# Canon EOS



## George.gm (Aug 27, 2010)

When I use my Canon 75 - 300 lens with my 30D jt doesn't always pick up first or second time. I get a blank screen and am unable to focus.
I remove and replace the lens and it generally works.
Is the fault (if there is one) with the lens or the camera ?


----------



## zuluclayman (Dec 16, 2005)

Are you focussing manually or using autofocus?
If auto - the longer lenses do sometimes struggle to find auto focus, especially if the light is a little low, in these situations it is usually better to use manual focus if possible.
If it is happening when you are using manual focus you may need to take the lens and camera to have it checked out - how old is your camera? and the lens?


----------



## WereBo (Apr 5, 2008)

Hi George.gm and welcome to TSF :wave:

Have you tried cleaning the electrical contacts between the lens and camera-body? Use a soft lint-free cloth, preferably with a few drops of Isopropyl-Alcohol (as used in DVD/video head cleaners etc.)


----------



## George.gm (Aug 27, 2010)

Thanks gentlemen. I cleaned the contacts and that seems to have sorted the problem.
Although I am a little concerned about having the lens detatched for too long in case muck gets on to the sensor. Cost me £45 last time.
Next question : the camera is four and a half years old and I would like to upgrade but I don't want to have to pay for a video facility - just a normal camera with a few more pixels than the 30D. Canon if possible to retain the lenses. Any suggestions ?


----------



## DonaldG (Aug 23, 2007)

Hi George
If you have a set of Canon lenses, then unless you want the cost of replacing them with another brand (Nikon et al) I suggest that you stay with Canon.

With respect to spending £45 to have your sensor cleaned, you can do it yourself if you have the right kit and understanding.

I have two Canon cameras, 20D & 5DMkII. Stock lens on the 20D and a 28~300 on the 5D2 most of the time. I also have a 70~200 & a 50mm prime. As you can appreciate, the lenses are being on/off all the time and dust is an issue.

I use various techniques - one of the aids I use is a 'Rocket Blower' to remove dust from around the lens & camera before dis-mounting the lens. Pop into Jessops and get one - only about £8 or cheaper on eBay (Search Rocket Blower)

I also use the blower to blow out the sensor cavity of the camera and the back end of the lens before re mounting it. Likewise, I blow the camera and lens caps too....

For serious cleaning, I use an 'Arctic Butterfly' in conjunction with a sensor loupe. Both are manufactured by VisibleDust. See here. It is expensive but all you need to do is clean your sensor 3 times and it is paid for!

The last item I use is a 'Dust-Aid Platinum' sensor cleaner. See here

Also I suggest that you Google 'sensor cleaning'. There are many YouTube videos on sensor cleaning...

... Oh, by the way... A warm welcome to TSF & especially to the Photographer's Corner...:wave:

Donald


----------

