DA*135-400mm F4.5 would you buy it?

Started Feb 10, 2010 | Discussions thread
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CSPronken Senior Member • Posts: 1,648
DA*135-400mm F4.5 would you buy it?

Well for all the wildlife shooters, birders, plane and sport lovers, how would you feel about a DA*135-400mm F4.5 ?

Explanation of the focal length 135-400mm:

  • 135-400mm is not overly ambitious, at F4.5 optically it can be made very good.

  • 135mm goes on where the 50-135m F2.8 leaves off.

  • up to 400mm covers most peoples tele needs (read not all)

  • Could be seen in a way as the digital incarnation of the 250-600mm F5.6

Explanation of the F4.5 aperture:

  • F4.5 takes it a step beyond the more mass market zooms ending at F5.6

  • At F4.5 it will be a lot smaller, lighter and cheaper (roughly 30%) then a F4

  • At F4.5 the lens can be made very sharp right wide open at every focal length

You could see this lens for instance as a big brother of the 60-250mm F4 which is also not extremely fast, but is also very sharp wide open across it's focal range with an image rendering very close to a prime. You could also see it as similar to the well regarded Konica-Minolta 400mm F4.5 prime, just with a whole lot of additional flexibility going all the way down to 135mm. It would appeal more to people who are looking for a zoom with a very special, almost prime like image rendering rather then specification bragging rights.

I reckon a F4 would get too expensive for the market position Pentax is in now and in the foreseeable future. Furthermore the F4.5 has significant advantages regarding size and weight. I would be interested in hearing from the tele shooter guys what they would prefer more an F4.5 or still an F4 that would be roughly 40-50% heavier, larger and more expensive? 40-50% more could mean $1000 more at expected prices. Same goes for 500mm vs. 400mm which would be roughly twice as expensive, heavy and large.


Why not up to 500mm? Would get too large, expensive and heavy in my view, not enough potential buyers for such a monster.
Why not F4? See above.

Why only F4.5 at the wide end? Well at 135mm it's still enough for shallow DOF purposes and it allows it to be very sharp wide open at the wide end which a DA* needs to be.

Image Circle 35mm
Focal Length 135-400mm
Max Aperture f/4.5
Min Aperture f/32
Diaphragm Blades 9 rounded
Lens Construction 15 elements in 13 groups, including 2 ED elements
Closest Focus 1.8m / 5.9 ft.
Magnification Ratio 0.15x
Filter Size Integral
(Length x Diameter) 290mm x 110mm / 11.4 in. x 4.3 in.
Weight 2100g / 74 oz

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Current cam: K10D, TZ1
Wish cams: LX3 or lens stabilized compact micro 4/3.
Current lens: 18-55mm F3.5-5.6, 50mm F1.4, Sigma 105mm F2.8 macro

Wish lens: 17-90mm F3.2-4.5. A 70-300mm F3.2-4.5, usable quality with 1.4TC, 60mm F2 macro, 150mm F2.8 macro.

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