AF and sensor issue

Hi there,

I'm having an issue with my CANON EOS 1100D, on the viewfinder there are black marks and i'm not sure why - I think it's effecting the focus as well as the AF has now turned into a blurry red dots.

I've ordered a cleaning kit, if anyone has got any advice would greatly appreciate it!

Best,
Ellen

Your viewfinder itself has no impact on AF, just your sanity when looking through it.

Now if the mirror is dirty, that could effect what you are seeing in the viewfinder and the AF. Be careful how you clean that mirror, it is easily damaged. A sensor cleaning kit isn't what you want for that.

There is another element that you see in the viewfinder, and that is the focusing screen that lies above the mirror, and that could be dirty, but also is a sensitive item to clean.

Your sensor is under the mirror and you don't see that ever in the viewfinder, nor is it used for AF when using the viewfinder, so that isn't the issue.

I would first clean the outside viewfinder glass (which your eye goes up to) with a qtip and see if that fixes things. Next take off the lens and look at the mirror and see if it seems clean. Then look up at the focusing screen with a good flash light. Before you touch any of these items, I would do some research on the best ways to tackle each item. The only thing I would try out of the gate is to buy a bulb blower and blow off the mirror and everything up in that pentaprism/focus screen area without touching anything.

Hi, that is super helpful thank you.

As an amateur photographer, I panicked and obviously opened the lens up and started poking around with a dust cloth, I was careful but I fear maybe not enough.

I have a bulb blower coming this evening but it might be too late.

Perhaps when repair shops are open I can take it in for a look to see if it's salvageable.

Thanks for your help anyways!

...and if you have any trouble getting the mirror to lock up review the thread at https://photography-on-the.net …/showthread.php​?t=1286150. Specifically the content by “mainbyte”, #7.

ellenl wrote in post #19070227
Hi there,

I'm having an issue with my CANON EOS 1100D, on the viewfinder there are black marks and i'm not sure why - I think it's effecting the focus as well as the AF has now turned into a blurry red dots.

I've ordered a cleaning kit, if anyone has got any advice would greatly appreciate it!

Best,
Ellen

?
Could it be you've accidentally turned the diopter setting?

soeren wrote in post #19070284
?
Could it be you've accidentally turned the diopter setting?

See https://support.usa.ca​non.com …page=content&id​=ART138120 in case you need help on what "soeren" mentions.

Hiya,

I've just checked that and that doesn't seem to be the problem.

When the red light when it focuses on an object flashes up when I try to auto-focus but the red light is a blur, and not the red dot that it usually does... :/

ellenl wrote in post #19070313
Hiya,

I've just checked that and that doesn't seem to be the problem.

When the red light when it focuses on an object flashes up when I try to auto-focus but the red light is a blur, and not the red dot that it usually does... :/

Just as a point of interest, how long have you had this camera and do you have the manual?

Hiya, I've had this camera for 10 or so years, I don't have the manual, probably worth looking it up online as a starting point..

ellenl wrote in post #19070447
Hiya, I've had this camera for 10 or so years, I don't have the manual, probably worth looking it up online as a starting point..

The manual can be found at https://gdlp01.c-wss.com …rt3-eos1100d-im2-c-en.pdf. I suggest you save it somewhere for reference. Maybe start by looking up the section on focus settings and how they might change your viewfinder display.

Not that it is likely related to your problem, but you might also want to do a firmware update. There have been 5 or 6 as I recall. You only need to do the latest, all other fixes are rolled into the most recent version.

I might be jumping to a conclusion, but the "red dot" is generated on the focus screen, which is the horizontal piece of glass above the mirror. Also, it's "after" the mirror and not actually used when taking the picture. Either the focus screen has been knocked out of place, or it's the diopter setting...

And I can see that you said that it's not the diopter. But just to make sure, ignoring the red dot, look at the green lettering at the bottom of the viewfinder. Are those green marks clear?

Hi there,

The green numbers and marks at the bottom of the viewfinder is all clear, there is definitely something somewhere obstructing the focus of the camera as I took it out yesterday on a hike and it wasn't focusing on particular things.

I might have to get it cleaned and fixed somewhere locally when shops open back up again!

Thank you for the suggestions!