Issues with focusing on a 50mm manual lense

[Rehesan]

Hello all,

I have a question for you:

About a month ago I got a Nikon 50mm f/1.8D lense in order to experiment and to practice with a manual lense. The thing is I have had hard time when focus. I should mention my camera is an entry level Nikon D3000, in other words is a DX format.

My problem is when I see the image fully focused in the viewfinder the photo comes out of focus, no matter how hard I try to focus I still get some photos out of focus. I should mention I use correction lenses and I have adjusted the dioptries in my viewfinder, but using an AutoFocus lense, that never had been an issue.

So my question to you guys is: are there any specific or special considerations I should take into account when focusing with the nifty fifty?. Is the DX format has something to do with the way this lense focuses?.

Thanks all in advance for your attention.

[Henry Wilt]

Is all of the picture out of focus or is a part of it in focus?

If part if it is in focus then I think you may well be having issues with the DoF. Remember, the wider the aperture (smaller f number), the smaller your DoF will be.

Alternatively, have you tried using the live view with the magnification to focus. I use varifocal lenses and have found that to be the best way for me if I want to manual focus. (I'm assuming Nikon have this).

Hope that helps.

If not, maybe you can post an example with EXIF so it would be easier to advise.

[OsmosisStudios]

THe D3000 doesn't have Live View.

Manual focusing on digital is hard, regardless of format, and the DX sensor size has no effect on the focusing youre doing.

As Henry has pointed out, it's likely depth of field issues. It takes practice.

[Shokinen]

Especially if you are at f/1.8. The nose will be in focus and they eyes wont. You need a longuer focal lenght to compress the image.

Try it at f/8 - f/12 and see if you get better results.

[TheEagleSpirit]

I wear glasses too, however with any lense at f1.8 will throw the background out of focus. Try putting the camera on a tripod for support and set the aperature at different settings taking the same subject and pay attention to the changes between Fstops and shutter speeds. I use aperature priority most of the time and let the camera set the shutter speed. If I do shoot manually, I make sure the camera is set to proper exposure. If in doubt, I bracket exposure.

[Rehesan]

Thanks all for your kindly replies, all are very helpful.

I think definately the issue I´ve been experimenting has all the variables you´ve mentioned: I´ve been shooting with wide aperture (f1.8 - f2.8) for two reasond mainly: to get a shallower DoF and nice bokeh and because I wanted to practice low light shooting; but I also shoot with shorter apertures, for instance to get a good DOF for night landscape (city skyline) and also I´ve been having hard time to properly focus, I thinks is because like Osmosis pointed out: "manual focusing on digital is hard" .

Here are two examples with exifs in order for you to see what I´ve been experimented, just as a reminder: in the viewfinder I see the subject in focus but when (even in the lcd the photo looks focused) but when I download it to the computer is blurry.

Two examples using low light and wide aperture:




Exif

Shutter speed 0.033 sec (1/30)
Aperture f/2.8
Focal length 50.4 mm
ISO 450
Exp comp 0 EV
Flash Off, Did not fire




Exif

Shutter speed 0.005 sec (1/200)
Aperture f/2.0
Focal Length 50.4 mm
ISO 800
Exp comp 0 EV
Flash Off, Did not fire


And an example using smaller aperture (f4.5), the subject looked completely focused on the viewfinder when shoot the photo:



Exif

Exposición 0.02 sec (1/50)
Aperture f/4.5
Focal lenght 50 mm
ISO 200
Exp comp 0 EV
Flash Off, Did not fire


Thanks again for your help mates!!

[inkista]

There's a little motion blur from shutter speed, but yeah, there's some misfocus. Have you tried keeping an eye for the AF confirmation dot lighting up? While the camera can't AF the lens, the AF system in the camera can still use the sensors to indicate when it thinks the image is in focus.

One problem with manually focusing dSLRs is that they're optimized for autofocus, not manual focus. And the focus screen in the viewfinder is actually optimized to give you the most light--NOT to render the DoF accurately. This typically isn't a problem at f/2.8 and smaller, but once you go wider than f/2, the DoF you're seeing in the viewfinder may not be what you're going to get. You start having to focus by braille and guesswork.

I'd say look for that AF dot to light up in the viewfinder before pushing the shutter button.

If you still can't focus accurately wide open with that guide, then you may want to look into swapping your focus screen for one with manual focus guides like a split circle and prism collar.

[Rehesan]

Originally Posted by inkista

There's a little motion blur from shutter speed, but yeah, there's some misfocus. Have you tried keeping an eye for the AF confirmation dot lighting up? While the camera can't AF the lens, the AF system in the camera can still use the sensors to indicate when it thinks the image is in focus.

One problem with manually focusing dSLRs is that they're optimized for autofocus, not manual focus. And the focus screen in the viewfinder is actually optimized to give you the most light--NOT to render the DoF accurately. This typically isn't a problem at f/2.8 and smaller, but once you go wider than f/2, the DoF you're seeing in the viewfinder may not be what you're going to get. You start having to focus by braille and guesswork.

I'd say look for that AF dot to light up in the viewfinder before pushing the shutter button.

If you still can't focus accurately wide open with that guide, then you may want to look into swapping your focus screen for one with manual focus guides like a split circle and prism collar.

I haven´t thought about the AF confirmation dot light, great tip! I always keep my attention to the exposure meter and even more to the screen trying to properly focus the subject. But you are so right, I will keep an eye into the AF dot light.

I had read also about the focusing screen, and I am seriously thinking about getting one, just to test and experiment with it, I found a not too expensive one at Focusing Screen, but there are two types: FSB and K3, the first cheaper than the other but I do not clearly understand the differences: Focusing Screen

Thanks again for your input, I will give a try to the AF dot and let you know.

[Almond.Butterscotch]

K3 will be a 35mm focussing screen; too big for your DX body.

EDIT: nvm. your links are just bad. http://www.focusingscreen.com/index.php?cPath=22_111

That said, if you're like me, then the split image + microprism is all you need to manually focus. Not sure what the extra ring around the microprism on the K3 does, but for a $30 difference, you may want to find out.

[Rehesan]

Originally Posted by Almond.Butterscotch

K3 will be a 35mm focussing screen; too big for your DX body.

EDIT: nvm. your links are just bad. Focusing Screen

That said, if you're like me, then the split image + microprism is all you need to manually focus. Not sure what the extra ring around the microprism on the K3 does, but for a $30 difference, you may want to find out.

Thanks for your help!!

I think I would be deciding to try the FSB screen, I think the split image and microprism is enough.

Thanks again!