canon rebel t7 autofocus

[tzegray]

When I point the camera at the sky to take photos of the sunrises etc...it zooms in and out but won't let me take the photo...also there is a big dot on the lower right corner..it works when I'm not pointing towards the bright light

[Tronhard · Accepted solution]

Hi and welcome to the forum

To get focus, you need to find something that has contrast, then, half-pressing the button will get the camera to focus and it should display a green box and beep. Then, holding the shutter button half-depressed, recompose to create your image, then fully depress the shutter button.

A camera needs something to focus on.  If there is no distinct object to select, then the camera cannot focus and will not take a photo.  It is definitely NOT a good idea to point your camera directly at the sun unless it is behind clouds, or very low in the horizon.  If you do so when the sun is at its brightest you can damage both your own eyesight and burn out the camera sensor.

In the example below, that makes the image work is the clouds that allow the colours of the setting sun to play across them and give tonal ranges of light - however the sun itself is not directly displayed.

Some of the most effective skyscapes are taken when the sun has actually gone below the horizon, but is still lighting the clouds from beneath. This not only gives much more contrast, but light on the clouds and clear points on which to focus.  Finally, one is not pointing directly at the sun.

Fuji X-T4, XF 15-80@52mm, f/10, 1/25sec, ISO-320

[Tronhard · Accepted solution]

Hi and welcome to the forum

To get focus, you need to find something that has contrast, then, half-pressing the button will get the camera to focus and it should display a green box and beep. Then, holding the shutter button half-depressed, recompose to create your image, then fully depress the shutter button.

A camera needs something to focus on.  If there is no distinct object to select, then the camera cannot focus and will not take a photo.  It is definitely NOT a good idea to point your camera directly at the sun unless it is behind clouds, or very low in the horizon.  If you do so when the sun is at its brightest you can damage both your own eyesight and burn out the camera sensor.

In the example below, that makes the image work is the clouds that allow the colours of the setting sun to play across them and give tonal ranges of light - however the sun itself is not directly displayed.

Some of the most effective skyscapes are taken when the sun has actually gone below the horizon, but is still lighting the clouds from beneath. This not only gives much more contrast, but light on the clouds and clear points on which to focus.  Finally, one is not pointing directly at the sun.

Fuji X-T4, XF 15-80@52mm, f/10, 1/25sec, ISO-320

[tzegray]

Why does manual focus work and not auto focus when it worked in the beginning

[Tronhard]

With manual focus you essentially disable the algorithm in the camera that demands a sharp element.  As to autofocus not working when it worked in the beginning.  If you don't continue to half-press the shutter, the focus is lost and had to be re-established.  As an exercise, try seeking something that has strong contrast, or hard surface edges.  The camera should snap into focus as soon as you half-press the shutter button. If you then continue to keep a gentle pressure on the shutter button and move the point of view to another location the focus should stay with the original object.

The trick is to lock focus on something that you want to concentrate on.  There is a technique that can assist with this, called back-button focusing.  There are multiple You Tube videos on how to set this up for Canon cameras if you are interested.

One question that does occur. You do not indicate what camera model or lens you are using, and that would be helpful, but you may have an issue with the autofocus feature that can happen with some lenses when manually focusing the lens when the autofocus switch is still on.  So: can you please indicate PRECISELY what camera model but also what LENS model you are using that information is written around the front face of the lens.

[tzegray]

Canon rebel t7

200mm lens EF-s18-55mm

Zoom lens EF 75-300mm

Just bought a 50mm online, it's coming Thursday

[Tronhard · Accepted solution]

Particularly with the 18-55mm lens, if it does NOT display the letters STM on the front of the lens, do NOT under ANY circumstances, try to manually focus the lens when the AF-MF switch is set to AF.  By doing so, you will screw up the mechanical focusing mechanism and it will not focus on AF properly again.  IF you HAVE done so it is important to let us know so we can try to help you with that.  To test if that is the case, try using autofocus on series of different objects that are clear and have hard outlines.  If it will not find focus, you need to fix that.

[John_Q]

Hello tzegray. I agree with Tronhard. There needs to be contrast in the shot for the lens to be able to AF(autofocus). From your description of the lens going in and out, it is struggling to AF. 

[tzegray]

Thanks..I love taking photos of the new sunrise, actually the beach I walk my dog on pretty much every morning usually has multiple photographers snapping photos. I understand now with everyones input. This problem I have a work around for...also, I'll be more cautious with my eyesight and my lenses. Everybody, thanks

[Tronhard]

Hi John:

You might want to switch the solution selected to the one on technique to autofocus, rather than the one the OP selected.