Ad
Ad
Ad
Pages: [1]   Bottom of Page
Print
Author Topic: Canon Mark 2 focus question  (Read 925 times)
kevs
Sr. Member
****
Offline Offline

Posts: 299


« on: November 11, 2013, 03:02:58 PM »
ReplyReply

Yesterday, I was shooting (studio strobes only) with a fixed 50mm 1.8, one subject full body head to toe.

I was having problems getting the face/ eyes consistently sharp.

My assistant offered a few suggestions, but I don't really know issue is solved, but these do help, any other ideas on this? These were his suggestions for now:

1) Use the 24-70 L lens I have as that is better glass. ( I own this lens too, and use it with stabilization on)
2) Shoot at 125, not 60 which I usually do.
3) Set the focus points to all, not just one, which I usually do I usually just use one focus point, the one at the top center near the eyes. He says use as many as you can.
4) Get a Mark 3 which is better at focus.
5) Consciously hold the camera very steady, which I admittedly don't pay enough attention to doing consistently. I always shoot handheld.

I always thought the shooting at 60, and not worrying about shake was not a big deal as the strobes (no ambient coming through windows, maybe a very small tad), should overpower everything and get the face sharp). So these suggestions by my assistant are good, but they did not solve the issue 100% even employing all his ideas. Note, that this focus issue disappears if I shoot a tight headshots. It's some about getting the face tack sharp on a head to toe shot that is the issue.

Logged

Imac 27"
10.6.8
CS5
robdickinson
Full Member
***
Offline Offline

Posts: 121


« Reply #1 on: November 11, 2013, 03:29:43 PM »
ReplyReply

I assume you mean a 5d mark 2? it has IMO poor focus especially the outer points. A mk3 would be much better.

I also assume you are shooting the 50 at 1.8? It is soft at 1.8 much better at 2.5.

1) Use the 24-70 L lens I have as that is better glass. ( I own this lens too, and use it with stabilization on)
I found my 50/1.8 focused fine on the 7d once micro adjusted. I dont think its a poor focusing lens at all. Just slow and clunky at times.

2) Shoot at 125, not 60 which I usually do.
Camera shake results in softness over all the photo. Examine the photo see if it is camera shake or missed focus ( see if any part is in focus/sharp).

3) Set the focus points to all, not just one, which I usually do I usually just use one focus point, the one at the top center near the eyes. He says use as many as you can.
CRAZY. Canon cameras will focus on the closest thing under ANY focus point if they are all enabled. This is almost always not what you will want in focus. This is a really really bad suggestion.

4) Get a Mark 3 which is better at focus.
If it is a camera focus issue yes - but focusing is as much down to the photographer as to the camera. Are you focus and recomposing? This will result in OOF photos. Look at your technique, do some testing.

5) Consciously hold the camera very steady, which I admittedly don't pay enough attention to doing consistently. I always shoot handheld.
Hand held is OK but 1/60th is pushing it for consistency depending on your holding technique. again see no 2.


Look up correct hand holding techniques and proper focus use. Dont focus and recompose fast lenses. Move the focus point around, Properly test your technique and the lens, micro adjust its focus if needed.
Logged
kevs
Sr. Member
****
Offline Offline

Posts: 299


« Reply #2 on: November 11, 2013, 05:13:06 PM »
ReplyReply

thanks Rob, I was shooting at f/22!

Sorry forgot to mention that.

Hard to know if shake create the softness.

Rob, yet, focus on eyes, but then need to move the camera down a few inches for composition.

Logged

Imac 27"
10.6.8
CS5
robdickinson
Full Member
***
Offline Offline

Posts: 121


« Reply #3 on: November 11, 2013, 05:30:14 PM »
ReplyReply

f22 will create its own softness through diffraction.

Why are you shooting at f22? Turn the flash power down some or drop the ISO. Pick a reasonable aperture for dof like f8 or f11.

Also in studio when you are focusing with flash there may not be much ambient light for the camera to lock on, what are the ambient light levels like?


And most of all post an example, and 100% crops (or link to the full sized image) - with exif intact. this helps a lot.
Logged
kevs
Sr. Member
****
Offline Offline

Posts: 299


« Reply #4 on: November 11, 2013, 07:14:43 PM »
ReplyReply

Rob,
"f22 will create its own softness through diffraction."

What does that mean? never heard of that.

Because I was also shooting 4x5 film which really needed good depth of field, the 4x5 was at f/32.  Last shoot I shot the 4x5 at f/ 11 and everything was out of focus.

But with Canon, why would good depth of field be bad?

Rob: there is enough ambient for the focus square to turn red and beep. Aren't I good then? Still the face is out of focus.

This is unpublished fine art project, so I cannot release images online for everyone to see. Just a face out of focus, the data is simple, f/22, 125 shutter, iso 200...

If you are in LA I would invite you by to look at everything...
Logged

Imac 27"
10.6.8
CS5
robdickinson
Full Member
***
Offline Offline

Posts: 121


« Reply #5 on: November 11, 2013, 07:23:21 PM »
ReplyReply

http://www.luminous-landscape.com/tutorials/understanding-series/u-diffraction.shtml

The 5d2 sensor is a lot smaller than the 4x5 film... Which means diffraction will affect the image sooner, which is why you will see it at f22 on a 5d2.

For DOF use a DOF calculator to see what aperture you need to stop down to before you shoot. You will be able to use a larger aperture on the 5d2 than you do on the MF/lf stuff. http://www.dofmaster.com/dofjs.html


If you get a beep the camera thinks it has locked focus, at f22 you should have plenty of dof - I dont think this is a focus issue.

If the images are not publishable then go and shoot a test shot under the same conditions for us. Its much easier to sort out problems with examples.
Logged
kevs
Sr. Member
****
Offline Offline

Posts: 299


« Reply #6 on: November 18, 2013, 03:05:27 PM »
ReplyReply

ROB
Excellent post.

Wow, so you feel with the Canon, if I shoot 50mm at f/ 11 the images will be way sharper than 16, 22? And really, because its 35mm the DOF should be fine?

Whereas, 4x5, at f/16 with 210 lens, you get only a foot or two DOF!

So 35 and 4x5 just two different worlds, 4x5 is so much more problematic with DOF.

The DOF calculator was real nice.

Do you think f/ 32, 45 on the 4x5  210 lens though will give me focus issues/ defrations issues?   

For 35mm you want to be stopped down how many stops from the max aperture? Same question for 4x5 lenses.  You don't think this had anything to do with the 50mm lens on Canon not being good glass, or focus points, or other stuff my intern/ assistant was suggesting?  Still even at 22, we did manage to get some sharp shots, just not consistently. Is he correct in thinking the 24-70 L lens set at 50, is better than using a fixed canon 50 1.8?
Logged

Imac 27"
10.6.8
CS5
robdickinson
Full Member
***
Offline Offline

Posts: 121


« Reply #7 on: November 18, 2013, 05:18:24 PM »
ReplyReply

The canon 50/1.8 is one of canons sharpest lenses (when stopped down).

Achieving an mtf score of 3722 at f4 for centre frame - http://www.photozone.de/canon_eos_ff/415-canon_50_18_ff?start=1

Where the 50/1.2L only manages 3584 - http://www.photozone.de/canon_eos_ff/472-canon_50_12_5d?start=1

And the super 'sharp' new 24-70f2.8 mkII gets 3709 (at 40mm) peak.  http://www.photozone.de/canon_eos_ff/773-canon2470f28mk2ff?start=1

If you look at the 50/1.8 numbers the centre peaks at f4 but the edges increase to f5.6 and level off.

According to lenstips f22 is about the same as shooting it wide open (poorer centre better corners).


http://www.lenstip.com/27.4-Lens_review-Canon_EF_50_mm_f_1.8_II_Image_resolution.html
Take a look at the 50/1.2 mtf graph you can see the curve dropping off past f4/5.6

When I had a 50/1.8 I was never dissapointed in its sharpness - perhaps yours is damaged? Its fairly frail.

As for medium format I have no practical experience of it though I assume its a similar change from aps-c crop to ff/135, you can, and need, to stop down some more.


Logged
kevs
Sr. Member
****
Offline Offline

Posts: 299


« Reply #8 on: November 19, 2013, 03:01:53 PM »
ReplyReply

thanks Rob,
I understood 1/2 of that.

Damaged, how would I know, to me it works or does not. Have not dropped it that I'm aware of.

But what f/stop is ideal for the lens? thanks!
Logged

Imac 27"
10.6.8
CS5
robdickinson
Full Member
***
Offline Offline

Posts: 121


« Reply #9 on: November 19, 2013, 05:47:39 PM »
ReplyReply

f4 to f5.6 is the best for the 50/1.8 for centre sharpness. Corners improve to f11 or so.

But that is useless if you require a different (more or less) depth of field!
Logged
Jim Pascoe
Sr. Member
****
Offline Offline

Posts: 709


WWW
« Reply #10 on: November 20, 2013, 06:35:41 AM »
ReplyReply

I would suggest that if you are working from a tripod that you focus in live view, and then if the lens is also stopped down f4 to f8 it's highly unlikely anything will be out of focus - if you are shooting a person full length.
I think Rob has said about everything else.
Jim
Logged
Pages: [1]   Top of Page
Print
Jump to:  

Ad
Ad
Ad