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Forum: Pentax SLR Lens Discussion
11-14-2014, 08:53 AM
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i don't disagree you need to look at equivalence, what i disagree with is marking lenses with anything other than physical properties, i.e. focal length and aperture. you could perhaps add a 3rd property, Image circle diameter. since many lenses do have a limit either due to the rear barrel dimensions or the front end filter ring (or hood if integral to the lens), but lets not add a reference to a format, whether it be 35mm or what, because every sensor is slightly different any way, like the Q vs Q7, so there is no way to mark lenses with multiple equivalent focal lengths or fields of view any way.
It is up to the photographer to know his gear.
We are adding a whole level of complexity for nothing in an attempt to dumb down the issue.
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Forum: Pentax SLR Lens Discussion
11-13-2014, 07:34 PM
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No , but you had 120 roll film 2 1/2 x 3 1/2 mini speed graphics, 4 x5 and 8x10 all using the same shutter/lens combos. This lasted for years. It is only now in digital we discuss equivelents. 110 cameras didn't give FF equivelents. Neither did the pentax 110 camera.
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Forum: Pentax SLR Lens Discussion
11-13-2014, 12:23 PM
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this entire thread simply confirms something that has been known for a long, long tome.
In the bad old days, focal length was focal length, and each format's users knwe what was wide, normal and long for each format they used. My folding KodaK #3 camera didn't have a 4x5 or 8x10 equivelent. the lens just said F=127mm F4.5 or something like that.
however, the world's population was much smaller when the kodak #3 was made.
here is the point,
Intelligence is a constant, the population is growing!
I think at times this is really really true. the longer the human race exists, the dumber we get. there was no need for the first 150 years of photography to have equivalences. they are unnecessary unless it is proof we really are getting dumber
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Forum: Pentax SLR Lens Discussion
11-12-2014, 02:54 PM
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Why not recreate the definition of "normal lens" with focal length equal to sensor diagonal as 1:1 with tele being greater than 1 and wide angle being less than 1. Then every one would talk the same ratio,
Oops. We can't do this because some lenses are used on many formats. How do you label the FA77 for example. It would have one number for film, one for APS-C and two for the Q at present (q and q10 are one size, q7 another)
Forget it all, state focal length and be on with it
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Forum: Pentax SLR Lens Discussion
11-12-2014, 12:32 PM
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steve, perhaps not your fault you are just last in line.
Start of rant
just to "focus" the discussion a little (yes pun intended) we also need to remind people that like focal length, F Stops are also a physical property of the lens, specifically focal length over diameter (of aperture or smallest part of the light path)
we either accept, like all other format shooters that focal length is focal length, or we simply throw it all away.
we don't label 645 or 6x7 lenses in 35mm equivalent, or visa versa, so why should we start now.
end of rant
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Forum: Pentax SLR Lens Discussion
11-12-2014, 11:46 AM
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to me, it looks about 1 stop down at 80% of the frame, and 3 stops down right at the corner. this may be due to a shield at the back of the lens, like the rectangular ones pentax used to put on film lenses to limit stray light from entering the mirror box. if so, jjust remove the shield and you have a FF lens. anyone have a shot of the rear of the lens to confirm
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Forum: Pentax SLR Lens Discussion
11-12-2014, 10:38 AM
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Forum: Pentax SLR Lens Discussion
11-12-2014, 10:17 AM
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but every pentax camera since the A series could control the lens through the body
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Forum: Pentax SLR Lens Discussion
11-12-2014, 09:55 AM
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as others have noted, focal length is focal length. full frame or APS-C does not matter in the focal length. Lenses are labled for focal length which is a physical property, not for the 35mm equivalent because it is meaningless
As for using the lens on full frame, there is nothing that prevents this lens from being used on full frame, other than possible vignetting.
there is a thread running presently with APS-C lenses tested on full frame (using film body)
check if the lens has been tested. Just because it is a DA lens, does not mean specifically it cannot actually cover a full frame acceptably.
Note, while i do not own this lens, my sigma 10-20 covers 100% of my PZ1 viewfinder by 13mm.
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