CONTAX CLUB Carl Zeiss 討論區

[/img]http://www.fotop.net/Rico

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大師級作品!

Rico 兄把 645D 的優點發揮得淋漓盡致!

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Wah
理事 - Board of Members
www.flickr.com/dicksonlau

Really great photo!!!

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事務局長

Damn, my Calon Segur heart fall in love with Haut Brion

Great capture and unique

thank you 各位,歡迎大家賜教

LIKE!!

VERY LIKE!!!
BTW, what is the chop factor for Pentax 645D?
The only little problem is the photos seem a bit packed........but due to limitation of the Chop Factor of 645D.

Chop factor should not be related for a photo (for which I guess you mean the framing here) to be packed or not......

You can always get a wider lens to achieve any field of view you desired...........remember the lens of Pentax 645D could be as wide as 25mm (which equal to 20mm in 135 format)

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Wah
理事 - Board of Members
www.flickr.com/dicksonlau

I am not sure about the lens design for Pentax 645D.
But I am sure the same 100mm f/2 lens on a full frame will not have the dof of the 50mm f/2. Lens design and configuration of elements.
So despite you can have a same Field of View but the DOF is not mean to be there. At least for existing 135mm system. Not 100% sure about Pentax 645D

For your information, the crop factor of Pentax 645D (so as Phase One IQ140 and Hasselblad H4D-40) are all 1.3x (44mm X 33mm) in respect to full frame 645 format

Other backs like Hasselblad H4D-50, Phase One P45+, Leaf Aptus-II 7 are having 1.1x (with sensor size of 49mm X 37mm), and for the Hasselblad H4D-60, Phase One IQ160/180, Aptus-II 12, manufacturers usually claimed that they are having 1.0x crop factor with the sensor size of 54mm X 40mm (frame size of 645 film supposed to be 56mm X 45mm)

Ref: http://www.phaseone.com/en/Digital-Back ... Specs.aspx

Therefore, the field of view of a 80mm lens on Pentax 645D should be similar to a 100mm lens on full frame 645, and my salute to you if you can tell the DoF difference between a 80 and 100mm lens easily (considering the relatively smaller maximum aperture value on medium format lenses say f/2.8 only)

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Wah
理事 - Board of Members
www.flickr.com/dicksonlau

I think there are reasons for those classic 21mm, 25mm, 28mm 35mm 50mm 85mm 100mm 135mm 200mm 300mm 400mm 600mm etc.
And I am just using OM as an example.
If I use a Planar 50mm f/1.4 it becomes a 100mm f/1.4 lens on OM format. Then it is a 100mm Planar but not mean for a Portrait lens.
It will be completely different to if I use a 100mm f/2.0 Planar on a Full-Frame body (no matter film or digital).
The field of view is so much packed and un-natural because the crop factor will not make you a real Portrait lens.
So same for Pentax.........they will have to aim for FF future; I guess most of the lens now are designed for Full-Frame future? RIght? Not 100% confirm.

I hope you can refer to my previous reply.

The choice of focal lengths to me is clearly customary only, afterall it is just the final field of view of the image which does matter

And again should we go back to the crop factor of 1.0x vs 1.3x for Full Frame 645 vs Pentax 645D for the discussion here? (Instead of using your extreme example of 1.0x vs 2.0x for full-frame 135 vs Four-thrids)

And always remember even with the same focal length, a medium format lens is offering much larger angular field than a 135 format lens, e.g. 50mm lens is a standard lens on 135 format, and with 1.3x crop factor (such as Leica M8, Canon EOS1D Mk.IV) it becomes something like a mid-tele of 65mm

While for medium format a 50mm lens is similar to a 28mm lens in 135 format, and even with the crop factor of 1.3x it is still a moderate wide angle like 35mm lens in 135 format

Pentax is currently offering all lenses in full frame 645 format even with the new D-FA25/4, and they did not, and I guess will not, produce any lenses in 1.3x crop factor only. (Due to not much saving on both lens size and cost)

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Wah
理事 - Board of Members
www.flickr.com/dicksonlau