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02-05-2011, 02:07 PM   #1
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Which macro Pentax DA 35 f2.8 or the Sigma ex 70 f2.8

Advice gratefully received, I own the pentax K5 together with 16-45, 50-135, 35 smc f2 and the 50 smc 1.7 plus just acquired the sigma 50mm 1.4. I have decided to take the plunge and buy a macro but cannot make up my mind I've not owned one before so I am new to this area.

I have two in mind the Pentax DA 35 f2.8 macro and the sigma 70mm f2.8 I appreciate they are differing focal lengths but these are the two I will choose between. I have a commercial job coming up which will require the macro capability. It's an engineering company so will have shots at the works and on location at installations.

02-05-2011, 04:26 PM   #2
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I can't talk about those specific lenses. I *can* say that the basic difference between a 35mm and 70mm lens, and those in the 90-105mm range, is working distance. No non-reversed lens can focus closer than its focal length; and that's also the point of maximum magnification. You didn't mention how much magnification you need. If it's 1:1, then a 35mm lens puts the front objective 35mm from the subject; similarly for 70 or 105 or 200 or whatever. So 50mm and shorter are usually considered appropriate for close studio-lab work, and 70mm and longer (maybe much longer) are better for field work.

So: How much magnification do you need, and how close/far will you be from subjects? Will you be shooting in controlled settings? Will you shoot handheld or 'podded, in ambient light or with ringlight or flash? These factors will impact your choices.
02-06-2011, 03:47 AM   #3
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which macro

Thank you for the informed reply, the job is likely to be generally non tripod, I would think, the company fabricate all sorts of stuff most of which is large , fences, railings etc..

I may use some flash Metz 58 af 1 but think most will be available light I intend to get shots of the workforce crafting the product so combination of close and mid distance I will also want to use the dof to highlight specific elements.

There maybe occasions were I look at 1:1 but not in the main.
02-06-2011, 05:01 AM   #4
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A lot depends on what distance you can be shooting at. I really like the DA 35 limited, but to do true 1:1 macro, you need to be really close. For this reason, it doesn't work so well with bugs, but I don't think that would be a problem for your purposes. It does seem to me to be easier to hand hold than longer macro lenses.



02-06-2011, 09:05 AM   #5
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DOF is not a function that is correlated with focal length in macro photography
assuming the subject is projected at the same size on the sensor.
Its a matter of working distance and amount of background what lens to choose.
02-10-2011, 06:33 PM   #6
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If you won't shoot macro much then you won't need a macro lens -- except that macro lenses are so SHARP and nifty to have, so maybe you need one after all.

Then between the 35mm and 70mm you are considering, you might think about AOV (angle of view). For a 35mm lens on an APS-C sensor, that about 46 degrees, and for the 70mm lens it's about 23 degrees. For comparison, a 'normal' 28mm lens has AOV of about 57 degrees. Or so my spreadsheet tells me. So, just how much AOV do you want and need?

And you say "...combination of close and mid distance I will also want to use the dof to highlight specific elements." To me, that sounds like a job for the 70mm lens.
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