Focus testing
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This may sound a daft question, But is there a good DIY way if checking a zoom lens for its focus.....Perhaps taking shots of a eye test card at different focal lengths etc etc,
Welcome to TP
There are lots of test charts about (not that you need one) and quite a bit of chat about it one here if you search. All I would say is, if you go looking for a problem, you'll quite likely find one even if it's not significant or relevant.
Using the popular downloads of an A4 sheet of paper shot at 45 degrees and at very close distance is a great way to discover non-existant problems because a) it is very prone to user errors, and b) because the test is done at an artificially close distance which pushes the lens to the extreme of its design tolerance, you sometimes do find slight errors.
The danger is, if you then try to microadjust the AF to compensate for that, you throw it out for more normal distances.
Proceed with caution
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why would you want to check it ? do you think there is something wrong ?
the reason for bad focussing is very often down to bad technique, not bad equipment. Post a couple of example shots up, but please do not "save for web" as that removes important exif data of the camera settings.
the reason for bad focussing is very often down to bad technique, not bad equipment. Post a couple of example shots up, but please do not "save for web" as that removes important exif data of the camera settings.
Well as you suggest it could well be my technique.....heres the info. i have a 400d and using a canon 28-135 IS USM lens, and Im not sure this lens is crisp as id expect..went to take this pic this morning, and In my humble opinion due to the light i went with AV mode and got the slowest speed id chance, (thinking to get the higher F Stop and longer DOF) I also set the ISO at 400. However in my opinion the pic isnt sharp at all, and considering the train was slow, and the lens is an IS lens i would have hoped for at least the front of the Locomotive to be sharp......Hope my explanation make sense :thinking
Hmm, for a start, an IS lens will not make a moving train any sharper, well, not as such anyway. IS will reduce YOUR movement but not the subjects.
One of the biggest problems with trains, is they are big n dark (black even in the Duchesse's case!) and moving! Freezing this can be very hard. If lighting conditions were not good it makes it all the harder. From the look of it, the non moving part of your pic looks sharp enough to me.
You went the wrong way by going AV, at the distance you would be from the train, the DoF would not make a huge difference. You would be far better using a faster shutter speed to freeze the train while trying to focus on the smokebox number plate.
Hope this helps.
Edit: Just checked your exif data, you were in TV mode and took the photo at 320 sec. All in all, I'd say its not too bad an effort.
One of the biggest problems with trains, is they are big n dark (black even in the Duchesse's case!) and moving! Freezing this can be very hard. If lighting conditions were not good it makes it all the harder. From the look of it, the non moving part of your pic looks sharp enough to me.
You went the wrong way by going AV, at the distance you would be from the train, the DoF would not make a huge difference. You would be far better using a faster shutter speed to freeze the train while trying to focus on the smokebox number plate.
Hope this helps.
Edit: Just checked your exif data, you were in TV mode and took the photo at 320 sec. All in all, I'd say its not too bad an effort.
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I'd say it's just misfocused, and the good news is that it's user error, not the camera/lens.
The focus is around the middle of the loco (judging by the tracks) and shooting at f/5 is quite a low f/number with relatively shallow depth of field that will fall away more quickly in front of the focus point, ie the front of the loco is just out of focus. The shutter speed of 1/320sec is fine.
You either focused mid-way along the loco, or it has moved slowly forward a few yards after you focused, and before you pressed the shutter release.
If it was an equipment error, it's miles out. You would have noticed that first time you used it and not have a single sharp picture.
The focus is around the middle of the loco (judging by the tracks) and shooting at f/5 is quite a low f/number with relatively shallow depth of field that will fall away more quickly in front of the focus point, ie the front of the loco is just out of focus. The shutter speed of 1/320sec is fine.
You either focused mid-way along the loco, or it has moved slowly forward a few yards after you focused, and before you pressed the shutter release.
If it was an equipment error, it's miles out. You would have noticed that first time you used it and not have a single sharp picture.
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Not too bad actually. A quick fiddle with a tiny extra sharpen (30) and contrast (6) in DPP and it is quite respectable (even if limited by the low resolution causing a bit of jaggy mess here and there on sharp edges).
You are using multiple focus points, ie. letting the camera decide on which focus points to use, so you are not in control.
It claims focus point was top right focus point on right hand edge of the round door (just to right of the bottom hinge), also the buffer plate using bottom right focus point and bottom focus point on middle of closest (small) wheel.
Also you are in one shot focus mode for a moving subject.
Normally with a moving subject by the time it's decided on focus points and focussed the lens, locked on and then let you press the shutter all the way the subject will have moved on slightly. Tracking it with a single focus point on AI servo mode should cope a lot better. However, I dont think its done too bad here.
f5 is going to give you a shallow DOF
This taken as a jpeg? The picture mode was "standard", so no adjustment except sharpen of 3. Was it taken at full resolution or reduced size? Did you resharpen after resizing for internet?
Did you use a lens hood? the contrast seems a bit washed out and looking at the bright bright sky there was a lot of bright diffuse light knocking about. I wonder if that just dulled the contrast down a nadge and makes it feel softer than it really is. Adding a little contrast helps lots. Do you use a filter, and if so what make? (sometimes they can cause problems).
You are using multiple focus points, ie. letting the camera decide on which focus points to use, so you are not in control.
It claims focus point was top right focus point on right hand edge of the round door (just to right of the bottom hinge), also the buffer plate using bottom right focus point and bottom focus point on middle of closest (small) wheel.
Also you are in one shot focus mode for a moving subject.
Normally with a moving subject by the time it's decided on focus points and focussed the lens, locked on and then let you press the shutter all the way the subject will have moved on slightly. Tracking it with a single focus point on AI servo mode should cope a lot better. However, I dont think its done too bad here.
f5 is going to give you a shallow DOF
This taken as a jpeg? The picture mode was "standard", so no adjustment except sharpen of 3. Was it taken at full resolution or reduced size? Did you resharpen after resizing for internet?
Did you use a lens hood? the contrast seems a bit washed out and looking at the bright bright sky there was a lot of bright diffuse light knocking about. I wonder if that just dulled the contrast down a nadge and makes it feel softer than it really is. Adding a little contrast helps lots. Do you use a filter, and if so what make? (sometimes they can cause problems).
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The focus point indicator tells you which focus point/s were used, not what part/s of the subject they were covering at the time, which us usually a bit different in the final image, and often completely different (eg focus recompose technique).
Theres a few lessons for me to take in there, and that is so much appreciated....i have a lens hood but as it wasnt bright light I didnt use it, and as for the house thats cropped out when I play about with the shot. When us say DPP is that a program thats recommended, I use PhotoShop Elements, but in a very basic way. This is one i have messed in Pshop with. which i think is a lot better, even with a shallow DOF. Once again chaps, your advice and education is very much appreciated.....
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DPP is Canon's Digital Photo Professional, its free on the CD with canon DSLRs and is a very competent basic editor for whole shots and rectangular cropping (it does not do selective area edits). It's especially useful for raw conversion but also can do a reasonable job of jpeg adjustments.
As Hoppy clarified, if you were in one shot mode and panning then the actual focus distance will be slightly further back from the focus points locations displayed. I think I should have phrased myself more clearly last time, and concluded:
As Hoppy clarified, if you were in one shot mode and panning then the actual focus distance will be slightly further back from the focus points locations displayed. I think I should have phrased myself more clearly last time, and concluded: