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10-15-2008, 05:07 PM   #1
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How does DOF preview function?

I have a ME super and K1000 and want to get an MX but was wondering how DOF preview works and how valued this feature is?

10-15-2008, 05:25 PM   #2
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DOF Preview`

DOF Preview simply causes the lens to be stopped down to the selected aperture, rather than remaining wide open for focusing.

The drawback is that the image will usually get much darker and harder to see, depending on how bright the light is and what f-stop you're using. This can make it harder to see the focus differences that stopping down is supposed to show.

In cases in which you need a particular depth of field for the artistic or technical purpose you're going for, DOF preview can be a godsend. Typically, I don't think that very many people use it for every or even most of their shots.

My very first good camera was a Pentax Spotmatic. This camera had no wide-open metering and used screw-mount lenses. Think of a K-1000, without the bayonet mount lenses and no wide-open metering. You would focus the image, turn on the meter (which stopped the lens down) and center the meter's needle to get the proper exposure. In effect, I was using DOF preview on almost every shot. I did not find the DOF preview aspect to be very useful, because of the afore-mentioned darkening.

Hope this helps.

Paul Noble
10-15-2008, 05:40 PM   #3
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I like a camera to have a DOF preview. Usually use it for close, DOF critical shots.

All things being equal, I would go for a camera with DOF preview.

But if I had the choice of a beat KM (with DOF preview), or a mint K1000, at the same price, I'd go with the K1000.

In a pinch, you can always release the lens, and turn it 10 degrees to stop the lens down. As far as I know this works with all Pentax K-mount bodies. So even if there is no DOF preview button, all cameras can check the DOF.
10-15-2008, 07:25 PM   #4
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Just to show my ignorance, the lens apeture on my me-super and k1000 actually stays wide open for focusing until the shutter is released? I didnt know that but I guess makes sense really to think about it!
I am learning things everyday, I am yet another one who has turned away from digital photography to film because it is alot more fun! I think this tendency will actually increase especially with younger generations who havent had any film camera experience.
On a side note I now have a Yashica Electro 35, the two Pentax, a contax IIIa, palmat automatic, a ricoh xr-10m I bought for the pentax lens, olympus stylus epic, Kalimar A, canon datelux, and on its way a fed 3 and Kiev4. I love trying them out and comparing and its made photography fun again.

10-15-2008, 08:44 PM   #5
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DOF

QuoteOriginally posted by Heldur Quote
Just to show my ignorance, the lens apeture on my me-super and k1000 actually stays wide open for focusing until the shutter is released? I didnt know that but I guess makes sense really to think about it!
That's exactly right. Back in the late sixties, that was considered a big advance for Pentax. As I said, my Spotmatic used a technique called "stop down metering", meaning that the lens had to be stopped down to shooting aperture in order to meter the scene. Many people hated this. I never found it to be a problem.

On your K-1000 or ME Super, turn the camera around and look through the lens from the front. Turn the aperture ring from widest to smallest aperture. Nothing appears to happen. Now, set the shutter speed to something really slow, like one second and set the aperture to f/16. Trip the shutter. You should be able to see the aperture blades close down and re-open when the shutter closes.

Around 1972, Pentax introduced the ES and ES-II, followed by the Spotmatic-F, which featured the necessary linkage for the lens to "tell" the camera what its aperture was set to. This allowed the camera to meter the scene with the lens aperture wide-open.

Then, in 1975 or so, the K2 and K-1000 introduced the k-mount bayonet lens mounting system that is still with us today, although its capabilities have been extended. The K-1000 is mechanically very similar to the Spotmatic-F, except for the bayonet mount.

Paul Noble
10-15-2008, 09:39 PM   #6
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The DoF button makes a bar slide and hit the aperture lever...this is manual on the MX, but if you have a digital body, you can also see how it works using optical preview.

I find it useful to determine if I really want a shot at f/5.6 or if f/8 is more appropriate, for example. I'd say I use it maybe 5 times on a 24exp roll.
10-16-2008, 02:14 PM   #7
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Depth of Field preview can be very useful. For me, it's indispensible for macro work, and I like to check foreground sharpness in landscape shots too. Soft foreground has ruined many of my shots that I forgot to check. Also aids "focus bracketing" ie several shots with the focus bumped slightly for each.
Takes some getting used to (took me 10 or 15 years, but you may be quicker).
10-19-2008, 02:26 PM   #8
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QuoteOriginally posted by Heldur Quote
I am learning things everyday, I am yet another one who has turned away from digital photography to film because it is alot more fun! I think this tendency will actually increase especially with younger generations who havent had any film camera experience.
On a side note I now have a Yashica Electro 35, the two Pentax, a contax IIIa, palmat automatic, a ricoh xr-10m I bought for the pentax lens, olympus stylus epic, Kalimar A, canon datelux, and on its way a fed 3 and Kiev4. I love trying them out and comparing and its made photography fun again.
Buying digital and entering the forums, have also peaked my curiosity in manual focus lenses and cameras. Fun to take more charge of things

10-19-2008, 11:06 PM   #9
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Okay....so how do you do it? I think this may actually classify as a "Stupid Question"......
10-19-2008, 11:30 PM   #10
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QuoteOriginally posted by Aaron1971 Quote
Okay....so how do you do it? I think this may actually classify as a "Stupid Question"......
Depending on the Camera model, there is a switch or button that stops the lens down. This means the lenses aperture closes to the setting the camera will use to take the picture.

Looking through the view finder, the image will get darker, but the depth of field will be visable. This is the same if you change the preview feature on your DSLR from digital preview to optical preview.

Cameras that do not have a dedicated preview button, can get the same effect by releasing the lens, and turning it 10 or so. The lens will stop down before it is able to be removed.

What camera are you using?
10-20-2008, 02:20 AM   #11
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QuoteOriginally posted by KungPOW Quote
Depending on the Camera model, there is a switch or button that stops the lens down. This means the lenses aperture closes to the setting the camera will use to take the picture.

Looking through the view finder, the image will get darker, but the depth of field will be visable. This is the same if you change the preview feature on your DSLR from digital preview to optical preview.

Cameras that do not have a dedicated preview button, can get the same effect by releasing the lens, and turning it 10 or so. The lens will stop down before it is able to be removed.

What camera are you using?
I have a K10D.
10-20-2008, 10:29 AM   #12
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QuoteOriginally posted by Aaron1971 Quote
I have a K10D.
While looking through the finder, move the lever under the shutter button to the right. It will stop down the lens and you can view the DOF then.


Dave
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