2nd 50mm APO - Doesn't Focus TO Infinity - More help needed, sorry.

[JTLeica]

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No, that's not the same title I wrote last time 😅

I have just sent back the 50mm APO today that had issues. Originally I thought that it focussed past infinity. That actually wasn't the case, it was just a complete dud. Maybe there were some elements that were centred properly, I don't know. But it was not sharp across the frame at any aperture, under 'test' conditions, on a tripod in daylight, focussing well past 300m.

I test against the Voigtlander 50mm APO that I bought this week purely to test something equally sharp, or reportedly.

I have today taken delivery of another 50 APO. This one, doesn't even get to infinity focus. At F2 - 3.5 maybe, there is softness in the far background.

It's low light now and never clear skies in the UK. So I have done what I can on a tripod with still a ralatively fast shutter.

I have lined all images on dropbox below. Please let me know what you think. There's also a load of CA / Purple fringing which shouldn't happen with this lens, right? Not that much anyway.

I started at F2 and worked to half stops maybe up to F4.

https://www.dropbox.com/t/AA49G8OMRLF7R98J

The furthest trees only sharpen up at F3.5/F4 - Obviously I am guessing the aperture slightly. So I now have a 50mm APO F4. Great.

Please let me know your honest opinions on this.

The voigtlander 50 APO, is perfect from F2 upwards.

PS - I know this isn't the norm and I am probably just unlucky which I accept. Just would like some expect opinion.

PPS - You can clearly (IMO) see the focal plane on the 50 APO is on the house to the right centre and not on the trees in the background.

Edited September 26, 2023 by JTLeica

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[Al Brown]

Your testing conditions are wrong. You test all lenses at widest f/stop and infinity in clear, open spaces. Half of the image is obstructed by a brick wall, in your case impossible to assess much because of Leica lenses having edge field curvature. You should redo the test.
Could be a decentered lens, could be a misaligned rangefinder couping, could be a dud or could be none of the above... so many variables which would only be revealed under the proper testing conditions.

Edited September 26, 2023 by Al Brown

[JTLeica]

6 minutes ago, Al Brown said:

Your testing conditions are wrong. You test all lenses at widest f/stop and infinity in clear, open spaces. Half of the image is obstructed by a brick wall, in your case impossible to assess much because of Leica lenses having edge field curvature. You should redo the test.
Could be a decentered lens, could be a misaligned rangefinder couping, could be a dud or could be none of the above... so many variables which would only be revealed under the proper testing conditions.

Al I totally agree is a shocking test

I only had 10 mins before the light went totally, hence the back garden images.

My only take was that at open apertures, the trees in the distance at the hard infinity stop, look visibly more out of focus (not by much granted) than the house in the middle.

But I will do it properly when I have some light tomorrow maybe.

[JTLeica]

Hi all,

I have re tested and re-pasted a link for those interested. The 50 APO may or may not focus to infinity I am not sure... However, at infinity at F2 and 2.8 the very left edge is sharp ish and everything else from centre to right, is awfully blurred. So it's a case of de-centring I think.

I have not ever had any QC issues with Leica lenses like this, odd its happened twice in a row on one of the more expensive lenses...

Anyway I won't hold it against them. Both could have been dropped for all I know.

https://www.dropbox.com/t/hhnGvU6XqgdXzpje

Above is a new link to 6 files. 3 with the Leica and 3 with the Voigt Lanthar - F2, 2.8 and 5.6

Am I seeing things now or is the Voigt ever so slightly softer on the left? Maybe just the darker foliage making details harder to see.

Appreciate any comments

[Panda2]

The 50 APO is not focusing at infinity here. Looking at the f2 shots, the plane of focus is in the water not far from land on the near side. The Voigtlander seems to be focusing at the right place with small bit of unevenness in sharpness.

Frankly, both lenses are not perfect. But where the Voigtlander is mere imperfection that you can maybe live with, the Leica you need to send back. 

I have the Leica APO, it focuses at infinity just fine. This isn't within normal parameters.

[Gobert]

I have two, never had infinity issues, as far as I know

[JTLeica]

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21 hours ago, Panda2 said:

The 50 APO is not focusing at infinity here. Looking at the f2 shots, the plane of focus is in the water not far from land on the near side. The Voigtlander seems to be focusing at the right place with small bit of unevenness in sharpness.

Frankly, both lenses are not perfect. But where the Voigtlander is mere imperfection that you can maybe live with, the Leica you need to send back. 

I have the Leica APO, it focuses at infinity just fine. This isn't within normal parameters.

Agreed. But I guess there's a debate that the left corner / edge is reaching infinity, but on average the frame is nowhere near. Returning tomorrow. 

[hdmesa]

On 9/27/2023 at 3:09 PM, JTLeica said:

Hi all,

I have re tested and re-pasted a link for those interested. The 50 APO may or may not focus to infinity I am not sure... However, at infinity at F2 and 2.8 the very left edge is sharp ish and everything else from centre to right, is awfully blurred. So it's a case of de-centring I think.

I have not ever had any QC issues with Leica lenses like this, odd its happened twice in a row on one of the more expensive lenses...

Anyway I won't hold it against them. Both could have been dropped for all I know.

https://www.dropbox.com/t/hhnGvU6XqgdXzpje

Above is a new link to 6 files. 3 with the Leica and 3 with the Voigt Lanthar - F2, 2.8 and 5.6

Am I seeing things now or is the Voigt ever so slightly softer on the left? Maybe just the darker foliage making details harder to see.

Appreciate any comments

That 50 APO is fucked if you have it focused to the infinity hard stop, but true focus is at the water's edge nearby.

For the Voigtlander, you need to retake the test where the horizon is not over the water. You could be experiencing uneven atmospheric distortion. Further, you need to test infinity focus like Gordon Laing does (look up one of his lens tests on YouTube). Angle the camera so that the horizon goes from corner to corner and take a shot. Then readjust the camera so that the horizon does the same thing on the opposite corners. The corners will much better reveal de-centering than the edges at the middle of the frame.

Edited September 30, 2023 by hdmesa

[JTLeica]

9 hours ago, hdmesa said:

That 50 APO is fucked if you have it focused to the infinity hard stop, but true focus is at the water's edge nearby.

For the Voigtlander, you need to retake the test where the horizon is not over the water. You could be experiencing uneven atmospheric distortion. Further, you need to test infinity focus like Gordon Laing does (look up one of his lens tests on YouTube). Angle the camera so that the horizon goes from corner to corner and take a shot. Then readjust the camera so that the horizon does the same thing on the opposite corners. The corners will much better reveal de-centering than the edges at the middle of the frame.

Thanks man,

Haha yes it certainly is. It was focussed at infinity hard stop yes. Yes I am not totally confident the voigtlander is decentered, I am going to redo this as you suggest with a diagonal into the corners. I did shoot a few of those but didn't post any.

I have two Apo Lanthars now... Just curious so I bought another and will return on. But I won't be buying another 50 APO Cron now, I feel it was a sign from the gods telling me to stop being a fool and keep the Voigt.

I'll report back.

[Al Brown]

On 9/27/2023 at 11:09 PM, JTLeica said:

Hi all,

I have re tested and re-pasted a link for those interested. The 50 APO may or may not focus to infinity I am not sure... However, at infinity at F2 and 2.8 the very left edge is sharp ish and everything else from centre to right, is awfully blurred. So it's a case of de-centring I think.

I have not ever had any QC issues with Leica lenses like this, odd its happened twice in a row on one of the more expensive lenses...

Anyway I won't hold it against them. Both could have been dropped for all I know.

https://www.dropbox.com/t/hhnGvU6XqgdXzpje

Above is a new link to 6 files. 3 with the Leica and 3 with the Voigt Lanthar - F2, 2.8 and 5.6

Am I seeing things now or is the Voigt ever so slightly softer on the left? Maybe just the darker foliage making details harder to see.

Appreciate any comments

I have checked your tests #2.
Your APO 50 is decentered, it is not the first APO that I have seen, I also wrote about it here and @hdmesa also wrote about his 35 being decentered.
When we sent one APO 35 to Leica they said it is not much they can do and it is "within normal tolerances". IT IS NOT and it is unacceptable.