Oh no! Say it ain't so Joe! (3 Viewers)

[RJM]

Finally got around to running some tests on my #820 Audubon 8.5x44mm ED. Despite the generous eyerelief, I never have seen a sharp fieldstop with this bin unless I tilted my head to one side or the other as if I had to see over/around something. No matter as the views are nice and I assumed I was just having a tough time with wide AFoV even though seeing the fieldstop in my Nikon 8x30mm EII with a similar AFoV has never been a problem.

Well it seems this #820 is not a true 44mm aperture afterall! There is some mechanical obstruction of the lightpath, probably from the one internal baffle. Just to be sure it wasn't the rubber amor, I folded it back as shown in the first pic. The objectives do physically measure 44mm too.

Below are some pics I took of the test results. Shinning the uber-bright light from a Powertank from ~2m distant through the eyepieces (focused at infinity) and projecting onto a flat piece of cardboard results in the objective lens true aperture being illuminated on the cardboard.

Using a micrometer, I measured a true aperture diameter of ~40mm! I also verifed this measurement by using a loupe to magnify the hash marks of a transparent ruler held over objectives while focused on a distant building. FWIW, only at close focus does the aperture widen to 43mm when measured this way.

Exit pupil appears to be ~5mm but I can't measure this spec with better than
±1mm precision. Definately has more mag than my other 8x bins but less than my 10x so it is in the ballpark.

Still a bit of a disappointment though I don't yet feel inclined to throw the Audubon in the dumpster!8-P

happy holidays,
Rick

 

[brocknroller]

Rick,

The usable ER is only 12mm. So it's not surprising you can't see the field stop. I have to tilt my Nikon 8x35 WF to see the field stop at the edge of its 8.2* FOV, because it only has 11mm ER. Excellent views otherwise.

With those hard, mammoth eyecups on the 820, I couldn't get my eyes close enough to the EPs to even see 7* FOV.

You should have bought my 804 FMC Audubon. I could see the entire FOV and there were no obstructions. The edges, however, were not as good as the 820s, which are more like my 804 MC Audubon.

The obstruction looks like the prism or prism housing intruding into the optical path, a common malady in WF bins. I saw this in the 820 I had too.

8.5x40 still isn't too bad. Certainly not as bad as the 10x37 Canon IS L.

I think you should move into the 21st century and buy a pair of the new ELs.

You did say that you wouldn't pay more than $700 for a pair of bins WITHOUT ED glass. These have ED/HD glass!

So get out that Mitsubishi Bank credit card and pre-order before they are all gone on Jan. 1.

Then when you finally come to your senses, you can sell them to Klippy on Amart, who will sell them to me a couple weeks later for half price.

Btw, you never showed up at Quarks on Friday so it's a forfeit. I couldn't drink the sake and blood wine by myself so I asked Leeta to have a drink with me, but Rom got jealous and challenged me to a drinking duel. Needless to say, he ended up with his ears down on the table after only two glasses of blood wine.

Rom can't hold his liquor, which is the only reason Quark trusts him to work at his bar!

 

[RJM]

Rick,

The usable ER is only 12mm. So it's not surprising you can't see the field stop. ...

I think you should move into the 21st century and buy a pair of the new ELs.

You did say that you wouldn't pay more than $700 for a pair of bins WITHOUT ED glass. These have ED/HD glass!

Brock I have no issues with eyerelief on this bino. I find it perfect with eyecups up when I wear contact lenses or eyecups down when I wear my glasses.

I have been playing with the holographic laser and am now confident it is the baffle. Good news is the exit pupil seems nicely illuminated and pincushion is certainly minimal for this AFoV. Sorry no way to get a picture of this.

And while my wife reminds me I am fortunate to have more money than common sense, there is NO WAY I will pay basically the same price for a dinky 40mm bino as I would for a topline 80mm fieldscope or 5" APO refractor. Beside when the weather is bad or I am hung over (which happens alot here), the views through a $3k bino will still suck, more so than it will through a $200 bino!:-O

cheers,
Rick

 

[Kevin Purcell]

What eyeglass prescription do you have, Rick?

 

[RJM]

Not sure if Japan uses the same measure as the USA but my contacts are -4.0 in each eye.

Rick

 

[Kammerdiner]

Beside when the weather is bad or I am hung over (which happens alot here), the views through a $3k bino will still suck, more so than it will through a $200 bino!:-O

cheers,
Rick

Ah, that's next: Blottovision. Automatically corrects for hangovers and bloodshot eyes. Of course the price goes up to $4k.

 

[falcondude]

thanks for sharing the method to measure the effective aperture. It bears the question whether those manufacturers should report effect aperture size in their advertisement or the physical size of the glasses. Someone once mentioned some 8x42 binoculars only had 36mm aperture size.

 

[brocknroller]

Brock I have no issues with eyerelief on this bino. I find it perfect with eyecups up when I wear contact lenses or eyecups down when I wear my glasses.

That's probably because you have flat facial features. The Japanese were thinking of Asian faces when they designed the Audubon 820, not users with deep set eyes and/or high bridged noses like me.

Not only are the hard, oversized eyecups too large to fit inside my eye orbits, but the focuser protrudes into the space btwn the eyecups and hits the bridge of my nose.

Even humans have reported the same issues with this bin. The 804's rubber eyecups fit my eyes better than any other bin, so this was a disappointment when I bought an 820 and mainly why I sold it.

And while my wife reminds me I am fortunate to have more money than common sense, there is NO WAY I will pay basically the same price for a dinky 40mm bino as I would for a topline 80mm fieldscope or 5" APO refractor. Beside when the weather is bad or I am hung over (which happens alot here), the views through a $3k bino will still suck, more so than it will through a $200 bino!:-O

That's "a dinky 42mm bino" unless the Swaro also has an obstruction in its light path.

I've said something very similar to the above about the Nikon EDG in that if I had $2,400 burning a hole in my pocket, I'd rather spend it on a TV 76 package or a higher power, large aperture bin such as a Zeiss 15x60 B/GA.

However, having neither money nor common sense (if common sense is so common, how come more people don't have it? , it's easy for me to say that.

After reading Napoleon Hill's "Think and Grow Rich" for the third time, I re-evaluated the situation by using visual imagery to imagine myself rich.

When I imagine myself using optics, it's not a scope or higher power bin that comes to mind, but a Nikon 8x42 EDG.

While the other choices deliver more "bang for the buck" in terms of magnification and aperture, I wouldn't use them daily like I would the EDG.

So if I think it terms of utility, and imagine that $2000 is to me is like $200 is to me now, my choice would be the EDG.

Would I rather have an updated, WP/FP full sized Nikon 8x42 EII in the body of 10x42 SE? Of course, but then I would have to read "Think and Become Bill Gates" to make that fantasy come true!

 

[ronh]

It is just so great to see that it isn't just us skywatchers who are hung up on this kind of thing. But, compared to the claimed aperture, this will increase your limiting magnitude by 0.2, which would only noticeable to experienced variable-bird observers.
Ron

 

[Kevin Purcell]

thanks for sharing the method to measure the effective aperture. It bears the question whether those manufacturers should report effect aperture size in their advertisement or the physical size of the glasses. Someone once mentioned some 8x42 binoculars only had 36mm aperture size.

Some?

A particular case is the Canon IS 10x42 which has been claimed to be 37mm aperture at infinity (and 39mm close focus) which has been mentioned here a couple times is the only one I've heard of amongst the "quality" makers.

 

[RJM]

Yeah I seem to recall even the BF current darling ZenRay 8x43ED2 has been measured to be 40mm at infinity and 38mm at close focus. Reduced aperture seems to be quite common in many brands.

In the case of this Audubon, it may be for the best if the aperture masking serves to mitigate aberations and increases the size of the sweet spot in an already huge FoV. It looks to me the difference in FoV at 40m between it and the Nikon EII is less than 2ft which is probably due more to mag differences.

Certainly the Audubon seems to have unusually large Depth of Field for its magnification, and that's a GOOD thing. And its exit pupil is definitely larger than any other bino I own and more fully illuminated than either my Kowa or Minox roofs.

cheers,
Rick

 

[Jonathan B.]

You should have bought my 804 FMC Audubon. I could see the entire FOV and there were no obstructions. The edges, however, were not as good as the 820s, which are more like my 804 MC Audubon.

The obstruction looks like the prism or prism housing intruding into the optical path, a common malady in WF bins. I saw this in the 820 I had too.

That same obstruction is visible in the FMC 804. I am sure it is the large prisms and the dark covers that are mounted over them, which look like a hard, black plastic. You can see the same slight obstruction while looking at the exit pupil and holding the bins away from your face.

It is present in mine, which was made in 1998 and is essentially identical to the one you sold, Brock; and I saw it in one that was being used by another birder I encountered one day (I deliberately looked in his to see if it was present). I think you are right that it occurs in other WF bins. I have no trouble seeing the field stop, and once I decided to ignore the "flaw," I again enjoyed the view. The optics are very fine, though not up to SE standard.

 

[RJM]

That same obstruction is visible in the FMC 804. I am sure it is the large prisms and the dark covers that are mounted over them, which look like a hard, black plastic. You can see the same slight obstruction while looking at the exit pupil and holding the bins away from your face.

Are you speaking of the slight flattening seen in the first pic at the 1 o'clock position in the left circle and at the 11 o'clock position in the right? I believe that clipping is caused by a prism edge intruding into the light path. Quite common to many small porros and is almost invisible when looking at the exit pupils naked eye in this case. I have seen many Vixen porros that had exit pupils that looked like STOP signs!

The aperture masking I have demostrated here is another matter.

cheers,
Rick

 

[Howard220]

Algol for that. Or are you referring to the famous Cepheid-breasted Nuthatch? Fascinating, just fascinating.... |:S|

It is just so great to see that it isn't just us skywatchers who are hung up on this kind of thing. But, compared to the claimed aperture, this will increase your limiting magnitude by 0.2, which would only noticeable to experienced variable-bird observers.
Ron

 

[Jonathan B.]

Are you speaking of the slight flattening seen in the first pic at the 1 o'clock position in the left circle and at the 11 o'clock position in the right? I believe that clipping is caused by a prism edge intruding into the light path. Quite common to many small porros and is almost invisible when looking at the exit pupils naked eye in this case. I have seen many Vixen porros that had exit pupils that looked like STOP signs!

The aperture masking I have demostrated here is another matter.

cheers,
Rick

Yes, that flattening in that one spot is what I'm referring to. And yes, it is invisible when you put it to your eyes and has no apparent effect on the view. Not to be confused with the squaring that results from prisms made of low-index material.

 

[RJM]

Here is a pic of what I think is the offending baffle. Someone who has use the same method tested the model #804 and posted on CN that theirs was full aperture.

 

[elkcub]

Finally got around to running some tests on my #820 Audubon 8.5x44mm ED. Despite the generous eyerelief, I never have seen a sharp fieldstop with this bin unless I tilted my head to one side or the other as if I had to see over/around something. No matter as the views are nice and I assumed I was just having a tough time with wide AFoV even though seeing the fieldstop in my Nikon 8x30mm EII with a similar AFoV has never been a problem.

Well it seems this #820 is not a true 44mm aperture afterall! There is some mechanical obstruction of the lightpath, probably from the one internal baffle. Just to be sure it wasn't the rubber amor, I folded it back as shown in the first pic. The objectives do physically measure 44mm too.

Below are some pics I took of the test results. Shinning the uber-bright light from a Powertank from ~2m distant through the eyepieces (focused at infinity) and projecting onto a flat piece of cardboard results in the objective lens true aperture being illuminated on the cardboard.

Using a micrometer, I measured a true aperture diameter of ~40mm! I also verifed this measurement by using a loupe to magnify the hash marks of a transparent ruler held over objectives while focused on a distant building. FWIW, only at close focus does the aperture widen to 43mm when measured this way.

Exit pupil appears to be ~5mm but I can't measure this spec with better than
±1mm precision. Definately has more mag than my other 8x bins but less than my 10x so it is in the ballpark.

Still a bit of a disappointment though I don't yet feel inclined to throw the Audubon in the dumpster!8-P

happy holidays,
Rick

These comments might be a bit confusing if not unnecessarily alarming. A binoculars' marketing specification, e.g., 8.5 x 44, simply describes the instrument's magnification (at infinity) and its objective lens diameter (measured in mm). The clear (or "effective") aperture of the optical system it contains, however, is determined by "aperture stops" of one sort or another. It's really a misnomer that the objective lens diameter should correspond with the system aperture. A number of design considerations determine the best placement of internal aperture stops, and these always make the clear aperture smaller. So, all we can really say is that the the physical diameter determines the upper limit.

Rather than being disappointed you should feel good about having an optimized system. :t:

Ed

 

[RJM]

Hi Ed,

Actually am pretty thrilled with this bin. Not being able to see a sharply defined fieldstop is just an asthetic issue. The Audubon is still an amazing value that can stand toe-to-to with optics 5x more expensive.

But it is the only binocular I own now that displays this characterist so I kinda have to somewhat disagree that it is a "misnomer." Afterall, masked aperture WILL AFFECT either the TRUE size of the exit pupil or the magnification specifications.

I can't help but wonder if we are to believe the #804 version to be a true 44mm, then perhaps we should assume a change to the optical formula for the #820 ED?

Rick

 

[elkcub]

Hi Rick,

The system aperture is only "masked" if you start out by thinking that it should be the same as the lens diameter. I don't understand that to be the case. A good friend of mine once said, "make no appointments, and have no disappointments."

Ed

 

[RJM]

Ed, since the OEMs all use aperture, magnification, and exit pupil specifications to describe, differentiate and PROMOTE their offerrings, I think any consumer has a reasonable expectation for all these specifications to be accurate since they are interdependent. And clearly if true aperture is amiss then it is a certainty at least exit pupil or magnification is also off.

Certainly it is possible to design and build binoculars to advertised specifications, so I don't feel it necessary to give an OEM a pass just because it is "good enough." Especially not when it may affect one's purchasing decision.

Rick