Manual Mode - Focus issues

[Happy Snapper]

Hi,

I have bit the bullet and are trying to grapple with manual mode, I have been experimenting with taking light readings from different sources sky / grass / grey board / palm at different f stops, then recomposing and taking the picture.

However I am suffering with focus and getting pin sharp images, for example I was told that on f22 particulary you need to be on manual focus and turn the focus ring to about the 2ft indicated then take the picture, I think I am missing something fundamental.

Any help appreciated.

[OldClicker]

I really have no idea what you are refering to here. Maybe I'll learn something.

AFAIK, focus is no different in Manual Mode than any other mode. f/22 is most likely past the sweet spot of your lens with diffraction contributing to your blur.

Maybe more information will help.

Terry

[Loupey]

...for example I was told that on f22 particulary you need to be on manual focus and turn the focus ring to about the 2ft indicated then take the picture, I think I am missing something fundamental....

Throw out that piece of advice as it might pertain to certain super wide angle lenses (and fisheye) that have such deep depth-of-field at f/22 that virtually everything is in focus.

Another reason to forget that advice is that diffraction starts to set in at f/22 and so image sharpness begins to decline. DoF at the compomise of sharpness begins to be the issue at around this aperture.

I don't recommend recomposing after manually focusing. If the focus is critical (i.e. macros, telephotos, and/or shallow DOF), the act of recomposing can throw the focus off. Instead, compose first and then manually focus - whereever the main subject happens to be. Better still, compose and focus at the same time.

Use the ENTIRE focusing screen - not just the focus points and especially not the center point. The irony is that the most sensitive and accurate point for AF is the center - and yet this is often where the subject is NOT located when properly composed.

[Happy Snapper]

Hi,

What I am trying to achieve is a landscape with focus and clarity from the foreground all the way to the background.

My Camera can goto to F29 , so F22 I think is reasonable.

I am not using AF, should I ?

I am using MF , I try to point the camera down to some point just in front, focus, recompose , then take the photo.

[OldClicker]

Hi,

What I am trying to achieve is a landscape with focus and clarity from the foreground all the way to the background.

My Camera can goto to F29 , so F22 I think is reasonable.

I am not using AF, should I ?

I am using MF , I try to point the camera down to some point just in front, focus, recompose , then take the photo.

Now I understand more of what you are asking. What camera? What lens? The more you tell us the better the answer.

You cannot get the entire range in focus. Here is a Depth of Field (DoF) Calculator.

http://www.dofmaster.com/dofjs.html

Punch in your numbers. The Hyperfocal Distance is the theoretical point where you want to focus to get infinity in focus as well as close as you can with what you have. Use the Hyperfocal Distance as the Subject Distance and the Near Limit will be as close as will be in focus. The calculator makes a lot of assumptions, but it will give you the idea.

Most lenses will be their sharpest at around f/8 to f/11. As you open the aperture more from there, you are trading off DoF for diffraction blur. You will have to see what is acceptable to you.

How you focus doesn't matter as long as whatever you are focusing on at the Hyperfocal Distance is in focus.

Terry

[Loupey]

Do you really have foreground objects in the frame that are only 2' away? Very small percentage of landscape images do so as you would have to have the camera very low to the ground and/or very close to an object.

If so, why not just manually focus on that object 2' away and inside your frame instead of arbitrarily focusing on the ground?

[Happy Snapper]

Hi,

Oldclicker, now I start to understand, I think
My Camera is a Nikon D80 at the time I had the 18-70 kit lens on I also have a 70-300 kit lens (both nikor).

So it seems the focus is a bit of a red herring, and that I was probably out of the scope of the f stop and focal length selected.

Form the link you provided I noticed that if I don't move the lens ie 18 focal length the greater performance seems to be possible.

But I was told that I need to use a high F stop to get back to front depth of field, but according to the calculator even on f8 and 18mm it can go to infinity.


Loupey, I had a grass field in front of me with a nice autum tree line in the background , the 2ft focus was arbitory. I now see that I cannot guess this.

[Greg McCary]

If you are manually focusing get your eyes checked. Years ago I had a fully manual camera and that is how I found out I needed glasses. All my pictures were just a touch out of focus. If you have an old manual lens with a scale you can always hyperfocus.
yeah f/22 is to high. The sweet spot on my lens seems to be around f/8 or f/10. Never just throw the camera up and focus to infinity while using AF try focusing one third way into the shot. Just google hyper focusing and you will get a ton of help.

[OldClicker]

Using the calculator:

If you use 18mm f/16 (I would start with f/16 and see if you need more.) and focus on something at about 3.4 ft away, it will be in focus from about 1.7 ft to infinity. But you may have way too much around the outside of the image that you don’t want.

If you go to 70mm (still f/16) and focus at 50 ft, you will see much less in the viewfinder (Field of View (FoV)) and focus will go from 25 ft to infinity.

Now, say you just want the tree in focus and the foreground and background blurred so that it doesn’t distract from the tree. To get just the tree and not much around it, go to 150mm and focus on the tree – say 50 ft away. You will be in focus from about 25 ft in front of your focus point to 25 ft behind your focus point. If you focus on a branch about mid-way through the tree, you should get the whole tree without distractions.

To keep going try 300mm at f/5.6 and you can isolate a raccoon sitting in that tree with everything in front of and behind him out of focus.

Get the idea?

Terry

[Grandpaw]

Another thing you need to know about is the diopter adjustment on your camera. This is the little wheel by your viewfinder that lets you adjust what you are seeing to match your eyesight. If this is not adjusted properly everything manually focused when this is out of adjustment will come out blurry.

Think of it as if you put on a friends pair of glasses on and tried to focus your camera or maybe you do not wear glasses and you put a pair of glasses on and tried to focus your camera.

Try placing your camera on auto focus and after you push down the shutter to activate the auto focus notice if it looks in focus in the viewfinder, if not, adjust the little wheel to make what you are seeing in the viewfinder in focus to match what the camera sees. Now that you have the diopter set properly try manual focus and see what you get, Jeff

I find that the auto focus on my D80 or D90 does a better job every time on focusing than I can doing it myself.

[Happy Snapper]

Gentlemen,

Thank you for all your advise, My last outing I have had some success adopting your hints and tips, think I am turning the corner.

Till the next post, tks