Jump to content

How and Why does 50 APO perform better than other 50s


MrFriendly

Recommended Posts

Advertisement (gone after registration)

22 minutes ago, farnz said:

But the four wavelengths of a Superachromat are all in the 400 nm to 720 nm visible spectrum are they?

Don't know.  Probably depends on the glass characteristics and the total design of the elements.  Just didn't want to leave the impression that apochromats focus all wavelengths to one spot.

  • Thanks 1
Link to post
Share on other sites

6 hours ago, farnz said:

The "APO" in the 50/2 APO-Summicron asph means that it has apochromatic lens elements that refract the wavelengths of light so that they faithfully hit the same spot on the image. 

Wavelengths are affected by refraction (think of a pencil in a glass of water where the pencil appears to be at a different angle below the water line).  The amount of refraction (the 'steepness' in the change of angle) varies depending on the particular wavelength of light.  

In standard and telephoto lenses the red, green, and blue wavelengths in the 400 nm to 700 nm waveband don't hit exactly the same spot owing to the inherent refractive indices of the glass  in the lens elements and therefore don't overlap very well, which creates a fuzzy spot with red green and blue edges where the overlap is less than ideal.  Apochromatic lens elements, which refract the wavelengths in the RGB waveband by the same amount, are used to improve the overlapping of the wavelengths to create spots on the image without the fuzziness and this produces 'sharper' images.  

I should note that the current 50/1.4 Summilux-M asph is actually a 50/1.4 APO-Summilux asph lens but, for reasons only known to them, Leica left the "APO" off the name.

The "asph" in the 50/2 APO-Summicron asph and other lenses refers to aspherical lens elements, which are produced so that their curved surface is not a perfect sphere.  The aspherical (ie non-spherical) surface helps to rectify spherical aberrations, which cause the light rays passing through the outer edges of a lens to strike the image at a different 'depth'.  This means that the light ray (which is really a cone of light) will strike the image with different sized spots, and the inevitable overlapping of the spots produces a fuzziness.  The aspherical element(s) cause the rays from the outer edges and the centre to strike the image at the same depth and produce 'sharper' images.

Apologies for the long post but I hope this provides some answers.

Pete.

 

I already knew all that, but I appreciate you taking the time to explain it.

The APO-Summicron-M 75mm is also apochromatic, it has aspherical lens elements and floating elements, but it doesn't perform as good as the 50 APO, and it's half the cost.

So we're left with tighter tolerance?, which somehow contributes to higher performance (and roughly double the cost) when compared to similar lenses.  Given how popular the 50 APO is, why haven't we seen the same tech that makes the 50 APO so great applied to other M lenses?

  • Thanks 1
Link to post
Share on other sites

  • 1 month later...

I've owned two 50mm APO Summicrons and three 50mm Summilux asph lenses and would not agree with the assessment that the APO is a better performer. Perhaps it does better on the charts, but to my eyes the Summilux produces a more pleasing image and has a far better bokeh. It's possible there are variations in the production of the Summilux that result in some copies being just okay and some great, but I'd have to say the one I'm using now falls into the great category. This is my current Summilux shot wide open just a few minutes ago.

By the way, the red along the edges of the long, slender leaves is not fringing. It's actually there.

Welcome, dear visitor! As registered member you'd see an image here…

Simply register for free here – We are always happy to welcome new members!

Edited by fotografr
  • Like 5
Link to post
Share on other sites

1 hour ago, fotografr said:

I've owned two 50mm APO Summicrons and three 50mm Summilux asph lenses and would not agree with the assessment that the APO is a better performer. Perhaps it does better on the charts, but to my eyes the Summilux produces a more pleasing image and has a far better bokeh. It's possible there are variations in the production of the Summilux that result in some copies being just okay and some great, but I'd have to say the one I'm using now falls into the great category. This is my current Summilux shot wide open just a few minutes ago.

By the way, the red along the edges of the long, slender leaves is not fringing. It's actually there.

Welcome, dear visitor! As registered member you'd see an image here…

Simply register for free here – We are always happy to welcome new members!

Hi Brent, You and I have has this exact conversation and we have used the same copy of the Black Chrome 50 APO yet I have to disagree with you, in that there is no questioning my eyes that the 50 APO out resolves the 50 Lux APSH. The out of focus renderings though 'are' different I agree, but thats more to do with how the 50 APO renders with that almost invisible glass and true APO design whereas the BC 50 Lux I have (you know the copy) is very sharp even at F1.4, and at F2 it comes close-ish to the 50 APO but it can't render the finest facial hairs, skin tones and especially the tonal ranges the 50 APO can. Is the 50 Lux APSH a stunning lens absolutely, and especially when the cost difference is factored in as the Lux ASPH is very sharp and as you point out in your attached photograph it possesses a wonderfully creative out of focus rendering, It still can't provide the invisible clarity and acuity the 50 APO can, but again they are both amazing lenses. 

  • Like 1
  • Thanks 1
Link to post
Share on other sites

28 minutes ago, insideline said:

Hi Brent, You and I have has this exact conversation and we have used the same copy of the Black Chrome 50 APO yet I have to disagree with you, in that there is no questioning my eyes that the 50 APO out resolves the 50 Lux APSH. The out of focus renderings though 'are' different I agree, but thats more to do with how the 50 APO renders with that almost invisible glass and true APO design whereas the BC 50 Lux I have (you know the copy) is very sharp even at F1.4, and at F2 it comes close-ish to the 50 APO but it can't render the finest facial hairs, skin tones and especially the tonal ranges the 50 APO can. Is the 50 Lux APSH a stunning lens absolutely, and especially when the cost difference is factored in as the Lux ASPH is very sharp and as you point out in your attached photograph it possesses a wonderfully creative out of focus rendering, It still can't provide the invisible clarity and acuity the 50 APO can, but again they are both amazing lenses. 

We don't disagree, which is why I included the words "to my eyes the Summilux produces a more pleasing image." For some people, the sharper the image the more pleasing it is. That's not where I am in my assessment. To me, a more pleasing image isn't necessarily the sharpest. This came up with an image posted the other day that was taken with the new APO 35 Summicron. It was a cropped portion of a portrait of a young woman and clearly showed the hairs around her lip and on her cheek. I don't consider that pleasing at all, even though that lens clearly resolves better than anything I've ever seen.

Edited by fotografr
  • Like 4
  • Thanks 1
Link to post
Share on other sites

Advertisement (gone after registration)

Not sure if bokeh is a matter of performance and it is hard to compare f/1.4 to f/2 anyway but i do like the OoF rendering of the 50/1.4 asph at full aperture too although it may show some somewhat gaussian blur when pushed to its limits or beyond them (pic). F/2.8 and around is another story though with a bit more harshness i feel and kind of ninja star bokeh balls i don't like much. Was one of the reasons why i got the 50/2 apo in the first place, also for its field curvature or lack thereof but i still favor the resistance to flare of the 50/1.4 asph and its general character but it's just me. 

Welcome, dear visitor! As registered member you'd see an image here…

Simply register for free here – We are always happy to welcome new members!

 

  • Like 3
Link to post
Share on other sites

4 minutes ago, lct said:

Not sure if bokeh is a matter of performance and it is hard to compare f/1.4 to f/2 anyway but i do like the OoF rendering of the 50/1.4 asph at full aperture too although it may show some somewhat gaussian blur when pushed to its limits or beyond them (pic). F/2.8 and around is another story though with a bit more harshness i feel and kind of ninja star bokeh balls i don't like much. Was one of the reasons why i got the 50/2 apo in the first place, also for its field curvature or lack thereof but i still favor the resistance to flare of the 50/1.4 asph and its general character but it's just me. 

 

Lovely image.

  • Thanks 1
Link to post
Share on other sites

On 3/18/2021 at 11:57 AM, insideline said:

Hi Brent, You and I have has this exact conversation and we have used the same copy of the Black Chrome 50 APO yet I have to disagree with you, in that there is no questioning my eyes that the 50 APO out resolves the 50 Lux APSH. The out of focus renderings though 'are' different I agree, but thats more to do with how the 50 APO renders with that almost invisible glass and true APO design whereas the BC 50 Lux I have (you know the copy) is very sharp even at F1.4, and at F2 it comes close-ish to the 50 APO but it can't render the finest facial hairs, skin tones and especially the tonal ranges the 50 APO can. Is the 50 Lux APSH a stunning lens absolutely, and especially when the cost difference is factored in as the Lux ASPH is very sharp and as you point out in your attached photograph it possesses a wonderfully creative out of focus rendering, It still can't provide the invisible clarity and acuity the 50 APO can, but again they are both amazing lenses. 

I've been shooting the Voigtlander 50 APO, and just got the 50 Summilux Black Chrome today. It's been quite painful to adjust to the Lux at f/1.4. The Lux is sharp in the center third of the frame at f/1.4, but anywhere toward the outside of the frame, and it literally will not come into sharp focus (verified with Live View – not even enough sharpness for focus peaking to show up well). I know the lens has compromises to be this small, but even with the Q at f/1.7 is incredibly sharp when focused anywhere in the outer frame except for the extreme corners. The results from the CV 35 f/1.2 III stopped down to f/1.4 are also sharper further out from the center. I guess lens design has come a long way since the current 50 Lux was released, and the M10-R is really pushing it to its limits.

Something else strange about 50 Lux BC is it seems much harder to shoot than the CV 75 f/1.5 when both are shot wide open. Not sure if it's the weight of the brass hood out at the end of the lens making it harder to keep the lens stable or what, but I am getting so many more blurred and/or out of focus shots with the BC. It's almost as if the DOF and focus falloff with the 50 Lux is more like an f/1.2 lens. I do love the bokeh from the Lux, but will have to see if it's worth the cost.

Edited by hdmesa
Link to post
Share on other sites

On 3/24/2021 at 6:26 PM, hdmesa said:

I've been shooting the Voigtlander 50 APO, and just got the 50 Summilux Black Chrome today. It's been quite painful to adjust to the Lux at f/1.4. The Lux is sharp in the center third of the frame at f/1.4, but anywhere toward the outside of the frame, and it literally will not come into sharp focus (verified with Live View – not even enough sharpness for focus peaking to show up well). I know the lens has compromises to be this small, but even with the Q at f/1.7 is incredibly sharp when focused anywhere in the outer frame except for the extreme corners. 

That's an interesting observation and it makes me wonder if you might have a defective copy. I have not experienced this with my 50 lux, which is a standard copy--not the BC. Maybe you could examine the image I posted above and tell me if you see evidence of what you have experienced with yours. My focus was on the long, slender leaf that flows from the top right to the low left center of the frame.

Looking at the image posted by lct, I also don't see this falloff in sharpness away from center. The red leaves just left of center are tack sharp, but also the green leaf tips below the red ones and toward the bottom left are equally sharp to my eyes. They are fairly far away from the center third of the image.

Edited by fotografr
  • Like 1
Link to post
Share on other sites

22 minutes ago, fotografr said:

That's an interesting observation and it makes me wonder if you might have a defective copy. I have not experienced this with my 50 lux, which is a standard copy--not the BC. Maybe you could examine the image I posted above and tell me if you see evidence of what you have experienced with yours.

The area I'm talking about that cannot be brought into perfect focus at MFD is where the red circle is in the image below, which was taken from this interview with Peter Karbe. (Note this is not the MTF for the 50 Lux.) If I backed up a meter or two from MFD, the focus point in this zone was sharper.

Welcome, dear visitor! As registered member you'd see an image here…

Simply register for free here – We are always happy to welcome new members!

 

Here is the 50 Lux ASPH MTF from Leica, but it doesn't say the distance at which it was measured, so I imagine the dip in Zone 10 is stronger at MFD, and this is where I had trouble achieving sharpness in low contrast lighting. 

It is also certainly possible I had a bad copy of the lens (new, made in Portugal copy).

Edited by hdmesa
  • Thanks 2
Link to post
Share on other sites

On 3/25/2021 at 12:26 AM, hdmesa said:

It's been quite painful to adjust to the Lux at f/1.4. The Lux is sharp in the center third of the frame at f/1.4, but anywhere toward the outside of the frame, and it literally will not come into sharp focus (verified with Live View – not even enough sharpness for focus peaking to show up well).

Never got such problems with my regular 50/1.4 asph so far. Not even needed to use focus magnification or peaking for this one. 
(M240, 50/1.4 asph, f/1.4, 0.7m, EVF, handheld, no extra sharpening).

Full frame:

Welcome, dear visitor! As registered member you'd see an image here…

Simply register for free here – We are always happy to welcome new members!

100% crop:

Edited by lct
Link to post
Share on other sites

25 minutes ago, lct said:

Never got such problems with my regular 50/1.4 asph so far. Not even needed to use focus magnification or peaking for this one. 
(M240, 50/1.4 asph, f/1.4, 0.7m, EVF, handheld, no extra sharpening).

Full frame:

100% crop:

I see a bit of micro-blur in the shot, but that's still about the level of sharpness I was seeing off-center, which is not sharp to my eye. It looks about on par with a image scanned from film.

I was getting fairly sharp results right in the center with the 50 Lux at MFD, but I was frustrated it didn't hold up outside the center. If I backed up a meter or so from MFD, then I could get much better results across the frame.

I posted this before, but below is a crop showing the sharpness I am getting with the CV 50 APO on the M10-R wide open at MFD anywhere in the frame. My Canon RF 50 f/1.2 gets ~this level of sharpness wide open anywhere in the frame, too, so I guess I am spoiled by: 1.) APO, 2.) IQ of gigantic lenses like the Canon RF 50 1.2, and 3.) the IQ improvements we see in more recently-designed lenses.

There probably wasn't anything wrong with my 50 Lux, but I've been used to lenses that deliver nice bokeh but still are sharp at MFD across the frame.

M10-R + CV 50 APO 1:1 crop (click to see a more clear version, the forum previews are soft).

Link to post
Share on other sites

1 hour ago, hdmesa said:

I see a bit of micro-blur in the shot, but that's still about the level of sharpness I was seeing off-center, which is not sharp to my eye. It looks about on par with a image scanned from film.

I was getting fairly sharp results right in the center with the 50 Lux at MFD, but I was frustrated it didn't hold up outside the center. If I backed up a meter or so from MFD, then I could get much better results across the frame.

I posted this before, but below is a crop showing the sharpness I am getting with the CV 50 APO on the M10-R wide open at MFD anywhere in the frame. My Canon RF 50 f/1.2 gets ~this level of sharpness wide open anywhere in the frame, too, so I guess I am spoiled by: 1.) APO, 2.) IQ of gigantic lenses like the Canon RF 50 1.2, and 3.) the IQ improvements we see in more recently-designed lenses.

There probably wasn't anything wrong with my 50 Lux, but I've been used to lenses that deliver nice bokeh but still are sharp at MFD across the frame.

M10-R + CV 50 APO 1:1 crop (click to see a more clear version, the forum previews are soft).

Welcome, dear visitor! As registered member you'd see an image here…

Simply register for free here – We are always happy to welcome new members!

Hard to compare f/1.4 to f/2 and this pic does not show edge to edge sharpness either but it was not intended to do so i guess. Now if you mean that the 'Lux 50/1.4 asph has more field curvature than the 'Cron 50/2 apo, i agree of course but if you focus on a corner with your 'Lux, this corner should be decently sharp normally. Just another test pic with no extra sharpening at f/1.4 here. M240 at 0.7m, focus on "Bresson" at the top right corner. Not sure any 50/1.4 M lens can do better than that but i may be wrong. 

 

Edited by lct
  • Like 1
Link to post
Share on other sites

32 minutes ago, lct said:

Hard to compare f/1.4 to f/2 and this pic does not show edge to edge sharpness either but it was not intended to do so i guess. Now if you mean that the 'Lux 50/1.4 asph has more field curvature than the 'Cron 50/2 apo, i agree of course but if you focus on a corner with your 'Lux, this corner should be decently sharp normally. Just another test pic with no extra sharpening at f/1.4 here. M240 at 0.7m, focus on "Besson" at the top right corner. Not sure any 50/1.4 M lens can do better than that but i may be wrong. 

 

I think an M 1.4 lens should be able to do that, but it would have to have been designed and produced in the last few years. The Lux ASPH was released in 2006, so the performance is probably excellent for the technology available at the time. It doesn't help that the M10-R lets us see much more closely how good the sharpness is or isn't at 1:1.

Here was a test I did focusing on the dangling things from a lamp. Here is the full target for reference. I kept the camera position in the same place, but just changed the focus point.

 

Focusing in the center, sharpness is excellent:

 

Focused to the left side, and the point of focus could never be made completely sharp (focus peaking would not even light up). I would get the same results this far off-center regardless of which side of the frame I focused on.

Edited by hdmesa
Link to post
Share on other sites

Here is the CV 35 1.2 III wide open at f/1.2. Of course at f/1.2, this lens is not as sharp in the center as the Lux, but the performance when focusing in the outer part of the frame is better. There is also quite a bit of backlight here reducing contrast (shot at midday, Lux was shot in the evening). This is at 0.7m so FOV will be wider of course. I don't have a CV 1.4 50 to test or I would have used that instead.

 

f/1.2 in the center (side story, but the green bokeh fringing is pretty strong with this lens):

Welcome, dear visitor! As registered member you'd see an image here…

Simply register for free here – We are always happy to welcome new members!

 

Wide open at f/1.2 focused over to the left. Not perfect, but definitely looks more in focus than the Lux at f/1.4:

Edited by hdmesa
Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...