Canon 50mm 1.8 MKII with 400D

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Hi everyone,

I am sure I am doing something very stupid! I have just bought the Canon 50mm 1.8 MKII to use on my 400D.

I got it because of its low light capabilities and general good IQ for such a low price, and to take portraits of my family (indoors without flash).

I can not, for the life of me, get it to focus and my camera will not let me take a picture unless there is lots of light (I am also cranking up the ISO). Please help!!!
 
lots more info needed really to be able to help... can you post an example shot with EXIF data intact?
 
How little light are we talking about? The AF system needs to be able to lock onto something, so it can't do it in the pitch black, but it should be able to cope in a dimly lit room for example.

Are you using it at f/1.8? The depth of field will be incredibly thin, could that possibly be the problem?

Chris
 
Unfortunately this is common problem caused by the lack of contrast in dark settings. i have seen in all the canon models up to the 5DII. i suspect the 1 series may not be prone to this.

the camera's AF works by a method of contrast detection (someone plz correct me if i am wrong). this works fine under normal lighting conditions but as the amount of available light decreases the so does the AF performance.

this has nothing to do with the lens.

your best bet is to either use the af assist beam frm a Speedlite or shine a torch on ** subject (thereby artificially increasing contrast). you can always use MF.

kickin up the ISO wont help AF.
 
Snap_Happy said:
It's also worth adding, that you could always just shoot in manual focus?
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That's great if you're not using the lens at f1.8, because as mentioned, the depth of field is tiny and mucking up the focus even a tiny bit will ruin the pictures.

I use the 400D & 50mm a lot, and it does struggle to focus when the subject isn't well lit. If you're walking around the room stumbling into things, it's too dark! :lol:
Make sure you (with your eyes) can properly make out people's features, then the camera should be able to see too. If it's too dark, you'll have slow shutter speeds even at f1.8, which makes hand-held pics much harder, as i'm sure you're aware :)
 
Don't want to ask a stupid question - but here goes. Is there an AF/MF switch and have you checked it's set to AF?
 
macro_man said:
the camera's AF works by a method of contrast detection (someone plz correct me if i am wrong).
Click to expand...

You're wrong :D

In "normal" AF it uses phase detection.

Contrast detection is only used for live view.

Things for our friend to try:

1) Make sure you are only using the centre focus point.

2) Try live view because it uses contrast detection - its slower but more accurate in dim light.

3) Tell your subjects not to move.

4) Make sure your problem is focus and not subject/camera movement - check the results you've got back for shutter speeds, if its too low increase the ISO.
 
i knew i should have checked wikipedia!!
I stand corrected.
 
Cyprino said:
That's great if you're not using the lens at f1.8, because as mentioned, the depth of field is tiny and mucking up the focus even a tiny bit will ruin the pictures.
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I use a manual focus 50mm 1.4 and I don't find focussing too much of a problem.
 
And unless my eyes deceive me you use a camera with a sensor half the size of full frame... meaning it's effectively an f/2.8 lens. I can just about focus fine for f/2.8 on manual.
 
trencheel303 said:
And unless my eyes deceive me you use a camera with a sensor half the size of full frame... meaning it's effectively an f/2.8 lens. I can just about focus fine for f/2.8 on manual.
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But the OP has a 400D which uses an APS-C sensor, not full frame and not that much bigger than a 4/3 sensor. ;)

frame-size.gif


(blue vs yellow)
 
I owned a 50mm 1.8 MkII and you will probably be better off with manual focus at f/1.8.

While it is a great lens for the money, the AF motor isn't very accurate and often stops just off target (enough to cause problems at f/1.8).

I upgraded to the 50mm 1.4 and was very pleased I did.

Does the 400D have an AF assist beam of it's own? I think some of the Canon models do.
 
James Wheeler said:
I owned a 50mm 1.8 MkII and you will probably be better off with manual focus at f/1.8.

While it is a great lens for the money, the AF motor isn't very accurate and often stops just off target (enough to cause problems at f/1.8).

I upgraded to the 50mm 1.4 and was very pleased I did.

Does the 400D have an AF assist beam of it's own? I think some of the Canon models do.
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You must be a lot better than me with your hands/legs/beating of heart as MF at 1.8 was nearly always hopeless for me. The AF motor of the 1.4 seems to be just as (in)accurate as the 1.8 in that poor light I often get a strong back or front focus. FTM helps correct this easily.

Luke: We've already established that it is not in MF.



grum said:
But the OP has a 400D which uses an APS-C sensor, not full frame and not that much bigger than a 4/3 sensor. ;)

frame-size.gif


(blue vs yellow)
Click to expand...

You made a comment about your ability to manual focus using a 1.4 lens on a 2x crop factor camera, and my comment was relative to that.

Your original comment actually bore little resemblance to the OP's problem in the first place...
 
Trencheel, I suppose it depends what you are taking pictures of, my tripod doesn't have a heart beat I don't think :)

My 50mm f/1.4 seems to be much more accurate than the f/1.8 I had in all the uses I have had from it so far. All lenses are not made equal as we know :)
 
trencheel303 said:
Your original comment actually bore little resemblance to the OP's problem in the first place...
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Er... I was suggesting that it's perfectly possible to manually focus fast lenses wide open which might be useful to the OP - f1.4 on a 4/3 sensor is presumably fairly similar to f1.8 on an APS-C sensor?
 
grum said:
Er... I was suggesting that it's perfectly possible to manually focus fast lenses wide open which might be useful to the OP - f1.4 on a 4/3 sensor is presumably fairly similar to f1.8 on an APS-C sensor?
Click to expand...

f/1.4 on a 4/3 sensor equals f/2.8. On a 1.6x it equals roughly f/2.2.

Now, I don't know about you, but I can see a visible difference in DOF between all of those f/ stops.
 
trencheel303 said:
f/1.4 on a 4/3 sensor equals f/2.8. On a 1.6x it equals roughly f/2.2.

Now, I don't know about you, but I can see a visible difference in DOF between all of those f/ stops.
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I'm sorry but aren't you trencheel303 and therefore by definition wrong about everything photography-related?

:D
 
of course how could i forget...
 
trencheel303 said:
f/1.4 on a 4/3 sensor equals f/2.8. On a 1.6x it equals roughly f/2.2.

Now, I don't know about you, but I can see a visible difference in DOF between all of those f/ stops.
Click to expand...

But f1.8 on a 1.6x crop sensor is almost exactly the same as f1.4 on a 2x crop sensor no?

I wasn't talking about f1.4 on a 2x crop camera - as that wouldn't be relevant to the OP. :p
 
We were at a wedding last week, by the time the early evening came my wife had to put away her 400D it just refused to focus without pre-flash.
The 50d (at last something positive to say about it) managed fine, I'd guess Canon built the 400d down to a price and expected 'entry' level users to never move from full auto or P (which I think fires up the flash - dunno we never use those modes, but I think I read that in the manual a while ago).

Matt
 
grum said:
I wasn't talking about f1.4 on a 2x crop camera - as that wouldn't be relevant to the OP. :p
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Well then why would you say the below when you own and use a 2x crop camera not a 1.6 camera?

grum said:
I use a manual focus 50mm 1.4 and I don't find focussing too much of a problem.
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By what you're saying your own comment above ^^ is irrelevant, then. I repeat, on a 2x camera DOF is larger than even on a 1.6 camera. You can't really compare, imo.

Anyway, let's stop @rsing about on this thread and let the OP have his subject back... :suspect:
 
Oh dear - this is getting rather silly.

- Someone suggested manual focus might be a good option.

- Someone else said manual focussing at f1.8 was too hard.

- I suggested that I found focussing ok on my camera at f1.4 - WHICH IS ALMOST EXACTLY THE SAME EXPERIENCE AS F1.8 ON THE OP'S CAMERA.

It's really not that hard to understand is it? I'm going to stop posting in this thread now.
 
Having just checked a plotter a 50mm lens at f1.8 gives an in focus window of +and - 3inches either side of the focussed point, at f2.8 this stretches to 4 inches and at f4, 7 inches. You or the subject do not need to be moving much to lose that pin shape image we are looking for.
As mentioned above my 400D focusses better on the centre cross point in low light.
 
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