split image microprism focusing screens

[Derrel]

T

*sighs*

First off, I want to know how you think that DoF you see through the viewfinder is somehow effected by the focusing screen design. I can tell you right now there's no real difference. What you will see is a bit of a pattern caused by the polymer used in out of focus specular highlights of the image, but this doesn't effect manual focusing to a significant extent.

Secondly, you're evidently confused about how the screen works. It is not (I say again, not; if you talk to any Canon rep briefed on the 7D they will tell you this) artificially brightened. The reason it goes dark when the power is off is because the polymer used becomes dark when there is no current running through it. Provide a current, and it becomes crystal clear.

As for the 7D having support for other focusing screens, that's a definite no from the folks at Canon. They tossed the idea of having interchangeable screens for the new one. Just part of the design really; there's a lot of delicate equipment on that screen that you probably wouldn't want to risk messing up anyway.

How do I know? Well, simply because I have been shooting TLR and single lens reflex cameras with photography longer than you have been alive. Your youth and know-it-all stance is duly noted. The excessive depth of field seen at the focusing screen in the Canon 7D is noted, many,many times by experienced, knowledgeable photographers in the Fred Miranda 7D master thread, and throughout the sportsshooter.com forums. As I told you in a PM some weeks ago, the depth of field seen through the viewfinder is a *DIRECT* function of the smoothness and clarity of the viewfinder's focusing screen. I'm sorry if your relative newness to SLR photography prevents you from having any experience with older technology,and that your basis of experience is so limited that you don't understand the basic mechanics of SLR camera viewfinder screens and alternative screen technologies.

How do I know? I have owned and used auxillary focusing screens that show "immense" depth of field, as in infinite depth of field. Like the Zeiss Ikon Contaflex; the aerial image [look it up] coming from the lens to the reflex mirror is captured by a viewfinder screen. The actual, physical characteristics the screen has determine the amount of depth of field visible; the glass used to be "ground", and was often equipped with Fresnel [look it up] rings, a split image, and a microprism doughnut [look it up]. The "smoother" the texture of the groundglass, the brighter the image. It is possible to make a viewfinder screen that is so,so smooth and bright that the depth of field appears INFINITE, even if the aerial image is WILDLY out of focus---as was the case with point and shoot D-SLR Cameras made in the 1950's and 1960's, like the Contaflex. Another example is the Kodak Duoflex TLR cameras--their viewfinder screen is SO smooth and bright that there appears to be infinite depth of field. As seen below.

Shutterbug: TtV Photography

I do not need to talk to a Canon rep--Canon Professional Network states it in Plain English, my native language:"This LCD screen can be illuminated in low light and enables several new views to be superimposed such as Single AF points, Spot AF points, AF Area, AF Zones, Spot metering circle and a Grid display. The LCD has a minimal effect on the viewfinder brightness, but if there is no power to the camera then the viewfinder will appear dark. With the battery installed the viewfinder will look normal and battery drain is negligible." Canon Professional Network - Inside the Canon EOS 7D

If a viewfinder "goes dark" when the battery is removed, the system is using artificial brightening. I know because I have decades of actual experience--with many types of viewfinder screens. I have six different screens for the Nikon F2 system,and have used multiple types of screens...some of which have focusing ability ONLY in the center of the screen. I also have a Fuji S2 Pro, which also has an artificially boosted screen brightness, like the 7D does:with the batteries removed, the finder goes "dark".

How do I know? Canon EOS 7D Master thread - FM Forums
I also lived through the entire "brighter, clearer viewfinder" marketing campaign of the Olympus OM-series of cameras. A brighter, smoother viewfinder image lowers contrast, making it more difficult to manually ascertain focus. I lived through the Beattie IntenScreen artificially brightened aftermarket screen craze of the 1980's-1990's. In short, I know because Canon's technical literature tells me the screen is artificially brightened and depends upon battery power to brighten the image. And because I have personal experience with ultra-bright , alternative viewfinder screens. In short, I know because other people like me, with decades of SLR experience, are pointing out the new screen has problems accurately conveying the depth of field of fast glass,and I am intimately familiar of the way SLR camera viewfinder screens can be modified to either enhance manual focus ascertainment (coarser grind, rougher look,higher contrast) or enhanced to promote optimum brightness-smoother grind, more polished finish, all the way up to the 1990's-2000's method of illuminating the viewfinder screen from INSIDE the camera so that dog-slow f/3.5~5.6 kit lenses look "bright". Put on a slow kit lens and zoom it out....then zoom it back to wide angle and watch the viewfinder brightness stay the same. then, come back and tell u how the camera overcomes the laws of physics, 'kay?

 

[musicaleCA]

*sighs*

First off, I want to know how you think that DoF you see through the viewfinder is somehow effected by the focusing screen design. I can tell you right now there's no real difference. What you will see is a bit of a pattern caused by the polymer used in out of focus specular highlights of the image, but this doesn't effect manual focusing to a significant extent.

Secondly, you're evidently confused about how the screen works. It is not (I say again, not; if you talk to any Canon rep briefed on the 7D they will tell you this) artificially brightened. The reason it goes dark when the power is off is because the polymer used becomes dark when there is no current running through it. Provide a current, and it becomes crystal clear.

As for the 7D having support for other focusing screens, that's a definite no from the folks at Canon. They tossed the idea of having interchangeable screens for the new one. Just part of the design really; there's a lot of delicate equipment on that screen that you probably wouldn't want to risk messing up anyway.

How do I know? Well, simply because I have been shooting TLR and single lens reflex cameras with photography longer than you have been alive. Your youth and know-it-all stance is duly noted. The excessive depth of field seen at the focusing screen in the Canon 7D is noted, many,many times by experienced, knowledgeable photographers in the Fred Miranda 7D master thread, and throughout the sportsshooter.com forums. As I told you in a PM some weeks ago, the depth of field seen through the viewfinder is a *DIRECT* function of the smoothness and clarity of the viewfinder's focusing screen. I'm sorry if your relative newness to SLR photography prevents you from having any experience with older technology,and that your basis of experience is so limited that you don't understand the basic mechanics of SLR camera viewfinder screens and alternative screen technologies.

Remember when I asked you to be less condescending in that other thread? Yeah.

How do I know? I have owned and used auxillary focusing screens that show "immense" depth of field, as in infinite depth of field. Like the Zeiss Ikon Contaflex; the aerial image [look it up] coming from the lens to the reflex mirror is captured by a viewfinder screen. The actual, physical characteristics the screen has determine the amount of depth of field visible; the glass used to be "ground", and was often equipped with Fresnel [look it up] rings, a split image, and a microprism doughnut [look it up].

Again, assuming others to be your lesser in every case by default is a very, very unwise decision on your part. You might know everything about cameras since the dawn of their invention, but you sure don't know how to apply that wisely. I knew everything you told me to look up. I would suppose that you had simply assumed that I had no idea. Try not being such an ass. Please?

The "smoother" the texture of the groundglass, the brighter the image. It is possible to make a viewfinder screen that is so,so smooth and bright that the depth of field appears INFINITE, even if the aerial image is WILDLY out of focus---as was the case with point and shoot D-SLR Cameras made in the 1950's and 1960's, like the Contaflex. Another example is the Kodak Duoflex TLR cameras--their viewfinder screen is SO smooth and bright that there appears to be infinite depth of field. As seen below.

Shutterbug: TtV Photography

I do not need to talk to a Canon rep--Canon Professional Network states it in Plain English, my native language:"This LCD screen can be illuminated in low light and enables several new views to be superimposed such as Single AF points, Spot AF points, AF Area, AF Zones, Spot metering circle and a Grid display. The LCD has a minimal effect on the viewfinder brightness, but if there is no power to the camera then the viewfinder will appear dark. With the battery installed the viewfinder will look normal and battery drain is negligible." Canon Professional Network - Inside the Canon EOS 7D

I suggest you re-read what you just quoted. They are not saying that the screen somehow brightens incoming light when it passes through the T-LCD screen. What they're saying is that the focus points can be illuminated red so that you can actually see them (or any other part of the screen, like the spot metering circle, grid, or AF groups). That minimal effect on brightness, if anything, is a bit of light loss. From the same article: "There had previously been significant disadvantages to using LCD screens inside viewfinders, one of them being that when their brightness was increased the wiring became visible. Through some fresh technological advances Canon has been able to implement the screen whilst maintaining viewfinder image quality." Canon's word choice is poor, perhaps, but they mean "not opaque". Damned if I know why they wrote it like that. We're talking about turning a T-LCD from being a black hole of nothingness (okay, that's hyperbole) to a clear display. The difference is whether or not you put some current through it.

IF the viewfinder were artificially brightened somehow, and the incoming light were amplified artificially as your final statement suggests, then would it not brighten the viewfinder when I use DoF preview as well. I mean, stopping a lens down will make the viewfinder darker, so shouldn't my nifty artificially brightened 7D's viewfinder brighten it back up a bit? I mean, even a third-stop difference should easily be corrected, yes?

some of which have focusing ability ONLY in the center of the screen.

Oh yeah! Those are kinda funky to use.

 

[seanfoulkes]

@ Derrel,

wow, you're kind of a pompous idiot aren't you? The reason people don't hold message boards in high regard to public information is the fact that most times someone asks a question it turns in to a dick-measuring contest with some dude who spend too much time honing his two-dimensional knowlege base with internet browsing, sans experience.

I use a 7D (alongside a trusty D300) for moving-vehicle PJ work over here in Iraq. The Transmissive LCD causes the viewfinder to go black due to lack of power, much like an LCD in a projector. The slight brightening is (i'm guessing) Canon's way of saying that their annoying red light indicators give off light and may "illuminate" the viewfinder. Jesus. I signed up for an account on this silly website because this poor guy is simply asking for some advice and you somehow distorted it into a way to talk down to him and assert your superiority in whatever sense you imagine it.

To the original poster: Split image focusing works great for manual focus lenses, but there is a lot of other aspects of manual focus photography on these consumer DSLR cameras that you might be overlooking. If you are worried about creatively using depth of field for your photography (i.e. portraits, shallow DOF for subject isolation) you might want to consider a full-frame sensor camera, as it gives approximately the same depth of field as a real 35mm film SLR would give you. Because of the crop factor of cameras like the 7D (and almost all other DSLRs currently on the market) your depth of field will suffer and it will be less shallow at the same apertures. An F/2 lens would give a depth of field similar to a F/2.8 lens on a film camera/FF body, etc. I use an old canon 5D (with a shaved mirror to fit some short back focal length lenses and also a 5D2 with a brighter canon focusing screen with a bunch of Leica R glass I use from everything from traveling to studio portrait/advertising stuff (its not so much the superiority of leica lenses, but the nostalgia/manual photography aspect gets me in a more creative mood, I end up with more shots I deem usable)

Also, are you interested in exploring manual focus simply for the fact, or is it a means to an end? Are you experimenting with non-canon lenses adapted to the body? Are you doing specific work that requires precise manual focus? If you are worried about focusing in environments so dark your current focusing screen or AF system won't do the job, you can slightly improve by getting a brighter screen, but if it is really that dark then you should think about practicing with your distance scale on your lens (if it has one) or learning the actual area of acceptable focus your lens gives at certain apertures and distances. Leica nuts and journalists have been doing that forever (you don't think all those epic vietnam photos were carefully focused and framed during the heat of battle, do you?) Anyway, those are just some things to think about and research before dropping $100+ on a focusing screen that may or may not alleviate your forseen problems.

Good luck!