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DPChallenge Forums >> Photography Discussion >> Working on focus (DOF)
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04/28/2003 02:52:11 AM · #1
In recent challenges, some comments that I've received on my photos suggest that I need improvment on my focus and DOF. Today, in my attempt to shoot for the transportation challenge, I got sidetracked and decided to work on my problem areas. Here is a picture that I took this afternoon and I would appreciate it if I could get some critiques on my focus and DOF in this picture. I feel the DOF is better, however, the focus in this macro is still off, especially on the buds. What do you think? Thanks in advance for taking a look at this

Yellow Buds
04/28/2003 06:36:53 AM · #2
In principle, pretty good: all of the foreground is in focus, all of the background is out - if that's waht you wanted to achieve, then you've done it.

A couple of thoughts: the image is quite flat - if you'd shot that twig and it's blooms from a more head-on angle, you'd get the effect of it seeming to loom out of the frame at you, as elements of it come into focus.

Secondly, there are a lot of sharpening artefacts around the edge of the flowers: those blurry, 'ghosting' kind of lines: this suggests to me a number of things - that you may have had to crop this too much out of another photo and thus it's like a looking at it at 100% magnification, or that you have used too much sharpening in post-processing, or it may simply be something that your camera does. I appreciate that this is an under-2 megapixel camera, so these kind of shots are tricky to get.

Depth of field is a tricky subject - a very subjective subject, actually. The obvious uses are that with a very shallow depth of field it can be very effective to bring a subject out from a cluttered and busy background - as with this shot.

Focus-wise there is something else going on here: I think you've got an anormously high contrast picture: the highlights are really too bright, and the shadows are perhaps too dark - partly this is due to light reflecting directly off the subject back at the camera, as the light is almost directly behind you when the shot is taken. This also has the effect of 'flattening' the picture, so that textures are wiped out a bit by the lack of shadows. If you shoot across the light, with the sun at 90 dgrees, you'll find that the textures come out more easily, and the light levels your camera is seeing are not so extreme between light and shade. There is nothing much wrong with the focus in itself - the edges are sharp, but that extremity of contrast makes it seem out of focus slightly.

And finally, I think the shot is over-exposed: not badly, but the colours have bleached out on the buds and that's also contributed to the feel of the focus being out - when that slight flaring happens, detail is also lost in textures. If this is shot on automatic mode (and I don't know how much flexibility your camera has), try setting exposure compensation to a negative number, or setting the shutter speed to the lower end of the camera's light metering.

Just a few thoughts, and of course only my opinion (so I'm pushing you toward what I like, of course!). The processing artefacts are the main issue though. Can you turn that off in-camera? Software processes are much more effective usually, those built into all but v high-end cameras aren't worth while at all.

Hope some of that's useful.

ed
04/28/2003 08:09:05 AM · #3
the focus is good :) ..

you're getting some artifacting, though. Don't know if this is from your post-processing or from your camera but theoretically the A40 is a newer camera so it should have clean images.
04/28/2003 10:55:04 AM · #4
I'm having trouble with DOF also. Macros no prob but anything further away I have trouble. I realize the CCD size, the focal length, and aperature all play a part. I asked the question before but will add on telephoto lenses help out?
04/28/2003 10:59:21 AM · #5
help in getting deeper DOF or shallower. Add-on telephoto will only make your DOF shallower. As focal length increases, DOF decreases.

Originally posted by orussell:

I'm having trouble with DOF also. Macros no prob but anything further away I have trouble. I realize the CCD size, the focal length, and aperature all play a part. I asked the question before but will add on telephoto lenses help out?
04/28/2003 11:39:16 AM · #6
IN Connie's photo of the yellow flowers, above, I feel that the harsh light could be affecting the DOF. Everything seems in focus, but the harsh light is affecting it. Perhaps some of you more experienced photogs could help us with the link between DOF and light.....
04/28/2003 12:20:48 PM · #7
DOF doesn't get affected by light. It will appear to be soft because of lighting, that's all, reflections, etc.



Originally posted by dsidwell:

IN Connie's photo of the yellow flowers, above, I feel that the harsh light could be affecting the DOF. Everything seems in focus, but the harsh light is affecting it. Perhaps some of you more experienced photogs could help us with the link between DOF and light.....

04/28/2003 12:45:41 PM · #8
The shot looks very sharp - as if it has been over sharpened perhaps ?

Also, the light is really harsh, mostly due to the time of day I'd suspect, making the picture really contrasty with harsh edges.

I'd suggest either early morning or late evening and have a look at your camera's sharpening settings or your processing workflow.

Light doesn't change DoF, but it does change our perception of sharpness, particularly side lighting makes things look sharper (as sharpness is mostly about edge contrast)
04/28/2003 02:47:40 PM · #9
My picture was taken around 5-6PM. If I remember right, I was shooting with the sun to the back of my left shoulder. It was a very clear day and the sun was shining brightly. Do you feel that a polorized lens would help in this instant? Doesn't the lens diffuse the light better and avoid some of the glare on the buds in my picture?

When people made comments concerning my camera could be oversharpening, I checked it and found that I've had it on a setting called "Vivid", so I suppose that could be posing a problem. I have ordered a close-up lens set as well as a polarized lens that will fit my camera. Hopefully, that will help my pictures some. I will have to admit that I did crop my picture and sharpen just a little in post-processing. This is the same picture directly out of my camera without any post-processing.

Yellow Buds - Origional

Probably another problem I have is that I don't use a tripod. Although I like to think I'm fairly steady with a camera, I'm sure that most of the blurriness that I get in my pictures are caused from that. I just feel that tripods are so bulky. I haven't found a tripod that I think I could easily use.

Also, I have another question concerning what Ed said. I have been with the understanding that the smudgy, ghosty lines around the edges in pictures were caused from Jpeg compression. Is it that or a combination of both sharpening and compression?

Thanks to all of you for your comments. I am learning a lot and I appreciate this discussion.

Connie
04/28/2003 03:12:18 PM · #10
ok. seeing the original makes it a lot more clear what's happening. the original looks blurry from camera shake. you sharpened the camera shake away but in the process introduced a lot of sharpening artifacts.

04/28/2003 03:17:22 PM · #11
Ok, i have the same camera.

The camera will warn you if there is a potential for camera shake... and its always right. You will have blurry pictures if you don't brace the camera somehow. Try taking pictures when there's plenty of light if your not going to use a tripod.

Also, make sure you don't oversharpen by using unsharp mask instead of sharpen.
04/28/2003 04:22:03 PM · #12
The original is in focus, at least the branch is :) Flowers are blurred either by wind or because the DOF is shallow and the focus point is on the branch.

Originally posted by magnetic9999:

ok. seeing the original makes it a lot more clear what's happening. the original looks blurry from camera shake. you sharpened the camera shake away but in the process introduced a lot of sharpening artifacts.

04/28/2003 04:24:01 PM · #13

The camera isn't always correct.

In general you need a tripod if your speed of exposure (equivalent to 35 mm) is less than the reciprocol of your focal length.

So if you're using telephoto equivalent to 35 mm @ 100 mm and your speed is at 1/60, you can introduce blurring. G2 for example will only warn below 1/30 second, which is not enough for 100mm focal length.


Originally posted by Budweezer:

Ok, i have the same camera.

The camera will warn you if there is a potential for camera shake... and its always right. You will have blurry pictures if you don't brace the camera somehow. Try taking pictures when there's plenty of light if your not going to use a tripod.

Also, make sure you don't oversharpen by using unsharp mask instead of sharpen.

04/28/2003 06:36:11 PM · #14
I tend to agree that the original appears to have some camera shake in it. If you have control over aperture / shutter speed then you could try increasing shutter speed to eliminate shake. Once you get somewhere around 1/60s you should be ok - depending on zoom distance and how much you shake (I shake a lot compared to most photographers).

If you find tripods too bulky then looks for something to sit the camera on, or even to learn your body against. Even how you hold the camera can help - try holding the camera in different positions to see if you find one more comfortable. You seem to have sorted out the focus and depth of field issues fairly well - time to move onto camera shake.
04/28/2003 07:17:59 PM · #15
a tripod really is the single most useful thing you could get to improve your picture taking.

It slows you down, it makes you think, it stops shake, it lets you use slower exposures, or work later into the evening or early hours of the morning.

Easily the best investment you can make to improve your picture taking.
04/28/2003 07:32:33 PM · #16
I couldn't agree more.

But don't buy a cheap tripod. That's one way to make fuzzy photos on tripod. Get a good sturdy one. If you're not going to hike with the tripod, get a 5 lb one (Like Bogen 8021 or something like that) and get a decent tripod head.

The light $20 tripod from BestBuy just wont' cut it. I have one, it's sitting in my closet collecting dust. It wont' even work with G2, it's so light that if a wind blows on it, the camera falls over....

Originally posted by Gordon:

a tripod really is the single most useful thing you could get to improve your picture taking.

It slows you down, it makes you think, it stops shake, it lets you use slower exposures, or work later into the evening or early hours of the morning.

Easily the best investment you can make to improve your picture taking.

04/28/2003 08:09:42 PM · #17
I agree. Even for what would seem like a "light" or "compact" camera. A good, sturdy tripod makes all the difference. I would love to get a gitzo on some carbon sticks. But I can't justify $600+ for a head/stick combo at the present. Bogen's offerings are nice, but for $175 and up, you should be getting something as basic as a bubble level on it. I haven't ordered one yet, probably will this week. I ended up liking the Slik pro400dx. Slik seems to make a good mid-level tripod/head.
04/29/2003 01:25:38 AM · #18
Thank you all for your suggestions. I am definately going to have to use my tripod. So, I dug in my closet and got it out. I'll have to get a new one eventually because one day I left it out and it turned into a chew toy for one of my dogs. There are bite marks on the handle. I couldn't go out today because it was cold and rainy, so I set up my lights and took advantage of what I learned in this forum discussion. I know the subject is a little dumb and the composition is yuck, but it was all I could find where I could set-up the elements I wanted to work on. The background is a blue towel that I hung on the wall to provide texture to blurr and then I set up fake flowers where the blue small ones are way in the back with the pink ones closer. I used the overhead light, light coming in the window and two desk top lamps. I turned off the "vivid" feature on my camera and used my tripod. The only adjustments that I did in post-processing was crop, resize, and some color and contrast adjustments. I didn't even touch the sharpen tool.

Teachers? Do you think I did better? I think they are better.



Focus Study #1 Focus Study #2

Thanks again,
Connie
04/29/2003 05:00:58 AM · #19
Connie, they're streets better - especailly like the first one, you've really caught the cloth texture on the flowers (and I'm no fan of flower shots!), and the lighting is just about perfect - there's still depth there, but now you have the texture too, and the dynamic range (between light and shade) is so much easier on the eye. Excellent colour combinations too - that piece of grey stuff really emphasises the pinks and blues.

Still a few artefacts, though far fewer than in the yellow buds shot- what's your process for re-sizing and saving to upload to the site - do you have control over the amount of compression that's being put on the photo? It's only around 70Kb, so less than half the file size that's allowed for challenge submissions ...

Another trick, that I don't think has been mentioned yet, is to use the self-timer on the camera even if it's on a tripod, especially for longer exposures - that way you don't have to touch the camera to release the shutter, and that takes away a little more possible shake.

edit: the ghostly lines, 'artefacts', can happen in both those ways. Unsharp mask is a lot better at not introducing them, if you have that in your editing software.

Ed

Message edited by author 2003-04-29 05:04:36.
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