21MM 3.4 Super Elmar Issue

[jferebee]

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Hello,

 

I have a new 21 Super Elmar and have been using it for a few days. I've found that it is not sharp when matching the f stop with infinity. In addition when reviewing exposure information in Lightroom 4 it's showing a 1 to 1 1/2 stop difference. For example, a shot at f/16 and the infinity symbol in line with f/16 on the lens the exposure in LR is reading f/13. At f/11 it registers at f/9.5 etc.

 

I then repeated the process shooting from the exact same spot and subject (a street sign 20 yards away) and manually focused, rather than zone focusing, and it was much better.

 

Leica has told me the readings in LR are approximate and the lens is fine. I'm not sure about that. I have the 50 f/2 and a 90 f/2.8 and the readings in LR are exactly as I've set them all of the time.

 

Zone and hyper focus are important to me in that I like working very early and late at it's often diffucult to focus manually in low light.

 

Is it possible, as rare as it is, I may have a defective lens? I know it's under warranty and I can return it but I'm disappointed and a little gun shy about the 21 SE at this point.

 

This is not one of the early models by the way.

 

Any feed back, especially from 21 owners or users, would be greatly appreciated.

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[marknorton]

My experience is that it is a great lens.

 

All aperture figures you see are approximate; the camera has no way of sensing the aperture ring and instead estimates aperture by measuring the relative intensities of light coming through the stopped down lens and the ambient light level in the direction the lens is pointing - the blue dot on the front of the camera.

 

But while the main metering cell inside the camera is sophisticated and sensitive and also sees the angle of view of the lens using a centre weighting, the ambient meter is a basic photo-diode looking out through a simple lens which makes it more spot-meter like.

 

With wide-angles, what each is seeing becomes radically different and you shouldn't expect to see accurate aperture estimations.

 

As for sharpness, I would be surprised. The 3.8 is probably the best 21.

[UliWer]

...

 

For example, a shot at f/16 and the infinity symbol in line with f/16 on the lens the exposure ...

 

I then repeated the process shooting from the exact same spot and subject (a street sign 20 yards away) and manually focused, rather than zone focusing, and it was much better.

 

...

 

Zone and hyper focus are important to me in that I like working very early and late at it's often diffucult to focus manually in low light.

...

 

You can only expect maximum sharpness, if you focus exactly - so with your experience with the street sign there does not seem to be much to worry. Though with the big depth of focus a 21mm lens generally has and a very small f-stop almost everything in front of your lens should be sharp even if you don't reach the maximum everywhere. If you try the lens not stopped down completely but perhaps at f/8 or f/5.6, the depth of focus will still be big, but perhaps the performance of the lens will be better as well. Working in low light with very small f-stops increases the risk of unsharpness by shaking as well.

[jferebee]

Thanks to you both for the feedback. I just went back to my sample spot and took the same photo again at 3.4, 4, 5.6, and 8 and manually focused. It was much sharper. Having never owned a super wide angle of any kind am I to infer that with zone or hyper focusing at f/16 tack sharp images from front to back may not be achievable?

 

I'm wanting small all purpose landscape lens and based on many online reviews the 21 SE was it. Perhaps matching that lens to my goal isn't realistic?

 

Would one expect to have a better chance at this with the 28 f/2.8 instead?

[rramesh]

There are 2 versions of this lens. The earlier one was discontinued and recalled by Leica, if I remember. Make sure you have the newer edition. It is the one with a slightly fatter base near the flange.

[jferebee]

Thank you. I thought of that but assume with SS# 4169474 it is not one of the older models that did have some issues.

[farnz]

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... am I to infer that with zone or hyper focusing at f/16 tack sharp images from front to back may not be achievable? ...

Unfortunately you're unintentionally setting obstacles in your lens's way. At f/16 it's very likely that diffusion will limit the sharpness that your lens will produce. My advise is to manually focus at no smaller aperture than f/8 and your pictures should be as sharp as the lens will allow but with very good depth of field owing to the wide angle.

 

Diffusion will also detract from the 28 f/2.8 in the same way.

 

Pete.

[jferebee]

Pete,

 

I appreciate your comments. When setting up for landscapes, especially in big vistas like the American West, infinity seems to be what I use most of the time.

 

I enjoy learning and perfecting my technique so are you suggesting that by manually focusing at f/8 for example on nearer objects the DOF capability of the lens will provide image focus and clarity on the far distance subjects as well?

[lct]

F/11 is the best compromise IMO.

[Les_Sismore]

At f/16 it's very likely that diffusion will limit the sharpness that your lens will produce. ...

 

Diffusion will also detract from the 28 f/2.8 in the same way.

 

Do you mean diffraction??

 

Cheers

[WilhelmR]

I'm just looking at the dof scale of my 21 mm lens:

 

setting focus to 2m and f-stop to f/8 I get a dof from 1 m to infinity. Not enough?

 

Wilhelm

[jaapv]

The DOF markings date back to film in the 1930-ies. For a digital sensor they should be reduced to the next smaller aperture at least (preferably two). Depending on the magnification throughout the chain it is best imo to keep in mind that only the plane of focus is sharp.

Quoting Günther Osterloh in a workshop: "If you want the horizon to be sharp you should focus to infinity".

 

It is not as if the focus is maintained within the DOF range. Maximum focus is in the plane of focus with the defocussing gradually increasing before and behind the sharp area. And the subject and contrast of the image.A sunny woodland landscape with much foliage will appear to have less DOF that greyish snow scene with large uniform expanses.

As long as our eye cannot resolve the amount of defocus we perceive the image as "sharp". This depends on the enlargement of the image and the viewing distance to the print and the individual variations of our eyes.

A computer screen is about the worst tool to judge DOF effects btw.

[Michael Geschlecht]

Hello jferebee,

 

Welcome to the Forum.

 

The circle of confusion of 1/30 mm which is used for depth of field scales on lenses is a holdover from an earlier time period when people's expectations for quality of image from enlargements was somewhat less critical than today.

 

If you want to have an image sharp over a range of distances:

 

Some people use the engraved depth of field lines for 2 STOPS LARGER to estimate acceptable depth of focus. This more agrees with today's expectations for final image quality.

 

Example: When the range of distances you want in focus is covered by the depth of field markings with the lens mount rotated (focussed) so that the subjects all fall within the engraved lines for F4 on both the near & far sides:

 

Set the aperture to F8. Adjust shutter speed for exposure for aperture of F8.

 

Do NOT adjust focus.

 

If the engraved lines for F5.6 encompass the necessary range of distances: Set the aperture to F11 & set the shutter speed for an appropriate exposure with an aperture of F11.

 

Do NOT adjust focus.

 

And so on.

 

Also: With modern floating element lenses which are sometimes sharper at the IMAGE PLANE: The engraved markings for depth of field sometimes reflect a shallower depth of field on either side of that image plane. The quality of the image of a floating element lens can deteriorate more rapidly in front of or behind the image plane than it might with a non-floating element design.

 

Don't forget: Traditional or floating element lens: There is only one image plane that is actually in focus. In front or in back of that image plane there is some varying degree of acceptable imprecise focus. That is what people call depth of field.

 

Best Regards,

 

Michael

[Malvolio]

I own one and its an extraordinarily sharp lens (even at max aperture); mind you, I tend not to zone focus a lot with the lens and focus manually so I would try and run some test shots deliberately focussing on a specific object etc.

 

If the sharpness is not there I would send the lens back.

[farnz]

Do you mean diffraction??

Yes. (Diffraction + confusion = diffusion.)

 

Pete.

[pgk]

I own the later version and its an extraordinarily good lens! In fact its the best 20/21mm I've ever used.

 

My rule of thumb if using a hyperfocal setting (that is, using the depth of field scales to focus) is to use the scale setting for an aperture 2 stops wider than the one actually being used (ie f/5.6 markings for f/11). This is pretty effective but even so for absolute maximum sharpness at the point where it is essential, accurate manual focus is still required.

 

Secondly, in my experience f8 and f/11 achieve excellent results (I'm hard pushed to tell the difference), but f/16 will produce softer images as diffraction becomes noticeable as has been commented.

[farnz]

Pete,

 

I appreciate your comments. When setting up for landscapes, especially in big vistas like the American West, infinity seems to be what I use most of the time.

 

I enjoy learning and perfecting my technique so are you suggesting that by manually focusing at f/8 for example on nearer objects the DOF capability of the lens will provide image focus and clarity on the far distance subjects as well?

There are a few variables here. Much depends on the distance between the nearer objects and the horizon although a 21 mm lens is wide enough to provide plenty of depth of field. If you focus on an object that's 1 metre away then the horizon will be out of focus at f/8 but if you focus on an object midway between you and the horizon then the horizon should be acceptably in focus.

 

Focussing at infinity will often provide very good results but it iss easy to unintentionally 'waste focus' behind the horizon owing to the nature of hyperfocal distance. Obviously you won't notice that the space beyond the horizon is in focus but if you were to adjust focus so that the horizon is just within the zone of acceptable sharpness then more objects in front of the horizon will also be acceptably sharply in focus.

 

Pete.

[250swb]

The other thing to consider is that the more you stop down the longer shutter speeds are. This has more of an impact on image sharpness than any small increase in diffraction between f/8 and f/16. So unless you use a tripod you are introducing the main problem with image quality, camera shake, when the lens is stopped down.

 

Steve

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[wattsy]

I appreciate your comments. When setting up for landscapes, especially in big vistas like the American West, infinity seems to be what I use most of the time.

 

Plenty of good advice already in this thread. With landscapes and non-TTL focussing like an RF I often find it useful to do a little focus bracketing, especially if I'm a little unsure where I want the actual plane of focus to be. When I'm later examining the images I can make a better judgement as to whether the photograph looks better with proper focus on the horizon or, for example, on an object that may be part of the landscape.

[jferebee]

Thanks to all of you that have responded. I have learned a few things especially zone focusing 1 or 2 stops off. That is new for me.

 

I should point out that with any of my serious landscape or long exposure work I use a tripod. So at f/16, slow shutter speeds, and a cable release I get outstanding sharpness and very pleased with my current 35MM Cron. My test shots with the 21MM were hand held and may not have been a fair way to evaluate the lens.

 

The more open test shots with manual focus were very nice but at f/16 the trees and foothills behind my test shoot, at infinity, were very soft and would not have been acceptable.

 

I'm going to breakout the tripod today for further testing and will let all of you who have kindly shared your expertize, how it turns out.