Newark727
Topic Author
Posts: 1425
Joined: Tue Dec 29, 2009 6:42 pm

Tell Me About The Canon EF 70-300 Is USM

Sat Aug 07, 2010 12:03 pm

I've owned one of these lenses since I received my first DSLR, a 50D, in December 2009. Mostly, I've used it for Imperial Hill shots at LAX though I've taken it to other airports as well. It's done a fairly good job but as the summer wears on I've noticed it's gotten harder to get crisp shots with it, especially for small aircraft (or most recently I was attempting to photograph a loon on a lake with it.) There's a lot of possible reasons, and I'm very much an amateur, so I'm hoping some more informed people might be able to clarify a bit as to what's frustrating me here. Here are the potential causes I can think of so far:
-I've been using the wrong aperture settings and not realized it. During the aforementioned loon-on-lake effort, I noticed that moving up from f6 or 7 to f10 or higher made things a bit crisper, though not completely so.
-Summer air in Los Angeles is just difficult. There is more smog/haze/etc. That might be making focusing harder I suppose.
-I'm using the wrong autofocus setting. Typically I use "one shot" mode with only the very center autofocus point in use. I know the 50D has an option to autofocus a moving target but I haven't done much experimentation with it.
-Something broke.
Anyway, thanks very much for any help anybody can provide.
 
GPHOTO
Posts: 799
Joined: Sun Aug 01, 2004 11:44 pm

RE: Tell Me About The Canon EF 70-300 Is USM

Sat Aug 07, 2010 1:08 pm

Hello Newark727,

I used this lens for a few years and it is ok, in fact very good for the price. It is noticeable soft above the mid to high 200mm range, exactly where depends on your copy, but that is not unusual in any consumer lens zoom in this class and should not be a cause of concern. Performance below 200mm is very good. This might help explain why you have more of a problem with small aircraft, where more zoom is needed.

The lens performs best, sharpness wise, around f8 or f9.

Autofocus on this lens can be a bit 'hunty' depending on light conditions. It's fine, just not the best. I found it could cost me some shots occasionally. I would recommend 'One-Shot' with this lens unless you are tracking quicker objects, then use 'AI Servo', the tracking option. One shot always seemed to work best for me as a rule of thumb.

Shots in the summer are always more difficult than the winter due to weather factors (atmospheric distortions caused by uneven heating and pollution). Not much you can do about this except get as physically close as you can to reduce the quantity of air you shoot through and go shooting early or late in the day when the air is often a bit more settled.

Putting all this together, it sounds like you and your lens are ok, you are just butting up against the conditions and the limits of this lens.

Best regards,

Jim
Erm, is this thing on?
 
Newark727
Topic Author
Posts: 1425
Joined: Tue Dec 29, 2009 6:42 pm

RE: Tell Me About The Canon EF 70-300 Is USM

Sat Aug 07, 2010 1:53 pm

That pretty much sums up what I've noticed so I imagine that the lens is working the way it's supposed to. Thank you very much for your comprehensive reply.
 
User avatar
NZ107
Posts: 4946
Joined: Sun Jul 10, 2005 6:51 pm

RE: Tell Me About The Canon EF 70-300 Is USM

Sun Aug 08, 2010 8:04 am

Hi Newark727,

I've owned one too since April of last year.

Quoting Newark727 (Thread starter):
Summer air in Los Angeles is just difficult. There is more smog/haze/etc. That might be making focusing harder I suppose.

Probably less about focusing but more about the end product. When you're shooting through that, it is very likely that you'll run into some sort of problems with quality.

Quoting Newark727 (Thread starter):
I'm using the wrong autofocus setting. Typically I use "one shot" mode with only the very center autofocus point in use. I know the 50D has an option to autofocus a moving target but I haven't done much experimentation with it.

I use AI Focus. I can never trust AI Servo as it keeps trying to focus on something else and it gets really annoying. I also tend to use an automatic AF point - generally it gets things right all the time. With a 400D, I don't have a great selection of different AF points - it's either one spot or automatic.

Quoting Newark727 (Thread starter):
Something broke.

LOL. Sorry, can't help with this one 
Best to get it checked out at a camera shop or something.


I agree with all points above in the reply from gphoto. It does tend to get soft after 200mm.

Quoting gphoto (Reply 1):
The lens performs best, sharpness wise, around f8 or f9.

I concur. But if light seems a bit on the dark side, I don't have much hesitation dropping it to 7.1.


Make sure you're using the right IS modes for different types of shooting. Mode 1 for normal 'still' stuff and Mode 2 for panning shots.

Cheers,
Nicholas
It's all about the destination AND the journey.

Who is online

Users browsing this forum: No registered users and 5 guests