07-25-2016 09:47 AM
I am user of Canon EOS Rebel T 5i.
With 55-250mm and 18 - 55 mm lenses I used to get good quality images. However of late I have problem in getting sharp and clear images.
I use power glasses. As suggested by a fellow photographer, I adjusted diopter, but it has not helped, especially in macros.
Should I clean the AF sensor? If so, what is the best way to do it?
Is diopter adjustment necessary? How can I change back to default settings?
Will these help to get sharp and clear focus?
Thank you for any help that I can get.
I am a new member here. Hope I will get good suggestions to solve the issues.
07-25-2016 09:50 AM
Do not clean the AF sensor!
Are you sure it is a focus issue? Take an image of a yardstick at a 45 degree angle. Is the focus point in focus? Is it in front or behind?
Diopter only changes what *you* see it does not affect the camera image at all unless you use manual focus.
Try using manual focus and live view magnification. Does that work better?
07-25-2016 11:02 AM
Your question is too vague. I need way more info in order to suggest something. What exactly are you trying to shoot and how? It may be you are asking the camera/lens to do something it can't. Macro is especially difficult to get sharp photos.
"I use power glasses. ... I adjusted diopter"
None of these things help the camera. They may help you 'see' if a photo is sharp but that's all.
"Should I clean the AF sensor? No, do not try it.
"Is diopter adjustment necessary?" No it isn't necessary but it is nice to have it correct.
"How can I change back to default settings?" There is no default setting per se. I guess 0 might be considered default. It is right in the middle of the button's travel.
Will these help to get sharp and clear focus? No.
What you need to do is go outside on a nice sunny day and try normal shots. The real easy to do stuff. Plenty of light and plenty of distance. Not too much motion or action. The camera on the "P" mode and the lens set to AF. ISO in the 100 range. If it works as it is expected, it is OK and the issue is elsewhere. Most likely in your technique.
07-25-2016 11:13 AM
Should I clean the AF sensor?
Is diopter adjustment necessary?Yes
How can I change back to default settings?
You have to reset them two places.
Clear all camera settings
Clear all Custom Functions
No way to know.
Will these help to get sharp and clear focus?But, watching these videos by Canon's Rudy Wilson (at least the first two) will.
A Look at The Canon Autofocus System Part 1
07-25-2016 11:16 AM
"... especially in macros. ..."
Neither the Canon EF-S 55-250mm f/4-5.6 IS STM Lens nor the Canon EF-S 18-55mm f/3.5-5.6 IS II Lens is a 'macro' lens.
07-25-2016 11:20 AM - edited 07-25-2016 11:22 AM
"I use power glasses. As suggested by a fellow photographer, I adjusted diopter, but it has not helped, especially in macros."
I use powerful glasses, too. The standard diopters are not really strong enough for me. Thank goodness, for auto focus. The diopter setting has no effect on Image Quality, not unless you are trying manual focus through the viewfinder. I use the LCD screen to manual focus in Live View mode, never the viewfinder.
Taking photos of subjects very close to the camera, or "macro" shots, can result in a very narrow depth-of-field, DOF, which results in some, if not most, of your subject not being in acceptable focus. This occurs naturally because of the physics behind how lenses and cameras focus. The following link is to an online DOF calculator, which I find very useful for estimating shots.
Use the EOS 70D camera to simulate the behavior of your T5i. Enter in a focal length comparable to what you might use for your macro photos. The table will give you depth of field values for varying distances and f/stop settings. Notice how narrow DOF gets when you are close to the one foot distance from the camera.
07-25-2016 11:54 AM
07-25-2016 11:08 PM
You do not have a macro lens. The main quality of a macro lens is that it can still focus on a subject even if you get the lens just a few inches from touching the lens. Other lenses can not focus when they are that close. You may just be getting your lens too close to focus.
As stated you also get a very shallow depth of field in focus when you are very close. At true macro close distance, even something as small as a bee or a coin will be too big to have the entire object in focus. With an insect you may need to choose what part you want in focus (typically the eyes) and the rest of the insect may be blurry and out of focus. It is very tricky to focus when you are very close to the subject.
07-26-2016 03:26 AM
The definition of a true macro lens is, it is able able to reproduce a life size image of an object on the sensor.
In other words a magnification factor of 1:1 at its closest focus setting.