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12-25-2013, 09:49 AM   #31
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QuoteOriginally posted by gofour3 Quote
The white dot indicates F4 on your lens.

You match up the "red" distance with the "red" aperture, for the hyper focal range. So it's F8 and 15 feet/4.5 meters for your lens.

Phil.
There are 2 click stops between 2.8 and 5.6 on the M35/2.8, so I think it is F3.5.

12-25-2013, 10:05 AM   #32
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QuoteOriginally posted by boriscleto Quote
There are 2 click stops between 2.8 and 5.6 on the M35/2.8, so I think it is F3.5.
I can't find an online version, but if you have the SMC PENTAX-A LENSES guide, it has a picture on page 6 with the aperture values.

The white dot next to the lens full aperture is one full stop slower, which would be F4. The next click would between F4 and F5.6 would be F4.8.

Phil.
12-25-2013, 01:22 PM   #33
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So to sum up, the white dot on the M35/2.8 indicates F4 or F3.5.

5.6 - click - white dot - 2.8
12-25-2013, 02:15 PM   #34
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QuoteOriginally posted by glasbak Quote
Aperture is a parameter of the lens, so the most intuitive and logical place to control it, is on the lens.
What he said.


Steve

12-25-2013, 02:19 PM   #35
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QuoteOriginally posted by Pontax Quote
So to sum up, the white dot on the M35/2.8 indicates F4 or F3.5.

5.6 - click - white dot - 2.8
...and the "pearl" is the "no look" mounting aid. On most (all?) K-mount film cameras, the pearl is oriented such that when it is aligned with the lens release lever on the body, the lens is positioned properly to mount. With a little practice, you can mount a lens by feel alone. Does not work with modern dSLRs.


Steve
12-25-2013, 02:28 PM   #36
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The "pearl" is a guide to help you attach the lens in the dark/low visibility when you can't see the red dot on the bayonet. The pearl aligns with the lens release button, then you give the lens a twist to attach it.

Edit: Oops! Must've posted at the same time!
12-25-2013, 03:08 PM   #37
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QuoteOriginally posted by Pontax Quote
So to sum up, the white dot on the M35/2.8 indicates F4 or F3.5.

5.6 - click - white dot - 2.8
F4

F5.6 F4.8 F4 (white dot) F2.8

Phil.
12-25-2013, 04:07 PM   #38
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Control freak here...Even on my aperture ring equipped A-lenses, I will keep in manual and turn the ring instead.
I like the physical action of resetting the ring to wide open and then counting a number of clicks to put me exactly at the aperture setting I want. Also, as mentioned already, extension tubes, reverse rings, can sometimes benefit by an aperture ring.

12-26-2013, 07:56 AM   #39
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Oh and btw, some say that the zone focusing guides are not accurate when it comes to digital cameras, and that you should shift one stop just in case. The zone focusing/DoF scales were always for "acceptable" performance - which is dependent on the medium. With the newer high pixel density sensors (some people blame APSC), you need tighter tolerances. So if you shoot f8 on modern, you should zone focus as if its f5,6. I personally don't really trust zone focusing with many lenses and I use DoF preview or zoom in to a digital preview photo.
12-26-2013, 10:40 AM   #40
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The DOF is based on a particular size film (sensor) and how large you print. Believe it is for about 8"x10" print from full frame digital (or standard f35 mm film). As the Penatx dslr is smaller by 1.5, printing to the same size print involves greater blowup--and the required f stop is proportionately smaller by about 1.5. It would work out to 1 stop more closed (e.g., 1.5*f/11= f/16). If we print much smaller, or larger, or crop, we can adjust the DOF for our particular scenario--but usually it's good enough and other choices may be more important.
12-26-2013, 10:50 AM   #41
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I have a Pentax K-r with an assortment of lenses, and when I want to get the best shots of people, I pick up my Sears 50 mm 1.7 fully manual film lens and set everything to manual on the camera. This Sears 50 mm lens has an aperture ring that feels so right: click—click—click. Each click tells me and shows me that I am getting closer to correct exposure. (I rarely use the "stopping down" exposure method with this lens.) It's really foolproof. There's no describing the clicks. They are not stiff. They are not loose. They are perfect.
12-26-2013, 11:10 AM   #42
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QuoteOriginally posted by Ray-uk Quote
I can understand why you want the A setting but these two sentences contradict each other, because using the A setting gives the camera aperture control.
However I do agree with all your other statements.
With an A-Ring with A-Setting, you can still control the Aperture, just via the Camera (easier) than turning a dial on the lens.
12-26-2013, 05:30 PM   #43
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It is very useful for adapting the lens to another system (e.g. mirrorless). You can use a cheap, "dumb" adapter with no aperture control, and avoid the aperture guessing game on more expensive adapters with aperture control.

On my m4/3 system, instead of buying a native macro lens, I just use my DFA 50 with a cheap, simple adapter for macro purposes. Full half-stop aperture control, with real time DOF on the VF, and macro work generally needs MF anyway.

Last edited by Cannikin; 12-26-2013 at 05:37 PM.
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