An interview with Gerold Dobler, leader of the SF design team (1 Viewer)

[Alexis Powell]

Nice interview!

Too bad about the variable-ratio focus, but I wonder what research was really done on this and if the concept was understood by those who were polled. If asked about dual-ratio focus, most folks would imagine something complicated with a clutch, or with two focus knobs (fine and course). I don't want that either. But a variable pitch gear, or whatever it is that has already successfully been used by Brunton, Minox, and Pentax in some of their bins does not introduce any complication or come at a weight penalty (as far as I can tell). I think users would love it, or else would benefit from it without even realizing that it was there.

I see nothing like it in the SE 8x32, but I had a close look at the Absam/SE ring in the Swarovision 8x32. So it´s more critical in 10x models?

I don't see it in the Nikon 8x32 SE either, but it is very obvious to me in the Nikon 10x42 Venturer LX/HG.

--AP

 

[bh46118]

:-O

BH

You poor fellow, I don't know how you manage to endure the burden of looking through that SV but I am sure you will survive.

Lee

 

[Troubador]

Thanks Lee, great interview.

Tobi

Bitte schoen

Lee

 

[Troubador]

Nice interview!

--AP

Thanks Alex.

Gerry was quite clear on this point, that a variable speed would add some grams and you wouldn't believe how they have chased down every single last gram. They don't allow themselves to say, 'well its only an extra 5 grams and that is nothing', because these 5=0 add up and they gave themselves a strict weight target.

Lee

 

[Troubador]

Cutaway Drawing of SF

This drawing is larger and clearer than the one posted by Gijs, but all credit to Gijs for posting first:t:

Lee

 

[henry link]

Lee,

Thanks for posting the cutaway.

Looking at the ocular, I'll have to admit that I'm a bit skeptical about how well the off-axis aberrations can be corrected. Certainly if this diagram is interpreted as a 6-element Erfle with a field flattener, then a singlet field flattener does not seem like enough to fully correct the well known field curvature and astigmatism of the Erfle design at 70º. But, the three achromats don't quite follow the classical Kaspereit modified Erfle pattern, in which the internal spacings are equal and the cemented surfaces of the eyelens and middle doublets curve in the same direction, so maybe this design has been changed enough to work as advertised. We shall see. If all it takes is an additional singlet to fix up the old Erfle I wonder why it hasn't been done before.

Henry

 

[bh46118]

Henry, is your IQ in the 200 range ? :eek!::-O

Lee,

Thanks for posting the cutaway.

Looking at the ocular, I'll have to admit that I'm a bit skeptical about how well the off-axis aberrations can be corrected. Certainly if this diagram is interpreted as a 6-element Erfle with a field flattener, then a singlet field flattener does not seem like enough to fully correct the well known field curvature and astigmatism of the Erfle design at 70º. But, the three achromats don't quite follow the classical 6-element Erfle pattern, in which the internal spacings are equal and the internal cemented surfaces of the eye lens and collecting lens doublets curve in the same direction, so maybe this design is modified enough to work as advertised. We shall see. If all it takes is an additional singlet to fix up the old Erfle I wonder why it hasn't been done before.

Henry

 

[henry link]

Henry, is your IQ in the 200 range ? :eek!::-O

Don't confuse high IQ with the brain of an obsessed hobbyist, crammed full of trivia.

 

[Binastro]

. Would exotic glass in the eyepiece elements make a difference?
Or possibly aspherics?
Although wide angle eyepieces in well designed roof prism
binoculars seem to display fewer ghost images of bright light sources than in Porro prism binoculars, I would like to try the SF to see if it as free of ghost images as some Leicas or, say, the Canon 10x42 IS.

Internal structure diagrams do not always tell exactly what the maker has done.

 

[henry link]

Well, the back surface of the field flattener looks like it could be aspherical, but no mention of it from Zeiss.

Another geeky point of interest is the objective doublet, which looks like a Steinheil design with the "flint" in front of the "crown".

 

[Binastro]

.If the Flint element is right in the front then they must take great care to protect it, I suppose.

 

[Troubador]

Lee,

Thanks for posting the cutaway.

Looking at the ocular, I'll have to admit that I'm a bit skeptical about how well the off-axis aberrations can be corrected. Certainly if this diagram is interpreted as a 6-element Erfle with a field flattener, then a singlet field flattener does not seem like enough to fully correct the well known field curvature and astigmatism of the Erfle design at 70º. But, the three achromats don't quite follow the classical Kaspereit modified Erfle pattern, in which the internal spacings are equal and the cemented surfaces of the eyelens and middle doublets curve in the same direction, so maybe this design has been changed enough to work as advertised. We shall see. If all it takes is an additional singlet to fix up the old Erfle I wonder why it hasn't been done before.

Henry

Henry

It took more than one can of midnight oil to optimise this arrangement....

Lee

 

[Chosun Juan]

This drawing is larger and clearer than the one posted by Gijs, but all credit to Gijs for posting first:t:

Lee

Lee,

Thanks for posting that slightly better drawing. When do we get to see an actual physical cutaway? :eek!: :t:

Good to see there's no rolling balls in there! |8.|

Let's hope there are no ghosts in there either ..... (o)<

Do you have any details on the specifics of exactly what was done to rectify the ghosting /flare issues of the prototypes? Likewise, details on the focus, eyecup, and armour (and any other - ring, or other?) issues? ..... :brains:

Promotion has to be a two street ya know!

Thanks,

Chosun :gh:

 

[Graham Osborne]

Best binocular thread I have read on BF for a long time. Thanks Lee and others.

 

[james holdsworth]

Why speculate when you can view with the actual unit? Wait for the real thing, all this predictive modelling is getting oh-so-familiar here.....even with Brock somewhere off in the weeds.

 

[Holger Merlitz]

.If the Flint element is right in the front then they must take great care to protect it, I suppose.

In this case, the CaF2 element is the sensitive one and should be kept inside. Now, the "flinty" (negative) element is in front, but actually it is made of a crown glass. In other words, the "ED" element replaces the crown, and a crown replaces the flint - in this way the dispersion of the entire setup is reduced (as is mentioned by R. Ceragioli somewhere in his writeup about telescope lenses).

The question is: Are these doublets actually cemented, or does there exist a tiny air space? If they are in fact cemented, I wonder how they managed to keep the aberrations sufficiently low.

Cheers,
Holger

 

[NDhunter]

In this case, the CaF2 element is the sensitive one and should be kept inside. Now, the "flinty" (negative) element is in front, but actually it is made of a crown glass. In other words, the "ED" element replaces the crown, and a crown replaces the flint - in this way the dispersion of the entire setup is reduced (as is mentioned by R. Ceragioli somewhere in his writeup about telescope lenses).

The question is: Are these doublets actually cemented, or does there exist a tiny air space? If they are in fact cemented, I wonder how they managed to keep the aberrations sufficiently low.

Cheers,
Holger

Holger:

The success of this binocular will be determined when they actually are
being sold on the retail marketplace.

Zeiss is on notice with questions about the HT 54 models, that
have been found to be lacking over the former FL models.

I suspect most, if not all of those that designed and checked off on that
binocular were involved with the SF.

Jerry

 

[Holger Merlitz]

Holger:

The success of this binocular will be determined when they actually are
being sold on the retail marketplace.

Zeiss is on notice with questions about the HT 54 models, that
have been found to be lacking over the former FL models.

I suspect most, if not all of those that designed and checked off on that
binocular were involved with the SF.

Jerry

Hi Jerry,

It seems that Dobler/Seil were forming a separate team, which worked independently and wasn't involved in the HT design (the HT does in fact look very much like a classical Victory design, while the SF is quite a bit different and closer to the Swaro EL).

I am convinced that they got the aberrations well controlled - just want to know how they did that. Because the textbooks are telling us that cemented doublets are offering an insufficient number of degrees of freedom to control the aberrations. The HT is an air-spaced triplet, quite a bit more complex than the design of the SF's objective. I guess that the latter is in fact air-spaced, but if it is not, then Konrad Seil must have had some good ideas to make it work.

Cheers,
Holger

 

[stereotruckdriver]

Why speculate when you can view with the actual unit? Wait for the real thing, all this predictive modelling is getting oh-so-familiar here.....even with Brock somewhere off in the weeds.

Deja vu, I mentioned this in the other thread.

Bryce...

 

[Troubador]

Lee,

Thanks for posting that slightly better drawing. When do we get to see an actual physical cutaway? :eek!: :t:

Good to see there's no rolling balls in there! |8.|

Let's hope there are no ghosts in there either ..... (o)<

Do you have any details on the specifics of exactly what was done to rectify the ghosting /flare issues of the prototypes? Likewise, details on the focus, eyecup, and armour (and any other - ring, or other?) issues? ..... :brains:

Promotion has to be a two street ya know!

Thanks,

Chosun :gh:

Sorry CJ I have no info on the details on how the design was originally conceived nor how the design and manufacture has been optimised.

But, since SFs are being delivered into the market place, initially at a slow rate, if we are patient there will be production SFs for us all to try and discover for ourselves.

Don't forget that I haven't actually tried a full production unit yet, so my comments need to be regarded as 'provisional but confident'.

With these drawings out in the open it at least demonstrates Zeiss's willingness to step away from their recent optical trains to achieve a different quality of performance.

I really feel there is room for both HT and SF in the market as they offer different flavours to appeal to different observers.

Lee