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11-25-2008, 12:30 PM   #1
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Join Date: Sep 2006
Location: North Carolina
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Pentax-M 40-80mm f2.8-4 Zoom

Lens is actually f2.8-4 but I fat fingered the title. I decided to play around with this lens just a bit. It has been sitting in a Pelican case for several years without use. Now that I have a K20D I thought I should dust it off and use it a bit.

Background on the images. I am in the process of having a custom made carbon fiber tandem built, I have spent the best part of the summer collecting components for it. Since I am also a "Weight Weenie" when it comes to cycling equipment I have also done some 'bolt tuning' and judicious parts replacement. At the same time I like to document each bicycle build with photographs an blog entries. So what better way to do this than with a new K20D. I am also using a cheap (eBay) lightbox. Only issue with the lightbox is that the 50-watt lamps do not put out enough light to really use low ISO and small apertures at the same time.

Back to the 40-80, it is a two ring zoom with a macro setting. The good thing about the macro setting is that it is at the 80mm end. the bad thing is that once in the macro region the focus ring is more push/pull than turn. Even with a magnifier it was hard to tell whe it was in good focus, or what I was actually focused on. Also the small aperture at 80mm (f4) makes it more difficult to see clear focus.

I know this is not the most well liked of Pentax lenses but it is adequate for web images that will be reduced to small screen size.

All images were post processed in Lightroom. Auto white balance, auto exposure, and camera profile changed to a custom K20D I created with Adobe Camera Profile Editor, a few were minimally sharpened, all had some minor spot removal. All shot in PEF and then when imported into Lightroom copied as DNG. I had no idea it was so easy to save as DNG. I was using the DNG converter but this eliminates that step completely. All images exported as 60% JPGs sharpened for screen and saved with sRGB color profile. The more I learn about Lightroom the more I like it.

I believe they are all underexposed, but did not mess with that much. I think changing focusing screens as has been mentioned in other threads will partially correct this and make the 40-80mm easier to focus at the same time. I also believe the third image is just a bit out of focus. I guess my old eyes aren't what they used to be.

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Last edited by WheresWaldo; 11-25-2008 at 12:55 PM. Reason: Lens f-stop correction

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bit, dng, focus, images, k-mount, k20d, lightroom, macro, pentax lens, profile, slr lens, time
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