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08-14-2009, 05:26 AM   #1
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Question on extension tubes

Hello,

I do "macro" photography for Model Cars magazine. Up to know I've been using non-Pentax (GASP! ) equipment but I want to change that. The Pentax macro lenses I have are the A70-210 and the old Takumar 28-80. The 70-210 works fine but I need to get too far from the subject. The old Takumar works fine but IQ and contrast are not the greatest. I'm looking at eventually getting a good macro lens but I just thought that extension tubes combined with my A50 f1.7 may be the ticket. I don't need 1:1 magnification and depth of field is key, so fast apertures are not required. I find myself usually shooting up to f22 so the whole item is in focus.
What do you think?

Thanks,

08-14-2009, 08:04 AM   #2
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QuoteOriginally posted by ismaelg Quote
Hello,

I do "macro" photography for Model Cars magazine. Up to know I've been using non-Pentax (GASP! ) equipment but I want to change that. The Pentax macro lenses I have are the A70-210 and the old Takumar 28-80. The 70-210 works fine but I need to get too far from the subject. The old Takumar works fine but IQ and contrast are not the greatest. I'm looking at eventually getting a good macro lens but I just thought that extension tubes combined with my A50 f1.7 may be the ticket. I don't need 1:1 magnification and depth of field is key, so fast apertures are not required. I find myself usually shooting up to f22 so the whole item is in focus.
What do you think?

Thanks,
Ismeal, I fear your current set-up won't offer you a way for improvement. There is already a severe contradiction in your paragraph: "The old Takumar works fine but IQ and contrast are not greatest" - so, if IQ and contrast are poor, what's fine about that lens?

I would buy a secondhand, manual focus macro lens of about 100mm focal length (i.e. Tamron 90, Tokina/Vivitar/Pentax 100mm) and all IQ and contrast problems should disappear. These lenses are all very good and the IQ differences usually not noticeable.

The problem with the small depth of field stems from the high magnification factor and cannot really be remedied easily. The best way to deal with that, would be a tilt lens or a camera with tilt movements, but both is going to be a bit more expensive and complicated to use. Nevertheless, there are Ukrainian tilt adapters for Pentax K available on ebay, which should be combined with a 80mm medium format macro lens (Mamiya is quite cheap) - and that could be exactly the right choice for your particular application, without being overly expensive.

Ben
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