I want digital neutral filter in my k-5, so ...

006 · 12-21-2010, 02:05 PM

neutral filter can sometimes be usefull function in the camera. You can set long time exposure without changing aperture. I think it costs nothing to add this function to camera's software. how do you think, who should i contact to present idea like this? is there any feedback unit in Pentax? I just want my camera to be better.

Acheron · 12-21-2010, 02:31 PM

you can't reproduce that with software since it is directly related to exposure and CMOS sensitivity.
you need to buy ND filter or camera with minimum ISO rating lets say 6

**DigiMack** · 12-21-2010, 02:41 PM

I have used Hoya PRO 1 Digital filters ND8 and ND4 with good results.

Wheatfield · 12-21-2010, 02:56 PM

Originally posted by acheron

you can't reproduce that with software since it is directly related to exposure and cmos sensitivity.
You need to buy nd filter or camera with minimum iso rating lets say 6

+1

2345678

Huck Finn · 12-21-2010, 03:22 PM

Originally posted by Acheron

you can't reproduce that with software since it is directly related to exposure and CMOS sensitivity.
you need to buy ND filter or camera with minimum ISO rating lets say 6

Well, you can, actually.

At least with my K20d, but I'd be surprised if it wasn't the same with a K5.

Just select an exposure, then set multi-exposure on and select the number of shots to be taken (2 to 9 on the K20d), then select also the "Auto EV adjust" check box.

What did you meter? 1 sec @ f/2.8?
At f/16 it'd be 30". Make it so.

If you selected 9 multiple shots the camera will shoot nine 30-seconds (270" or 4 minutes and a half) shots and average out the exposure as well, giving you basically a 9X ND filter.

Try it.

jolepp · 12-21-2010, 03:26 PM

Implementing this in software would not work, I think, because after a pixel has reached its maximum capacity to register light it will not continue to register any more; in this sense the sensor is exactly like film, with too much light there is overexposure. Of course, the software could automatically adjust ISO downward (lower amplifier gain) and after hitting the limit with that maybe use a multiple short exposures during the nominal long exposure for an effect almost but not quite totally unlike an NDF :-)

WerTicus · 12-21-2010, 09:48 PM

at 80iso the camera is probably using near zero amplification (or some minimum operating amount), merely reading out what is produced by the sensor itself. This is where the problem is.

Huck Finn · 12-22-2010, 02:08 AM

Originally posted by jolepp

...and after hitting the limit with that maybe use a multiple short exposures during the nominal long exposure for an effect almost but not quite totally unlike an NDF :-)

That's not what I was suggesting. I'm not saying to divide a 10 seconds exposure in 5 2 seconds ones. I'm saying that if you tick the "Auto EV adjust" check box the camera will average out the images, therefore obtaining the same result of an exposure as long as the sum of all the exposures made.

BTW this will also have a good effect on any digital noise you may have in dark areas, since the noise is randomly scattered and it will be smoothed over by the multiple exposure.

Actually this works better than a physical ND filter, since this kind of filters (at least the darker ones) often induce color dominants in the picture. To have a truly neutral ND filter you have by a quality, expensive filter.

jolepp · 12-22-2010, 03:37 AM

What I meant was really using a duty cycle in the exposure corresponding to to the degree of the filter, say for -2 stops 25% shutter open 75% shutter closed like so:

@0.000s : open shutter
@0.125s : close shutter
@0.500s : open shutter
@0.625s : close shutter
@1.000s : open shutter
@1.125s : close shutter
...
@9.625s : done

Huck Finn · 12-22-2010, 03:48 AM

Originally posted by jolepp

What I meant was really using a duty cycle in the exposure corresponding to to the degree of the filter, say for -2 stops 25% shutter open 75% shutter closed like so:

@0.000s : open shutter
@0.125s : close shutter
@0.500s : open shutter
@0.625s : close shutter
@1.000s : open shutter
@1.125s : close shutter
...
@9.625s : done

In fact that's simply a 2.5 seconds exposure diluted in 10 seconds. My solutions instead creates a real long exposure through the fusion of up to 9 shorter ones.

You've got to try it.

stanic · 12-22-2010, 03:49 AM

Originally posted by Huck Finn

Well, you can, actually.

At least with my K20d, but I'd be surprised if it wasn't the same with a K5.

Just select an exposure, then set multi-exposure on and select the number of shots to be taken (2 to 9 on the K20d), then select also the "Auto EV adjust" check box.

What did you meter? 1 sec @ f/2.8?
At f/16 it'd be 30". Make it so.

If you selected 9 multiple shots the camera will shoot nine 30-seconds (270" or 4 minutes and a half) shots and average out the exposure as well, giving you basically a 9X ND filter.

Try it.

great, will try today when I get home from work
thanks

Entropy · 12-22-2010, 10:51 AM

Great trick! (the multiexposure) I'm going to use it for waterfall shots next summer! Makes it a lot easier to compose/focus without an ND on.

jolepp · 12-22-2010, 11:06 AM

Originally posted by Huck Finn

...
You've got to try it.

I have no particular application for an ND filter in mind at this time, but try to keep it in mind in case one turns up :-) Anyway, that multi-exposure-with-duty-cycle-variation idea popped up when I was trying to convince myself that an ND filter cannot be implemented in software; I suppose it kind of could like that, but wouldn't be quite the same, nor terribly useful.

shadmanaj · 12-22-2010, 12:46 PM

Originally posted by Huck Finn

Well, you can, actually.

At least with my K20d, but I'd be surprised if it wasn't the same with a K5.

Just select an exposure, then set multi-exposure on and select the number of shots to be taken (2 to 9 on the K20d), then select also the "Auto EV adjust" check box.

What did you meter? 1 sec @ f/2.8?
At f/16 it'd be 30". Make it so.

If you selected 9 multiple shots the camera will shoot nine 30-seconds (270" or 4 minutes and a half) shots and average out the exposure as well, giving you basically a 9X ND filter.

Try it.

Thanks.
Will try it soon. One query though. Is the multiple exposure photo RAW or Jpeg?

Huck Finn · 12-22-2010, 12:55 PM

Originally posted by shadmanaj

Thanks.
Will try it soon. One query though. Is the multiple exposure photo RAW or Jpeg?

I guess whatever you chose in your in-camera settings.
Personally I use RAW+.

12-21-2010, 02:05 PM	#1
006 Junior Member Join Date: Dec 2010 Photos: Gallery \| Albums Posts: 38	I want digital neutral filter in my k-5, so ... neutral filter can sometimes be usefull function in the camera. You can set long time exposure without changing aperture. I think it costs nothing to add this function to camera's software. how do you think, who should i contact to present idea like this? is there any feedback unit in Pentax? I just want my camera to be better.

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12-21-2010, 02:31 PM	#2
Acheron Senior Member Join Date: Jul 2009 Location: Croatia Photos: Gallery Posts: 100	you can't reproduce that with software since it is directly related to exposure and CMOS sensitivity. you need to buy ND filter or camera with minimum ISO rating lets say 6

12-21-2010, 02:41 PM	#3
DigiMack Site Supporter Join Date: Dec 2010 Posts: 169	I have used Hoya PRO 1 Digital filters ND8 and ND4 with good results.

12-21-2010, 02:56 PM	#4
Wheatfield Moderator Join Date: Apr 2008 Location: The wheatfields of Canada Posts: 15,981	Originally posted by acheron you can't reproduce that with software since it is directly related to exposure and cmos sensitivity. You need to buy nd filter or camera with minimum iso rating lets say 6 +1 2345678

12-21-2010, 03:22 PM	#5
Huck Finn Inactive Account Join Date: Dec 2010 Location: Italy Photos: Albums Posts: 32	Originally posted by Acheron you can't reproduce that with software since it is directly related to exposure and CMOS sensitivity. you need to buy ND filter or camera with minimum ISO rating lets say 6 Well, you can, actually. At least with my K20d, but I'd be surprised if it wasn't the same with a K5. Just select an exposure, then set multi-exposure on and select the number of shots to be taken (2 to 9 on the K20d), then select also the "Auto EV adjust" check box. What did you meter? 1 sec @ f/2.8? At f/16 it'd be 30". Make it so. If you selected 9 multiple shots the camera will shoot nine 30-seconds (270" or 4 minutes and a half) shots and average out the exposure as well, giving you basically a 9X ND filter. Try it.

12-21-2010, 03:26 PM	#6
jolepp Veteran Member Join Date: Oct 2010 Location: Finland Photos: Albums Posts: 3,196	Implementing this in software would not work, I think, because after a pixel has reached its maximum capacity to register light it will not continue to register any more; in this sense the sensor is exactly like film, with too much light there is overexposure. Of course, the software could automatically adjust ISO downward (lower amplifier gain) and after hitting the limit with that maybe use a multiple short exposures during the nominal long exposure for an effect almost but not quite totally unlike an NDF :-)

12-21-2010, 09:48 PM	#7
WerTicus Veteran Member Join Date: Mar 2009 Location: Perth Australia Photos: Albums Posts: 1,514	at 80iso the camera is probably using near zero amplification (or some minimum operating amount), merely reading out what is produced by the sensor itself. This is where the problem is.

12-22-2010, 02:08 AM	#8
Huck Finn Inactive Account Join Date: Dec 2010 Location: Italy Photos: Albums Posts: 32	Originally posted by jolepp ...and after hitting the limit with that maybe use a multiple short exposures during the nominal long exposure for an effect almost but not quite totally unlike an NDF :-) That's not what I was suggesting. I'm not saying to divide a 10 seconds exposure in 5 2 seconds ones. I'm saying that if you tick the "Auto EV adjust" check box the camera will average out the images, therefore obtaining the same result of an exposure as long as the sum of all the exposures made. BTW this will also have a good effect on any digital noise you may have in dark areas, since the noise is randomly scattered and it will be smoothed over by the multiple exposure. Actually this works better than a physical ND filter, since this kind of filters (at least the darker ones) often induce color dominants in the picture. To have a truly neutral ND filter you have by a quality, expensive filter.

12-22-2010, 03:37 AM	#9
jolepp Veteran Member Join Date: Oct 2010 Location: Finland Photos: Albums Posts: 3,196	What I meant was really using a duty cycle in the exposure corresponding to to the degree of the filter, say for -2 stops 25% shutter open 75% shutter closed like so: @0.000s : open shutter @0.125s : close shutter @0.500s : open shutter @0.625s : close shutter @1.000s : open shutter @1.125s : close shutter ... @9.625s : done

12-22-2010, 03:48 AM	#10
Huck Finn Inactive Account Join Date: Dec 2010 Location: Italy Photos: Albums Posts: 32	Originally posted by jolepp What I meant was really using a duty cycle in the exposure corresponding to to the degree of the filter, say for -2 stops 25% shutter open 75% shutter closed like so: @0.000s : open shutter @0.125s : close shutter @0.500s : open shutter @0.625s : close shutter @1.000s : open shutter @1.125s : close shutter ... @9.625s : done In fact that's simply a 2.5 seconds exposure diluted in 10 seconds. My solutions instead creates a real long exposure through the fusion of up to 9 shorter ones. You've got to try it.

12-22-2010, 03:49 AM	#11
stanic Veteran Member Join Date: Aug 2010 Location: Zakopane Photos: Gallery \| Albums Posts: 389	Originally posted by Huck Finn Well, you can, actually. At least with my K20d, but I'd be surprised if it wasn't the same with a K5. Just select an exposure, then set multi-exposure on and select the number of shots to be taken (2 to 9 on the K20d), then select also the "Auto EV adjust" check box. What did you meter? 1 sec @ f/2.8? At f/16 it'd be 30". Make it so. If you selected 9 multiple shots the camera will shoot nine 30-seconds (270" or 4 minutes and a half) shots and average out the exposure as well, giving you basically a 9X ND filter. Try it. great, will try today when I get home from work thanks

12-22-2010, 10:51 AM	#12
Entropy Veteran Member Join Date: Jun 2007 Location: Owego, NY Posts: 976	Great trick! (the multiexposure) I'm going to use it for waterfall shots next summer! Makes it a lot easier to compose/focus without an ND on.

12-22-2010, 11:06 AM	#13
jolepp Veteran Member Join Date: Oct 2010 Location: Finland Photos: Albums Posts: 3,196	Originally posted by Huck Finn ... You've got to try it. I have no particular application for an ND filter in mind at this time, but try to keep it in mind in case one turns up :-) Anyway, that multi-exposure-with-duty-cycle-variation idea popped up when I was trying to convince myself that an ND filter cannot be implemented in software; I suppose it kind of could like that, but wouldn't be quite the same, nor terribly useful.

12-22-2010, 12:46 PM	#14
shadmanaj Forum Member Join Date: Aug 2010 Location: NYC Posts: 82	Originally posted by Huck Finn Well, you can, actually. At least with my K20d, but I'd be surprised if it wasn't the same with a K5. Just select an exposure, then set multi-exposure on and select the number of shots to be taken (2 to 9 on the K20d), then select also the "Auto EV adjust" check box. What did you meter? 1 sec @ f/2.8? At f/16 it'd be 30". Make it so. If you selected 9 multiple shots the camera will shoot nine 30-seconds (270" or 4 minutes and a half) shots and average out the exposure as well, giving you basically a 9X ND filter. Try it. Thanks. Will try it soon. One query though. Is the multiple exposure photo RAW or Jpeg?

12-22-2010, 12:55 PM	#15
Huck Finn Inactive Account Join Date: Dec 2010 Location: Italy Photos: Albums Posts: 32	Originally posted by shadmanaj Thanks. Will try it soon. One query though. Is the multiple exposure photo RAW or Jpeg? I guess whatever you chose in your in-camera settings. Personally I use RAW+.