Subject Isolation by DOF control:

[AB26]

I am back to square 1, learning Photograph.

Isolating my subject by using DOF control. This was shot in Jpeg, again, 70-300 MM Sigma lens (the cheapie one) at 450mm (DX Crop factor) Full Manual, WB Preset, 1/13sec, F8 (for lens sweet spot), ISO 100 (I hate noise), Manual focus.

The image was sharpened and a tad of contrast was added in post.

In my opinion the image is very much “monochromatic”, can I say that? For a cheapie Sigma lens I think the bokhe is not too bad. Is it sharp enough?

Any advice on improvement? Please be frank with any comment or critique?
Thanks for looking.

PS: Looking at the larger image you might notice a little bit of a 3D effect.

[MrB]

Andre, perhaps a shooting angle, if possible, that would exclude the light green leaves from the background?

Cheers.
Philip

[RichardTaylor]

I find the out of focus foreground a bit of a distraction.
Try filling the frame with the subject so you have less background to worry about.
How does it look when shot wide open wide open to blurr the background even more?

The image appears sharp on my screen.

[Stagecoach]

Andre,

It looks sharp enough to me and the bokeh looks clean.

But I'm a wee bit confused in that your title states isolation by DoF control and then you suggest the aperture chosen is due to it being the sweet spot? It may well be that the isolation amount you wanted happened to coincide with f8 (sweet spot).

The way I see it is that to frame the cactus as this with the background being fixed your only option for isolation is adjusting aperture.

As for improvement I can not see anything other that shooting at an angle that removed the majority of the OOF leaves in the front although I suspect that was impossible.

Grahame

[AB26]

Andre, perhaps a shooting angle, if possible, that would exclude the light green leaves from the background?

Cheers.
Philip

A valid comment, thanks Philip. The light green leaves had more light falling on it than the cactus itself.
I think it is possible to adjust in post.

[AB26]

I find the out of focus foreground a bit of a distraction.
Try filling the frame with the subject so you have less background to worry about.
How does it look when shot wide open wide open to blurr the background even more?

The image appears sharp on my screen.

Thanks Richard,

If I remove the OOF foreground it also removes the feeling of depth in the image. Does the OOF foreground lead your eye away from the main subject? If so, it is distracting.

Shooting wide open will narrow the DOF to the extent where I will lose focus on most of my main subject, hence the smaller aperture.

[AB26]

But I'm a wee bit confused in that your title states isolation by DoF control and then you suggest the aperture chosen is due to it being the sweet spot? It may well be that the isolation amount you wanted happened to coincide with f8 (sweet spot).

Thank you Grahame,

Aperture is not the only factor controlling DOF. Focal length and subject to focal plane also affects DOF.

I need to learn to control DOF while using the “sweet spot” of a lens.

The distance between the foreground and the background is less than 500mm. I will re-shoot using different focal lengths and different apertures changing focal plane to subject distance and see what the results are.

[bnnrcn]

I understand what you are trying to do Andre.A depth of field calculator downloaded to your mobile phone (if possible) might be helpful.Yesterday I went out for shooting because the rain stopped and I used my depth of field calculator,it was very helfpul especially with my 70-300 lens.I was trying to shoot the branches of trees because they were full of flowers at this season and I wanted everything to be seen sharp and clear and nothing out of focus. I roughly guessed the distance from my main subject and by using DOF calculator I tried to get the best place to shoot .So I would suggest you the same thing,if you want a blurred background and a clearly seen object with F8,just choose the shooting distance by using the DOF calculator

Thank you Grahame,

Aperture is not the only factor controlling DOF. Focal length and subject to focal plane also affects DOF.

I need to learn to control DOF while using the “sweet spot” of a lens.

The distance between the foreground and the background is less than 500mm. I will re-shoot using different focal lengths and different apertures changing focal plane to subject distance and see what the results are.

[chauncey]

FWIW...I once ran a test to check the bokeh differences in my two favorite lenses that are very highly rated for their IQ, a 300 f/2.8 and a 180mm macro. I ran each lens through the gamut with both lenses at the same f/stops while maintaining about the same field of view...with surprising results. If I maintained the same FOV and the same f/stop on each lens...I could not discern any difference in bokeh nor perceived difference in DOF.
The first image was taken with the 180 macro, the second image is the 300mm...both taken at f/3.5 using AF.





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[ajohnw]

I think Adobe products have a method of sharpening by detail level but don't know how it's done. A web search might bring something up.

The sort of result it can give is like this Done by making a super sharp fine detail copy and then blending it into the original using layers. Done that way rather than directly on the image as it offers more control. It's just a case of changing the opacity of the sharpened one.

If you want to do something like that and how far to go in the sharpening is another matter though.



I can't translate this into Adob-ease.

John
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[TonyW]

FWIW...I once ran a test to check the bokeh differences in my two favorite lenses that are very highly rated for their IQ, a 300 f/2.8 and a 180mm macro. I ran each lens through the gamut with both lenses at the same f/stops while maintaining about the same field of view...with surprising results. If I maintained the same FOV and the same f/stop on each lens...I could not discern any difference in bokeh nor perceived difference in DOF.
. . .

This result for DoF is to be expected. For a given f number, the depth of field depends only on the magnification, i.e. on the field of view for a given size sensor. This means that if you use different lenses with the same f number but with the same scene filling the field of view, you must get at least approximately the same depth of field. I have checked this rule with a few examples from the DoF calculator and it seems right. Also, the DoF is proportional to the f number so that if you go from, say, f/4 to f/8 you double the depth of field.

[chauncey]

I agree Tony...subject isolation is lens dependent, there is glass that is more competent than other glass, as well as f/stop/FOV. All enters into the equation.

[Ken Curtis]

Hi Andre.

I find the background distracting because there is enough detail there to pull the eye towards those background objects.

Don't know if you have tried focus stacking. I recommend it. Opening the aperture as wide as it will go will blur the background more and possibly blend the colors so that the cactus (or whatever it is) will stand out better because of its sharper details. Taking multiple shots (on a tripod of course) with each shot set to focus at a slightly different distance, and then using software to stack the shots, will allow you to get the bristles nearest the camera and furthest from the camera very crisply in focus.