How do you focus accurately?

R

Richtiger

Member
I'm a fairly new user of the GH13. It seems very difficult to get accurate focus using the small LCD screen. Even when focussing through the viewfinder, often after checking the footage it seems very soft and just slightly off focus.
I am used to using Canon XH-A1 and various other video cameras over the years. Also I take a lot of stills using Nikon DSLR gear.
The lenses I'm using are Nikon 50mm F1.8 and Tamron 17-50 F2.8. I have played around a bit with other slower Nikon lenses as well. Is it just that I'm not able to focus or is this a problem for others as well?
When I look at the footage from many other users it is usually quite sharp.
I find it almost impossible to be sure of my focus when shooting. It's only later when I view on a larger screen that I realise the focus is not right.
I try to use the focus assist to enlarge the shot to focus as well.
I use a tripod as well as hand held.
This makes my footage disappointing as I'm really wanting to get the results I see others getting on this site.
Am I using the wrong lenses ... I do not have a kit lens.
Richard
 
Hi Richard...welcome!

i'm a former XHA1 user, and now i use the GH13 exclusively. man, where to start haha.

this might turn into a thread about the lack of external monitoring, but all i can say for now is, continue to use the viewfinder more than the lcd, and make sure the diopter on the viewfinder is true to your best perception. i wear glasses/contacts, and sometimes i think the viewfinder is accurate, but my eyes might be dry or something, because i run into similar problems with out-of-focus footage.

practice makes perfect, and shooting with prime lenses will give you some deceiving results in a well lit enviornment when you only look at the lcd or viewfinder quickly. spend the extra time, play with the focus, and look in that viewfinder constantly. remember, we're adapting 10/20/30 year old primes to a camera that they were never meant to be attached to. and with the modified firmware, things like focus are even that much more critical. just keep on keepin on. feel free to post footage here in case you're having problems that constantly bug you and you need help.

hope that helps.

Chris
 
it comes with practice for me too after reviewing early footage that were out of focus. as suggested take the time to calibrate your viewfinder to match focus. I also try not to stop down too much unless absolutely necessary. I have limited myself to shoot more at f2 than f1.4 simply because the DOF is unforgiving focus wise and even then its quite tricky. the panny 20mm f1.7 has made life abit easier with quick on the spot autofocus for low light stuff =) Other than that I quite enjoy using manual lenses
 
I always thought the manual focus assist on the GH1 was easy to use. I only wish you could use it while actively recording.
 
I never have problems with focus unless with superfast glass and DOF of below 1-2 cm. In those cases as said above: close down the iris. I prefer the viewfinder over the lcd for accuracy, my nearsightedness is still inside the range of viewfinders diopter adjustment.
 
[1] I Calibrate viewfinder first.
[2] Then Use Zoom feature to focus on subject.
[3] Manually Focus and set.

I found the sharpest image acquisition is between f/2.8 - f/5.6

Practice makes perfect until HDMI out is enabled in GH13 for external monitor.

Cheers
 
Actually, you can use an external composite monitor for focusing. After you connect the monitor, you need to hold down the trashcan button for a few seconds to activate it. As is widely known, however, the monitor will go blank as soon as the camera starts recording video.
 
Richtiger said:
I'm a fairly new user of the GH13. It seems very difficult to get accurate focus using the small LCD screen. Even when focussing through the viewfinder, often after checking the footage it seems very soft and just slightly off focus.
Click to expand...

With the lens wide open, ISO (should be in the 'low' 200's or 100's...) and lighting adjusted for a 'reasonable' image:

Lay out a ruler on the table and angle the camera so you are at a somewhat 'small' angle looking down the run of the ruler. Focus on a specific inch/cm marking on the ruler, then press record...

Look at your footage on the type of display you will ordinarily want to present (computer, home HD display, your buddy who runs the local metroplex, and has just installed a new Digital presentation system... whatever...)

Then evaluate for 'sharp'.

Then run your test clip through an unsharp mask filter operation, to slightly 'clean' up sharpness and contrast... see if that helps in getting a 'sharper image'.

A number of things can affect the perception of 'sharpness' for humans. One is obviously focusing on the 'wrong thing'... another has to do with image contrast and edge definition. The unsharp mask 'helps' the latter problem. Humans will 'perceive' an 'out of focus' but 'contrastier' image as 'sharper' than one which has 'exact focus', but is 'flatter' or has less edge definition (the latter is also dependent on subject and environment as well'...

So the 'ruler' will tell you whether whether you can focus on what you think you want in focus, and the evaluations as to what processing needs to happen for your image to be preceived as 'sharp'.
 
j1clark@ucsd.edu said:
With the lens wide open, ISO (should be in the 'low' 200's or 100's...) and lighting adjusted for a 'reasonable' image:

Lay out a ruler on the table and angle the camera so you are at a somewhat 'small' angle looking down the run of the ruler. Focus on a specific inch/cm marking on the ruler, then press record...

Look at your footage on the type of display you will ordinarily want to present (computer, home HD display, your buddy who runs the local metroplex, and has just installed a new Digital presentation system... whatever...)

Then evaluate for 'sharp'.

Then run your test clip through an unsharp mask filter operation, to slightly 'clean' up sharpness and contrast... see if that helps in getting a 'sharper image'.

A number of things can affect the perception of 'sharpness' for humans. One is obviously focusing on the 'wrong thing'... another has to do with image contrast and edge definition. The unsharp mask 'helps' the latter problem. Humans will 'perceive' an 'out of focus' but 'contrastier' image as 'sharper' than one which has 'exact focus', but is 'flatter' or has less edge definition (the latter is also dependent on subject and environment as well'...

So the 'ruler' will tell you whether whether you can focus on what you think you want in focus, and the evaluations as to what processing needs to happen for your image to be preceived as 'sharp'.
Click to expand...

Good advice - it's sort of like using a focus card which might also be something you should consider if you're having trouble eyeballing it for now - it's something that does take practice, comes naturally for some, not for others, seems easier for those who have a photographic background vs. video but we're all merging these days and can help each other out!
 
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