50mm 1.2 help

With DoF that thin, there's no way you're going to nail the focus manually unless on a tripod using live view at high magnification.
 
HoppyUK said:
That's an interesting comment. I've not seen that before, but the evidence is there in your other shot in post #27.

However, if it was the raised mirror, would that not clip the underside of the highlight circle? And you say it does not disappear until f/4. Just thinking out loud, but I can't equate that to any intrusion in the mirror box. Confused as to what's going on :thinking:
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What I thought, too :thinking:

But CT is a genius so no doubt he'll help us understand :)
 
HoppyUK said:
That's an interesting comment. I've not seen that before, but the evidence is there in your other shot in post #27.

However, if it was the raised mirror, would that not clip the underside of the highlight circle? And you say it does not disappear until f/4. Just thinking out loud, but I can't equate that to any intrusion in the mirror box. Confused as to what's going on :thinking:
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Ah good point Hoppy. The phenomenon is well documented and usually attributed to the mirror which I've never questioned, but I see where you're at. I'm out this evening, but I'll cogitate on the matter. :D
 
how is this

IMG_1170.jpg


just a quick attempt!! be kind LOL
 
HoppyUK said:
However, if it was the raised mirror, would that not clip the underside of the highlight circle? And you say it does not disappear until f/4. Just thinking out loud, but I can't equate that to any intrusion in the mirror box. Confused as to what's going on :thinking:
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woooooooo I know something you guys don't thats never happened before, the image on the sensor is upside down same as in the eye :D

so the mirror clips the bottom of the light which is the top of the pic
 
david1701 said:
woooooooo I know something you guys don't thats never happened before, the image on the sensor is upside down same as in the eye :D

so the mirror clips the bottom of the light which is the top of the pic
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Beat me too it... so obvious innit? :D
 
david1701 said:
woooooooo I know something you guys don't thats never happened before, the image on the sensor is upside down same as in the eye :D

so the mirror clips the bottom of the light which is the top of the pic
Click to expand...
Actually that was going to be my quick initial response, but it doesn't really answer Hoppy's question. By the time the image circle hits the mirror it would already be upside down and reversed laterally having already passed through the lens so it should be the bottom of oof highlights getting clipped. :LOL:
 
They're much better than your early shots. I have the f/1.4 and to be honest it's really only worth using at f/2 or smaller unless you accept the shot won't be that sharp.

The photo of the dog is a vast improvment. Try to focus on his eyes and use an aperature of say f/4, then f/2.8, f/2 and f/1.4 and see what you like the most.
 
I think you were compressing the files too much, which is why some of them shown what you called noise. ;)
They were also lacking sharpness, but it seems you are now solving this problem.
 
CT said:
Actually that was going to be my quick initial response, but it doesn't really answer Hoppy's question. By the time the image circle hits the mirror it would already be upside down and reversed laterally having already passed through the lens so it should be the bottom of oof highlights getting clipped. :LOL:
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thats the point, the lens makes the image upside down, the mirror clips the bottom of that upside down beam of light then the sensor records it and makes it the right way up in post, I would guess a piece fo film is upside down in camera too


and to add i 50L ..... (L)
 
david1701 said:
thats the point, the lens makes the image upside down, the mirror clips the bottom of that upside down beam of light then the sensor records it and makes it the right way up in post/
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Nope. :D The image is turned upside down as it passes through the lens. If the mirror was clipping the bottom of those oof highlights (while they were at the top - the image being upside down) then when the onboard software flipped the image the right way up, they'd be on the bottom still.

I would guess a piece fo film is upside down in camera too


and to add i 50L ..... (L)
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It is - in fact it's upside down and also flipped laterally - just as it is with a digital sensor.

This is Hoppy's fault. ;)
 
confuddled if you clip the bottom of something upside down, you clip the top of the resolved bit surely, though as its clipping top or bottom only lateral flipping won't affect it
 
Lateral flipping doesn't come into it with this problem, until you turn the camera to portrait orientation - then it does. :D

Actually, I see Hoppy's point. Something is clipping the oof highlights for sure, and every explanation I've seen puts it down to the raised mirror, but when you think about it, it doesn't make a lot of sense, although I've had a few pints now. :beer:
 
CT said:
Lateral flipping doesn't come into it with this problem, until you turn the camera to portrait orientation - then it does. :D

Actually, I see Hoppy's point. Something is clipping the oof highlights for sure, and every explanation I've seen puts it down to the raised mirror, but when you think about it, it doesn't make a lot of sense, although I've had a few pints now. :beer:
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LOL ;)

None of this makes any sense to me at all :thinking: And after a quick google I can't find any other reference to this effect. Only a lot of other photos showing perfectly circular bokeh, which is what you would expect.

There must be something going on in the pic CT posted, in the background that we can't see, which is clipping those out of focus highlights in the image itself. IMHO there's no other answer.
 
HoppyUK said:
LOL ;)

None of this makes any sense to me at all :thinking: And after a quick google I can't find any other reference to this effect. Only a lot of other photos showing perfectly circular bokeh, which is what you would expect.

There must be something going on in the pic CT posted, in the background that we can't see, which is clipping those out of focus highlights in the image itself. IMHO there's no other answer.
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Have a look at this review. There are others with better examples of the effect, but I'm damned if I can find them.

http://www.lens-scape.com/article/50mm-12vs14/50mm12vs14.htm
 
I wonder if the aperature is perfectly round when fully open? Maybe it's the base of the lens causing the issue?

EDIT - Just seen your link CT. Interesting the clipped bit is on different sides of the circles at the top and bottom of the pic
 
30psi said:
EDIT - Just seen your link CT. Interesting the clipped bit is on different sides of the circles at the top and bottom of the pic
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Yeah - I noticed that - just to confuse the issue further! :D

The effect is definitely there with this lens and as I say it's always been attributed to the raised mirror, but that explanation doesn't seem to make a lot of sense when you really think about it.
 
CT said:
Have a look at this review. There are others with better examples of the effect, but I'm damned if I can find them.

http://www.lens-scape.com/article/50mm-12vs14/50mm12vs14.htm
Click to expand...

That's really interesting CT. I've got it now :)

The OOF highlights are clipped on the bottom at the top of the frame, and on the top at the bottom, which is because the light cone is wider than the throat of the mirror box. The mirror box (not just the mirror) is narrower on the top and bottom.

I have to say this isn't very good (although hard to avoid without a hugely over-size mirror box) for a lens often purchased for the quality of its bokeh. I'm guessing that the 35mm f/1.4 will perhaps be okay in this respect, both in terms of shorter focal length and slightly smaller aperture, but the 85mm f/1.2 will be worse?

And also, while it might be f/1.2 in DOF terms, it is not f/1.2 in exposure terms!
 
Mirror box sounds like sensible answer if it isn't the back of the lens itself of course.

Is this an issue on all sensor sizes?
 
HoppyUK said:
That's really interesting CT. I've got it now :)

The OOF highlights are clipped on the bottom at the top of the frame, and on the top at the bottom, which is because the light cone is wider than the throat of the mirror box. The mirror box (not just the mirror) is narrower on the top and bottom.
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Actually I've just been doing some tests to duplicate the effect and that's the conclusion I've come to which does make sense. It's also the exact amount by which the the specular highlight is oof which produces the effect - you can lose it by adjusting the amount by which it's oof. The brightness of the highlight also makes the effect more pronounced.

I have to say this isn't very good (although hard to avoid without a hugely over-size mirror box) for a lens often purchased for the quality of its bokeh. I'm guessing that the 35mm f/1.4 will perhaps be okay in this respect, both in terms of shorter focal length and slightly smaller aperture, but the 85mm f/1.2 will be worse?

And also, while it might be f/1.2 in DOF terms, it is not f/1.2 in exposure terms!
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Agreed, it's not good, and there would certainly be images where the effect is undesirable. The lens is also noted for pronounced CA in some circumstances.

Overall though, I have to say, it's still a great lens. I previously owned the 1.4 version which is excellent, but the 1.2L produces better colour saturation and contrast and is sharper at 1.4 than the 1.4 version. It also handles flare much better and is great for shooting into the light.

It's a matter of personal choice whether you can live with the weight and the cost when comparing the two lenses.
 
Not sure where you're going with that one, looks poor to me.

Re clipping - to my mind interfering part must be behind the apperture as otherwise it would show just a "squashing" of the highlight, like OOF highligths at the edges due to light restriction on the front element (i.e. 135mm F2.8 for example).
 
butterfly.shel said:
ok this was the last try and it was after a good half a bottle of wine......

Exposure: 0.02 sec (1/50)
Aperture: f/1.6
Focal Length: 50 mm
ISO Speed: 100
Exposure Bias: +2/3 EV

IMG_1192.jpg


hows that??
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It doesn't look sharp Shel, probably I suspect because you haven't sharpened the image after you've reduced it in size. This will always need doing with any image from any lens because when you reduce the size the image loses resolution (sharpness). In short it's hard to determne from that shot how sharp you got it.

It's a pretty poor test subject anyway to test focusing and sharpness. I suggest you set up something like this...

3307928254_e0996a9451_o.jpg


Take different shots, focusing on different bottles to see the effect it has.

If this is your first DSLR Shel, the 50mm 1.2L is a pretty demanding lens to learn the basics with. Do you have any other lenses?
 
another thing is that the cameras AF might be off. I borrowed a friends (abused) 300d and it was miles out with all my lenses.
 
butterfly.shel said:
ok this was the last try and it was after a good half a bottle of wine......

Exposure: 0.02 sec (1/50)
Aperture: f/1.6
Focal Length: 50 mm
ISO Speed: 100
Exposure Bias: +2/3 EV

IMG_1192.jpg


hows that??
Click to expand...

Looks soft to me.

Presuming you are about 2 metres away from the lamp your DOF is 5cm ! @f/1.6

If you want the whole lamp in focus, you'll need to change the DOF to 5.6 - 8.

See this useful calculator. http://www.dofmaster.com/dofjs.html
 
Here's a couple of kids portraits shot at F/1.2. The first one obviously a close up. Look at how little is in focus. The second is a crop on a larger picture. The further away the subject, the greater the area that is in focus at a given f stop.



 
i started off with a 400D and have now got the 40D i do have a 1.8 lens and some other lenses too like the 70-300 IS

i have always struggled with the technical stuff and find it easier to learn by having someone actually showing me................... i am trying to take everything you say in but your all so technical LOL............this i'm sure is why its a mainly male dominated area!!

i promise i will get there, might take some time but i will!!
 
have you tried a focus test chart with this or any other lens? Yes I realise they're not 100% but will give a pretty good idea if something is off. IMO the shot is OOF rather than lacking in sharpening.
 
This is the Canon 50mm F1.2 lens yes? the one that's about £1200 ????

I mean no offence at all and I hope you manage to get this sorted, but there is no way I could bring myself to spend that sort of money unless I knew exactly how I was going to be able to use the lens.

P.S. Good look though as I have struggled at times with the 1.8 version to get the shots I intended so I know it can be frustrating
 
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