Viewfinder DoF / Focusing screens, etc.

Hey guys,

Currently have a 7d with 17+85 IS and 50/1.8 and very pleased. However, I notice & I've read a lot about it showing the correct DoF with the viewfinder.

I've come to understand this is because camera manufactures prefer to have a more lit VF rather than a darker, yet more accurate one, if you're using a slow lens. I also don't really enjoy using Live View that much...

With that cleared up, that's fine

So I was thinking about buying a 2nd body to use my 50/1.8 lens on. The Canon 20d came to mind and I've done some reading, the VF on this shows down to f2.8, whereas the 7d shows f4, so I read, an improvement but still not true to the lens I'm using.

I've then gone onto read about replacing focusing screens, but apparently the 20d focus screen cannot be replaced?

It seems the 40d & 5d are the "cheapest" bodies with replaceable focusing screens? And the screen I'd be looking for is called a Ee-S, can anyone confirm?

So I'm just wondering what to do really. The 20d sounded a perfect solution, and still could be, since eBay shows 2nd-hand ones going for about £150 however, 2nd-hand 40'd go for about £360, which is somewhat more.

Suggestions & advise welcome? Thanks everyone.

Although here is a 20d replacement/modified focusing screen?
http://www.katzeyeopti​cs.com …-Canon-20D--prod_20D.html

It's Ee-S for the 5D, Eg-S for the 5D Mk II, Ec-S for the 1-series - so I'd guess if it exists for an APS-C camera it would end in -S. The "S" stands for "super precision", where "super" is defined as "as good as a camera from 1983".

As to why camera makers would do this on some cameras, my guess is it's because they don't want returns with the customer complaining about a blurry viewfinder with fast lenses.

The 20D focus screen is interchangeable, Canon just doesn't make any. Canon -S screens can show DoF down to f/2, standard ones show f/4 to keep the VF brighter.

From what I understand, the 20D, like the 7D (and the rebel series), although you can replace them yourself, there is no official canon replacement (unless you get it serviced or something).

I've replaced mine on the 7D (from focusingscreen.com though, not the katzeye one)...really simple to do. My only problem is it seems a little fickle. I've been having trouble w/ focusing a little (even w/ a tenpa magnifier) and noticed it seemed off. So I adjusted the focusing screen a few times and most recently decided that I needed to try using their plastic shims (thinner) instead of the the metal shim that comes w/ the camera. Anyways, it worked fine close up, but it wasn't accurate at far distances. I recently re-adjusted it and it seems to work fine now...but I'm not sure if it'll need re-adjustment later.

It's up to you if you want to use a katzeye type focusing screen (if you want that microprism collar). Although I find it useful (and I use it for focusing most of the time), if you use manual lenses, which require stopping down, it becomes harder to use the collar, especially in low(-ish) light.

Metering also gets a little weird though, so you may not be able to use stuff like spot metering and may be forced to use evaluative or center weighted. Also, the exposure compensation that's required for the viewfinder isn't the same when I switch to liveview...so I have to remember to lower it when I make the switch.

If you're planning on using manual focus a lot, either get a focusing screen, or just get used to using live view. I would actually say go for live view at this point (based on my previous frustration w/ the focusing screen + tenpa magnifier), because you can see exactly what's in focus (using the x5 or x10 magnification). You can even get an LCD loupe to use "live view" like a viewfinder, instead of holding it away from your body.

If you don't care about manual focusing at all and are just concerned w/ getting a more accurate idea of the DOF for a given shot, then i would say avoid all of the above and just take a couple of shots at various apertures if you think that the DOF would be too shallow.

Hey everyone, thanks for all your replies.

To be honest I'd rather not go modifying my Canon 7d so I'm ruling that out for replacing the focus screen. I'd rather get a second (cheaper) body to modify and to primarily use on my 50mm f1.8. I always use f1.8 for my shots - that's just the kind of shots I always want to do - its just the VF on a 20d only stops down to f2.8 which won't represent the photo I'll be taking.

So - back to the original question really - you say the focus screen ARE replaceable on a 20d which is good news, but I can't seem to find a focus screen which fits the bill? I've been on focusingscreen.com but can't find a suitable one? I've done some research and it seems I'm looking for a "Type S" one, which is "Super Precision".

If anyone can point me in the direction of one, or give me some more details into which focus screens are able to stop down further, that'd be great

The 20d focus screens from that website are all found here,
http://www.focusingscr​een.com/index.php?cPat​h=21_40

But little information about what apertures they are able to work at?

The problem is that, if indeed Canon never offered an -S screen for the 20D, there is also no exposure correction curve for one in the camera's firmware. Therefore, the metering would be wrong. This is probably why the vendor you link to doesn't offer a screen based on the Ec-S, only (e.g.) the Ec-B, which might meter closer to the 20D's stock screen. (And if it does meter like the stock one, it won't do what you want. These screens are probably for people using manual focus lenses.)

I agree with your strategy of running two bodies with two separate screens. Even when Canon support interchangeable screens for a body, they are still a pain in the neck to change.

Hmm sucks really doesn't it. The cheapest only other option I have is buying a 40d with properly interchangeable screens, but that is a fair bit over my budget.

However, reading that the 20d's VF shows f2.8 compared to the 7d's f4, is certainly an improvement. And for the price of used 20d's around the £150 mark, I think I'm tempted to go for it even with the stock focus screen.

I have both the EE-A and EE-S screens for my 5D. I used the EE-S screen for a long time, but I found that it didn't really make for a huge difference in my ability to judge how the depth of field would look in a print.

If you think about it, DOF is most influenced by the size of the print, and your focus screen has no way to know what size print you are going to make. I'd say the EE-S screen gives you an accurate idea of the DOF in small prints, perhaps 4x6 to 8x10 kind of range. For bigger, forget it.

Although you don't like live view on the 7D, have you tried it using it in conjunction with a rear mounted loupe? This will probably give you far better results than the 20D with a modified screen and cost you far less.

The least expensive is the Hoodman - it's adequate and has dioptre correction. Zacuto makes some superb (but expensive) models. Alternatively, you could make your own Hoodman equivalent - for around $20. All you need is a 3x loupe, heavy elastic bands, some duct tape and a small bit of 3/32 ply.