Best non alpha Compact binocular ? (3 Viewers)

[Kevin Purcell]

It seems companies often (always?) keep the same exit pupil when different magnifications of the same model are made by putting different objectives on the same ocular + prism assembly. Is there a design constraint, or is this just a design convention?

Often? Hmmm, I would have said rarely and usually with porros e.g. Nikon SE are the most famous example all about 4mm exit pupil.

In this case it seems to be more about saving money in design and production with a single standard prism housing/prisms/eyepieces the varying the objectives.

It's not so common in roof prisms which seem to keep the same enclosure and prisms but vary the EP and perhaps the objectives too. I guess making a single one-size-fits-all enclosure with common prisms is a component pricing win for those designs.

I think the Victory shows that Zeiss don't like bins with EP of less than 2.5mm but once they get above that they're willing to let users decide if they want a 4 or 5 or 6mm EP.

 

[Alexis Powell]

It's not so common in roof prisms which seem to keep the same enclosure and prisms but vary the EP and perhaps the objectives too.

Yes, I agree that it is more common with porros...but I'm still left with the same question, which is why WHEN IT IS THE CASE THAT different powered binos utilizing the same ocular + prism assembly are made, it is often or maybe always the case that they are made with differing diameter objectives such that they have equal or nearly equal exit pupils. This situation applies to the premium pocket roofs. As for roofs, maybe it's not so common in the premium brands, and maybe not as much these days. In the past, we had the Zeiss 7x42 and 8x56, 8x30 and 10x40 Classics, the B&L 7x36 and 8x42 Elites to name a few off-hand, and it's been very common in the mid-priced range to have 8x42 and 10x50 pairs.

--AP

 

[Kevin Purcell]

... binos utilizing the same ocular + prism assembly are made

I don't see much evidence for that assertion in roofs. The exit pupil preference combined with a magnification preference seem to explain all the differences.

I think there is a difference (as I explained) between the very bottom end where it's clear that Zeiss and other makes are sticking to a minimum exit pupil. So that's a constraint.

For the others they have more latitude but it seems to be the case that an exit pupil between 4mm, 5mm or 6mm is certainly preferred for compact and full size bins. Combine that with the different preferred magnifications (7x, 8x and 10x) and you end up with a rather limited set of numbers some of which have the same exit pupil in the same family. Add a desire to keep the weight down for most people and the combinations become even more limited.

For example the Zeiss 8x30 and 10x40 I think comes down more to commercial factors. People want 8x bins and 10x bins and you want to deliver them with 4mm minimum exit pupils. If you want 5mm exit pupils then you make 8x40 and 10x50 (though that latter starts to have a problem with weight). So you tend to go for 8x30, 8X40, 10x40 AND 10X50.

In the cases like the 42 versus 56mm or 30mm versus 40mm bins I doubt there are many shared components: the case sizes are different, the prisms are probably different (though without pulling a bin apart we can't know for sure) and the oculars are probably different too (different focal length objectives need different oculars).

But sometimes the overall design can be shared e.g. 8x30 and 10x40 Classics is a good example of this with both having the same overall roof prism design with moving objectives. I doubt but I'm not certain they don't have the same oculars as the bigger enclosure in the 10x40 case gives gone a bit more freedom. In that case I think the designers are just trying to cover two markets with a related design.

 

[Alexis Powell]

Not sure I entirely follow, or whether we're asking/answering the same questions, but I understand you to be asserting that you don't think there are any design constraints on offering different exit pupils when switching out objectives on the same ocular + prism assemblies. So the reason that we never got, for example, a Nikon 8x42 SE or 8x40 EII is because the designers decided up front that a certain exit pupil (4 mm for the SE) was desirable and proceeded from there.

--AP

I don't see much evidence for that assertion in roofs. The exit pupil preference combined with a magnification preference seem to explain all the differences.

I think there is a difference (as I explained) between the very bottom end where it's clear that Zeiss and other makes are sticking to a minimum exit pupil. So that's a constraint.

For the others they have more latitude but it seems to be the case that an exit pupil between 4mm, 5mm or 6mm is certainly preferred for compact and full size bins. Combine that with the different preferred magnifications (7x, 8x and 10x) and you end up with a rather limited set of numbers some of which have the same exit pupil in the same family. Add a desire to keep the weight down for most people and the combinations become even more limited.

For example the Zeiss 8x30 and 10x40 I think comes down more to commercial factors. People want 8x bins and 10x bins and you want to deliver them with 4mm minimum exit pupils. If you want 5mm exit pupils then you make 8x40 and 10x50 (though that latter starts to have a problem with weight). So you tend to go for 8x30, 8X40, 10x40 AND 10X50.

In the cases like the 42 versus 56mm or 30mm versus 40mm bins I doubt there are many shared components: the case sizes are different, the prisms are probably different (though without pulling a bin apart we can't know for sure) and the oculars are probably different too (different focal length objectives need different oculars).

But sometimes the overall design can be shared e.g. 8x30 and 10x40 Classics is a good example of this with both having the same overall roof prism design with moving objectives. I doubt but I'm not certain they don't have the same oculars as the bigger enclosure in the 10x40 case gives gone a bit more freedom. In that case I think the designers are just trying to cover two markets with a related design.

 

[Nessus]

Yes, but wouldn't a Zeiss Victory 8x25 be as small and compact?

Yep, too bad it doesn't exist, at least not in anything recent because I wanted to buy one, I'm still pissed they dont make one.

I guess the problem is the 8x20 Victory is so damm good they don't feel the need to go for the 25, it would probably be so bright it would steal 8x32 customers.

Cameraland has the 10x25 Victory's for $400 right now, this thread has me thinking evil thoughts.

 

[Kevin Purcell]

Not sure I entirely follow, or whether we're asking/answering the same questions

Me too.

... but I understand you to be asserting that you don't think there are any design constraints on offering different exit pupils when switching out objectives on the same ocular + prism assemblies.

I didn't say that ... clearly there are.

For example, if the prisms aren't big enough you have to limit the FOV as would be the case if you decided to add 40mm objectives with the right focal length for 8x magnification. The light cone would be too big for the prisms.

So the reason that we never got, for example, a Nikon 8x42 SE or 8x40 EII is because the designers decided up front that a certain exit pupil (4 mm for the SE) was desirable and proceeded from there.

They wanted to keep one enclosure/prism/ocular design so had to stick with a single exit pupil size rather than the other way around.

So they picked one that would work with all of the magnifications they were planning along with other constraints tp the design (e.g. weight). They could have chosen 5mm exit pupil but that would have made the family 8x40, 10x50 and a 12x60 which clearly would have been too heavy.

The 10x50 were already out of style when designing these bins but the 10x42 was the primary bin (and was introduced first ... the 8x and 12x came the next year).

You can see this effect in families that have a 8x40 and a 10x50: the FOV of the 10x bin often suffers more than you might expect.