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01-07-2009, 10:10 AM   #1
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probably a newbie question

Is it possible to create extended exposures using a m42 mount lens?

I just received a SMC Tak 50/1.4 and pentax adapter. On my K20d the only acceptable settings are Av and Manual. The exposures all look fine except when I try to adjust the shutter speed. I always get over-exposed images when I leave the shutter open for more than 1 second. (Even with f/16)

Am a missing a setting? I'd like to be able to take photos of water with extended exposures using this lens.

Thanks for any feedback.

01-07-2009, 10:18 AM   #2
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I'm just going to guess here and say that even at f/16 a 1second exposure is way to long and you'll get an over exposed photo every time.

What you really need to do is buy some ND filters to reduce the amount of light getting to the camera, then you'll be able to increase your exposure time to get the results you want.


Hope that helps
John
01-07-2009, 10:25 AM   #3
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Isn't there a switch on those old lenses that leaves the aperture wide open all the time unless you're using a specific body? I haven't used Takumar lenses in a very long time and never with a K10 or 20D body. I'm just throwing that out there to maybe jump start someone else's train of thought
01-07-2009, 10:27 AM   #4
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Just as an example, on a sunny day at ISO 100 the exposure should be around 1/125 of a second at f/16. If you leave the shutter open longer than that the picture will be overexposed.

So the only way to use a 1 second speed (given that the lens won't stop down far enough for it) is to cut down on the light somehow. As John suggested, ND (Neutral Density) filters are the way to do that. Another alternative is to use two polarizer filters and to rotate them so they block out the light - that's a kind of "variable ND filter" (although it can result in a colour cast).

01-07-2009, 01:42 PM   #5
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Hello,

I'm not sure wether i well understand you question (i'm not a native english speaking), but, just to be sure: if you use your M42 lens in M mode, then you should use the "green" button to allow your camera to measure light and set the shutter speed. If you use it in Av mode, then you should only use the diaphragm ring on your lens to switch the f/stop value, and not change speed using the dial on the camera, otherwise you will apply a correction value to the measurements done by the camera ...

Moreover, i wouldn't trust too much the exposure measurements giving a shutter time of 1" or longer ...

So, my suggestion: if you have a bit of time, try this: put your camera in M mode, enable the diaphragm ring operations in your setup, focus on a subject, select the f/stop value you want to use, and then hit the green button on the top to let the camera select the right speed ...
Your picture should be correctly exposed ...

Hope this helps

Best regards
01-07-2009, 02:48 PM   #6
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QuoteOriginally posted by AK_shooter22 Quote
Is it possible to create extended exposures using a m42 mount lens?

I just received a SMC Tak 50/1.4 and pentax adapter. On my K20d the only acceptable settings are Av and Manual. The exposures all look fine except when I try to adjust the shutter speed. I always get over-exposed images when I leave the shutter open for more than 1 second. (Even with f/16)

Am a missing a setting? I'd like to be able to take photos of water with extended exposures using this lens.

Thanks for any feedback.



Pentax K20D
S-M-C Takumar 35/2


That's a 10 second exposure.

The Takumars are the same as any other lens; you have to use a shutter speed and aperture combination that is appropriate for the amount of light coming into the camera. If you want longer shutter speeds and you've already closed the aperture down as far as you can, then your options are to lower the ISO and/or use ND (neutral density) filters. The above photo was done with an ND8 (kills three stops of light) and a linear polarizer.




Pentax K20D
S-M-C Takumar 35/3.5


Same filter setup, but as this was in a shadier location it is a 30 second exposure.
01-08-2009, 10:39 AM   #7
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Thanks. I didn't even know what a neutral density filter was until now! I'll have to look into those.

BTW Mike those are great photos.
01-09-2009, 07:28 AM   #8
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Glad you liked them.

A neutral density filter is basically just sunglasses for your camera. The numbers indicate the degree of light they cut down. ND2 cuts light in half, so that's one stop. ND4 cuts light to 1/4, so that's two stops. ND8 cuts light to 1/8, which is three stops. I think the darkest one commonly available is something like ND400, which is akin to what goes in an arc welder's face mask. You can use that one to take looooong exposures even in broad daylight. I've seen shots of busy streets/sidewalks done with those where cars and pedestrians don't even show up, as they aren't sitting still long enough to be captured.

Here are some ND400 examples from Flickr.

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