The awesome Canon 50mm 1.8 II

Manfr3d

I bought the el cheapo fantastic plastic 50mm/1.8 II lens today ... now check out what it does on my 21MP 5D II .. at f2.0, 1/400s, ISO400:

100% crop center:


100% crop corner:


Full scene (resized):


All images are straight from RAW -> 96% JPEG without any postprocessing.

Holy cow, what a lens!!! Everyone should own one .. the focus is fast too btw. :barb

firstarsbrnwhite

damn that is sharp

Scott_Quier

You got a good one!

The 50mm f/1.8 II can be a terrific lens, if you get a good copy ... and there's the rub. Some are good (maybe most, the copy I had was also quite good) and some are just a touch off.

They do focus well in adequate light. It's when the light starts to drop a bit that the AF starts to have problems, at least on my 20D & 30D cameras.

Manfr3d

Scott_Quier wrote:

You got a good one!

The 50mm f/1.8 II can be a terrific lens, if you get a good copy ... and there's the rub. Some are good (maybe most, the copy I had was also quite good) and some are just a touch off.

They do focus well in adequate light. It's when the light starts to drop a bit that the AF starts to have problems, at least on my 20D & 30D cameras.

The 50 focuses pretty reliable on the 5D II even in low light - as long as I
focus on something with a little contrast. The focusing speed itself is really
good, much better than on my 10D. I also tried the Sigma 50mm/1.4 EX in
the shop but it was almost indistinguishable from the 50/1.8 at f2 and has
a much slower af speed. Go figure

codrus

Scott_Quier wrote:

You got a good one!

The 50mm f/1.8 II can be a terrific lens, if you get a good copy ... and there's the rub. Some are good (maybe most, the copy I had was also quite good) and some are just a touch off.

I've heard people say this kind of thing before, but I don't understand why. Aren't the AF detectors, circuitry, and software all in the camera body, with the only relevant part in the lens being the motor? How can the light level affect the performance of the motor?

--Ian

Scott_Quier

codrus wrote:

I've heard people say this kind of thing before, but I don't understand why. Aren't the AF detectors, circuitry, and software all in the camera body, with the only relevant part in the lens being the motor? How can the light level affect the performance of the motor?

--Ian

I don't know why I get performance differences from one lens to another in the EXACT same situation. I actaully ran a test to determine for myself if this performance difference was real or just an artifact of my skewed perceptions. It's real - at least for my cameras/lenses.

As to why AF works better in good light versus not so good - AF work on the basis of contrast, I guess under the assumption that if the camera sees a sharp contrast boundry it's got a good focus. Contrast improves with improved light. For example, take a look at a white t-shirt against dark jeans in good light and then again after you turn out the lights (do this just before sunrise or just before sunset so you can actually see when you turn off the lights). Better contrast with the lights on - No?

divamum

Scott_Quier wrote:

You got a good one!

The 50mm f/1.8 II can be a terrific lens, if you get a good copy ... and there's the rub. Some are good (maybe most, the copy I had was also quite good) and some are just a touch off.

They do focus well in adequate light. It's when the light starts to drop a bit that the AF starts to have problems, at least on my 20D & 30D cameras.

Agreed on all counts. Love mine (in fact, in recent weeks it's become the lens that stays on my camera since it always seems to be the one I wind up using in all but the most distant situations) but boy can it hunt when light is low! It usually gets there in the end, but sometimes I have to trick it into find something to latch onto or, of course, use mf.

But it deserves all the praise it gets especially since so little in photography land is AFFORDABLE like it is!

ziggy53

codrus wrote:

I've heard people say this kind of thing before, but I don't understand why. Aren't the AF detectors, circuitry, and software all in the camera body, with the only relevant part in the lens being the motor? How can the light level affect the performance of the motor?

--Ian

In addition to what Scott said about AF being more sensitive and accurate in good light (a dSLR AF module uses a sensor similar to an image sensor*), AF accuracy also depends partly on how the lens motor and focus elements are controlled.

When a lens is being focused it has to move optical elements within the lens body. Those elements have mass and the combination of helical screw pitch of the focus mechanism plus the speed and torque of the AF motor as well as the drag inherent within the focus mechanism all play a part in the control of the AF process.

When a lens is being focused, those parts which rotate have momentum, as does any object in motion. In order for the AF to work properly, it has to cut the AF motor just before the point of prime focus or the lens will overshoot because of the momentum. (Try to stop a spinning bicycle wheel instantly with your hands and you will understand about momentum.) The exact moment that the motor is cut is calculated as a function of momentum versus drag/braking.

If the lens focus elements have too much drag/braking, the lens will stop short of prime focus during its travel. If the lens focus elements have too little drag/braking, the lens will go beyond prime focus during its travel.

Lenses which exhibit consistent front and back focus, miss-focus, can often be adjusted for drag/braking to correct the miss-focus. Older lenses and damaged/dropped/abused lenses are often suspect.

Lenses which exhibit consistent front or consistent back focus have different issues and sometimes the micro-adjust feature of some of the newer cameras can help.

* More information about how autofocus systems work:
http://en.wikipedia.org/wiki/Autofocus

codrus

Scott_Quier wrote:

I don't know why I get performance differences from one lens to another in the EXACT same situation. I actaully ran a test to determine for myself if this performance difference was real or just an artifact of my skewed perceptions. It's real - at least for my cameras/lenses.

As to why AF works better in good light versus not so good - AF work on the basis of contrast.

Sure, I understand why AF works better when there's more light. It's the part about how different lenses on the same body can be affected differently by changing light levels that doesn't make sense to me. I can see how maximum aperture would affect it (AF wide open, wider aperture means more light, better contrast detection), but if that were all that was going on then I'd think that, being an f/1.8, the cheap 50mm lens would AF better in low light than an f/2.8 L zoom lens, which does not seem to be the case.

And yeah, per ziggy53's response about the physical inertia of the focusing mechanism, the L lens is going to be more responsive. Surely that difference in response shouldn't change with the light level, though?

--Ian

Manfr3d

Maybe because lens influence contrast and sharpness? Just guessing Some lenses also transmit distance information back to the camera body while others dont.

Scott_Quier

codrus wrote:

Sure, I understand why AF works better when there's more light. It's the part about how different lenses on the same body can be affected differently by changing light levels that doesn't make sense to me. I can see how maximum aperture would affect it (AF wide open, wider aperture means more light, better contrast detection), but if that were all that was going on then I'd think that, being an f/1.8, the cheap 50mm lens would AF better in low light than an f/2.8 L zoom lens, which does not seem to be the case.
And yeah, per ziggy53's response about the physical inertia of the focusing mechanism, the L lens is going to be more responsive. Surely that difference in response shouldn't change with the light level, though?

--Ian

I would think the same thing - it would seem to make sense and I have no explaination. This is something I would love to better understand.

My experience has been:

• Tamron 28-75 f/2.8 - in low light situations, it will tend to hunt a bit. Not too bad, I've done a couple of wedding receptions with this lens and I have a friend that uses this lens as his work-horse.
• I've done a part of a receptions with an EF 24-105 f/4L IS. It doesn't hunt nearly as much as the Tammy and, based on the maximum aperture I would expect it to be worse in low light. But, it's not.
• Then, there's my EF-S 17-55 f/2.8 IS ( this lens). It's my work-horse, my first "go to" lens. It very, very seldom hunts. I think it would find focus lock on a gray mist in an unlit cave.

BTW - all three of the above examples are with the same (Canon 30D) body. I can't provide anything that would even come close to a reasonable explaination for this obvserved behavior. I just know, for my lenses, that this is a fact of life and I compensate my behavior accordingly.

Is there anyone who can offer up a reasonable explaination to account for this observed behavior?

wsquared

Re: the Canon 50mm F1.8

I have this lens too. It's a no cost low light weapon and you're not lugging around an F 1.2 tank. Try maxing out your ISO setting to 3200 or beyond, switching to monochrome & lurking in dim settings with this lens where you still need the low end 1.8 f-stop. It's like being transported to a film noir set.

WW

LKN Dave

Nikon
Anyone have the Nikor 50mm 1.8? I have read some good things about it, but since I have the Canon 1.4 I don't really know. I am thinking about picking it up from my Brother.

David_S85

• Then, there's my EF-S 17-55 f/2.8 IS ( this lens). It's my work-horse, my first "go to" lens. It very, very seldom hunts. I think it would find focus lock on a gray mist in an unlit cave.

ziggy53

LKN Dave wrote:

Anyone have the Nikor 50mm 1.8? I have read some good things about it, but since I have the Canon 1.4 I don't really know. I am thinking about picking it up from my Brother.

The Nikkor 50mm, f1.8D is better than the Canon equivalent, but only on the Nikon cameras. Since you have the Canon EF 50mm, f1.4 USM you have a "very" good AF 50mm lens, and at f1.8 it is as good as the Nikkor f1.8 IMO.

If you want a manual focus lens of extremely good heritage I can recommend the Pentax 50mm, f1.4 SMC. Used with one of the adapters with focus confirmation it's actually usable and the results are very nice.

http://www.dgrin.com/showthread.php?t=62165

time2smile

LKN Dave wrote:

Anyone have the Nikor 50mm 1.8? I have read some good things about it, but since I have the Canon 1.4 I don't really know. I am thinking about picking it up from my Brother.

get it - i use mine quite often. even better get the
85 f1.8D - now thats a sharp lens

jeffreaux2

ziggy53 wrote:

The Nikkor 50mm, f1.8D is better than the Canon equivalent, but only on the Nikon cameras. Since you have the Canon EF 50mm, f1.4 USM you have a "very" good AF 50mm lens, and at f1.8 it is as good as the Nikkor f1.8 IMO.

If you want a manual focus lens of extremely good heritage I can recommend the Pentax 50mm, f1.4 SMC. Used with one of the adapters with focus confirmation it's actually usable and the results are very nice.

http://www.dgrin.com/showthread.php?t=62165

Hey Ive got one of those.....thanks for the info...Ill check it out.

I had gotten some great shots with my 50mm F1.8......and then some not so great. I found it to be stunningly good when it was good, but also very inconsistant in results. It wasn't soft, but instead was misfocusing now and then. I have sold it, and plan to replace it soon with the Canon 50mm F1.4.

ziggy53

jeffreaux2 wrote:

...

I had gotten some great shots with my 50mm F1.8......and then some not so great. I found it to be stunningly good when it was good, but also very inconsistant in results. It wasn't soft, but instead was misfocusing now and then. I have sold it, and plan to replace it soon with the Canon 50mm F1.4.

I have both the Canon 50mm, f1.8 and f1.4 and yes, the f1.4 is much more accurate and consistant to focus.

BTW, I have some more samples of the Pentax 50mm, f1.4 SMC here:

http://www.dgrin.com/showthread.php?t=38398

jeffreaux2

ziggy53 wrote:

I have both the Canon 50mm, f1.8 and f1.4 and yes, the f1.4 is much more accurate and consistant to focus.

BTW, I have some more samples of the Pentax 50mm, f1.4 SMC here:

http://www.dgrin.com/showthread.php?t=38398

The Pentax lens I have is the 50mm Pentax-M with the bayonet mount. It fits my old ME-Super. I Think it might be F1.4. It came with that camera.

ziggy53

That would be the Pentax "K" mount, also known as the "PK" mount. I think you can get Canon body adapters with focus confirmation for that mount, but I haven't really researched it.

I have both Pentax/Universal/M42 screw mount lenses and PK mount lenses, but my better lenses are the screw mount. Surprisingly good are:

Soligor 28mm, f2.8
Pentax 50mm, f1.4 SMC
Vivitar 105mm, f2.8
Pentax 200mm, f4 Super Multi Coated
Vivitar 500mm, f6.3
Pentax 500mm, f4.5 SMC (the Beast)

Manfr3d

But remember that Pentax PK mount lenses are not compatible (even with adapter) to Canon fullframe cameras. The lens reaches too far into the mirror box. I have an old Pentax PK SMC-M 50mm/1.7 and tried it myself, without luck.

LKN Dave

Thanks for all the comments about the Nikon 50mm. I decided to get one for my brother and his Nikon.