Unable to focus manually

ph0enix · Dec 2, 2011

I've attempted manual focus several times and have never been able to get it anywhere close to AF even when shooting still objects. Basically my eye sees the subject as sharp within a certain range - not a single setting. Is there a trick to manual focus? I'm using a Nikon D90.

Thanks!

Infinite_Day · Dec 2, 2011

Are you using a tripod?

bazooka · Dec 2, 2011

Why are you manual focusing?

Assuming it's for a good reason, you can still use the camera's AF system to tell you when the selected AF point is in focus, or it will tell you which points are in focus if you have all selected. This is what I do with my TS lens which is MF only. However, as you pointed out, with such a small and often dark screen, it can be difficult if not impossible to tell when something is in focus.

If you have liveview, you can use it to zoom in to tweak focusing. I will do this sometimes with macro shots when I'm on a tripod.

ulrichsd · Dec 2, 2011

That's actually a great question, I'm curious to see what other people do.

I usually zoom out until my focus point is blurry, then focus in until it is blurry and then try to slide the focus in the middle of those two points. I think I do this since it is similar to how I tune two strings on a guitar. Lower it out of tune and then bring up it into tune.

I like the idea of using the screen and zooming in if using a tripod.

SCraig · Dec 2, 2011

Make sure the diopter adjustment on the eyepiece is adjusted to your eye. Let the camera autofocus on something and then adjust the diopter adjustment knob for the best view.

Manual focus on the D90 does work. I use it a lot. As long as you don't use the DOF preview button you are seeing the focus through the lens at maximum aperture, so whatever you see in focus should be in focus in the image.

Soulz3urn3lack · Dec 2, 2011

I generally always use manual focus because I like ultimate control. If your camera has the zoom in live view focus use it. Just tweak it till every hair/fiber is perfectly detailed.

DiskoJoe · Dec 2, 2011

There should he a focus indicator in your view finder, a little dot. When you see the dot there is something in focus. other then that I would say just keep practicing. Practice makes perfect.

Overread · Dec 2, 2011

Setting the diopter on the camera correctly is the first important step. To do this point the camera at a white wall or any surface that is free of distractions. Then set the focus of the camera to be completely out of focus, so that all that can be seen is blurred. Then adjust the diopter wheel (located just to one side of the viewfinder on most cameras) until the square boxes that represent the AF points are shown as sharp as possible.

If this proves to be impossible chances are that you might require a diopter adaptor or the wearing of glasses when focusing the camera manually.

Rephargotohp · Dec 2, 2011

Unfortunately, cameras' or I should say viewfinders these days are not deigned as well for manual focus as they were back in the "Olden Days" of manual focus only cameras, where we had splits or mosaics or rangefinders to assist us with obtaining a great manual focus.

So like other's have suggested adjust your diopter. A great way is to remove your lens and adjust the diopter till your focus screen points are their sharpest. Or press the shutter till your info comes up on the bottom of the screen and adjust till those numbers are their sharpest

Big Mike · Dec 2, 2011

It sounds like maybe your diopter is out of adjustment, so as mentioned, that should be the first think you check.
Look in the viewfinder and adjust the little dial beside your viewfinder. You're not necessarily trying to make the image in the viewfinder sharp, what you should be doing, is looking for the focus points/lines to be sharp. This is easiest if you aim the lens at a white wall.
Once that is set, then what you see as in-focus, should actually be in-focus.

And also as mentioned, you can use the focus indicator light (green circle in the viewfinder) to confirm your focus, even when manually focusing. You may have to be half-pressing the shutter release to activate the AF/metering.

And also as mentioned, why are you manually focusing? AF is superior in almost all situations.

Derrel · Dec 2, 2011

Unable to focus manually...they have pills for that now...

KmH · Dec 2, 2011

Ho boy. Here's the straight scoop.

In SLR type cameras that don't auto focus, the mirror that bounces light from the lens up to the viewfinder is 100% reflective. Most of those cameras also have a manual focusing aid called a split screen/microprism focusing screen. Plus they usually also have a pentaprism to further deflect the light fom the lens to the viewfinder eyepiece.

Zoom lenses today are not parfocal. With a parfocal lens you can zoom in close, focus nice and sharp, and zoom back out without the lens focus changing.

The main mirror on auto focus cameras, that bounces light from the lens up to the viewfinder is 50% transparent. It's called the main mirror, and is 50% transparent, because there is a secondary mirror behind it that reflects the other 50% of the light down to the auto focus module in the bottom of the camera.

Since the camera is auto focus, they do away with the manual focusing aid, split screen/microprism focusing screen. However, the stock, no-manual-focusing-aids-on-it focusing screen can be changed in most of today's DSLR cameras: KatzEye Optics - Custom Focusing Screens.

In the entry-level cameras they do away with the pentaprism to, and use less reflective pentamirrors instead.

People today demand smaller and lighter, and they get it. So as cameras get smaller and lighter, so do viewfinders, making it difficult to provide a nice, bright, large viewfinder image that helps facilitate manual focusing.

But, auto focus is not the be all to end all, and manual focusing is often the best/only option.

So, replace the stock focusing screen with one that has a splitscreen microprism on it.

Manual focusing is now a lost art, and like most things in life there are best practices, and no so best practices.

The best practice is to - Start with focus in front of your subject. Then change the focus so it is behind your subject. Then move your focus back to your subject. Do the 3 steps in a smooth continuous process.

ph0enix · Dec 2, 2011

DiskoJoe said:
There should he a focus indicator in your view finder, a little dot. When you see the dot there is something in focus. other then that I would say just keep practicing. Practice makes perfect.

I thought that only works in AF mode, not in manual.

Thanks everyone! After reading your replies, I'm convinced that the diopter needs adjusting. I tried doing that already but I was setting it so the image in the viewfinder is sharp instead of the focus points. That makes sense.
As for the question as to why I would want to focus manually instead of using AF, the answer is: simply for the sake of knowing how to do it.

Vtec44 · Dec 2, 2011

For me, I just wait for the focus indicator light to stay on before taking the shot.

table1349 · Dec 2, 2011

KmH said:
Ho boy. Here's the straight scoop.

In SLR type cameras that don't auto focus, the mirror that bounces light from the lens up to the viewfinder is 100% reflective. Most of those cameras also have a manual focusing aid called a split screen/microprism focusing screen. Plus they usually also have a pentaprism to further deflect the light fom the lens to the viewfinder eyepiece.

Zoom lenses today are not parfocal. With a parfocal lens you can zoom in close, focus nice and sharp, and zoom back out without the lens focus changing.

The main mirror on auto focus cameras, that bounces light from the lens up to the viewfinder is 50% transparent. It's called the main mirror, and is 50% transparent, because there is a secondary mirror behind it that reflects the other 50% of the light down to the auto focus module in the bottom of the camera.

Since the camera is auto focus, they do away with the manual focusing aid, split screen/microprism focusing screen. However, the stock, no-manual-focusing-aids-on-it focusing screen can be changed in most of today's DSLR cameras: KatzEye Optics - Custom Focusing Screens.

In the entry-level cameras they do away with the pentaprism to, and use less reflective pentamirrors instead.

People today demand smaller and lighter, and they get it. So as cameras get smaller and lighter, so do viewfinders, making it difficult to provide a nice, bright, large viewfinder image that helps facilitate manual focusing.

But, auto focus is not the be all to end all, and manual focusing is often the best/only option.

So, replace the stock focusing screen with one that has a splitscreen microprism on it.

Manual focusing is now a lost art, and like most things in life there are best practices, and no so best practices.

The best practice is to - Start with focus in front of your subject. Then change the focus so it is behind your subject. Then move your focus back to your subject. Do the 3 steps in a smooth continuous process.