdom bow.gif

 

Thanks for sharing them.


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#3 Erik Bakker

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Posted 19 January 2019 - 07:46 AM

Now on your question about the perfect astronomical duo with your APM 20x80 ED, choosing either an 8x56 or 10x56, here are my thoughts, having observed with both the FL 8x56 and FL 10x56 and SLC 8x56 and SLC 10x56 for extended periods of time, side by side. See my full review of them under the stars here that I did 5 years ago.

 

Under your conditions, the 8x56 would be my instrument of choice, since you already have your higher magnification covered by the 20x80 ED, see my recommendations on 8x56 or 10x56 here.

 

The views are very relaxing, especially on the occasion you wish to us them hand held. The 8x56 are significantly wider and brighter than the 10x56 of the same model, specially under your dark Canary Island skies, with your pupils dilating to 7mm or wider.

 

For observing the widest possible fields, edge correction is a thing to consider. On axis, the usual image quality considerations count.


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#4 Mad Matt

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Posted 19 January 2019 - 07:49 AM

That is a wonderful story Erik, many thanks for sharing!

You might want to consider the 10x70 (or 11x70) to compliment your 20x80’s. It sounds like you already have a good daytime 10x binocular so why not focus on one that provides maximum EP performance. I would recommend the APM 11x70 very highly.

#5 RickyD85

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Posted 19 January 2019 - 08:07 AM

I’d go for the wider FOV of the 8x56. The 20x80 take care of higher mags, so an even wider FOV on the smaller mounted 56mm bino’s makes sense. 

 

You may may miss the portability of your little 10x42, so don’t get rid of them until you’ve spent more time with the 56mm aperture. You may find the 10x42’s find a new job as your ‘carry around’ bino’s. 


Edited by RickyD85, 19 January 2019 - 08:09 AM.


#6 PETER DREW

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Posted 19 January 2019 - 08:15 AM

I have a place on Tenerife and use 10x50 and 20x102 binoculars there. If my pupils would still dilate to 7mm I would go for the 8x56 to add to your 20x80.



#7 Mark9473

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Posted 19 January 2019 - 08:38 AM

 

I have always suspected, though, that as much as I like it, the weak link of this fantastic observational duo was the 10x42. Nice as it is, I have always felt that it was a little on the dim side. Last week I borrowed a friends Nikon Aculon 10x50 and placed it next to the 10x42 for testing. Aculon may not be the best bino around, but I was shocked at how much brighter and detailed it was, both day and night. It didn't really show a massive improvement in the number of stars it showed (even though it did show a little more), but the views were clearly brighter and  should I say, more vibrant...?

 

They both have about 80% light transmission, so unless there's a noticeable discrepancy in effective aperture, the difference you see is entirely due to the difference in exit pupil size. 5 mm versus 4.2 mm puts 40% more light into your eye. A 10x50 with higher transmission would bring another 10-15%.

 

8x56 sounds great but you have to be certain that your eye pupils can deliver a sharp enough image at that exit pupil size.

They also don't tend to have an impressively wide apparent field of view compared to most 10x50.


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#8 ERHAD

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Posted 19 January 2019 - 02:28 PM

Erik,

 

Your father spoke words of wisdom bow.gif

 

Thanks for sharing them.

Thanks Erik. He often did...

 

Now on your question about the perfect astronomical duo with your APM 20x80 ED, choosing either an 8x56 or 10x56, here are my thoughts, having observed with both the FL 8x56 and FL 10x56 and SLC 8x56 and SLC 10x56 for extended periods of time, side by side. See my full review of them under the stars here that I did 5 years ago.

 

Under your conditions, the 8x56 would be my instrument of choice, since you already have your higher magnification covered by the 20x80 ED, see my recommendations on 8x56 or 10x56 here.

 

The views are very relaxing, especially on the occasion you wish to us them hand held. The 8x56 are significantly wider and brighter than the 10x56 of the same model, specially under your dark Canary Island skies, with your pupils dilating to 7mm or wider.

 

For observing the widest possible fields, edge correction is a thing to consider. On axis, the usual image quality considerations count.

Thanks for your input. Your links have been great read and very informative.



#9 ERHAD

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Posted 19 January 2019 - 02:30 PM

That is a wonderful story Erik, many thanks for sharing!

You might want to consider the 10x70 (or 11x70) to compliment your 20x80’s. It sounds like you already have a good daytime 10x binocular so why not focus on one that provides maximum EP performance. I would recommend the APM 11x70 very highly.

Thanks Matt for your kind words. I have seriously considered the 10-11x70, but ultimately it´s its narrowish FOV what puts me a little off, and draws me towards one of the mentioned models with wider fields. I can see myself owning one some day, though...


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#10 ERHAD

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Posted 19 January 2019 - 02:32 PM

I’d go for the wider FOV of the 8x56. The 20x80 take care of higher mags, so an even wider FOV on the smaller mounted 56mm bino’s makes sense. 

 

You may may miss the portability of your little 10x42, so don’t get rid of them until you’ve spent more time with the 56mm aperture. You may find the 10x42’s find a new job as your ‘carry around’ bino’s. 

Thanks Ricky. I have no intention of getting rid of my Endeavor. I'm very fond of it, and indeed it´s a great daytime bino.



#11 ERHAD

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Posted 19 January 2019 - 02:34 PM

I have a place on Tenerife and use 10x50 and 20x102 binoculars there. If my pupils would still dilate to 7mm I would go for the 8x56 to add to your 20x80.

Thanks Peter. I used to live in Tenerife. Some of the best years of my life. Unfortunately, I wasn't into astronomy yet then. Those skies up in Teide are something else. I live in Gran Canaria now, still decently dark skies up in the mountains.

 

If I may ask, what is that 20x102 you mention?

 

Thanks!!



#12 ERHAD

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Posted 19 January 2019 - 02:38 PM

They both have about 80% light transmission, so unless there's a noticeable discrepancy in effective aperture, the difference you see is entirely due to the difference in exit pupil size. 5 mm versus 4.2 mm puts 40% more light into your eye. A 10x50 with higher transmission would bring another 10-15%.

 

8x56 sounds great but you have to be certain that your eye pupils can deliver a sharp enough image at that exit pupil size.

They also don't tend to have an impressively wide apparent field of view compared to most 10x50.

Mark, I agree, I attributed the brighter views to the larger aperture of the Aculons. When you mention sharp images at 7mm Ep, do you mean sufficiently dilated pupils to accommodate the light cone or are you referring to other eye-related aberrations affected by EP size?

 

One of the reasons I am considering the 10x56 is precisely, as you say, the wider AFOV. I am used to 65-68º AFOV binoculars and tend to dislike the ones with narrow views. I'm spoilt...



#13 ERHAD

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Posted 19 January 2019 - 02:42 PM

Interestingly, your opinions mostly seem to favour the 8x56. Guess it makes sense if they are to be used in conjunction with the 20x80 (the wider field et all...). Hmm, food for thought. Thanks!



#14 Mark9473

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Posted 19 January 2019 - 03:11 PM

are you referring to other eye-related aberrations affected by EP size?

Exactly this.



#15 ERHAD

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Posted 20 January 2019 - 06:20 AM

Exactly this.

Thanks Mark. I’ve read sparsely about this, but not really familiarized. I guess the main concept  is that bigger EP tend to accentuate any eye flaws, whereas smaller EP produce sharper images that better mask any eye defects , correct? So a 7mm EP would, for instance,accentuate any astigmatism you may have then? Thanks.


Edited by ERHAD, 20 January 2019 - 06:20 AM.

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#16 Erik Bakker

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Posted 20 January 2019 - 07:29 AM

Thanks Mark. I’ve read sparsely about this, but not really familiarized. I guess the main concept  is that bigger EP tend to accentuate any eye flaws, whereas smaller EP produce sharper images that better mask any eye defects , correct? So a 7mm EP would, for instance,accentuate any astigmatism you may have then? Thanks.

 

That is right. But they show more brightness, even if not looking perfectly sharp due to our eyes' defects. Best sharpness occurs with less than 4 mm pupil diameters. That helps 10x32 look so sharp wink.gif



#17 Jon Isaacs

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Posted 20 January 2019 - 07:46 AM

Thanks Mark. I’ve read sparsely about this, but not really familiarized. I guess the main concept  is that bigger EP tend to accentuate any eye flaws, whereas smaller EP produce sharper images that better mask any eye defects , correct? So a 7mm EP would, for instance,accentuate any astigmatism you may have then? Thanks.

 

The sharpness issue is important but also important is the diameter of your dark adapted pupil.  If your eye dilates to 5 mm maximum,  the advantage of an expensive pair of 8 x56's over 8x42s is much reduced. 

 

Jon



#18 dries1

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Posted 20 January 2019 - 11:06 AM

Between the two I would suggest a 10X56, if using in areas of light scatter from the city, or cloud cover, I would see more with the 10X. For watching wild life there along the coast during the day, I would still prefer the 10X56. 

Regarding 8X, a good quality 8X42 to me would be more useful/versatile than an 8X56 in that locale, just my opinion, YMMV.

 

Andy W.


Edited by dries1, 20 January 2019 - 11:06 AM.


#19 hallelujah

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Posted 20 January 2019 - 01:20 PM

 

Regarding 8X, a good quality 8X42 to me would be more useful/versatile than an 8X56 in that locale, just my opinion

 

Andy W.

Depends upon who you are....

In my collection I once had both the Pentax 8x40 PCF WP II, & the Bell & Howell 8x40 wide angle binoculars.

I traded one & gave one away.

For me, neither one was as good as my Vixen 8x56 Geoma Porro when it comes to an all around binocular for bird watching & stargazing.

I like the extra aperture/brightness of the 8x56 both during the daytime

(cloudy/dawn/dusk) and during the evening.

The 56mm does better on faint stars. like-button.jpg

 

Stan


Edited by hallelujah, 20 January 2019 - 01:22 PM.



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