Question regarding focus issues with the Conquest HD 8x32 (1 Viewer)

[Troubador]

Hello Lee,

this point is of course very controversial, Holger Merlitz said the following ...

"This expectation would be unproblematic if one simply got the property of a short near point as a treat on top. Like a piece of cake that comes with the icing as an extra.

It's different with binoculars, because a short near point can only be achieved with compromises in other performance parameters. Like: The cake with icing is only available with fewer cherries in the batter.

Therefore one should only demand such a function as the near point if one really needs it and is prepared to accept compromises elsewhere (among other things: more complicated, more error-prone mechanics, additional lenses, i.e. heavier and in connection with a light one Loss of contrast, etc."

Re: Nahgrenze bei Ferngläsern

www.juelich-bonn.com

Andreas

I hesitate to disagree with Herr Merlitz and I am certainly prepared to accept there might be compromises in some areas due to larger visual 'envelope' within which close focusing binos must function. My experience over many years leads me to be quite relaxed about these compromises.

Lee

 

[ZeNiTh-PbArM]

Hi

Please let me show how most simple roof focusers work.
The focus knob rotates a leadscrew (2) around a fixed shaft (5) which is usually the tip of the hinge pivot.
Around this leadscrew (2) is a nut (1) which slides back and forth as the screw rotates.
As a result pushrods (3) and (4) also slide back and forth, moving the focusing lenses in left and right barrel respectively.
The nut is attached to pushrod (3) which locks its angular position respective to the shaft. To allow for IPD adjustment, pushrod (4) only slides around the lip of the nut (1)
The attachment of nut (1) to pushrod (3) is not particularly stiff, and thread machining tolerance allow for some slack between nut (1) and screw (2)
Rotation of the focuser generates an effort on nut (1) which results in a tilt angle (a) between the nut and the focuser axis. Depending on focuser direction the angle (a) will be positive or negative, generating the focus difference between left and right barrels.
It is worth mentioning that the market demand for close focus bins has pushed many manufacturers to increase pushrod travel without increasing the length of screw (2) and length of the whole focuser, for cost and ergonomy reasons. Instead they have reduced the height (d) of nut (1) to allow for more travel within the same package. Needless to say the shorter the nut, the worse the tilt gets.

Cheers,
zp*

 

[Conndomat]

I hesitate to disagree with Herr Merlitz and I am certainly prepared to accept there might be compromises in some areas due to larger visual 'envelope' within which close focusing binos must function. My experience over many years leads me to be quite relaxed about these compromises.

Lee

Hi lee,

It is just very annoying for some people who do not use the near focus if this has a negative effect on the stability.
The survey in the Jülich Forum showed that around 55% of people do not use close focus. Unfortunately, almost all Alpha binoculars now have this feature because the manufacturers want to provide all-round coverage.

Of course, the survey was not representative of that too few people took part, but let's just take 50% of the people who buy a feature that they don't need, which may make the focuser weaker, the imaging performance is minimized and more expensive.

Just as there are alpha glasses that are not compatible with spectacle wearers, there should also be alphas that are possibly a bit cheaper and do not have such an extreme near point, then everyone can decide what they want to buy.

means,
Andreas

 

[Troubador]

Hi lee,

It is just very annoying for some people who do not use the near focus if this has a negative effect on the stability.
The survey in the Jülich Forum showed that around 55% of people do not use close focus. Unfortunately, almost all Alpha binoculars now have this feature because the manufacturers want to provide all-round coverage.

Of course, the survey was not representative of that too few people took part, but let's just take 50% of the people who buy a feature that they don't need, which may make the focuser weaker, the imaging performance is minimized and more expensive.

Just as there are alpha glasses that are not compatible with spectacle wearers, there should also be alphas that are possibly a bit cheaper and do not have such an extreme near point, then everyone can decide what they want to buy.

means,
Andreas

For sure I support the idea that there should be more choice.

Lee

 

[Jessie-66]

Rotation of the focuser generates an effort on nut (1) which results in a tilt angle (a) between the nut and the focuser axis. Depending on focuser direction the angle (a) will be positive or negative, generating the focus difference between left and right barrels.
It is worth mentioning that the market demand for close focus bins has pushed many manufacturers to increase pushrod travel without increasing the length of screw (2) and length of the whole focuser, for cost and ergonomy reasons. Instead they have reduced the height (d) of nut (1) to allow for more travel within the same package.

Do spring forces act on the nut or push rods to prevent free play of focus wheel due to necessary thread play for tilting of nut and to hold the inner focusing lenses in a fixed position according to diopter adjustment? Or is this solved differently? The picture shows a Nikon focus?

 

[ZeNiTh-PbArM]

Hi

Usually the pushrods aren't spring-loaded. If you were to use springs, the focuser would be easy to turn in one direction and hard to turn in the opposite direction.
The stickiness the sliding lens assembly is usually enough to hold parts in position while the focuser doesn't turn.

To remove the free play, you can tighten the screw and nut machining tolerance and/or match parts to operate with a minimal amount of clearance, which will increase manufacturing cost and reduce profit.
It is much more tempting to hide the problem with damping grease so the user hopefully won't notice there is focus slop. And so, if there isn't too much slop and enough grease is used, you might get away with it.
A dead giveaway of this issue is the focus difference between left and right barrels depending on the direction you just rotated the focuser. If you look for it on targets which requires sharpness (license plates or equivalent) you'll see many bins have this problem to a certain extent, including expensive ones.
A magnitude higher is the infamous focus "dead zone" where you can turn the knob up to 1/4th of a turn without altering focus. Some users can live with it, others don't.

This design can be made to work flawlessly but not without care and expense. If you are buying from a top company you can expect this kind of performance and if your sample has an issue it's their duty to correct it. If you are buying a lower cost model it's a matter of luck whether you'll eventually find a sample which matches your requirements.

Cheers,
zp*

 

[Jessie-66]

Hi
Usually the pushrods aren't spring-loaded ...

Finally a hello from me too and many thanks for the explanations. I have so far assumed that dipotric compensation on internal focusing lenses is done with a small gear integrated into the focus wheel and kink bridge which is engaged by pulling out the focuser wheel or an extra diopter wheel, e.g. by bringing gears into mutual engagement. The gear with conversion of rotation into translation (e.g. thrust screw gear similar to focusing drive) moves a pull-puh-rod of 1 internal focusing lens so that both lenses perform a relative movement (dioptric compensation). The tilting thing is simple (cheap), but seems messy and error-prone for frequent use to me. Better 1 eyepiece with thread then. That is my conclusion for mid-range binoculars. The technical possibility 'tilting nut' was unknown to me until now. Best wishes. Jessie
(English with technical terms is difficult to me. Fortunately, at least I understand my text.)

 

[Troubador]

Hi lee,

It is just very annoying for some people who do not use the near focus if this has a negative effect on the stability.
The survey in the Jülich Forum showed that around 55% of people do not use close focus. Unfortunately, almost all Alpha binoculars now have this feature because the manufacturers want to provide all-round coverage.

Of course, the survey was not representative of that too few people took part, but let's just take 50% of the people who buy a feature that they don't need, which may make the focuser weaker, the imaging performance is minimized and more expensive.

Just as there are alpha glasses that are not compatible with spectacle wearers, there should also be alphas that are possibly a bit cheaper and do not have such an extreme near point, then everyone can decide what they want to buy.

means,
Andreas

Hi again Andreas, I am replying again after further pondering on this topic.

Firstly, looking at the Juelich Forum survey and allowing for the unscientific nature of such tests the result was more or less 50% use close focus and 50% don't and while this is hardly conclusive I find it profoundly sad that such a high percentage of people have such a narrow interest in the world of nature. They are missing so much fascination and enjoyment.

And the very interesting posts from zp* suggest that at least some of the problems with close focus do not derive directly from the close focus but from bino brands trying to achieve it in a cheap and unreliable way.

My New Year's Wish is that more people discover the joys of observing more of nature by using close focus and so develop a broad appreciation of the world of nature rather than continuing with a narrow specialist view.

Lee

 

[Conndomat]

Hi again Andreas, I am replying again after further pondering on this topic.

Firstly, looking at the Juelich Forum survey and allowing for the unscientific nature of such tests the result was more or less 50% use close focus and 50% don't and while this is hardly conclusive I find it profoundly sad that such a high percentage of people have such a narrow interest in the world of nature. They are missing so much fascination and enjoyment.

And the very interesting posts from zp* suggest that at least some of the problems with close focus do not derive directly from the close focus but from bino brands trying to achieve it in a cheap and unreliable way.

Lee

Hello Lee,

It doesn't necessarily have to be true that if you don't use the close focus with binoculars you would have very little interest in nature.

I prefer to take photos of everything in close range, a magnifying glass is always with me!
I am collecting all kinds of stuff and then putting it under a microscope to study it closely.

zp*but also mentions that the costs would increase significantly if the close focus were built reliably, it seems like an emergency solution, which is a bit more expensive but is prone to errors!

It is important to me to mention again in this context that I am not against the fact that there are binoculars with an extreme near point, but that now all alphas fulfill this feature I find a bit questionable.

Andreas

 

[Troubador]

Hello Lee,

It doesn't necessarily have to be true that if you don't use the close focus with binoculars you would have very little interest in nature.

I prefer to take photos of everything in close range, a magnifying glass is always with me!
I am collecting all kinds of stuff and then putting it under a microscope to study it closely.

zp*but also mentions that the costs would increase significantly if the close focus were built reliably, it seems like an emergency solution, which is a bit more expensive but is prone to errors!

It is important to me to mention again in this context that I am not against the fact that there are binoculars with an extreme near point, but that now all alphas fulfill this feature I find a bit questionable.

Andreas

I have to agree that a camera and close-focusing lens is a great companion, and we also use Zeiss 6x18 monoculars.
Swarovski's EL 8.5x42 has a close focus of 3.3m. Would this still be considered 'too close'?

Lee

 

[Conndomat]

Swarovski's EL 8.5x42 has a close focus of 3.3m. Would this still be considered 'too close'?

Hello Lee,

that EL 8,5x42 is no longer the current Swarovski alpha glass, that is now the 8x42 NL!

In addition, it was artificially castrated, the near point is actually closer.
A new optical calculation should actually take place so that this glass would be even better.

Andreas

 

[Troubador]

Hello Lee,

that EL 8,5x42 is no longer the current Swarovski alpha glass, that is now the 8x42 NL!

In addition, it was artificially castrated, the near point is actually closer.
A new optical calculation should actually take place so that this glass would be even better.

Andreas

OK, sorry, I interpret 'alpha' a bit more widely than this, not simply to mean the most expensive of any brand. Of course the 'castration' of the EL is designed to make anyone who wants the best close focus compelled to buy the NL. Anyway I hope the Covid restrictions relax later this year and you are able to get out with your binos, camera and magnifying lens.

Lee

 

[Paskman]

I have to agree that a camera and close-focusing lens is a great companion, and we also use Zeiss 6x18 monoculars.
Swarovski's EL 8.5x42 has a close focus of 3.3m. Would this still be considered 'too close'?

Lee

I have a solution to the castrated close focus on my ELs - I just take my glasses off and they focus to about 1.5 m 😂🙂

 

[Conndomat]

OK, sorry, I interpret 'alpha' a bit more widely than this, not simply to mean the most expensive of any brand.

Hello Lee,

Of course, the Swarovski EL 8.5x42 is an alpha glass, just like the SLC, the Ultravid, the HT and also the FL and others.
The example should only show how strongly the near focus is used as a purchase argument, although many users do not use or need it.
Swarovski wanted to make clear with the castration of the 8.5x42, look here the NL are now number 1, good stray light suppression or other optical subtleties are just a weaker sales argument, 2m. or 3.3m. is clearer there.

Andreas

 

[Troubador]

Hello Lee,

Of course, the Swarovski EL 8.5x42 is an alpha glass, just like the SLC, the Ultravid, the HT and also the FL and others.
The example should only show how strongly the near focus is used as a purchase argument, although many users do not use or need it.
Swarovski wanted to make clear with the castration of the 8.5x42, look here the NL are now number 1, good stray light suppression or other optical subtleties are just a weaker sales argument, 2m. or 3.3m. is clearer there.

Andreas

Hello Andreas, there is an interesting aspect of Swarovski's manipulation of close focus to make NL their numero uno model. If half the market do not use or need close focusing are they harming NL's prospects? Probably not because the other half of the market does use it. You could even argue Swarovski is supplying the needs of both halves of the market with NL + EL.

Lee

 

[ZeNiTh-PbArM]

Hi,

In post https://www.birdforum.net/threads/swarovski-odd-business-policy-near-point.391737/post-4027377 swarovski said :

Long story short: we were proud of the 1.5m we achieved with the EL. Reducing it to 3.3m was incredibly painful. But it does help to allow us to significantly save costs and sell the EL at a much reduced price.

So you heard it from the horse's mouth how expensive it is to manufacture a good quality focuser which has a long travel in a tight package.

No wonder cheaper binoculars with near focus have other shortcomings, all the more if most users don't detect it. Personally I always enjoy a butter-smooth, no backlash, no tilt focuser mechanism. Others may prefer close focus and fiddle with the focus wheel. Some can afford both a precise focuser an close focus.
As long as everyone is happy with what they got, it's all fine with me.

Cheers,
zp*

 

[Troubador]

Hi,

In post https://www.birdforum.net/threads/swarovski-odd-business-policy-near-point.391737/post-4027377 swarovski said : Long story short: we were proud of the 1.5m we achieved with the EL. Reducing it to 3.3m was incredibly painful. But it does help to allow us to significantly save costs and sell the EL at a much reduced price.


So you heard it from the horse's mouth how expensive it is to manufacture a good quality focuser which has a long travel in a tight package.

Cheers,
zp*

Thats if you believe what they said rather than the whole point was to make NL superior so that if you want a decent close focus you need to buy NL.
That is just my speculation and I have no evidence to support it.

Lee

 

[Conndomat]

Hello Andreas, there is an interesting aspect of Swarovski's manipulation of close focus to make NL their numero uno model. If half the market do not use or need close focusing are they harming NL's prospects? Probably not because the other half of the market does use it. You could even argue Swarovski is supplying the needs of both halves of the market with NL + EL.

Lee

Hello Lee,

The close focus of the NL is just one aspect that makes this binocular to number 1.

Bigger FOV, softer focuser, better balance and some say that the optics are a bit superior to the EL, but I don't know the NL yet.
These advantages are of course also attractive for people who do not need close focus.
The focuser of the Swarovski 8,5x42 is not automatically more stable due to the lock, you would have had to adjust the focuser again.

Andreas

 

[Troubador]

Hello Lee,

The close focus of the NL is just one aspect that makes this binocular to number 1.

Bigger FOV, softer focuser, better balance and some say that the optics are a bit superior to the EL, but I don't know the NL yet.
These advantages are of course also attractive for people who do not need close focus.
The focuser of the Swarovski 8,5x42 is not automatically more stable due to the lock, you would have had to adjust the focuser again.

Andreas

Yes Andreas I understand there is more to NL than close focus, but what I mean is that I suspect that the close focus was taken from EL by Swarovski to downgrade it and to make clear that NL is their top model and so that EL does not compete with NL.
I am sorry that I do not understand this statement, or what prompted you to post it: "The focuser of the Swarovski 8,5x42 is not automatically more stable due to the lock, you would have had to adjust the focuser again".

 

[Conndomat]

I am sorry that I do not understand this statement, or what prompted you to post it: "The focuser of the Swarovski 8,5x42 is not automatically more stable due to the lock, you would have had to adjust the focuser again".

Lee,

well, I think the optical calculation is still at 1.5m for the 8.5x42. Accordingly, a lock only shortened the optical focus, whether this makes the focuser more stable is questionable ?!
Of course, I cannot answer the question clearly either.

Andreas