BetterPhoto Q&A
Category: New Answers

Duncan J. McFarlane		Object photography Hi all, This is my first time and may be a dumb question, but here goes. I am doing a photography job, which is photographing objects to put into a catalogue. Although I am not using a studio for this I am using a Cobra flash, which is giving me sufficient amount of lighting, however, I am finding that the pictures of the objects are out of focus. I am using a 50mm lens set at f5.6, which is what the flash was indicating I should set it on. Should I set the camera to f22 to improve my focus and adjust the flash level accordingly? Or should I change the lens altogether? I only have a 28mm and a 70-210 so my options are limited, but I think a 35mm lens may do the job better - is this correct? Obviously I would have to buy one - so can I get away with a 50mm? Regards duncan To love this question, log in above October 08, 2002

Jeff S. Kennedy		It really doesn't matter which lens you use because DOF is relative to image perspective. IOW to get your subject to appear a certain size on film you will adjust your distance from the camera and this will make the DOF the same whether you are using a 50mm, a 35mm, or a 200mm. You need more DOF so your solution is to stop the lens down to f22 as you suggested (and crank up the flash power). To love this comment, log in above October 08, 2002

Tom Darmody		Duncan- Like Jeff wrote, you need more DOF. Doing this with 35mm is really tough because of the limited DOF and lack of perspective correction. Because of the small 35mm format, a larger enlargement is needed and a the diffraction caused by the small apature will be very noticeable on the final image. I'd stick with the 50mm prime, you don't want zoom distortion added on top of that. I use a view camera (4x5)for this type of work. Aside from apature, I can adjust the lens plane to get more of the image in sharp focus (dof), then adjust the film plane to correct the perspective. I also use hot lights, they are alot easier to work with. These shots take time and patience, they aren't as easy as they look. To love this comment, log in above October 08, 2002

Duncan J. McFarlane		I have been doing some more tests, although my client is getting a bit frustrated, and have found that increasing the f stop solved the DOF problem, but I hadn't incresed the flash power so I got a couple of films that were underexposed. I have now been increasing the flash power and the results are beginning to look much much better. Thanks Jeff K and Tom D for your help, I now have much more confidence and have learnt a lot. Regards Duncan To love this comment, log in above October 10, 2002

Duncan J. McFarlane		I have been doing some more tests, although my client is getting a bit frustrated, and have found that increasing the f stop solved the DOF problem, but I hadn't incresed the flash power so I got a couple of films that were underexposed. I have now been increasing the flash power and the results are beginning to look much much better. Thanks Jeff K and Tom D for your help, I now have much more confidence and have learnt a lot. Regards Duncan To love this comment, log in above October 10, 2002

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