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I've recently bought an 85mm f1.2 lens, which is absolutely amazing, but I noticed after my day out playing with it, that lots of my photos were out of focus, even though they appeared sharp in the viewfinder.

When I switched to live-view, and zoomed in twice, I could fine tune the focus, and it appeared perfectly in the final photo.

I initially thought that the dioptric adjustment must have been out, so I played with it a bit, but nothing seemed to help.

I then read somewhere that the standard focusing screen in the 60d isn't good enough for a lens as fast as the f1.2.

It seems that the ef-s focusing screen is the correct one, but on the Canon web site, it states that this focusing screen is optimized for apertures of f1.8-f2.8 which isn't enough for an f1.2. Will this help? or do I need another type of focusing screen?

The other alternative is to just use auto-focus all the time, as I'm sure this is more accurate, but I'm just used to using manual focus.

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Focusing screens for cameras with autofocus tend to be - almost per definition - optimized for use with autofocus lenses, which tend to be relatively "slow" with an aperture in the f/3.5-5.6 range. In olden days, focusing screens were optimized for fast, manual-focus screens, but those screens had the downside that they grew unusably dark when used with such slow autofocus lenses. The price paid for the extra brightness of the modern screens is a decrease in focusing accuracy; it is accurate enough for this kind of AF lens but does not show sufficiently accurate focus information for lenses much faster than f/2.8... the reason being that there are microprisms in the screen itself that impose a certain minimum depth of field to the image. Think of it as the focusing screen being an f/2.8 lens looking at the image from your f/1.2 lens, what you see in the viewfinder will be at least f/2.8 no matter what.

This is a bit of a dilemma - you can't really have your cake and eat it too. Your focusing screen can either be accurate but dark, or bright but inaccurate.

While Canon do not find it worth their while to offer superfast focusing screens for fast lenses (with the exception of some of their top-end camera models) third-party suppliers such as Katz Eye Optics do. What they do is basically to take a good old-fashioned manual-focus focusing screen and file off the edges (quite literally so in some cases, at least that is how it used to be) so that it fits into your modern camera. These screens can be of the classic coarse-grained type, which give a good "focus pop" on fast lenses, or they can be of the kind that have a split-prism in the center of the image. In either case, they will be very good for manual focusing of fast lenses and possibly utterly useless with slow autofocus lenses! In other words, you will want to swap focusing screens when swapping between slow and fast lenses.

I am not sure if the Canon 60D is designed for user-replaceable focus screens, if it is not then swapping out the screen can be a bit fiddly and probably something you would want to do at the kitchen table and not out in the field. Even if it is designed for replaceable screens replacing one can still be a bit fiddly so be warned :)

Of course, the camera's light meter meters the light AFTER it has passed through the focusing screen. In other words, replacing the screen affects metering, possibly in a non-linear way. This is an added complication when using third-party screens, you will want to meter the light with a separate light-meter as the camera can no longer be trusted - and you will have to use the camera in M mode instead of any of the automatic-exposure modes. Effectively, you will have entered a photographic timewarp and will have to work like they did in the early seventies.

Note that even if you use an official Canon screen other than the standard one you will have to go into the camera's menu system and tell it exactly which screen you are using, the camera will then know how to compensate the light metering accordingly.

  • Thanks, that's very informative. I'll hold out before choosing the 'answer', as I'd ideally like to hear from someone who has actually tried the ef-s or KatzEye on my configuration (Canon 60d & 85mm f1.2). – Rich S Aug 20 '14 at 22:00
  • Probably wise... I can't help you there, I do have an 85/1.2L (mark one) but am using it on a full-frame 1DsII with the Canon super precision matte screen. I do rely on autofocus, the 85L is painfully slow to focus in manual mode. Not that it is pleasantly fast to autofocus either of course :) – Staale S Aug 21 '14 at 0:12
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Yes, in my opinion, it will help. I installed an Eg-s focus screen in my 5DMkII for use with an adapted 50mm f/1.2 manual focus (Olympus OM-mount) lens, and it was like night and day in being able to nail focus with the lens wide open. The super-precision screen does render DoF more accurately than the default focus screen. Whether it will be enough for you to nail focus with an 85/1.2 on a crop body could be up for debate (and on personal ability/eyesight), but it will be better than what you have now.

I installed a split-circle/prism collar Katzeye focus screen in my 50D for use with the same lens, and it wasn't nearly as useful as the Eg-s on the 5DMkII was, and I was planning on swapping my Katzeye for the ef-s (especially as I got tired of having to swap the Katzeye in and out with my standard ef-d screen whenever I wanted to go birding with the 400/5.6 to avoid the collar blacking out), but then I moved to micro four-thirds. :)

  • Very interesting, so it seems that the ef-s performs better than the KatzEye?, and is integrated with the 60d (ability to select the screen from the camera's menu) - so I just need to get an ef-s.. I think that, at the end of the day, I'll have to get used to using auto-focus... maybe I just don't trust it yet. – Rich S Aug 20 '14 at 22:03
  • I'm not sure the ef-s was necessarily better than the KatzEye so much as better for me and my usage. The KatzEye was about as accurate for me, but the prism collar blacking out at f/5.6 max aperture lenses was a pain for me since my 400/5.6 is a lens I use a LOT on the 50D, so I'd have to keep swapping it out with the ef-d. Not to mention the KatzEye is ~3x more expensive than the Canon screens ($100 vs. $35). – inkista Aug 20 '14 at 22:10
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    Actually, the focus screen setting is just to bias the metering properly. The "super-precision" screens are darker than the standard screen. The EF-S setting works pretty well with the Katzeye. – inkista Aug 20 '14 at 22:18

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