More Canon 85 EF 1.8 Woes - SLR Experts?
My original 85 1.8 went back to the dealer some months back due to massive back focus. We are talking about 50m at 50m, despite the image looking sharp through the VF. Close subjects at, say, 1m were completely blurry on film despite being sharp in the VF. I tested the lens on two digi bodies and same issue. I am talking wildly not even remotely in focus...
Now I have my second copy from the same dealer. It is smack on at portrait distances and surprisingly sharp at 1.8, gaining contract and resolution a stop down. However, the further the focus distance the more back focus starts to creep in. This is the same as the lat example but not nearly so bad!
I tried comparing manual focus and AF and found that results, oddly, were a hair sharper in MF; however, this did not change the appearance of growing back focus with distance.
At distance, say 15m, the lens will show sharp on centre in the VF but in fact be obviously very soft on film at 1.8 and still soft at f2.8/4, with actual focus somewhere behind (at about two metres behind the subject it is RAZOR sharp). The left side of the frame also appears sharper than the right at distance at the wider apertures. I have shot some subjects where - and I cannot get my head round this - sharpness appears at various points in the frame that appear unrelated to the plane of focus (i.e. focus a 50m. Centre soft as hell even at a stop down. Right side (parallel to focal point) even softer. Left centre (once again parallel to focus point, pretty sharp), lower left not bad, lower right, soft as hell, infinity about the same across the frame an much better than the point of focus! I am baffled. I have never had an issue with a canon lens before (apart from the last 85 1.8). I have many other brands for all formats and apart from a dodgy CV 21P which was massively decentered in a single plane, have not seen such gross errors with lens peformance. In this case its like a LF camera with swings and tilts I cannot make sense of (like subtle, multiple decentering AND back focus at distance)
How can the lens be pin sharp at 1m and then back focusing terribly at distance? Is this normal? At about 3m and wide open, I estimate about six inches of back focus, which is only nullified by stopping down to about F8!
Do you think there was just a bad batch of lenses? I assume the lens should perform very well at distance, despite being primarily used for portraits up close. I have not had such issues with their cheaper zooms, or L lenses. All have been great, focusing accurately throughout the range. This one is amazingly good at 1m but unusable at less than f5.6/f8 at medium and longer distances, requiring DOF to make up for back focus.
I am very confident it is not the body. This body performs spectacularly with my 70-200 f4, 135 f2L etc at ALL distances.
Any thoughts? Rapidly losing confidence in Canon here. I desperately need this FL/speed for a project (in progress) and have already missed shots because I had to send the last one back. Am I really going to have to spend $1900 on the 85 1.2 to get a lens that works as it is supposed to?
Sorry for the rant... V frustrated, annoyed, confused...
I don't know if your individual lens issue falls under this, but Canon has apparently been having some major issues both in design and quality control in both lenses and camera bodies. The bulk of the problems are falling on the AF with no tangible answers in sight.
While I am a Nikon shooter, I take no joy in this. I haven't seen the Canon 85mm 1.8 mentioned specifically, so hopefully your problem is isolated and not endemic.
Never had a focus issue with my EF 85 f 1.8. It is always fast and accurate.
I've been thinking about acquiring this lens, so I will follow this thread with interest.
Is the focus screen in correct register, a very slight issue there will have big ramifications on focussing.
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Q #1 Film or Digital ?
Q#2 Which body ?
Q#3 Is you manual focus ability accurate ? See Q #2.
WHAT are you trying to shoot ?
"Canon has apparently been having some major issues " Document that, please.
It is practically impossible for this to be due to 'bad lenses'. The 85/1.8 is a time proven standout.
Most 'back-focus' issues can be traced to digital issues, or inherent AF behavior.
Finally, what Ian asked.
"One of the painful things about our time is that those who feel certainty are stupid,
and those with any imagination and understanding are filled with doubt and indecision"
Doesn't the focusing screen of an SLR in proper adjustment see exactly the same focus as the film? I don't understand how the focusing screen could show something different from what wound up on the film, unless there is a camera problem.
I assume this is not happening with other lenses on the same camera? If not, I can't help.
But if the same thing happens with all lenses, then it could be that the mirror stop needs adjustment. The mirror only needs to be a little out of line to throw the film focus way off, whilst the image appears sharp in the viewfinder.
If it's only this lens, then I don't get it. If it's sharp on the screen, it should be sharp on the film, whatever the lens.
Mine is perfect and I've shot wide open quite a bit. It is my favorite Canon lens. Two bad ones in a row, however, would make me suspicious of the current production run. I'd ask your dealer to order two of three of them to increase your odds. If that doesn't work, perhaps Canon could service the one you have.
OK some answers to questions:
My eyesight is perfect and manual focus actually resulted in better sharpness on the close in tests. Fractional, but my eyeball is better than the AF.
Tested on an Eos 3 in perfect condition and was shooting perfectly with all other lenses, incl Canon 135 F2 wide open at distance. I will need to test this again but the 135 and 70-200 are in a different country now.
If mirror were out of alignment, would this not affect close distances too? The lens focuses perfectly in VF and on film at 1m. Spot on using a chart I use to check my RF cameras/lenses are aligned. The error creeps in at longer distances and is proportionate to distance.
At distance, say 50m, the lens does not appear to be performing uniformly across the frame. Right side is clearly worse than left. On film, focus is well beyond suject and only stopping well down sorts this issue out (same iss as shooting at 3-5m, where film focus is 6+ inches to rear)
I have checked the mirror and it is seated as it should be. The camera has had no impacts or knocks.
The first copy of this lens, used on same body, was so bad that every single frame from near to far was MILES out on film compared to what I saw in the VF. Were there a problem with the body, it would not explain how the first copy turned every frame to perfect bokeh on film, despite being sharp in the VF and the second copy very much better (the first being unusable in every regard, at every distance and every aperture i.e. shoot a brick wall at 5m and you cannot make out the bricks, only a haze with what might be fuzzy mortar lines. At 1m,focuising on the nose, on film you would have the back of their head sharp!) Shot at 50m, the focal point looked like the bokeh and 50-100m behind was pin sharp). The second copy; however, is still not usable without very obvious back focus, beyond the short range i.e 1m, but night and day better than the first. There are clearly serious differences between the two examples and the camera body has not left the cupboard between lenses.
Mirror issues would also not explain that focus does not appear consistent across the frame at distance. The right side is much worse than the left at wider apertures suggesting decentering.
I guess I will have to accept that this is a problem I wont be able to solve in a rush. I have a 12 month warranty so can shoot close up portraits (for which it is spot on) until getting a second body out here to check the lens against for longer distances. I am 90% sure the lens is the issue (after all I have had two lenses through with a common issue, just to very different extents), or, so looks like a second one will be going back to B&H once this is done....