50mm canon vs Sigma - Guess the pic

Quick guess: First and last ones are the nifty, middles are the 85. What really gives it away is the slight perspective difference; the child's head in 1 and 4 looks more three dimensional, whereas in 2 and 3 it's flatter.
 
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trencheel303 said:
Quick guess: First and last ones are the nifty, middles are the 85. What really gives it away is the slight perspective difference; the child's head in 1 and 4 looks more three dimensional, whereas in 2 and 3 it's flatter.
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So you are going soley on perspective and not image quality then - interesting. One lens costs £80, the other £350 and yet you couldn't pick from an image quality which was which, makes you think doesn't it!

You're wrong by the way:

1-50
2-50
3-85
4-85
 
It is - the 50mm f/1.8 is a fantastic lens, a part of me actually wonders why I ever actually sold mine (to buy the f/1.4 version... what a hunk of crap!)

I went (obviously wrongly) solely on perspective because I can't see any difference in image quality.
 
trencheel303 said:
It is - the 50mm f/1.8 is a fantastic lens, a part of me actually wonders why I ever actually sold mine (to buy the f/1.4 version... what a hunk of crap!)

I went (obviously wrongly) solely on perspective because I can't see any difference in image quality.
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I thought you said the 50mm was hardly remarkable - which is what led us to this comparison in the first place :thinking:
 
joescrivens said:
So you are going soley on perspective and not image quality then - interesting. One lens costs £80, the other £350 and yet you couldn't pick from an image quality which was which, makes you think doesn't it!

You're wrong by the way:

1-50
2-50
3-85
4-85
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I thought I was making a judgement based on image quality and I was still wrong.

Makes it even worse , if anything :lol:
 
joescrivens said:
I thought you said the 50mm was hardly remarkable - which is what led us to this comparison in the first place :thinking:
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I wasn't clear. For the price, yes it is good. But wide open it is poor and as we all know the build quality is shoddy. What puts it into context though is the f/1.4 version costing like, 3 times as much, certainly isn't 3 times as better. Also, at these sizes, you could take the picture with a lensbaby and they'd still look good.
 
trencheel303 said:
I wasn't clear. For the price, yes it is good. But wide open it is poor and as we all know the build quality is shoddy. What puts it into context though is the f/1.4 version costing like, 3 times as much, certainly isn't 3 times as better. Also, at these sizes, you could take the picture with a lensbaby and they'd still look good.
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wide open it's poor?

I think you my have had a poor copy to say that, two shots below, at 1.8, one with the 85, one with the 50 - neither look poor to me and although I can tell which is which, i wouldn't say the 50m was poor wide open.

4929159816_24300ff34d_b.jpg


4929160164_8cb7732d1b_b.jpg
 
They are both soft. The 1.8 is well known to be poor wide open but you stop it down to around f/2.5 to start getting rid of the abberations.
 
trencheel303 said:
They are both soft. The 1.8 is well known to be poor wide open but you stop it down to around f/2.5 to start getting rid of the abberations.
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they aren't soft, thats a 100% crop before any sharpeneing, the nifty after a sharpen:

4928580299_03b3af2bf9_b.jpg


if you think that is soft, then one of us needs to go to specsavers, and I must warn you I am already wearing glasses!

The only lens that I could get a sharper shot from would be my macro 2.8 L
 
So I take it Sigma isn't worth it unless you have micro AF adjustment function, which I don't. And even then it is no perfect.

Please correct me. I do want a decent 50mm, but Nikkor doesn't quite fit Canon.
 
I have the 50, 85 and 100 (non L) Canon lenses, my own feelings match Joe's.
I love the 85 and the 100 for their build quality etc but for sheer value for money without image compromise the 50/1.8 walks home with the trophy every time. I'd have no hesitation in recommending it. Build quality - well, considering its a photographic lens and not a mobile phone and we all seem to want second hand minty bodies/lenses why is it that people complain about the 50/1.8 in that its not well built, treat it gently (as its photographic kit and resale means it must be minty - or do people treat it roughly cos its cheap?) and it seems to behave well enough.

Sorry, bit off topic.

Matt
 
daugirdas said:
So I take it Sigma isn't worth it unless you have micro AF adjustment function, which I don't. And even then it is no perfect.

Please correct me. I do want a decent 50mm, but Nikkor doesn't quite fit Canon.
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Not sure about that, I think if I didn't have microadjustment I would probably send it of to be calibrated.

I'm still deciding whether the lens is better or not. It seems when I do specific comparison to a text subject it seems not, but when I actually take a real photo with it, it's lovely.

Well if that is always the case then who cares since I intend on spending the time taking lovely real pics.

I don't think the results are optically better than the 1.8 but i do see the bokeh difference for sure, and the build quality is obvious, thats not a bigger for me, but when filming i will notice the difference of the focus ring
 
MatBin said:
I have the 50, 85 and 100 (non L) Canon lenses...
I love the 85 and the 100 for their build quality etc but for sheer value for money without image compromise the 50/1.8 walks home with the trophy every time.
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Maybe it's just me but I never found the 50mm anywhere near as consistent as the 85mm 'in the field'.
 
"Would you say the Sigma would take a super sharp group shot at f/5.6 or f/8? I know Canon 50/1.8 would."


Siggy 50mm f1.4 is pretty sharp at f2 and at f4 I think it's probably as sharp as it's going to get.
 
I wouldn't mind the 50mm myself. Nothing said has put me off buying one.
 
Ok, so after a lot of testing and looking at all the results etc I have decided I will keep the sigma.

Overall I have found it to be less sharp than my 1.8, but with an unsharp mask I found the sharpness to be very good. The bokeh is really what has made me make the decision. I took these pics as a final test and really saw the difference:

1.8
4931411095_aaaa0b2185_b.jpg


1.4
4931410799_9c0caa4039_b.jpg


It was only when i paired these two that I saw how horrible the bokeh in the 1.8 really is. The 1.4 is much better and the overall image is improve because of it. I also decided to keep the lens because I already have a 30 1.4 and an 85 1.8 and a 100mm 2.8

If I didn't have the 30 or the 85 I think I would have kept my 50mm 1.8 and got either of those two but since I do have them and the only thing that is less good about the lens over the 1.8 is a small amount of sharpness difference I'm happy to use it instead given that an unsharp mask brings it right up to standard.

The 1.4 was also a factor. I put my camera on auto iso, manual shutter and aperture and from 1.4 to 1.8 I had to increase the ISO by 1000 to get the same exposure which is pretty considerable.

So overall the better build, nicer hood, better bokeh and 1.4 overided the slight lack of sharpness over the 1,8 given an unsharp mask fixes that.
 
which one falls to bits first, gets a marked coating first, focusses the fastest, and most accuratally

Blah Blah Blah
 
Gigabyte said:
Thanks.

I like the first pic. Nice and crisp. Plus, the 2nd one has been taken slightly closer.
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the first pic has horrible bokeh, very messy and scrappy, 2nd pic much nicer and smooth. 2nd pic wasn't closer, just what you find is that two primes both saying 50mm actually end up different - one is 50mm and the other is 52mm or one is 50 the other 48 etc
 
Gigabyte said:
Thanks.

I like the first pic. Nice and crisp. Plus, the 2nd one has been taken slightly closer.
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Look at the first pic. The background looks like it has been hit by someone building a steel drum. The second is far smoother. The second has better bokeh........
 
I agree, better 'bokeh' but i like the crispness of the face / detail. The 2nd one looks too soft
 
The 2nd one is at f1.4, it's not the sharpest lens in the world at f1.4.
 
Just a bit of a technical question that I'm sure somebody will explain (in simple mans speak preferably) Is it not the camera body that ultimately decides that the lens has achieved "focus" on a particular spot ie focus point within the view finder? What contribution to this process does the lens actually make? I'm confused :shrug:
 
diggerz said:
Just a bit of a technical question that I'm sure somebody will explain (in simple mans speak preferably) Is it not the camera body that ultimately decides that the lens has achieved "focus" on a particular spot ie focus point within the view finder? What contribution to this process does the lens actually make? I'm confused :shrug:
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The camera calculates the focus adjustment required of the lens and instructs it to make that adjustment. What the lens chooses to do with that instruction is up to the lens. The camera may make an inaccurate calculation, or the lens, either through poor calibration or mechanical wear, may not move by the correct amount. The lens does confirm that it has completed the instruction, and that's when you get the "beep". That does not mean you have a perfectly focused image, only that the camera and lens think you have perfect focus.

Sometimes a lens will overshoot the intended position, but knows enough to move itself back to where it should be. This can sometimes be seen as a small correction while focusing. This is not a sign of refining focus accuracy, just overcoming a slight overshoot in the initial focus movement.

This focusing procedure is "open loop", meaning that there is no further check made by the camera to confirm the focus is sharp. A "closed loop" system would be one where the camera re-checked focus and issued a further adjustment instruction if need be, and repeated this until the focus became no sharper.
 
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so to update this, the lens ended up going back because once I tried it on my new 5d mark 2 it was way out even after microadjustment,

just received the new copy today and happy to say it is spot on, without even needing a microadjustment!
 
tdodd said:
This focusing procedure is "open loop
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Never knew that :eek:

Are there any cameras that use a closed loop system ?, it'd be a tiny slower but open loop offends the technical side of me :bang:
 
mrgubby said:
Never knew that :eek:

Are there any cameras that use a closed loop system ?, it'd be a tiny slower but open loop offends the technical side of me :bang:
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Well, that was my understanding, but a quick Google has uncovered a discussion where things seem less clear cut.....

http://forums.dpreview.com/forums/readflat.asp?forum=1031&thread=31654233&page=1

What seems beyond doubt is that the typical implementation of phase detect AF systems are unable to confirm accurate focus and must rely on accurate calibration of the camera body and the lens mechanics in order to ensure (as far as possible) that focus is accurate. Even with perfect calibration I imagine that operational tolerances mean that perfection is not guaranteed from shot to shot or when significantly changing subject distance or, with a zoom lens, changing focal length.

The fact is that whenever the optical path for the focusing system differs from the path taken for the final image capture then exact precision is unlikely to be guaranteed. When using contrast detect AF, such as Live AF constantly adjusting until highest contrast is achieved at the sensor - the exact same place the image will be captured - then you can be reasonably confident that the focus will be very accurate indeed.

Of course, in the real world there are other little challenges such as subject movement and photographer wobble to further complicate things, or the chosen AF point latching onto something that is not the intended target - e.g. an eyelash instead of an eyeball.
 
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