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07-07-2008, 07:25 AM   #16
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And it'a also possible to meter using the optical preview,
just like the old manual cameras.

07-07-2008, 07:29 AM   #17
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QuoteOriginally posted by bdery Quote
The camera keeps the lens wide open until you press the green button (in which case it closes the iris to the set value) or when you press the shutter. It's really a simple thing to do. The green button (and the AEL button on K*00Ds) are very near the shutter, it's much, MUCH simpler than having to open the aperture to focus, then take the camera away from your face to reset the aperture ring to the desired value (or try to remember how many notches you turned it).

It would be better if Pentax had not crippled the mount, but hacking at the aperture lever is much more disabling, I would say.

Even after only three weeks with my K20D, I already find manual operation very easy. What's more, you don't even have to press the green button each time, only when your scene changes.

Try focusing with a lens stopped at f11 and see what you prefer
the scene may change enough for your shot to be completly junked without you even knowing it

i try to expose as much to the right as i can esp in bright conditions, one random extra ray of sunshine and my picture is overexposed.


while it is definetly not easy to focus at F11, considering we dont have split prisims its a moot point anyway.

F22 on my K100D with a katz eye is much better than on my K20D.


also, if you are really so picky, focus at wide open then stop down the aperture, the beauty of this is that you see the effects of depth of field right away, and since the camera is metering you can see all the digits in your viewfinder, you dont need to take away your camera from your eye.

there is no need to remember where the clicks are, aperture values are arbitrary anyway..
07-07-2008, 08:45 AM   #18
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Gooshin,
The M lenses have a appeture position tab buildin. The reason you have to use stop down metering is because they didn't provide coupling in the cripple KA mount used on our digitals. I have converted many lenses of other brands to Kmount and AV work just like you said. My latest is a Soligor 70 -220 f3.5 constant appeture. It is a internal zoom and weighs three pounds. I don't know who made it, but the IQ is pretty good. It cost over $500 twenty years ago. Watch out for filings when removing the lever.

Dave

QuoteOriginally posted by Gooshin Quote
M glass or not, what kind of idiot at pentax couldnt engineer a proper way to have no-contact lenses meter in AV mode without having to constantly press some silly button.
07-07-2008, 09:02 AM   #19
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QuoteOriginally posted by Gooshin Quote
M glass or not, what kind of idiot at pentax couldnt engineer a proper way to have no-contact lenses meter in AV mode without having to constantly press some silly button.
I have personally donated 2 different ideas to pentax to deal with non A lenses.

1) use the green button to stop down the lenses, and calculate change in exposure to know apature set.

2) feed in min and max apature and have the camera control the lens just like the A lenses. Note however, exposure accuracy will be a little different since the M lenses have the apature change diameter linearly with the lever where as A lenses have the apature area change linearly with the lever.

They have opted to do neither.

I prefer option 2 because the K10 has a metering problem as a function of maximum apature, and as a result, it really needs to know this data anyways to meter correctly.

ONe thing I won't do, however, is remove teh apature activating linkage from my lenses, because I still have 3 film bodies to use these lenses with, and I am hoping for a pro level camera that has the apature indicating coupling, plus TTL flash as options

07-07-2008, 10:45 AM   #20
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You've turned it into an M42 stop-down lens.
07-07-2008, 03:45 PM   #21
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QuoteOriginally posted by stevebrot Quote
Or

You could disassemble the mount and remove the aperture lever as opposed to cutting it off. (Just in case you have second thoughts...)
Thanks for the inspiration Gooshin and stevebrot!

I prefer the less violent solution for my lenses. Should have thought about this before.

Well, it took about half an hour after kids went to bed to convert one Panagor 135 mm f 2.8 macro (Kiron I think) and one Tokina 400 mm f 5.6 "M" lenses using a screwdriver. And now they measure nicely an any aperture.

Now this have other disadvantages as some pointed out after I left the laptop, which slightly have damped my enthusiasm. Once the sun is back to this side of the globe, I'll try it out to see which disadvantage I prefer, green button or not. Sure, I have turned both lenses into preset m42 lenses in some sense as someone pointed out.

A word of advice. The Kiron and the Tokina mechanical solutions were very different, and I assume Pentax K/M, Ricoh, Chinon, Sigma,.... will have other solutions. Non was really difficult, and no parts were lost, but I almost lost a small metal ball involved in setting the discrete steps on the aperture ring (but an aperture ring without steps would have been in agreement with an old m42 lens, right?). In the end, the bag with the left overs from the Tokina contains only one small part, the aperture lever itself. The Kiron construction appeared more sturdy, but was made in one big piece, and did not fall into pieces as the Tokina, so that bag contains the whole block in which the lever is sitting + 3 tiny screws. Unfortunately this leaves the back of the lens rather open to dust etc, but it works. And of course this is both lenses I decided I could spare if made a mess of it. But I'm quite confident that I can put it all together in case I decide the green button is better than this.

Time to go to bed. Wifes birthday tomorrow! (she is getting a Pentax point and shoot, time for her to go digital finally) Have to wake up the kids in time to celebrate her on the bed, of course.
07-08-2008, 05:42 AM   #22
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QuoteQuote:
while it is definetly not easy to focus at F11, considering we dont have split prisims its a moot point anyway.
My K20D tells me when I am focused. I see it as having an autofocus lens without a motor. If I act as the motor, then it's the same as autofocus, only marginally slower

QuoteQuote:
F22 on my K100D with a katz eye is much better than on my K20D.
Without Katz's eye, I gather.

QuoteQuote:
also, if you are really so picky, focus at wide open then stop down the aperture, the beauty of this is that you see the effects of depth of field right away, and since the camera is metering you can see all the digits in your viewfinder, you dont need to take away your camera from your eye.
It's a matter of personal taste, I guess. I finmd it hard to judge the DOF accurately when the lens is stopped down, as it gets dark in there anyway...

QuoteQuote:
there is no need to remember where the clicks are, aperture values are arbitrary anyway.
I'm not sure I agree (or understand what you mean). To me, aperture values and focal length relate pretty accurately to let me evaluate DOF. And aperture is calculated with known quantities (focal length and physical aperture), not arbitrarily.

At the end of the day, if you'Re happy hacking off at your lens, then that's good. I feel I would loose more than I gain, but YMMV.
07-08-2008, 06:20 AM   #23
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QuoteOriginally posted by bdery Quote
I'm not sure I agree (or understand what you mean). To me, aperture values and focal length relate pretty accurately to let me evaluate DOF. And aperture is calculated with known quantities (focal length and physical aperture), not arbitrarily.

lets say you are taking a picture of someone in front of some trees

which image is going to have more blurry backgrounds, F8 and the person standing 50 feet away from the trees, or F2.8 and the person standing right next to the trees?

07-08-2008, 06:53 AM   #24
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What you are doing is to force stopped down metering all the time by cutting the aperture coupler, thus make your K-mount lenses just like those M42 ones.

QuoteOriginally posted by Gooshin Quote
simply hack off the aperture tab and there you go...

i bought a Vivitar 50mm F1.7 today for 10 bucks, and it had the aperture tab and plastic block thingy sawed off, well, guess what slam that sucker in Av mode, and simply rotate the aperture ring and the camera adjusts its metering!

you even get to see the effects on DOF right away.

also i had a katz eye screen with me when i was testing the lens, and even at F22 there was enough visible light to work with a shot.


now i need to go find my file... i have a bunch of M lenses.
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