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Thread: The Sigma Fifty

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    Senior Member Lars's Avatar
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    The Sigma Fifty

    I picked up a Sigma 50/1.4 EX at the local store the other day. As some of you might recall, I've been a bit curious about its lens because of its nonstandard design. Here are some first impressions.

    Price: I paid 3995 SEK including sales tax, or 3196 SEK before tax. For you people across the pound that's today about USD 356 plus sales tax.

    Dimensions: This is one big lens! Dimensions and weight almost exactly match my 85/1.4D - just about 5 mm shorter. Filter thread is a whopping 77 mm.

    Construction: Focusing is traditional, with the entire lens assembly moving. The lens assembly is one fixed unit contained in an inner metal barrel. The front element is about 62 mm across, so Sigma could have gotten away with using a 67 mm filter thread. Instead, a larger outer barrel size was added, that houses the entire lens assembly. This outer barrel is made of composite material but seems quite substantial, protecting the lens assembly well.

    Lens mount bayonet is tight like it should be. The mount is actually oversized compared to Nikon's mounts, allowing the mount screws to be placed further apart, wich in theory would make the construction stronger.

    Included lens hood is of sculpted type, and mounts bayonet-style with a positive lock feel to it. The hood could have been slightly longer as there is some margin before any vignetting occurs.

    Filter threads are in the outer composite barrel, so it's not metal threads. This is a weak point, care should be taken when mounting filters and it's probably not a good idea to use a screw-in hood as it might rip out the filter threads if you drop the camera.

    All in all, with the exception of filter threads the construction inspires confidence. It would seem that Sigma has tried to make a lens that is sturdy and rigid. How well it actually takes a beating remains to be seen.

    Focusing: The manual focusing ring has about 90 degrees rotation from endpoints to 45 cm, and feel is OK for an AF lens. MF override is possible in AF mode, or you can turn off AF on the lens. The lens has a built-in AF motor, so it should work with all current Nikon cameras. Focusing speed is good without being stellar - sligthly faster on my old F5 than on my new D700. There is the occasional hunt as the camera/lens combination overshoots. The lens assembly is quite heavy, which can be felt as the focus motor starts and stops. I suspect that it drains the camera battery a bit more than a smaller lens.

    Now the optics.

    Color and contrast: to my eyes color rendering seems neutral, possibly with an ever so slight warm cast but I'm not quite sure. Overall contrast is moderate, in LF terms more like Rodenstock than Schneider if you can relate to that.

    Wide open there is a slight falloff towards edges. The only way to tell is to fire two shots after each other at different apertures and then flip back and forth between them. At f/1.8 any falloff is gone.

    Sharpness and microcontrast: At f/1.4 there is a softness just outside the focus plane, and depth of field is so narrow that it's very difficult to nail the focus exactly. For this reason it's easy to dismiss this lens as being soft wide open, when in fact it's not. AF on my D700 is not precise enough, and manual focusing using the viewfinder is even worse (at least with my eyes). Using tripod-mode live view on the D700 I was able to obtain proper focus. Most of this wide-open softness around the focus plane is gone at f/1.6, and completely gone at f/1.8. As with most lenses, resolution drops slightly at f/16 which is the smallest aperture. Resolving power is sufficient for my D700, someone else will have to test on a camera with higher photosite density like D90, D300, D3x.

    Towards the extreme corners (the very last 1-2 mm) the image falls apart wide open, with noticeable coma. Getting the corners together requires stopping down to f/8-11. On DX sensor this is not a problem as the inner image circle has good definition at all apertures.

    Now on to the interesting part...

    Bokeh: So you put the 50 on a body, look through the viewfinder and bokeh seems good, with the limitations of a viewfinder screen. You fire a test shot, look at the display on the D700, and go "Whaaat???" Background bokeh is all cream. Just whipped, thick cream, with sugar added. Foreground is just as creamy and smooth. Transition from focus to blur is exquisite (this is where the wide-open softness comes in). Background specular highlights are rendered as perfect filled circles, with virtually no edge. Bokeh performance is extended through the aperture range, with only the wide-open softness lost. I've only seen this rendering quality in Cooke lenses, that's the closest comparison I can think of.

    When discussing this lens, I think it's important to come up with some kind of definition: what is the Sigma 50?

    The way I see it, it does at 50 mm what my 85/1.4D does at 85 mm: Render aesthetically pleasing photographs. This reason is enough motivation for me to carry it around despite its huge size and weight.

    It's also important to define what it's not:
    - It's not your general purpose normal lens - too big and heavy.
    - It's probably not the sharpest 50 you can buy. It will compete with most of them I'm sure, but it might not be the sharpest. A comparison would be interesting, but resolution is not the sole reason to use this lens.

    So if you are looking for something small and light, or if you are a resolution buff and don't care much about bokeh then this lens is not for you.

    If on the other hand you have interest in lenses with that subjective rendering quality, then the Sigma 50 might be of interest. I could also envision this as an interesting portrait lens on 4/3, if its resolving power is sufficient.

    I'll follow up with some sample shots over the weekend. (Please tell me what kind of setups you would like to see.)

    Lars
    Last edited by Lars; 27th February 2009 at 08:25.
    Monochrome: http://mochro.com

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    Subscriber Member Jorgen Udvang's Avatar
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    Re: The Sigma Fifty

    Lars,
    Great and very thorough review. Your findings confirm what I've been hoping for, and the lens is on the shopping list for my F-mount cameras. If it works well on the E-620, I may even buy an additional one in 4/3 mount. In spite of the size and weight, I may use it as a night-time walk-around lens with that camera. With in-body IS, it will really be the "King of the Night", and the 100mm eqv. focal length is just perfect for street portraits.

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    Senior Subscriber Member Steen's Avatar
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    Re: The Sigma Fifty

    Congrats with your new fast prime, Lars. Fortunately it sounds like you have got one of the good samples of the lens.
    On another forum I have read about some less good samples with front focus and also shift focus as you stop down.
    I have been thinking about getting either this Sigma 1.4/50 or the new Nikon 1.4/50G AF-S myself, in lack of new fast high end mojo primes from Nikon itself. So I'm looking very much forward to see some of your results and conclusions.

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    Super Duper
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    Re: The Sigma Fifty

    This is a nice lens. I had one for a couple of weeks.

    Since getting the new Nikon one which is smaller for use on my F6, I sold it to a forum member. But still, a nice lens.

  5. #5
    Senior Member Lars's Avatar
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    Re: The Sigma Fifty

    Jorgen,

    There is always the question mark around compatibility with Sigma. This lens seems to work OK with my two Nikon bodies. I've read comments by Canon shooters that focusing didn't work so well, Canon's focusing communication seems difficult to implement. Hopefully you can find comments from other 4/3 shooters using this lens in 4/3 mount.

    The hood that accompanies the lens is for 50 mm angle of view, so it's far too narrow (wide?) for 4/3 crop. Maybe it would be a good idea to check with Sigma if the hood for their 80-200/2.8 would physically fit this lens - if so it could be ideal for 4/3 crop.

    Some additional comments about the lens:

    The rear element protrudes past the rear rim when focused past infinity, so it's important to be careful when removing the lens - either set focus to near or put down the lens front down. Silly design mistake by sigma, extending one of the rear flanges by a millimeter would have been enough. Perhaps the rim design was correct if the lens stopped at infinity, but mine goes a bit past infinity.

    Corner coma is not quite as bad as I first thought, it seems to be gone at f/4. I'll do some more tests tonight.

    I'm going to do some comparison shots later today, using similar lenses that I have (85/1.4D, 50/1.8 AiS).
    Monochrome: http://mochro.com

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    Subscriber Member Jorgen Udvang's Avatar
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    Re: The Sigma Fifty

    The 4/3 version isn't available yet, and I will try the F-mount lens with an adapter before making a decision. The focus problem on Canon seems to be a problem with many third party lenses, and with Sigma being a member of the 4/3 consortium, it shouldn't be a problem for the Olympus, but nobody knows until it has been tried.

    What will be interesting with the 4/3 version is if the new 12MP sensor is less critical with regards to the principle of telecentricity in the 4/3 system. The fact that it's being used with m4/3, which has a shorter flange to sensor distance should indicate that, but again, seeing is believing. I will try with a number of OM-lenses as well, to see if it has improved.

    Using the 70-200 hood may be a good idea if it fits, unless they make a special hood for 4/3. I don't hold my breath for that though. The problem I can see with the large hood is that it won't fit backwards for storage. Not good for travel, in other words.

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    Senior Member Lars's Avatar
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    Re: The Sigma Fifty

    Here are some bokeh samples, all f/1.4, NEF processed to JPG in camera.
    Monochrome: http://mochro.com

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    Senior Member Lars's Avatar
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    Coma samples

    Here are coma samples at f/1.4, f/2 and f/2.8. Actual pixel crop along left edge of frame, 6% of full frame width, about half way to corner. As you can see, coma is mostly gone at f/2.

    (Shot through triple-pane window, so please don't draw any conclusions from contrast.)
    Last edited by Lars; 3rd March 2009 at 05:23.
    Monochrome: http://mochro.com

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    Senior Member Lars's Avatar
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    Re: The Sigma Fifty

    After some tripod testing with live view focusing I have to revise my comments re sharpness wide open - this lens resolves at least as much as my D700 sensor can take, even wide open. Full resolution is there wide open in roughtly the DX frame, then edges improve when stopping down to f/2. Microcontrast is a tad lower wide open but resolution is there.
    Monochrome: http://mochro.com

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    Senior Subscriber Member Steen's Avatar
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    Re: The Sigma Fifty

    If the focusplane is where you want it to be / expect it to be, it looks like you've got yourself an excellent lens and a keeper

  11. #11
    Senior Member Lars's Avatar
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    Re: The Sigma Fifty

    Quote Originally Posted by bondo View Post
    If the focusplane is where you want it to be / expect it to be, it looks like you've got yourself an excellent lens and a keeper
    Yep. Close range focus plane is spot on close using AF. It looks pretty good.

    It's not fully apochromatic though - just out of focus specular highlights can get a slight green or purple tint in transition from darkness to light. I just have to remember to stop down to f/4 when shooting Harleys in sunlight
    Last edited by Lars; 3rd March 2009 at 14:25.
    Monochrome: http://mochro.com

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    Senior Member Lars's Avatar
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    Re: The Sigma Fifty

    This lens is slightly wider than my Nikon AiS 50/1.8, so if the Nikon is a true 50 then the Sigma has a focal length of perhaps 47 mm.
    Monochrome: http://mochro.com

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