Composition - Horizontal Line

There is an easy trick to see if you are facing a flat object straight on, just hang/tape a small mirror to it's surface, and align the camera so that the lens is looking at itself in the reflection, the camera will then be perpendicular to the wall.

Kolor-Pikker wrote in post #12619837
There is an easy trick to see if you are facing a flat object straight on, just hang/tape a small mirror to it's surface, and align the camera so that the lens is looking at itself in the reflection, the camera will then be perpendicular to the wall.

That would work if and only if the mirror itself was exactly parallel to the wall. A wall made of brick makes it difficult to ensure that a small mirror will be parallel to it, since any one brick could be slightly off. The mirror would have to be large enough to span at least several bricks but then it would not be so easy to tell if the reflection of the lens is parallel...

It looks like you've shot at a slight angle L-R. The focus is much sharper on the left side. A brick wall might be an un-interesting subject to photograph for most people, but they can be difficult to get a photo of without some distortion. This also happens with grids on paper & computer screens. Tilt & shift lenses are usually used to correct perspective in buildings etc, but are expensive. Longer focal lenses used from further back can also help to reduce distortion, but are unlikely to totally eliminate it.

PhotosGuy wrote in post #12619577
If you had, wouldn't you expect to see the same sharpness at the right as at the left?
You have to remember to not tilt the camera, & to keep the back vertical (Parallel to the wall) to avoid keystoning.
What is Keystoning

@400dabuser: the lens i used to capture that picture is Sigma 50mm f1.4

I guess the reason why it looks focus more on the left is due to the f1.4 that i used, hence the DoF ... I would only be able to focus on 1 single point, on which I focused on the left, and leaving the right Out of Focus. But it makes me think, if the angle is right, since the brick wall is on the same line, the right should also be in focus.

@photoguys: i will try it again sometimes this week. but is that the rules of thumb? not to ever tilt the camera? it does make sense thougt, because i don't see the need of tilting the camera, because we know brick of wall or any other architectural work should be straight (horizontal and vertical)

Try making the line at the same height as your camera straight, not the top or bottom. Any angling you do to straighten the bottom is keystoning the top, and vice-versa.

kakegawa wrote in post #12630221
@400dabuser: the lens i used to capture that picture is Sigma 50mm f1.4

I guess the reason why it looks focus more on the left is due to the f1.4 that i used, hence the DoF ... I would only be able to focus on 1 single point, on which I focused on the left, and leaving the right Out of Focus. But it makes me think, if the angle is right, since the brick wall is on the same line, the right should also be in focus.

@photoguys: i will try it again sometimes this week. but is that the rules of thumb? not to ever tilt the camera? it does make sense thougt, because i don't see the need of tilting the camera, because we know brick of wall or any other architectural work should be straight (horizontal and vertical)

Why ,why are you doing this? The whole idea of watching your horizontal and verticle lines is for composition. Leave the brick walls alone and go take some real photographs!!

kakegawa wrote in post #12630221
...because we know brick of wall or any other architectural work should be straight (horizontal and vertical)

Forget that. If everything appeared in perfect rectilinear fashion you would have no feeling of perspective in the picture. Sometimes that's good, sometimes it's bad. I've seen several posts by RE photogs that indicate they do not want to remove ALL traces of perspective distortion (keystoning).

You're getting keystoning in your shot, but it's horizontal rather than the typical vertical. And it's normal. If you're shooting down the length of a brick wall, you usually SHOULD see it converge to some extent. Otherwise the picture will lack depth. The convergence of objects is one of our cues to help us interpret their size, position and orientation. It's a variation of when you have a near object that is larger than a far object.

Everyone keeps saying "lens distortion," but isn't this actually perspective distortion, not lens?

Yes, and it's not totally accurate to think of it as distortion anyway. You are seeing the correct perspective-based geometry of your subject, but for some purposes you may want to minimize or eliminate it.

Sort of like world maps. A Mercator projection has MASSIVE distortion in certain ways because of its attempts to make 3D into 2D.

A point worth considering is, that the glass in your lens is not flat. The elements (which are not flat) are shaped to direct & focus the light onto your sensor (which is flat). Some distortion is likely to happen when the light is being re-directed, but lens manufacturers try to minimise it.