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RAUK - Archived Forum - Focus and Depth of Field

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Focus and Depth of Field:

Author	Message
GemmaJF Admin Group Joined: 25 Jan 2003 No. of posts: 2090 View other posts by GemmaJF	Posted: 02 Apr 2006 Hi guys, I finally feel like I'm getting there with my piccies, particularly of snakes heads. With camera set to fully manual, a click or two under exposed, my homemade bean bag and shooting in RAW I've finally ended up with a whole days shots where I can think..yeah..not bad at all So, now for a bit of fine tuning. I'm a bit clueless about depth of field. I've seen the effect, I grasp the concept, but I'm struggling to really understand how it relates to my camera settings. I've tried taking shots of objects close-up and changing the settings to alter the depth of field, I could barely percieve any difference, so couldn't really learn much from it. I'll give a couple of examples. Both were shot at F2.8 on my 60 mm macro. I'm using this setting almost exclusively as it seems the only way to get an acceptable shutter speed and as far as I can grasp this setting gives the maximum depth of field for my lens i.e a large aperture opening. OK, first example, I focused on the eye for this shot, depth of field looks acceptable, but the centre of the field isn't where I wanted it. The sharpest part of the image is the top of the head, I wanted the side of the head to be really sharp. What should I do? Should I focus between the eye and the nostril to achieve this, or should I have tweaked the focus manually? Second example, OK depth of field nightmare.. might look nice and arty to some, but this wasn't what I wanted! What I wanted was the eyes and tongue in focus too.. If I'm right in thinking that F2.8 gives me the maximum D of F for my 60 mm macro, is this shot with the eyes and tongue in focus just not feasible with this lens, or am I missing something? (or course I also wanted the tongue flick to be straight but that was down to the subject, not my photography ignorance ) Thanks for any thoughts Gemma Fairchild, Independent Ecological Consultant

Vicar Senior Member Joined: 02 Sep 2004 No. of posts: 1181 View other posts by Vicar	Posted: 02 Apr 2006 I think...you have your camera set up to give you the narrowest depth of field possible :P Try the other extreme of very small aperture (= better DoF) and live with the longer shutter duration (if possible). Half-decent article here: http://www.cs.mtu.edu/~shene/DigiCam/User-Guide/950/depth-of -field.html Steve Langham - Chairman Surrey Amphibian & Reptile Group (SARG).

GemmaJF Admin Group Joined: 25 Jan 2003 No. of posts: 2090 View other posts by GemmaJF	Posted: 02 Apr 2006 LOL Steve, I wouldn't be at all suprised if I have..might explain a lot I'll have a good read of the above article Gemma Fairchild, Independent Ecological Consultant

GemmaJF Admin Group Joined: 25 Jan 2003 No. of posts: 2090 View other posts by GemmaJF	Posted: 02 Apr 2006 The penny finally drops..(time for RAUK members to meet Purple Gertie me thinks) Ta Steve, I'll post up the results when I get another chance to try this shot for real I think a lot of my trouble before was that without a bean bag my shots were so blurred I couldn't really appreciate the depth of field in any case . Still as ever, I hope my fumblings with my camera help others to get better shots too Gemma Fairchild, Independent Ecological Consultant

Alan Hyde Senior Member Joined: 17 Apr 2003 No. of posts: 1416 View other posts by Alan Hyde	Posted: 02 Apr 2006 Hewwo Gemma ! I'm pleased you're getting on so well with the new lens , your pics are looking great For the kind of pc i Like to take I use close up filters and F4 on my olympus. And I see you've already discovered above for canon and macro lenses. Quite often I pay no attention to what aperture i'm using. As conditions vary I will lay with the subject infront of me and keep my finger on the dial to adjust aperture. Then looking through the lens I keep an eye on shutter speed and how the subject looks while turning the dial back and forth. Works for me O-> O+>

B Lewis Krag Committee Joined: 24 Aug 2004 No. of posts: 146 View other posts by B Lewis	Posted: 02 Apr 2006 Hi Gemma and all, I like this thread and little 'Purple Gertie' really shows how D of F works. I didn't get in early enough to explain but you've found it already the greater the F# the more detail and D of F you'll have. I know when people take landscape shots they are often between F11 and F22 to maximise the detail on both foreground and distance. Also as you've found you do lose a little light, but often condition are sunny enough to not worry about that when herping. This is another reason for using a tripod, bean bag, elbow&belly etc.. as it means slower shutter speads and more risk of camera shake. Here's another good article for you. It helped me..! http://www.ephotozine.com/techniques/viewtechnique.cfm?recid =63 Brett. B Lewis38809.8491898148 Lewis Ecology Brett Lewis Photography Kent Reptile & Amphibian Group DICE - University of Kent

GemmaJF Admin Group Joined: 25 Jan 2003 No. of posts: 2090 View other posts by GemmaJF	Posted: 03 Apr 2006 Ta Al and Brett, I was using the opposite method Al, setting the aperture to F2.8 and twiddling the wheel to get an acceptable shutter speed to get the exposure, I'll try your method instead. Each day I've put aside for photography as opposed to recording this year has been breaking sun.. so I've been twiddling the wheel rather a lot as the sun went in and out! So what does a close up filter do?? Thanks for the link Brett, now I've some idea what the funny numbers are on my 60 mm (helps with my landscape shots too, I've not really got the right lens yet, but I enjoy taking landscapes whilst out and about recording) I can now see I'm going to need a nice sunny day for my 'nose on' tongue flick pic.. so I get good depth of field and a reasonably fast shutter speed to freeze the tongue. I also now know what a 'circle of confusion' is too, and it doesn't describe my own attempts at understanding how the controls on my camera work so much any more Gemma Fairchild, Independent Ecological Consultant

Deano Senior Member Joined: 23 Aug 2005 No. of posts: 133 View other posts by Deano	Posted: 03 Apr 2006 The Purple Gertie idea is a very good way of seeing what DoF will look like under controlled conditions. This is a simlified version of the Moose Peterson teddy bear test http://www.moosepeterson.com/techtips/teddybear.html used by many wildlife photographers to test exposure. I would suggest using rubber toy snakes and lizards (for the texture as much as anything). Remember "Practice makes slightly less awful". Deano Better to be lucky than good looking.

Alan Hyde Senior Member Joined: 17 Apr 2003 No. of posts: 1416 View other posts by Alan Hyde	Posted: 03 Apr 2006 Hi Gemma , Using your camera and the 60mm you'll probably not achieve anything using close-up filters . I only use these on my Olympus with the standard 35mm lens. Close-up filters would probably be a plus if you wanted to do some super close pics of insects showing the eyes ,hairs and all , but for snakes the 60mm gets cloe enough on it's own O-> O+>

GemmaJF Admin Group Joined: 25 Jan 2003 No. of posts: 2090 View other posts by GemmaJF	Posted: 03 Apr 2006 Ta for that Al, I need to get some sort of filter for the macro, as currently I've got no protection for it, I guess a plain UV protective filter will do for now then. Gemma Fairchild, Independent Ecological Consultant

Alan Hyde Senior Member Joined: 17 Apr 2003 No. of posts: 1416 View other posts by Alan Hyde	Posted: 03 Apr 2006 That's what I have on mine Definitely wise as you'll be laying down in undergrowth alot of the time O-> O+>

Deano Senior Member Joined: 23 Aug 2005 No. of posts: 133 View other posts by Deano	Posted: 09 Apr 2006 Or stumbling over as you look for herps. This happened to my friend Cliff and he was using my 100-400mm L IS lens! Fortunately an inexpert commando roll saved the lens and made the rest of us laugh. But you can never be too careful. Deano Better to be lucky than good looking.

B Lewis Krag Committee Joined: 24 Aug 2004 No. of posts: 146 View other posts by B Lewis	Posted: 10 Apr 2006 Well here's a couple for your comments.. Taken using my 105mm Macro on a 300D. F5.6 @ 1/125sec, ISO-250. You can guess from the shot that the day was overscast and lighting was poor but does help to bring out the contrast and saturation a little. In my opinion I would take it down a stop or two so that the yellow ring wasn't burnt out. Then increase ratios in PS to bring it back up to suitable limits.. It's also a fine line to get the speed right for better DOF. I tried to get the tongue in but in doing so lost some detail in the BG, but I think it's okay otherwise. Kind regards, Brett Lewis Ecology Brett Lewis Photography Kent Reptile & Amphibian Group DICE - University of Kent

- Focus and Depth of Field

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