My First Slug - Help needed please

[jackiex_x]

Hi guys
I wonder if any of you experts can help me please. I was out taking photos of this cute little slug in my garden today (between the rain showers!) and I'm not happy with the results but I don't know what I'm doing wrong. Am I right that a larger aperture will make the background blur more and decrease the DOF?

They seem to be blurry behind and infront of the slug but the horizontal section thru middle of photo is all in focus even tho I chose only the centre AF point to be in focus. I took all of these on manual. I was aiming to blur the whole photograph except for the slug.

This is ISO320, 1/40 f/5

This one's ISO 800, 1/60 f/5

Then i gave up on the larger aperture and tried:

ISO3200, 1/15 f/20
I like the texture on the slug in this one tho.

C&C appreciated please.

 

[Overread]

Welcome to the world of macro

Focusing - considering what is "in focus" its best to imagine the focus of your camera is like a sheet of paper, or a book, which is parallel to the front of your lens. This "in focus" section moves back and forth as you adjust the focus on the lens (either with AF or manually) and changes its thickness as you adjust the aperture. As you can see in your photos you can easily get an infocus strip running through them when you've a thinner depth of field and an angle which brings in foreground and background which are outside of the depth of field (the width of your book).

The AF points are not so much showing what part of the shot you want in focus at a cost of all others, but more what point the camera is using to determine the focus point; so when you selected the slug with the middle point the camera shifted the focus to that point - all else that is at the same distance from the lens as that point is also rendered in focus as well.

You can actually get the kind of effect you are after, where you've a circle of out of focus with a middle section that is in focus using attachments called "Lens Babies". It's more a creative choice popular with some and not with others (like most things). Note that you can use editing to simulate, but its not quite the same and can take considerable time to make it look right.


As for the depth keep an eye on how far you close the shutter down, pushing smaller and smaller might get the depth of field up, but will, at some point (around f13/f16 on crop sensor) start to noticeably soften the photo and going smaller will further increase the softness. This softness is caused by diffraction and you can't counter it no matter how fast your shutter speed nor low your ISO is. This places limits on what you can do with the camera settings; thus the rest has to rely upon you mastering the use of the angle of your shooting to best used teh strip of in-focus shot you have to realise your creative concept.

 

[jackiex_x]

Thanks very much for your feedback.

 

[hydkaran420]

Here is a picture DOF vs Aperture from cameratechnica.comdof-diagram2 by hydkaran420, on Flickr

 

[robertandrewphoto]

Your exposure settings are confusing me a little bit. Mainly the iso, I'm no expert on macro but I tend to never raise my iso above 800 unless it is dark.

Now if you want to make the slug the ONLY thing in focus, the easiest way to do it with these particular shots would be to add a gaussian blur to the background in photoshop, this gives an added effect of low D.O.F.

In my rendition I seperated the slug from the background and applied a gaussian blur with a very small setting of 1.1 so it wasn't too obviously edited.

I also did a little dodging and burning to draw more focus to the subject.

 

[KmH]

They seem to be blurry behind and infront of the slug but the horizontal section thru middle of photo is all in focus even tho I chose only the centre AF point to be in focus.

That's the way any camera works. The focal point in the viewfinder you use is actually choosing the focus point distance from the image sensor.
The DOF is a plane that is parallel to the image sensor, and it extends from edge to edge. The depth of that plane of focus can be controlled by the photographer, but the width cannot.

If the image sensor (camera) is tilted up or down the plane of focus stays parallel to the image sensor but because the camera is tilted that plane is now on a diagonal relative to plumb.

I took all of these on manual. I was aiming to blur the whole photograph except for the slug.

That can't be done in the camera, for the reasons stated above.