Thinking about the 50mm Sonnar - but those f/1.5 vs. f/2.8 threads make my head hurt!

Z

ZebGoesZeiss

Established
Local time
5:24 AM
Joined
Feb 2, 2008
Messages
137
View My Gallery
I'm gonna try my best to keep from flogging a dead horse here...

There are a lot of threads about the Zeiss 50mm Sonnar, and the focus shift "problem". Depending on which lens one gets, it will be optimized for either f/1.5 or f/2.8. There will be focus shift at some apertures, no matter what.

What is not clear to me, is to which extent this is a problem. Originally, it came optimized for f/2.8, which caused some focus shift at f/1.5 and f/2. But after that, it was all good.

The ones that are optimized for f/1.5, shows focus shift at smaller apertures (f/2.8-f/?).

A lot of people seem to think that the f/1.5 version is the better way to go, after all - it is a f/1.5 lens, right? But earlier this year I was lucky enough to get to borrow a M8.2 to use with my 35mm Summilux ASPH for a couple of weeks. The lens was spot on at f/1.4. Like in "spot on". Really. It was so good that when I sold it a while back, I got almost $4000 for it. The buyer got to try it, and happily reported the same thing: Sharp as razor at f/1.4, but focus shift on smaller apertures. And the f/1.4 sharpness was what he was after.

One of the things that annoyed me with that lens, was that focus shift. From f/2.8-f/8, it was hard to find any sharpness "worthy" of the Leica badge. So, even though it was brilliant at f/1.4 and f/2, I found it a nuisance to use from f/2.8-f/8.

What I would like some input on is this:
Does the f/1.5 optimization render the lens "unsharp" at f/2.8-f/8, to the point that DOF doesn't cover the focus shift?

The f/1.5 version is the one that I can get hold of the easiest, and the one I'm looking to buy. But I'm not willing to sacrifice the whole range of mightily useful apertures from f/2.8 - f/8 to get improved performance at f/1.5 and f/2. If the focus shift is covered by the increased depth of field, I'm happy. Any input would be greatly appreciated.
 
Are you using film or digital?

I bought a C-Sonnar brand new from Matsuiyastore, which apparently was f2.8 optimised. I didn't do lens tests, but just used the lens (on film bodies). I could see no evidence of focus shift, and was happily using the lens at all apertures. I'm bemused by the amount of coverage of this issue on the net. Perhaps my standards are low. Perhaps it only affects digital users.
 
Sorry for not mentioning that! I'm all film, can't afford that M9, and in the end I never got along with the crop factor of the M8. 🙂

Thank you for your response!
 
Take a look at this thread.

In short, the "f/1.5-optimised" version is more precise at f/1.5 and f/2, is off the mark at f/2.8 to f/5.6, and gets the focus point back in focus at f/8.

For the record that one was taken on film, but for focus it does not matter what medium sits behind the lens, just how far it is away.
 
Last edited:
Get one optimized for F1.5. That's what fast lenses are made for. With a little practice, you could learn to compensate for the focus shift yourself. Just turn the focus ring slightly when you are using F2.8 or F4. With the increased DOF, it should be fairly forgiving.

For film vs Digital: there is a slight difference as film is not perfectly flat in the camera. Camera manufacturers make some assumptions on hot it will sit in the camera relative to the lens. Sensors tend to stay flat and not bow out.
 
Do what I did, get a Sonnar optimised for the fastest speed possible without sacrificing focus at f2.8 - f5.6 (focus point @ back of the DOF but still within the DOF). That's exactly how Cosina adjusted two Sonnars for me even though I sent them in to be "optimised for f1.5". They worked great at any aperture.
 
Last edited:
I have some MF lenses that have to be stoped down for good image quality, and it doesn't worry me. But a f1.5 lens ought to focus properly at full aperture. So get one optimized for f1.5 and enjoy it wide open or close to wide open. I had one of the f1.5 Sonnars that came optimized for f2.8 or something like that, and I sent it back. The focus shift is very substantial to put it diplomatically.
 
I bought one optimized for 2.8 because shallow DOF is not really my thing.
As far as i'm concerned, my sonnar is a 50mm f2.8 lens (with the added bonus of f1.5 if i need it)
There is focus shift at f1.5 and f2 which i just try and learn to compensate. I don't use such large apertures often enough for the focus shift to bother me.
 
The C Sonnar wide open is a different lens from the C Sonnar at f 2.8 or 3.2. Wide open, it has a completely different contrast, and the oof passage is comparable to an 0.95 lens, so you have to decide what are you going to use it for. I find it easier to adjust the f2.8 version when shooting wide open, than the other way round. As far as I am concerned this is an f 1.5 or an f 3.2 lens. I prefer the f3.2 rendering, but I have both and intend to keep both.

f 1.5
1971721096_00f3e29ecf.jpg


f 3.2
3756615757_e9ce58a97e.jpg
 
Last edited:
I had mine optimized for 2.8 and liked it like that.

If shift really bothers you, there are alternatives with great bokeh and less focus shift:

Nokton 1.5, Canon 50/1.4, Summilux pre-asph and asph. Etc.

The pre-asph Summilux has quite a Sonnar type rendering to it. Similar center/corner fall-off, beautiful OOF.
 
Last edited:
I now have Simon's C-Sonnar, I use it on film, but mainly with the M8.

It is optimised for f/2.8 and I never worry about it - whether at f/1.5 or whatever... As Simon, perhaps I am not pixel-peeping enough - I just make prints....
 
back alley said:
mine is one of the originals and in real world shooting has caused me no grief at all, on film or the rd1.
Click to expand...
Ditto. Focus shift, shmocus shmift. You want technical image perfection at all apertures? I've heard the 50mm Summilux ASPH is pretty good.
 
I have two of them - one is a very early M-mount so it is probably optimized for 2.8 - but I have never had a problem with it shooting it @f1.5.
The other one is one of the last #264 of the Nikon SC mounts. Dont know what it is optimized for - but it works perfectly on my S2/S3/SP's.
As said, just get it and start using it - it is a great lens and particularly in black/white it has a "lush-ness" in the shadows that I cant find in another 50.
 
Hi all, I can't find the answer to my simple question in the thread. How can I distingish the one optimized for 1.5 and the one optimized for 2.8? I would like to buy this lens for my M8 in a couple of months, and would like to get the 1.5 version. Has the serial number something to say about this? Thanks in advance.
 
I had one of these lenses optimized at f/2.8. The focus shift bothered me quite a bit - but then I do most of my shooting at f/2 or wider. Sent it back to Zeiss to have it optimized at f/1.5. Liked it much better.

Stillwish: That's the problem you are going to run into. I don't believe there is any sort of visual inspection that can be done to determine what the optimization is. I don't know if they still do it, but Zeiss used to take the lenses back and re-optimize as part of the warranty.

You may just have to test the lens yourself - or buy it from someone who knows which version they have.
 
Just buy the lens and use it.
Forget everything you read about it and enjoy.
This whole issue is blown out of proportion, when it comes to practical use of the lens.
I did not even know if my lens was optimized for 1,5 or 2,8.
Used it faithfully at both apertures.
 
StillWish said:
How can I distingish the one optimized for 1.5 and the one optimized for 2.8? [...] Has the serial number something to say about this?
Click to expand...

From the serial numbre I think you can't. Zeiss converted some to f1.5, but without asking the owner it will be difficult to tell.
 
AFAIK they come from the factory optimized for f2.8. A few folks have sent them back and Zeiss has changed the backfocus a little for them. Perhaps Zeiss is making a record of the serial numbers of the lenses they perform the mod on, but again AFAIK they are not stamping them "Optimized for f1.5!" or otherwise marking them. You could contact them and ask if they are recording serial numbers. If they are not keeping track, I suppose that would say something about how important ZEISS considers the issue.

Optimizing the older LTM Zeiss Sonnars for perfection at f1.5 is fairly easy - I have done a couple of lenses myself following instructions published by Brian Sweeney. This sort of hacking causes no cognitive dissonance for me on lenses costing under $200, but I am disinclined to take a screwdriver to my otherwise perfect kilo-buck ZM Sonnar to see if DIY optimization is possible.
 
You must log in or register to reply here.
Back
Top Bottom