Quirky 70-300IS

My Canon 70-300IS usm has this strange quirk. I have tested this both on my 7D and my wife's 40D. When taking pictures through glass, such as car or home (very clean) the images are blurred, they almost appear to have image shake. There are no sharp focal points anywhere within the images. I use center focus only and can take pictures at 1/1000 sec., use one shot focus, even manual focus, but images still look out of focus... blurred. This lens produces perfect shots outside or when no windows are involved. I have a 28-135IS which produces sharp images under the same conditions.

Any Ideas?

David W.

More magnification at 300 than 135? Could show up more. I have usually found shooting through windows to degradee the photo a bit, when using great glass. The 28-135 is not the sharpest lens around to begin with. So maybe it doesn't show so much change. Don't really know what you have going on, but for me, I have found I get best results not using windows. That does not mean that I don't ever shoot through windows, I do, I just know it works better if I can avoid it.

Are you holding the lens up to the glass, as for stability? That would be similar to putting the camera on a tripod, and, if the image stabilizer is on, would cause its own blur... that being the reason IS is supposed to be off when using a tripod.

cc10d: I Know that extra non optical glass will degrade the image, this is much worse than that. I shot the 70-300 at multiple focal lengths. It didnt matter if I was close or couple feet away. I prefer to shoot away from windows myself but some of my best people shots have been from inside looking out.

EdZep: How I hold the camera either close to glass or farther out, with or without IS doesn't make any difference. The images look similar to image shake blur even when shot at high speed...1/1000. I can use the 28-135IS at the same focal length, same aperture, same shutter speed, same distance, same window, same target, the 28-135 will be a little soft but not much...the 70-300 has what looks like ghosting and very unsharp images. This lens (70-300) has no problems if I open the window.

Thanks for the replies
DW

Are you using a UV filter? Some lenses don't take well to UV filters - the 100-400 is a notorious example.

Could you post a photo or two that displays the problem you're talking about?

alduin wrote in post #9103560
Are you using a UV filter? Some lenses don't take well to UV filters - the 100-400 is a notorious example.

Could you post a photo or two that displays the problem you're talking about?

Never use filters.

How does the filters effect 100-400? Maybe this is related to any extra glass.

Will post photos when the sun comes back out here in Denver.

DW

Here are pictures: cropped 100% I know the subject is a little soft but every shot had focus lock.

DW

Through the window IS off 400ISO 1\1000 F5.6 200mm

HTTP response: 404 | MIME changed to 'image/gif' | Byte size: ZERO | PHOTOBUCKET ERROR IMAGE

HTTP response: 404 | MIME changed to 'image/gif' | Byte size: ZERO | PHOTOBUCKET ERROR IMAGE

HTTP response: 404 | MIME changed to 'image/gif' | Byte size: ZERO | PHOTOBUCKET ERROR IMAGE

HTTP response: 404 | MIME changed to 'image/gif' | Byte size: ZERO | PHOTOBUCKET ERROR IMAGE

interesting...unfortun​ately i don't really have time to test mine out with the sun already on it's way down...but if i have an opportunity to test my 70-300mm out tommorow, i'll try and do it for you and see if i get the same results

Is the sun reflecting off the glass?

No the sun was not reflecting off the window.

Maybe the problem is something with the glass on your window?
I have this lens for a week and shot some birds through the window just ok

Don't shoot through windows?

does it do it with any window?...mine didn't do it at all...so i think you've got a bad window...send it into canon

tkbslc wrote in post #9121578
Don't shoot through windows?

I usually don't shoot through windows. I do like going to the boulder mall here in Colorado drink my coffee at starbucks and take candid shots of the mall people. Sounds sneaky but I do let the person see what I have done and then offer to send file through email, or delete.

[QUOTE=Techuser;912145​5]Maybe the problem is something with the glass on your window?
I have this lens for a week and shot some birds through the window just ok


I don't think so. My 28-135, 100 macro don't have any issues.