EF 50 F/1.4 Lens Seems Soft

[jkelley]

I recently purchased the EF 50 F/1.4 lens and was taking some test shots this last weekend. I took a few shots where I was focusing at infinity and aperature wide open and noticed that the focus seemed very soft. Taking the same shot with the lens set at around 5.6, the image was very sharp.

How can I determine if that is normal for this lens. If anyone who has experience with this lens could give me an opinion based on some actual shots, I would be glad to post them.

Thanks for any help.

[EXA1a]

All lenses give softer pics wide open than stopped down a bit. The 50/1.4 is no exception. It is a great and sharp lens though!
I use this lens mainly for portraits at the moment. With ambient light I shoot at down to f2.0 normally. That gives me a small safety zone when taking pictures of our baby. For that purpose it's not too soft.
Why do you want to shoot wide open at infinity? Just as a test? For landscapes you would stop down anyway.
When your pictures are soft I can imagine a few main reasons:

1. camera shake or object movement at too low shutter speeds (use a tripod to avoid)
2. some softness due to wide open shooting (don't shoot wide open when you need really crisp pics)
3. focusing problem (do some testing at different object distances to figure out if your camera does front or backfocusing
4. scattered light flare (use a lens hood to avoid)

If you are really interested in what's going on you have to figure it out 1-4 systematically. Without some posted example photos nobody can really tell you.

--Jens--

[robertwgross]

EXA1a wrote:
Why do you want to shoot wide open at infinity? Just as a test? For landscapes you would stop down anyway.


Normally, I only shoot wide open for one of a few reasons:
(A) Extremely low light -- unusual for infinity shots.
(B) Extremely low light, ISO already maxed high, and using flash is unacceptable.
(C) Extremely low light, ISO already maxed high, and I still need to get flash range.
(D) I'm trying to carefully control the DOF, so I need to get the aperture wide open. By control of the DOF to near infinity, I would only be attempting to get rid of foreground objects from focus.

Yes, shooting wide open at infinity is kind of unusual, but then some of us are an unusual breed.

---Bob Gross---

[jkelley]

Shown below is an example of the issue I was trying to explain in my original post. Both of the images were taken with an EF 50 F/1.4 lens that I recently purchased. Both were taken under essentially the same lighting conditions. Both were taken at ISO 100 and were focused at infinity. The sharp image was shot at F6.7 and 1/90 sec. The soft image was taken at F1.4 and 1/3000 sec.

Are there any opinions out there as to whether this lens is generating the expected image quality at the F1.4 setting? The image is definitely more soft at wide open aperature, but I don't have any way to judge if this is normal image quality for this lens. I'm trying to determine if I have a good lens, or if I need to exchange it for a new one.

Any opinions would be greatly appreciated.

http://www.seanet.com/~jkelley/EF50_14_Test.jpg

[boobops]

The images you have are exactly what you should expect. What's your problem? F1.4 minimal DOF F6.8 reasonable DOF. Something to do with the physics, I believe!

[RichardtheSane]

boobops, your answer is most unhelpful and you don't seem to have taken into consideration that jkelly is asking the question because he doesn't know the answer. Please think 'is that how I would talk to someone I don't know face to face' before posting.

jkelly, infinity is definitly not the best range to be testing focus/sharpness of a lens. I would recommend testing it at a shorter range and also on a tripod/support.
What you have described is normal performance for the lens, but the images you posted do look soft - however I am sure that has a lot more to do with the conversion for web than the lens.

Try finding something to focus on at about midway through the lens focal range (probably about a meter) and use a tripod. Try to have the subject well enough lit so you can keep the shutter speed above 1/125th of a second and use mirror lockup/self timer.
View the images at 100% and see how different they are, also if you post back post a crop so we can see the images a 100% too - makes it much easier to judge then.

Good luck

[mishkin]

jkelly, it's not soft, it's misfocused. It's a typical issue with 50/1.4. Here's mine, 100% crop from D60 at f/1.4, blurry shot is AF, sharp shot is the best from the several bracketed MF shots:
http://canondslr.com/temp/AF/50_014_AFvsMF.gif

50/1.4 does get softer towards the edges at f/1.4, but it's tack-sharp in the center.

Try to focus manually (bracket with fine steps) and see the result. You may be impressed.

Learn about AF variations:
http://www.canondslr.com/articles/ai-servo/
http://www.canondslr.com/articles/af-accuracy/

Even 1Ds can have focusing issues with fast lenses:
http://www.fredmiranda.com/forum/topic/54574

Mishkin

[jkelley]

Richard,

Thanks so much for your input. I will try your suggestion and post other test images early next week. I realize that for practical purposes, shooting wide open and focused at infinity is not very common in real shooting situations. What I am trying to do is test a new lens that I recently purchased to see if it is "up to par". BTW - my previous images were crops of the full frame, although, there may have been some change in the resolution when I saved the final image that I posted.

I appreciate any and all input. Thanks...

[jkelley]

Mishkin,

Just saw your reply. Thanks. I'll also give the manual focus bracketing a shot in addition to trying the things that Richard suggested.

I'm beginning to get the feeling based on some of the replies, that the consensus is that the lens is normal.

BTW, Mishkin - your method of posting the overlaying images was VERY cool and helpful. Did you create an animated image file to do that, or was that a posting trick on the discussion forum?

Thanks...

[mishkin]

jkelley, I created animated GIF with Adove Image Ready. Then I embedded the image in the message as usual - using (img)...(/img) (with square brackets) tags.