How to obtain focus at 1.5 with Zeiss 50mm f1.5 sonnar

[colonel]

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Hi, 

I am thinking of buying the 50m f1.5 sonnar as I love the character of the pictures I have seen

I understand this lens has focus shift and is optimised from the factory at f2

Therefore at f1.5, how would I estimate focus (I have a Mp 240) without using the EVF

Is it a small lean forward ? is there a focus change I can measure on the dial forward or back ?

Anyone any advice ?

thanks

 

[a.noctilux]

When I have a doubt on focus, I take time to learn the behavior of the lens.

With liveview, it took me a couple of minutes.

To discover that in many cases, it's my fault in RF focussing technique or lack of...

 

If I have doubt on focus shift, I'd just use LV or EVF (M10/M240/246) at my distance/aperture of use then take time to learn in which direction

to correct when I use RF focussing.

As I use many lenses, I put a marking (or tape with mark) on the focus ring depending on the way (Right or left) of focus ring.

 

As side note, my Noctilux 1.0 is used  at f/1.0 or f/5.6 onward (too much troubles with F/1.4 to f/4.5 ...)

Edited January 22, 2021 by a.noctilux

[sinjun]

The focus shift on this lens has never really bothered me. Rather than backing off on the focus ring, I lean forwards slightly after focussing at f1.5 for a subject that's within a few metres, though you can establish your own technique by experimentation - live view isn't necessary since I find this quite easy to do by reviewing images on the M9 LCD. You probably know that close-distance sharpness isn't the best with this lens wide open anyway.

[lct]

Fous shift is a real problem on rangefinders but you can ask Zeiss for a calibration at f/1.5. At least i could do it in the past. I would ask your dealer about that.

[colonel]

25 minutes ago, lct said:

Fous shift is a real problem on rangefinders but you can ask Zeiss for a calibration at f/1.5. At least i could do it in the past. I would ask your dealer about that.

Thanks. I explored this, but it then focus shifts above f1.5 all the way to f8, so I'd rather have f2 and above work, as generally I would be using f1.5 at night with some distance between me and the subject, i.e. not close range

[BrianS]

Focus shift for this lens is towards infinity. A Sonnar lens optimized for F2 means that focus at F1.5 will be in front of the point you focused on. That means you need to lean back a little bit, like 2cm at 1m. For Monochrome/Black+white users: focus shift for deep yellow/orange/red is also towards infinity with the Sonnar.

https://www.35mmc.com/29/04/2020/zeiss-jena-5cm-sonnars-the-magic-of-the-prewar-uncoated-sonnar-by-brian-sweeney/

100% crop of the fence post shows focus shift on the Sonnar.

Edited January 22, 2021 by BrianS

[sinjun]

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4 hours ago, BrianS said:

Focus shift for this lens is towards infinity. A Sonnar lens optimized for F2 means that focus at F1.5 will be in front of the point you focused on. That means you need to lean back a little bit, like 2cm at 1m.

Don't you mean lean forward a little when shooting wide open?

[Nilei]

Yes, at F1.5 there is a front focus

[BrianS]

3 hours ago, sinjun said:

Don't you mean lean forward a little when shooting wide open?

No, I mean lean back slightly IF the lens is Calibrated for F2 for the rangefinder and you are shooting at F1.5. The focus will be slightly in front of what the RF indicates, so you have to shift back slightly. ALSO- this works for the vintage Summarit 5cm F1.5, which I found 5 of them to be calibrated for close-focus at F2.8. The Summarit will focus too close when used at F1.5, so lean back slightly. When stopping down to F4 or so, lean forward. 

Think of this as having a lens where all the elements are floating elements, and you are one with the camera in being part of  the mechanism. "I am one with my Leica"

Edited January 22, 2021 by BrianS

[tgray]

I bought mine about 1.5 years ago and appears to be calibrated for f/1.5. 

[stephengv]

Same here, I bought the Sonnar last December 2020 in B&H, it was calibrated to 1.5

[sinjun]

12 hours ago, BrianS said:

No, I mean lean back slightly IF the lens is Calibrated for F2 for the rangefinder and you are shooting at F1.5. The focus will be slightly in front of what the RF indicates, so you have to shift back slightly. ALSO- this works for the vintage Summarit 5cm F1.5,

Maybe I'm being stupid,  but if the focus is in front of what the RF indicates, isn't the solution to lean forward to bring the point of focus to where the RF originally indicated? That is what works with my Sonnar and also, as you say, with my old Summarit.

As an aside I find front focus can work in your favour if you are shooting people or animals coming towards you - in that a slight delay between achieving focus and pressing the button can compensate.

[Nilei]

vor 3 Stunden schrieb sinjun:

Maybe I'm being stupid,  but if the focus is in front of what the RF indicates, isn't the solution to lean forward to bring the point of focus to where the RF originally indicated? That is what works with my Sonnar and also, as you say, with my old Summarit.

As an aside I find front focus can work in your favour if you are shooting people or animals coming towards you - in that a slight delay between achieving focus and pressing the button can compensate.

Thats also my experience.

[BrianS]

My apologies to everyone- I got it backwards. 

 

The RF indicates 1.0m, the actual focus is at F1.5 is (let's say) 0.97m- so you need to lean forward. Too long stuck inside and not taking any pictures.

Edited January 23, 2021 by BrianS

[roelandinho]

I think different people use different definitions for “in front”. 
 

In any case, the plane of best focus always moves further away (towards infinity) as you are stopping down. On my copy it corresponds perfectly with the rangefinder at f2, moves further away at f2.8 and smaller. When opening the lens to f1.5 it moves very slightly closer to me (front focus). 
 

I usually don’t compensate (by focusing further of leaning forwards) for the focus shift at 1.5 because it’s very slight. I have found that when I try to compensate I tend to “overdo” it which leads to a worse result. I only use the 1.5 setting if I have to, when there isn’t enough light. The lens renders more beautifully with better subject separation at f2. 

[Photon42]

Turn the focus ring slightly to the left at short distances. On longer distances it does not matter. Try for yourself with a tripod and something you can focus on. It is a very nice lens.

[BrianS]

2 hours ago, roelandinho said:

I think different people use different definitions for “in front”. 
 

 

I my case I can claim both "Senior Moment" and "Covid-Cornered Confusion".

I should have known better. I've shimmed a lot of lenses for back-focus. For the Summarits, changed the element spacing for front focus.

[sinjun]

Knowing that you're such an expert Brian, I really had to think twice about this! Easy to get mixed up I suppose.

[Mark T]

On 1/22/2021 at 10:50 PM, colonel said:

Thanks. I explored this, but it then focus shifts above f1.5 all the way to f8, so I'd rather have f2 and above work, as generally I would be using f1.5 at night with some distance between me and the subject, i.e. not close range

I agree with this. To be honest, the focus shift has never really bothered me and for the type of photo you describe, I think it will be fine. I prefer to shoot at f2-4 anyway as the out of focus is more pleasing at these apertures. At 1.5 you lose a lot of contrast as well which bothers me more than the focus shift does - if that tells you anything? That said, you're on the right track, lean slightly forward at 1.5 or focus slightly behind they eyes. It's subtle and only really a problem taking a portrait, at minimum focus distance and maximum aperture. But then, this is asking for trouble irrespective of the lens. I avoid this even when focus shift is not an issue...

Best of luck with it!

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[MarkP]

On 1/23/2021 at 1:24 AM, lct said:

Fous shift is a real problem on rangefinders but you can ask Zeiss for a calibration at f/1.5. At least i could do it in the past. I would ask your dealer about that.

I contacted Zeiss Germany and they did this for me at no charge some 8 years ago.  I only paid for shipping to Germany, they optimised and shipped it back for me at no charge.  14 day turnaround from the time I sent it off from Sydney till I had it back in my hands.  

Leica, are you reading this?