Mystery component 550d!!!!

Somewhere during the process of replacing the focussing screen in my 550d, a very thin, brass looking "clip" has dislodged from somewhere within the mirror/shutter mechanismor maybe its another part of the focussing screen fixings.

For the life of me I cant see how to put it back to where it should be, anybody know what this is and where it goes?





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Michael.

My guess it's a flange that goes under the focusing screen on something, to raise it a little making the viewfinder image sharper. If there's no problem with sharpness I guess it's not necessary.

Try searching for focusing screen replacement using google, you may find a manual/tutorial that describes where it goes.

Hope this helps! Good luck!

mja_dpr said:

Somewhere during the process of replacing the focussing screen in my 550d, a very thin, brass looking "clip" has dislodged from somewhere within the mirror/shutter mechanismor maybe its another part of the focussing screen fixings.

For the life of me I cant see how to put it back to where it should be, anybody know what this is and where it goes?





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Michael.

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Be careful not to scratch mirror & delicate matte surface of focusing screen. You might lose the red AF points.

There are two of those thin frames in the both side of focusing screen. Other one works as a frame between viewfinder/body and focusing screen and another one locks the focusing screen to it's place.

Just take out the locking frame, focusing screen and put that part inside. Use flash light - you should see some notches which way to put the frame in. Drop it down there, put focusing screen over it and use the locking frame to put it together.

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mja_dpr said:

For the life of me I cant see how to put it back to where it should be, anybody know what this is and where it goes?
Michael.

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These metal shims are used to fine-tune the focus screen position when the camera is calibrated. The number of shims used and the thickness of each shim varies. They should be replaced in the same order and same position as you found them.

If there is only one shim, it probably fits into the frame before the focus screen. Install it and then take a few focus test shots to check for front or back focus.

As others have already said, take care! Dirt or damage on the screen is almost impossible to remove without leaving visible marks in the viewfinder.

Thanks to all for your advice, the shim and new screen are back in place now and all is fine except for a few items in my viewfinder, but I clearly dont have the skill to avoid that so Im leaving well alone from now on

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Michael.

It is very detailed and would have told you those were calibration shims. Good thing you only have one, mine only has one as well but supposedly some camera's can have two or even more. I wonder if too many shims means your camera is slightly back/front focused in the sensor (but at the same time electronically calibrated so that lens should still be 'ok' on them).

You are a brave soul if you did a focusing screen replacement without looking at something like the KatzEye tutorials. Focusing screens are ridiculously sensitive and fragile. Not only that but they are extremely fine-grained matte so there is absolutely a reason why it clings to dust is because of the rough matte surface. Cleaning sensors are so easy compared to focusing screens and IMO my advice now is to NOT bother if you have specks on your viewfinder...its almost by design at this point and you'll get it eventually if you use your camera outdoors...even weather sealed camera's like D7000 or 7D as well if you look hard enough (and the 7D you can't even user service or at least need a higher level of skill).

Timbukto said:

Cleaning sensors are so easy compared to focusing screens and IMO my advice now is to NOT bother if you have specks on your viewfinder...

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I agree completely. But there's an inexpensive alternative: order new focusing screens from Canon. They cost only a few bucks — you might as well buy a few because the shipping will cost more than the screens.

Then when your focus screen gets dirty, damaged, or loses one of the reflective focus-point dots, you can replace it with a new one.

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550D screens are not supposed to be user replaceable

Doug Pardee said:

Then when your focus screen gets dirty, damaged, or loses one of the reflective focus-point dots, you can replace it with a new one.

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Canon has no problem selling them to you however. It certainly won't come with tools or instructions, but again with the KatzEye tutorial its not that difficult, decent tweezers and a steady hand + gloves.

They force you to buy in packages of 5 and can be pretty pricey in the end actually. Remember we live in the iPhone era...it is being assumed (and perhaps rightly so) that users become less and less competent at mechanical aptitude and repairing/servicing their own devices as time goes on.

I think Nikon won't even ship any parts to practically anyone anymore so that makes it impossible to user service, more pricey to service at third party repair locations, making you deal with sub-par and over-worked Nikon servicing (at least that is what Yelp is telling me for the El Segundo location).

bigdaddave said:

550D screens are not supposed to be user replaceable

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That just means that Canon doesn't provide any alternative screens, nor does the T2i/500D support metering changes for alternative screens.

Canon part number for T2i/550D screen: CY3-1621. Apparently these come in a box of five, and in the US a box will cost you about $40 plus $10 shipping. So $10 per screen. Sometimes you can find people selling their left-overs on fleaBay.

Do take care not to damage the mirror while working in there. The silvering is on the front side, so it's vulnerable.

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Timbukto said:

It is very detailed and would have told you those were calibration shims. Good thing you only have one, mine only has one as well but supposedly some camera's can have two or even more. I wonder if too many shims means your camera is slightly back/front focused in the sensor (but at the same time electronically calibrated so that lens should still be 'ok' on them).

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Autofocus happens in the bottom of the mirror box. It doesn't depend on the focus screen in any way.

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WilbaW said:

Timbukto said:

It is very detailed and would have told you those were calibration shims. Good thing you only have one, mine only has one as well but supposedly some camera's can have two or even more. I wonder if too many shims means your camera is slightly back/front focused in the sensor (but at the same time electronically calibrated so that lens should still be 'ok' on them).

Click to expand...

Autofocus happens in the bottom of the mirror box. It doesn't depend on the focus screen in any way.

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Right, but if you do actually manual focus through the viewfinder (general not a great idea with these rebel viewfinder screens), then you could get wrong focus.

WilbaW said:

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Click to expand...

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