How to test 70-200 F4L

I have the 70-200 F4L but am not getting very good results. I do however need to clean my sensor and need to know if this affects the focus as the shots I take are not at all sharp. In fact I get better shots with my 18-55 kit lens.

What distance and settings should I test the lens at. Or do I take it to my local shop. Do they generally test lenses or will I need to send it to Canon. It's still under warranty.

Many thanks.

Choccy...

hi Choccy! could you post some samples so we could could determine what the problem is? the 70-200 f4 L is one of the sharpest zooms available & IMO, one of the safest buys in the Canon line meaning there are none/very limited units with "issues".

Agreed with nordstern.

Sensor cleaning will not affect focusing. I'm willing to bet that your issues lie with shutterspeed and camera shake, or something else not related with the lens itself.

I am thinking it's user error. What is the distance from the subject for sharp in focus images. In good light from a couple of metres I get good results.

I'll post some images when I get home.

Choccy...

The only problem I have had is forgetting when I set the focus range to 3m and I try to take a picture up close. I curse and wonder what's wrong and end up beating the lens against a tree which usually moves the switch the switch to the 1.2m position and it works again.

Test your lens in good bright lite so you can get a fast shutter speed or put it on a tripod for your tests. Because of the longer focal length it is more sensitive to a slow shutter speed and camera shake.
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This lens is what made me sell my 18-55 kit lens and buy a 24-105L. When looking at my photos on the computer screen the 70-200 ones were noticably sharper and had better contrast than the 18-55 kit lens. It was not too difficult to tell which lens took what picture (yes, I know the focal lengths do not overlap) without looking at the metadata.

Something is a miss here, we need samples. This is probably canon's most reliable performer- there is no way a kit lens can produce better images.

Choccy, is it possible that the shutter speed you're using is too slow and that you are introducing camera shake into your pictures? Your 18-55 is shorter and lighter and will not have the tendency to "wobble" as much when being used.

If you REALLY think there is something wrong with lens, put it on a tripod and aim it at a brick building or something else with good detail, outside in good lighting. Also, give us some EXIF info and image samples so we have something to go on. - Stu

I'll have to wait until the sun comes out tomorrow to get some pictures. Can you give me some examples of targets, speed, settings and distance. I got some today of flowers from about 8m with ISO 100, F4, 1/250, spot metering, mirror lock up, tripod, AF single shot, timer and centre spot focus. They didn't come out too well and seemed to focus on the foreground more. When I changed the focus point to the bottom point and aimed at the target I got much better results. All the other shots seem out of focus.

Choccy...

That's helpful.

The fact that yoo're at 1/250 sec really should be enough to freeze any motion or jiggling of the camera. Target examples would be anything with sharp detail as I suggested..... a brick wall, fence, parked cars, etc...

I have a strong suspicion that this "lack of sharpness" may be in the way you are using your autofocus point(s) as evidenced by your bottom AF point experiment. Sometimes when you use a spread of focus points the camera has a mind of its own and delivers what it "thinks" you want.

I always use the center AF, but that's just me and I'm not saying it's the right or wrong thing to do. But you may want to just try using that one for a while. This way YOU will always being telling the camera what YOU WANT to be in sharp focus.

Choccy wrote in post #6756489
I'll have to wait until the sun comes out tomorrow to get some pictures. Can you give me some examples of targets, speed, settings and distance. I got some today of flowers from about 8m with ISO 100, F4, 1/250, spot metering, mirror lock up, tripod, AF single shot, timer and cetre spot focus. They didn't come out too well and seemed to focus on the foreground more. When I changed the focus point to the bottom point and aimed at the target I got much better results. All the other shots seem out of focus.

Choccy...

I do use just the one AF point, usually the centre but when I tried the bottom of the 9 points I got much better results, not perfect but better.

Choccy...

Sorry - my misunderstanding. I believe you said you shot those at f/4? If that's the case then and you were focused in pretty close then you will have a relatively shallow DOF.

Choccy wrote in post #6756676
I do use just the one AF point, usually the centre but when I tried the bottom of the 9 points I got much better results, not perfect but better.

Choccy...

How close should I be with F4. I've taken shots 8m, 15m, 30m and 50m and none seem sharp or in focus.

Stu can give me the numbers I need to punch in and I'll do them tomorrow then give you the results please. I'm still learning and can't quite work out what's going wrong. I'm pretty sure it's not the lens or the camera but I can't put my finger on the problem

Also Stu love some of your landscape photos in your gallery. These are the sorts of shots I want to produce.

Choccy...

Thank you for the kind words Choccy - I appreciate you're taking the time to look. Most of what you see there was shot near the wide end, usually with my 24-105.

Regarding some suggested numbers - bump your ISO up a little more to 200 or 400, with aperture around f/8. That will give you better DOF and allow faster shutter speeds by 1-2 stops. Try shooting just some large objects then, and 25 - 100ft should be ok if not longer. We look forward to seeing some samples .

Choccy wrote in post #6756763
How close should I be with F4. I've taken shots 8m, 15m, 30m and 50m and none seem sharp or in focus.

Stu can give me the numbers I need to punch in and I'll do them tomorrow then give you the results please. I'm still learning and can't quite work out what's going wrong. I'm pretty sure it's not the lens or the camera but I can't put my finger on the problem

Also Stu love some of your landscape photos in your gallery. These are the sorts of shots I want to produce.

Choccy...

Cheers Stu and thanks for the quick replies. Looks like I'm going to follow you wide and mid choice hopefully with the 17-40 and 24-105. I almost went for the 70-200 F2.8 but it was just too big and heavy for the range.

I take it from your pictures and equipement list you're a professional wedding photographer. This is the sort of thing I would have liked to have done but I feel I've left it too late in my career to be able to learn this trade. I bet it's 110mph for the whole day.

Choccy...

Well Choccy, I'm a pro in the sense that I've been doing weddings, bar mitzvah's and other social events part time for about 35 years. I don't do the volume or service of those FT guys in their own brick and mortar shop, but I deliver quite a good package. I tried to go the FT route at the start back in the 70's but it never worked out. This supplements the regular job.

I also donate some of my photographic time and talent to the local PBS station since they couldn't afford my rates anyway .

http://pearlphoto.blog​spot.com …k-comes-to-cleveland.html

That's been very gratifying. It's allowed me to meet some very interesting people and also become involved in fascinating projects that normally would not have come my way.

Choccy wrote in post #6757153
......I take it from your pictures and equipement list you're a professional wedding photographer. This is the sort of thing I would have liked to have done but I feel I've left it too late in my career to be able to learn this trade. I bet it's 110mph for the whole day.

Choccy...