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Author Topic: After-market Focusing Screens  (Read 5842 times)

Harley

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After-market Focusing Screens
« on: September 17, 2011, 03:36:23 PM »
Has anyone had any experience with after-market split-prism focusing screens for their DSLR?  I have a 7D and a converted FL-series manual focus lens.  Although I can get autofocus confirmation through the AF, I think, at least for me, it would be helpful (and enjoyable) to have a split-prism / microprism focusing ring in my viewfinder. 

I see that there are some products available like KatzEye Optics:

http://www.katzeyeoptics.com/cat--Canon-DSLRs--cat_canon.html

I would appreciate any feedback that the forum members would have to offer.  Thanks!
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After-market Focusing Screens
« on: September 17, 2011, 03:36:23 PM »

Dave

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Re: After-market Focusing Screens
« Reply #1 on: September 17, 2011, 03:56:32 PM »
AFAIK the 7D has no interchangeable sceen because of this build in LCD stuff.

Harley

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Re: After-market Focusing Screens
« Reply #2 on: September 17, 2011, 04:23:59 PM »
If you go to the link above, the last item in the list is for the 7D.  This is a direct replacement for the internal focusing screen.  It's recommended that the installation is performed by a camera tech.  It has nothing to do with and doesn't affect the LCD viewscreen.
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neuroanatomist

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Re: After-market Focusing Screens
« Reply #3 on: September 17, 2011, 04:37:30 PM »
If you go to the link above, the last item in the list is for the 7D.  This is a direct replacement for the internal focusing screen.  It's recommended that the installation is performed by a camera tech.  It has nothing to do with and doesn't affect the LCD viewscreen.

Dave is referring to the transmissive LCD inside the viewfinder light path, not the rear LCD.  Unlike most other Canon bodies, where the AF points are etched on a clear plate, the 7D's AF points are shown on a transmissive (clear) LCD screen, which facilitates the electronic level display, allows the grid display in the viewfinder, allows AF points to be differentially displayed depending on AF mode, or turned off altogether (something not possible in a 'typical' viewfinder display).  Try this - with your 7D powered off, look through the viewfinder - you see through the lens, but no AF points or spot metering circle - they require power to the LCD to be shown.  Pick up any other body, and you'll see the AF points and the metering circle even with the power off.

The issue is that the focusing screen sits right adjacent to that transmissive LCD, and it's very easy to damage the LCD when changing a focusing screen.  That's why Canon does not make alternate focusing screens for the 7D, and they also do not consider the focusing screen a user-replaceable part (which accounts for the recommendation by the 3rd party vendor for a camera tech to do the replacement).
« Last Edit: September 17, 2011, 04:44:00 PM by neuroanatomist »
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Re: After-market Focusing Screens
« Reply #4 on: September 17, 2011, 04:57:46 PM »
After-market focusing screens are typically machined to the size and shape from focusing screens that were originally for FF or even MF cameras.  Many for Canon are Camon FF screens that are milled to size. 

Some of them are enhanced with a treatment to make them "Brighter", but all, for the most part make your viewfinder darker, and become a issue with slow lenses that are f/5.6.  (You can't manually focus on something you can't see)  Used with fast primes they work well.

always double check focus accuracy after you install one, in some cases, shims are needed to adjust the lens to screen distance to make the focusing accurate.

Harley

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Re: After-market Focusing Screens
« Reply #5 on: September 17, 2011, 06:13:41 PM »
That's helpful information.  I really didn't know much about focusing screens prior to today and have been doing some online reading to educate myself...

So, theoretically, as long as I'm using fast lenses (currently my slowest is an f/4) an alternate focusing screen could provide more snap and depth of field without negatively affecting the viewfinder performance.  Assuming you can get it installed properly on the 7D in the first place.

When I was a kid I used to play around with my mom's Canon AE-1 -- that's where my interest in photography began.  Last week, I had the pleasure of playing around with a Canon F-1 and was reminded how nice it was to have a viewfinder with a good manual focusing screen.  I haven't felt an image "snap" into focus like that in years!  That's what started me down this road and when I discovered that you could replace the focusing screen in a DSLR, I wanted to know more . . . and hopefully benefit from others' experience. 
EOS 7D, EF 17-40mm f/4 L, Sigma 24-70mm f/2.8 DG EX, FD TS 35mm f/2.8, FL 55mm f/1.2, FD 300mm f/2.8 L

Harley

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Re: After-market Focusing Screens
« Reply #6 on: September 17, 2011, 06:15:00 PM »
...meant to say "more snap and shallower depth of field..."
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Re: After-market Focusing Screens
« Reply #6 on: September 17, 2011, 06:15:00 PM »

neuroanatomist

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Re: After-market Focusing Screens
« Reply #7 on: September 17, 2011, 08:46:39 PM »
...meant to say "more snap and shallower depth of field..."

Correct. The standard focusing screens in all modern dSLRs are laser microetched to provide a brighter viewfinder for typical consumer lenses, the majority of which are f/3.5-5.6 or something similar.  The consequence of that laser microetching is that lenses faster than f/2.8 (e.g. f/2 or f/1.4) show the depth of field of about f/2.5.  With a fast lens, it's easy to confirm this, just hold down the DoF preview button as you stop down, and you won't see the viewfinder get any dimmer until you hit about f/2.5.  The light is still getting in, it's just blocked by the focusing screen. Interestingly, you can directly see this on the 7D, because light 'washes out' an LCD display. So, with my 7D and 85mm f/1.2L II, stopping down from f/1.2 to f/2.5, the viewfinder gets no darker, but the transmissive LCD showing the AF points does get progressively less washed out (on a sunny day at f/1.2, it's actually a bit hard to see the AF points).

Screens like the Eg-S for the 5DII offer a brighter VF and show the true DoF for fast lenses. But the consequence is a dimmer VF with slower lenses, so it's hard to see to compose, let alone focus, with an f/5.6 lens in a dimly lit room. 
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Harley

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Re: After-market Focusing Screens
« Reply #8 on: September 17, 2011, 11:01:16 PM »
Interesting and very helpful.  I hadn't thought about the flipside -- too much light washing out the features of the transmissive LCD. 

My fastest lens is f/1.2, I have a couple f/2.8's, and the slowest is an f/4.  I don't intend to purchase anything else slower than f/2.8 (with the possible exception of a 24-105mm f/4 IS L if I find a deal on one), so it still sort of makes me want to try out an alternate focusing screen provided I could be confident about the install...
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Re: After-market Focusing Screens
« Reply #9 on: September 18, 2011, 03:06:22 AM »
please let us know what you bought and how does it work out for you
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Forceflow

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Re: After-market Focusing Screens
« Reply #10 on: September 18, 2011, 03:25:42 AM »
please let us know what you bought and how does it work out for you

+1

I had the katzeyes focusing screen  for my 40D and absolutely loved it. I wanted to get it for the 7D as well, but I am a bit worried about the difficulty of installing it. (And sadly the store I bought it at already told me that they will not do this replacement) So I would love to hear your experiences with it!
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Harley

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Re: After-market Focusing Screens
« Reply #11 on: September 18, 2011, 02:48:28 PM »
If I follow through with it I will definitely share with the forum. 

Forceflow, are you saying that Katzeyes will not do the installation or is it another shop that you were planning on doing the installation through.  I know that Katzeyes' website says they will perform the installation if you send your camera in, but maybe they won't do that for the 7D...??
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Re: After-market Focusing Screens
« Reply #12 on: September 18, 2011, 04:17:46 PM »
I was talking about the store that I buy all my stuff at. Since I am located in Germany sending the camera to them is not really an option for me :( Miss the focusing screen on my 7D. Could have really used it this Friday. The low light I was shooting in killed the AF on my 24-70...
Canon 7D - Canon 50mm 1.8 - Canon 24-70mm 2.8 L - Canon 100-400mm 4.5-5.6 L IS - SIGMA 85mm 1.4 - SIGMA 150mm 2.8 OS Macro - SIGMA 10-20mm 3,5

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Re: After-market Focusing Screens
« Reply #12 on: September 18, 2011, 04:17:46 PM »

elflord

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Re: After-market Focusing Screens
« Reply #13 on: September 19, 2011, 06:28:52 PM »
please let us know what you bought and how does it work out for you
I have the EG-S on a 5D Mark II.  This screen looks like the standard focus screen except that it shows max aperture dof during focus for fast lenses (and I take it a darker image for slow lenses)

With an f/1.4 lens I can easily/accurately manually focus at f/2.8 with the viewfinder. At f1.4 it's somewhat more hit and miss (though I may find practice helps) - I need to rely on focus confirmation more. However even with wide open shots it is useful because I can manually get the focus in the right ballpark more easily.

Harley

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Re: After-market Focusing Screens
« Reply #14 on: September 19, 2011, 07:59:30 PM »
Since the 7D conversion isn't going to be as reversible as it would be with a more user-servicable camera, it's nice to get a feeling for how a different focusing screen has worked (or not) for you in the field.  Thanks for the feedback! 
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Re: After-market Focusing Screens
« Reply #14 on: September 19, 2011, 07:59:30 PM »