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Why no short FL reflex Sonnars ?
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PostPosted: Tue Oct 13, 2009 9:39 pm    Post subject: Why no short FL reflex Sonnars ? Reply with quote
There are many "normal" Sonnar lens options for RF users.
Some are as short as 35mm (my T2 has a 2.8/3Cool.

I love the look of the Sonnar in this FL range.
What happened when the reflex revolution started?
Why did this optical scheme not make it but fir longer FLs.
Slighlty less Sharp than a DG but, much better transition and flare control.

Opinions and Conjecture please!

Ok go!


PostPosted: Tue Oct 13, 2009 9:51 pm    Post subject: Re: Why no short FL reflex Sonnars ? Reply with quote
F16SUNSHINE wrote:

What happened when the reflex revolution started?


Sonnar remained in use for tele lenses.
Wide angle lenses in reflex cameras were only possible with retrofocus design, hence no wide Sonnars, no wide Planars, and no wide Biogons. New retrofocal schemes had to be designed.
The only focal lenght where Sonnar could be used and was abandoned, is 50mm, but it's easily explained: when reflex started, lens coating was already a reality, and so it was possible to make faster 50mm lenses using Planar scheme. As cheap slower alternative for 50mm, Tessar was preferred to Sonnar because less expensive and probably also easier to build in large quantities.


PostPosted: Tue Oct 13, 2009 10:09 pm    Post subject: Re: Why no short FL reflex Sonnars ? Reply with quote
F16SUNSHINE wrote:

What happened when the reflex revolution started?


The mirror got in the way.

For a simple lens, focal length f, the lens is placed at a distance f from the film/sensor plane for infinity focus. For a complex lens like the Sonnar I'm guessing that the point from where the focal length is measured sits somewhere in the middle of the lens. So the rear element has to be closer than this and, unless f is large it will hit the mirror. SLR short FL lenses are largely of the "retrofocus" design. Here the design is such that the plane from which the focal length is measured is behind the rear element.

Perhaps an optics expert can confirm or deny this. And, if true, expand it.


PostPosted: Tue Oct 13, 2009 10:21 pm    Post subject: Reply with quote
Still seems like a 50/55 would work.
Maybe Andy needs to google some diagrams. Confused


PostPosted: Tue Oct 13, 2009 10:28 pm    Post subject: Reply with quote
F16SUNSHINE wrote:
Still seems like a 50/55 would work.
Maybe Andy needs to google some diagrams. Confused


Yes, probably it would work, but as you know, industry decisions are often taken in perspective. With the advent of lens coating, the Planar suddenly appeared to have a brighter future (both metaphorically and literally) than the Sonnar, at least in the focal lenghts where building a Planar was financially sustaineable.
Hence the decision of all lens houses (Zeiss, Leitz, Nikon in primis) to go the Planar route for the new fast standard lenses.
And like I said, Tessar for the cheaper slower alternatives was a more marketing sensible choice than Sonnar.

it may also be possible that the shift focus problem of the Sonnar 1.5/50 might have also played a role in the abandon of the Sonnar design for the standard focal lenght.


PostPosted: Tue Oct 13, 2009 10:39 pm    Post subject: Reply with quote
CZJ Sonnar 2/54 for Olympus Pen F

http://www.taunusreiter.de/Cameras/Olympus_Sonnar.html

Discussion of mirror problem.


PostPosted: Tue Oct 13, 2009 10:58 pm    Post subject: Reply with quote
You are talking about prime lens here, right? The Contax Zeiss 35-70 zoom carries the Sonnar moniker.

I am still trying to figure out the famous' Sonnar' look, so count me out of any credible input. Confused Confused Confused


PostPosted: Tue Oct 13, 2009 11:07 pm    Post subject: Reply with quote
bawang wrote:
You are talking about prime lens here, right? The Contax Zeiss 35-70 zoom carries the Sonnar moniker.


It's a Vario-Sonnar (not Sonnar), and if you look at the schematics, you will notice that only the front part of the optical elements resembles the Sonnar scheme. The middle and rear parts, are completely different, and obviously so, since we are talking or a variable FL scheme.


PostPosted: Tue Oct 13, 2009 11:31 pm    Post subject: Reply with quote
Hi,

I believe the early (c. 1957) 58mm f/2 Takumar was a Sonnar design. But my acquaintance with this lens is limited to online sources - I gather it's rather uncommon - so I can't speak from personal experience.

In any event, Asahi quickly dropped both its Sonnar and Heliar normal-lens experiments, switching over to Gaussian designs.

Cheers,

Jon


PostPosted: Wed Oct 14, 2009 12:47 am    Post subject: Reply with quote
Univer wrote:
Hi,

I believe the early (c. 1957) 58mm f/2 Takumar was a Sonnar design. But my acquaintance with this lens is limited to online sources - I gather it's rather uncommon - so I can't speak from personal experience.

In any event, Asahi quickly dropped both its Sonnar and Heliar normal-lens experiments, switching over to Gaussian designs.

Cheers,

Jon


Yes Jon
Your right about that Tak. It is the only "normal lens" Reflex sonnar I'm aware of.
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