shallow dof and focus points

[33L]

its in focus, but since the freshener is not parallel (sp) to the camera's sensor the DOF seem very narrow and this almost looks like it was shot at the minimum focus distance and wide open.

simple test to prove my theory, shoot an object over a 2m away to increase the dof. Make it a stationary object more than a few mm thick. The freshener could have been rotating.

something like this shot with a 50mm f/1.4 @ f/2, but you get the drift.


Tiny Steel Ball by 33L, on Flickr


Lee

 

[Derek W]

Worked example here.

I used manual focus but if i was auto, the red blob would be the AF focal point used in the shot. Now the red line shows the plane of focus on the object. Now since i was using a macro lens i could get quite close (around 10cm if i remember correctly) and at f4 which this is shot at can still get quite a narrow depth of field (shown by the two blue lines where the image becomes blurry.

Now if i stood further away but kept everything else the same - focus on the same spot, keeping the f number at 4 I would achieve a slightly larger depth of field because as mentioned by Raikiri the depth of field is also relative to the distance to the object.

Try to apply this to your pictures and see where your focal point is, check your f stop and distance from object. Then retake the photo either slightly further away or with a higher / lower f number to see what difference it has on the image.

 

[laiman]

I'm taking a few shots that I hope will help at the mo so give me a few min to sort out an upload.

 

[Raymond Lin]

Wait until he sees a TS/E lens

 

[Rojin]

Is shutter speed definitely not a factor with this? 1/60 is generally a minimum for handheld, but if you have shakier hands this may have to be raised?

 

[Dunks]

Wait until he sees a TS/E lens

Think his head would explode

 

[laiman]

Right so hopefully this will help. Ignore the crappy composition and white balance.

Settings,
I used: Canon 450D with the 50mm f1.8 on a tripod to eliminate any shake.
Iso:400
Shutter speed was varied to keep the exposure the same.
Aperture varied f1.8, f4.5, f8.0 and f22.0
Distance from subject varied between sets.

Set A (at approx 60cm from subject)

Photo 1 taken at f1.8

Photo 2 taken at f4.5

Photo 3 taken at f8.0

Photo 4 taken at f22.0

Set B (at approx 160cm from subject)

Photo 5 taken at f1.8

Photo 6 taken at f4.5

Photo 7 taken at f8.0

Photo 8 taken at f22.0

 

[BruceLee]

Im sorry for being an annoying **** with this thread but if i dont get through this ill have a lifetime of taking soft pictures even when i finally figure out composition

With regard to your other thread it does look a bit OOF but it could also be DOF looking at it again, however something isn't quite right with it.

If you are in any doubt as to whether you will get the focus right a good tip will be to take multiple shots, then check on your PC which is in focus etc. I doubt anyone here can claim they get every shot they want in perfect focus the first time.

I wish you had the red square for focusing and could simply press buttons to make the square larger in the viewfinder, then just put everything you want sharp and in focus inside that square/rectangle and everything outside it would be nice and blurred.

There is, it's called LiveView and you can zoom in on that

 

[D.P.]

Is shutter speed definitely not a factor with this? 1/60 is generally a minimum for handheld, but if you have shakier hands this may have to be raised?

This brings us to another useful rule of thumb....

The required shutter speed for the average person under most conditions is proportional to the effective focal length. Logically, a lens with a longer focal length (i.e., you have zoomed in more), will have a higher propensity to suffer from camera shake.

Most people follow an inverse rule, so if the focal length of the lens is 300mm, then 1/300th of a second is good starting point. IMPORTANTLY, you must take into account the crop factor. That puts you at about 1/450th of a second on a Nikon DX camera. It is also wise to round up, especially if you have shaking hands. 1/500th of a second for a 300mm lens on a crop camera should mean most people have sharp photos most of the time.

There are a few other factors. Technique , especially on bigger lenses is important. Afferent people also have different tendencies. A trained army sniper can get away with a much shorter exposure. It is also a probability function, so you will have some chance of sharp photos at slower speeds, but also soft photos at higher speeds.

IS/VR is another discussion, as is proper tripod etiquette.

 

[laiman]

Right, trying to make sense of my rather large pics.

There are tons of factors involved in making the picture sharp.

One is shutter speed, as detailed by D.P. above, you want your shutter speed at least 1/focal length generally for hand held. By having a higher shutter speed you are trying to prevent any chance of camera shake. I used a tripod here as I have limited light and wanted to keep the ISO the same. This meant I could shoot at low shutter speeds without any worry about camera shake.

Another is general lens qualities, as you can see from pic 1 above although the image has a shallow depth of field and is in focus it still does not look pin sharp. That is because the 50mm f1.8 just isn't super sharp at f1.8, in picture 2 it looks better as the 50mm is just sharper at f4.5.

A third reason is getting the depth of field right which is what my pics are meant to show.

Set A are taken at a selection of different apertures (f-stop) but all at the same distance from the subject. You can clearly see the effect this has on the amount of subject in focus.

Set B are the same selection of different apertures (f-stop) all taken from more than double the distance away. This has much less effect on the amount of subject in focus.


Sadly what I did not show was how this affected the background of the photo as I used some plain mount board.

 

[Derek W]

why does this remind me of when father ted is explaining perspective to father dougal?

 

[Raymond Lin]

1 - See subject
2 - Pick a spot

3 - Hope for the best. lol



100%

 

[86JR]

Thanks for the help, everyone

 

[Erebus_UK]

Not too bump this up unnecessarily but this thread was really helpful, especially the photos by laiman and DerekW.

Cheers

 

[ElDude]

Not too bump this up unnecessarily but this thread was really helpful, especially the photos by laiman and DerekW.

Cheers

Yes I agree. There is a LOT of info on these boards regarding this sort of thing, going back years, but I think this is pretty much the first time someone has actually gone out of their way to post photos to show what they are explaining, which helps immensely.

I myself am a learn by seeing sort of person, and just reading the facts rarely sinks in with me. I spent about 2 years faffing around trying to learn all this and really could have done with this then!

I should add that I still suck as I tend to leave photography for months, then forget everything

 

[Schizophonic]

One factor. Even using text book techniques how to take a sharp picture.

Wouldn't the choice of camera and the lens still be a huge factor in sharpness?

I mean I would expect to get great shots with a 5DMKII and a Canon Prime L lens over a 350D and kit lens.

I used the great word loosely as people can argue that its not just the camera that takes good picture is also photographer. If you did a test side by side with a starter camera compared to a high end camera, the difference will be noticeable!

 

[BruceLee]

Well there is the case that experienced hands/eyes will get you a better shot than just the kit, I'm 100% sure you can fudge up a shot with a 5D and L glass
Better equipment just gives you more options/versatility, a good photographer should be able to make a good shot from whatever he has at hand

There's also nothing stopping you from doing those type of test shots to see how changing settings affect the image, in fact I'd probably recommend it as it will give you a better understanding of the choices you make when taking a shot.

 

[86JR]

Im basically rubbish at photography, i jumped from a d70 to a d300s and my shots got 10x better (but still rubbish) its all about composition and less about tech specs, lately ive been turning my 51 point af back onto minimum which i think is 7 or 9, same as a D70.

But every time i pick up the camera i feel more serious as its heavy and made from metal as apposed to a light peice of plastic.

Feels even better with the grip!

 

[D.P.]

One factor. Even using text book techniques how to take a sharp picture.

Wouldn't the choice of camera and the lens still be a huge factor in sharpness?

I mean I would expect to get great shots with a 5DMKII and a Canon Prime L lens over a 350D and kit lens.

I used the great word loosely as people can argue that its not just the camera that takes good picture is also photographer. If you did a test side by side with a starter camera compared to a high end camera, the difference will be noticeable!

You would be surprised how little effect the camera really has and how difficult it is to notice the difference when viewing small shots on a monitor.

Even the kit lenses are incredibly sharp these days, at least Nikons are. E.g., the Nikon 16-85 is mostly sharper than the pro 17-55 2.8.

Lenses are important to get the shot done correctly, thats the main difference between Pro lenses and consumer. Faster aperture, faster focusing, robust build, sharp wide open, etc helps the photographer get the the photo. But for something like landscapes the the 18-55 VR when stopped down to f/11 is basically as sharp as any prime or pro lens.

Technique trumps all. TBL is good example of getting Pro equipment (D300s) - sometimes the pro equipment just gets too complicated for beginners so you don't automatically get better with better equipment.



The only times better equipment will be a strong improvements is things like indoors sports (you need very fast lenses with very fast focusing and preferably a D3S). Or photographing small wild birds, having a very long lenses is the only practical way..

 

[mrthingyx]

You would be surprised how little effect the camera really has and how difficult it is to notice the difference when viewing small shots on a monitor.

I've actually tried taking a bad picture with a 5D Mk2 - I mean really, deliberately tried. And it was still awesome.

True, I was using a pin-sharp Sigma 50mm f1.4 and a Canon 24-70L, but...