[Klaus]

[quote name='Rainer' date='03 June 2010 - 09:55 PM' timestamp='1275598508' post='156']

Can you "deabbreviate" this for me?

[/quote]



"Residual spherical aberrations" - the lens suffers from focus shifts when stopping down.

The focus information is obtained at max. aperture so it's slightly off at other settings. At close focus distances this is a relevant problem.



RSAs are not so uncommon in this class.

[wim]

[quote name='Klaus' date='03 June 2010 - 11:02 PM' timestamp='1275598966' post='157']

"Residual spherical aberrations" - the lens suffers from focus shifts when stopping down.

The focus information is obtained at max. aperture so it's slightly off at other settings. At close focus distances this is a relevant problem.



RSAs are not so uncommon in this class.

[/quote]

No, it generally even is one of the reasons why bokeh with these lenses is better. Some of it is deliberately left uncorrected, and sometimes I think even deliberately introduced, in a more or less controlled way, as far as that is possible.



Kind regards, Wim

[Rainer]

Ok. Got it. The 50L has the same effect, albeit I

never found it to be overly serious in real live.

[wim]

[quote name='Rainer' date='03 June 2010 - 11:06 PM' timestamp='1275599180' post='159']

Ok. Got it. The 50L has the sam eeffect, albeit I

never found it to be overly serious in real live.

[/quote]

Rainer, you're talking focus shift?



Yes, older copies seemed to have it more often, especially in combination with the previous generation of bodies (40D, 400D, 5D Classic), at least, IME.



Kind regards, Wim

[Rainer]

[quote name='wim' date='03 June 2010 - 11:08 PM' timestamp='1275599302' post='160']

Rainer, you're talking focus shift?

[/quote]



Sorry, yes, I was commenting on Klaus ...



(a minor drawback of the new forum ... it is not that

obvious where the "uplink" goes to).



I use the 50L with my 5DMkI ... and I couldn't say

that I notice AF failures that I could blame to the

focusshift often (and if I do, they could be as well

my fault) ... but then ... I rarely use the 50L for subjects

nearer than about 1.2mtr.

[wim]

[quote name='Rainer' date='03 June 2010 - 11:13 PM' timestamp='1275599612' post='161']

Sorry, yes, I was commenting on Klaus ...



(a minor drawback of the new forum ... it is not that

obvious where the "uplink" goes to).



I use the 50L with my 5DMkI ... and I couldn't say

that I notice AF failures that I could blame to the

focusshift often (and if I do, they could be as well

my fault) ... but then ... I rarely use the 50L for subjects

nearer than about 1.2mtr.

[/quote]

I found that a well-calibrated 5D Classic and well-calibrated 50L do give obvious errors at times, probably about 1 in 20 of relatively close subjects (where it would generally be clear it was quite off, not just user error). This goes away with a 50D or 5D II <img src='http://forum.photozone.de/public/style_emoticons/<#EMO_DIR#>/biggrin.gif' class='bbc_emoticon' alt='' />.



Even so, I think that if you want some fun, I suggest you try some real close-ups with the 50L and an extension tube, or two. You may well be pleasantly surprised with the results <img src='http://forum.photozone.de/public/style_emoticons/<#EMO_DIR#>/biggrin.gif' class='bbc_emoticon' alt='' />. Ideally you'll need the EE-S focusing screen, and focus by moving closer and and away again, until you find the correc focusing point. Use F/8 or so, unless you want to do really special effects. And iso 1600 is not a problem either <img src='http://forum.photozone.de/public/style_emoticons/<#EMO_DIR#>/biggrin.gif' class='bbc_emoticon' alt='' /> (I do this relatively often, handheld, and even up to iso 3200 and occasionally iso 6400 on the 5D II).







Kind regards, Wim

[JN]

[quote name='toni-a' date='03 June 2010 - 09:11 PM' timestamp='1275595899' post='150']

Compared to Canon 50mm f1.8, this lens wins only when it comes to center resolution at large aperture, an absolute disappointment, I am surprised Canon 50mm f1.4 hasn't been tested on full frame, it should be a reference, as someone who knows this lens, I expect that the only advantage would be center sharpness between f1.4 and F2 on all other points Canon should win, especially the borders.

I was enthusiast for this lens, dunno if still it makes any logic getting it for use on full frame

[/quote]





I'm also surprised of no FF review of Canon 50mm f1.4. If its of use SLRGear did a 5 lens x 50mm (including Canon 50mm f1.4) comparison test on about the 1st-Feb-2010.

[Guest]

How distantly do you have to focus before the resolution drop at close distances goes away?

I had one for a while (quite liked it for short focal length environmental portraits in low light) and the annoying thing was that if I used microadjust to make it focus accurately at about 1.5 metres, then it backfocussed hugely at infinity. People tell me recent samples don't do this. DId you notice any such thing?



Congrats on the new forum!

[Guest]

As you can see the Canon 50 1,8 isn't any better than Sigma, [url="http://www.dpreview.com/lensreviews/widget/Fullscreen.ashx?reviews=23,27&fullscreen=true&av=1.667,1.667&fl=50,50&vis=VisualiserSharpnessMTF,VisualiserSharpnessMTF&stack=horizontal&lock=&config=/lensreviews/widget/LensReviewConfiguration.xml%3F4"]click[/url]. Am I right?

[mst]

[quote name='Rasho' date='04 June 2010 - 06:58 AM' timestamp='1275631108' post='176']

Am I right?

[/quote]



Only if you define "better" solely based on resolution.



The 50/1.8 does not really have outstanding bokeh, for example.



-- Markus