Focusing problem discussion

[spurssy]

Hi folks,

I have a DImage 5, and I loved it for the fact it has taught me a lot in terms of landscape photography - the fact that it's EVF shows me what I'm about to get without guessing.

However, I have always had this problem with portraiture and action shots, either due to equipment limitations or my skill limitations. To cut short, many times, I am unable to get a good focus with moving subjects, and the photos end up in a blur, even when the aperture is wide open and shot in daylight. I assume it's the slow focusing. Another problem that I experienced is the inability of throwing the background during a portraiture into blur, even with widest aperture at the longest end (250mm equiv.).

I just like to find out if anyone of fellow DImage (5/7/7HI/A1/A2) users have encountered these problems and had successfully achieve success.

Adams

 

[elkimoose]

> I am unable to get a good focus with moving subjects,

welcome to the out-of-focus-club
I can only speek about Dynax7 / analog Camera usage: The camera is only able to focus on some moving subject if this subject covers most of the image area. Otherwise the AF chooses the backround especially if the background is bright... I don't think this is different for digital.

> Another problem that I experienced is the inability of throwing the background during a portraiture into blur

I suppose the AF always chooses the background, thus the background wont get blurred. However... digital image and blur? where is the problem? :bsmilie: this is a job for photoshop, gimp, etc... motion blur, radial blur, selective blur, all is possible...

 

[sulhan]

> I am unable to get a good focus with moving subjects,

welcome to the out-of-focus-club
I can only speek about Dynax7 / analog Camera usage: The camera is only able to focus on some moving subject if this subject covers most of the image area. Otherwise the AF chooses the backround especially if the background is bright... I don't think this is different for digital.

> Another problem that I experienced is the inability of throwing the background during a portraiture into blur

I suppose the AF always chooses the background, thus the background wont get blurred. However... digital image and blur? where is the problem? :bsmilie: this is a job for photoshop, gimp, etc... motion blur, radial blur, selective blur, all is possible...

Hi There....

Juz to share some thoughts on the AF...for moving object.......Well, the automation of newer cams (AF) have led to one to be too far fetched in their expectations on AF results....

I always emphasized on my students on using the fact that we always can work around the "cannot AF on moving object" issue.....

What do we need to worry on AF when we are suppose to be "building the image in our minds for composition" ...rather than worry if focus or not.......
If you have subject that you wanna catch....and know that it will pass at a certain point....you could just focus on any stationary object, within the path of the subject(whee you have roughly picture what background to compose with when the subject comes into the frame), then leave the cam back to MF so that the focus would stay the same...and then now you can concentrate
on getting the subject in the position to be captured.....thats how many older pros on manual cams) get great pics.....

All this racking AF is sort of a gimmick at times.....

Imagine on a straght road, i wanna shoot a car.....just focus at the lane lines and concentrate on framing the subject and press the shutter at the point that you have locked focus on......

The rest is let DOF to do the job......

How about that???

rgds,
sh

 

[Xaler]

Hi There....

Juz to share some thoughts on the AF...for moving object.......Well, the automation of newer cams (AF) have led to one to be too far fetched in their expectations on AF results....

I always emphasized on my students on using the fact that we always can work around the "cannot AF on moving object" issue.....

...

Imagine on a straght road, i wanna shoot a car.....just focus at the lane lines and concentrate on framing the subject and press the shutter at the point that you have locked focus on......

The rest is let DOF to do the job......

How about that???

rgds,
sh

I agree! Many times when I'm taking moving objects, the AF actually throws the focus out by focusing on anything BUT the subject. I would be better off using MF. Manual may not be as sharp (possibly due to my short-sightedness) but at least the subject don't end up looking like bokeh :bigeyes:

 

[elkimoose]

Hi There....

I always emphasized on my students on using the fact that we always can work around the "cannot AF on moving object" issue.....

sh

absolutely right,
I expected too much from AF.
concerning your suggestion its sometimes quite complicated to predict the exact way of the subject (which lane an oldtimer will use, etc)

As an example I put one of my missed shots in my members gallery:
http://gallery.clubsnap.com/showphoto.php/photo/1674/size/big/sort/1/cat/500

focus is too far away (somewhere behind the ear). The picture is MF (of course Canon T90 :embrass: ) the hipo was quite slow but I was even slower :cry:
F4 was the only possible setting with ISO100 on this day and DOF is already quite small. Even with AF I would have missed this shot, bcos it would have been complicated to set one of the Dynax 7 AF sensors exactly onto the eye (in my opinion the required focus point) and DOF would have been even smaller with 80-200/2.8.
Conclusion: I'm too slow for MF, and too stupid for AF

rgds, Chris.

to cite Goethe: "Grau treuer Freund ist alle Theorie". Don't ask my for some translation, my english is too bad for this :dunno:

 

[sulhan]

Hiee....

Just a thought....for slow mo....like th ehippo in water...if its approaching you...how about doing the ambush method....focus on the nose....by the time you press the shutter....the frame captured would probably on the nose bridge and eyes area......

unless he's reversing...as he say you with your 80-200....!!!! :bsmilie: :bsmilie:

Here is an example where a pre-focus is done...on a predetermined and "estimation" of bird in flight....

It was a bet on those present there in the local bird park.......
that i could capture the lorikeet in flight.....- with my trusty A1.....

As i just waited to see their flight pattern....then roughly estimating the distance... i used the railing to guage the distance.....- seen here...the panning is even with its eyes fully 99% sharp....
rgds,
sulhan

 

[elkimoose]

Hiee....

unless he's reversing...as he say you with your 80-200....!!!! :bsmilie: :bsmilie:

Here is an example where a pre-focus is done...on a predetermined and "estimation" of bird in flight....

sulhan

don't worry for the 80-200: it's not mine.

i will consider your pre-focus advice,
but for the moment I prefer 'still sitting' birds like this one...

eagle

yes. it was a lucky shot, just enough time to get into position, mount tripod 300mm lens teleconverter check focus, recheck focus, tripple check focus :sweat: ... and the picture is cropped to some factor 0.75 to get rid of some unpleasant vignetting and I used some sharpening... but why not... Dimage is also using sharpening :blah:

rgds, Chris.

 

[spurssy]

Yes Sulhan,

I do try pre-focusing sometimes, when the subject is certain to cross a particular point. The extreme situations arises in situation such as your example, capturing a bird in flight, who will never fly to where you locked on.

Anyway, how about some feedback on my second problem, where I can't seems to throw the background into blur even when using wide apertures and long focal lengths.

Adams

 

[spurssy]

I suppose the AF always chooses the background, thus the background wont get blurred. However... digital image and blur? where is the problem? :bsmilie: this is a job for photoshop, gimp, etc... motion blur, radial blur, selective blur, all is possible...

Maybe it's the type of Metering mode (Multiple Segment) that I used, some pp do recommend using Center-Weighted or Spot... any comments on this?

Adams

 

[UY79]

Maybe it's the type of Metering mode (Multiple Segment) that I used, some pp do recommend using Center-Weighted or Spot... any comments on this?

Adams

Metering has nothing to do with AF. This is the second time I stating this. Unless there's something in the Dimage series that I do not know of.

Cheers!

 

[elkimoose]

Maybe it's the type of Metering mode (Multiple Segment) that I used, some pp do recommend using Center-Weighted or Spot... any comments on this?

Adams

even if UY79 said metering and AF are not correlated I would mention that the wide area AF in my Dynax 7 is strongly influanced by contrast and brightness difference among the single AF sensors. Why should this be different for dimage? If your problem is only present when you set some kind of wide area AF (no idea if this is the same system on dimage) you should avoid this mode with bright background and dark moving subject. just my 2 cents...

rgds. Chris. - not an expert for AF, I just switched two years ago to AF from an MF Canon T90.

 

[deslim27]

Metering has nothing to do with AF. This is the second time I stating this. Unless there's something in the Dimage series that I do not know of.

Cheers!

UY, if I not wrong, Ax flexi-spot also can serve as spot metering as well..

 

[UY79]

Otherwise the AF chooses the backround especially if the background is bright...

True. I've a roll of slides in which all the shots had the focus on the brighter white walls in front of or behind the subject standing close to them. Almost none of them had a good focus on the subject. And I've tried to get AF confirmation a few times before actually taking the shot.

However, when I moved to another location where there's lesser contrast, the AF was spot on.

Cheers!

 

[UY79]

UY, if I not wrong, Ax flexi-spot also can serve as spot metering as well..

Still, it should not affect AF.

Cheers!

 

[Flare]

Ok... think with everyone discussing on the AF, i'll focus on the second question, the bokeh thingy issue.

The general idea to achieve a out-of-focus back ground is to shoot with a lens of a long focal length and a wide appearture, which aims to reduce the DOF, so that the subject is in focus, while the background, which is outside the DOF, is out of focus. Works great with film cameras.

But when we come to digital consumers and prosumers, one can almost never achieve the effect as well as the film and dslr counter parts. why?
Let's look at consumer and prosumer digicams. They are all armed with tiny CCDs which has a fantastic 'crop-factor' when compared to tehir 35mm counterpart. When you are shooting at say 250mm-equivalent on your D5, the actual focal length is much less, i don't remember the exact length, but i think it's like 50-ish. for reference the Z1's lens runs at 5.8mm - 58mm (38-380mm-equivalent, woo~ 'crop-factor' of more than 6x! ). The 250mm on your D5 is an equivalent focal length, not actual, meaning that it gives you a manification that is similar to 250mm on a 35mm, that's all.

So what does that has to do with your problem? Well, due to the extemly short focal length, the resultant dof is giagantic! thus you are unable to throw the background too much out of the dof and thus, you can't achieve the super blur out, nice bokeh background when compared to 35mm counter part. (dun ask me about the optics/physics behind it... i have no idea)

So this is a limitation you have to work with, nothing much you can do about it. On top of using the largest aperture and longest focal length, You can try to place your subject so that it's near to you while the background is extremely far away so that you can blur out the background more. Or just do the super tedious photoshoping to achieve the effect. Oh, and don't worry, you are not alone, my D5 and A1 and most other consumers and prosumers both have the same problem.

Oh and try to use the flex focus point set in the middle and use the focus-then-recompose mehod, it's faster that letting the camera decide where to focus, and you need not have to waste the time trying to get the camera to focus on where you want it to focus by focusing again and again. And yeah, the AF is not fast enuff to track moving subjects, even the faster af of A1 does not allow me to.

~Cheers! another super long post by me.

 

[UY79]

For those interested, there's this DOF calculator here:
http://www.dofmaster.com/dofjs.html

Along with it on the site are articles on DOF, hyperfocal distance and circle of confusion.

Cheers!

 

[sulhan]

Yes Sulhan,

I do try pre-focusing sometimes, when the subject is certain to cross a particular point. The extreme situations arises in situation such as your example, capturing a bird in flight, who will never fly to where you locked on.

Anyway, how about some feedback on my second problem, where I can't seems to throw the background into blur even when using wide apertures and long focal lengths.

Adams

Hiee...Sp..

Its a matter of playing with the distance factors to get the blurred background effect( due to back subjects of of the depth of field).

Camera to subject (favourable to get lens which have a shorter as possible focus distance) - let this distance of Camera to subject be A

Subject to background (back drop) - B

Therefore, for blurred background...preferably to have B significantly larger than A and you would have a blurred effect.....

Therefore for portraiture.......you can just change the subject to background distance by changing your position and also get subject to turn on the spot.....

There may be restrictions.....but a try would not hurt....
you can then charaterise your cam and find work arounds to acheive some
favorable effect.....
Hope this may give you some head start....


For your second problem.....check this out....

rgds,
sulhan

 

[deslim27]

You shoot MF? :bsmilie:

Sori, OT :embrass:

 

[sulhan]

:devil: ......so now that i have owned up......so whats next....kekekekekek!!!!!

Need to know formats other than 35mm mah......else how to teach....

Anyway.....today marked my first Maiden Success in home processing......of B & W.......here are a couple of samples...


OT!!!!! Oppsss...


rgds,
sulhan

 

[deslim27]

:devil: ......so now that i have owned up......so whats next....kekekekekek!!!!!

How many MegaPix? ??? ???

Haa.. seriously, which cam? I was once thinking getting a TLR.. but drop the idea later.

Need to know formats other than 35mm mah......else how to teach....

Anyway.....today marked my first Maiden Success in home processing......of B & W.......here are a couple of samples...

Yes, lau shi.. ..

Wah.. from digital to MF.. from CF card to home processing B&W.. may be you should try pin-hole photography next.. :bsmilie: