Pentax K5 - Dark frame subtraction - possible to turn it off?

[godfrog]

He has answered that question in this thread:
http://forums.dpreview.com/forums/readflat.asp?forum=1036&thread=35469256&page=1

Nope - he hasnt. Must be wrong thread.

He has, but not in the first message. The below is one of the posts discussion the issue:
http://forums.dpreview.com/forums/read.asp?forum=1036&message=35478548

Basically, the "right light" might last for a very short time, and there is not always time to stand around waiting for the DFS. Look through some of his shots to see why timing is important

The dark frame is taken after the photo.

Exactly, which is the time when you want to be taking another photo before the light changes. At worst the camera is inoperable half of the time, which just is not good enough for everyone.

It does not affect me much anymore since Im using film for long exposures now (some posted to my Flickr), but it was very annoying for the long exposures I have done digitally (such as the earlier Tokyo Flowing Light, Flickr set). I was trying to catch the 30 seconds with the most intense light trails, often I missed because I was waiting for DFS.

If needed, a dark frame can be shot once the light has changed and used to do DFS manually afterwards.

Yep --- do you have software that can make DFS on the RAW image?

UFRaw, dcraw and RawTherapee all do it, but I have not used it since I can not disable the in-camera DFS. I do not know if there is some software that can do only the DFS and only affect the RAW file, but it seems likely that dcraw could do that.

--
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[Roland Karlsson]

... but I have not used it since I can not disable the in-camera DFS ...

http://www.pentax-hack.info/index.html

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[Roland Karlsson]

are you a native english speaker?

Lets see --- this is the posts more or less in order.

1. Someone asks if K5 can turn of DFS, because his K7 cant.

2. I ask why he wants to turn it off.

3. Someone says that it saves time.

4. I say that - OK then you can take only one dark frame.

5. Someone says - not with K7.

6. I say - we already know that.

7. You say - are you a native English speaker?

Can someone explain what the & &%¤ post #5 and #7 adds to the discussion? I am not a native speaker and I must have missed some of the finer meanings of those posts.

--
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[godfrog]

... but I have not used it since I can not disable the in-camera DFS ...

http://www.pentax-hack.info/index.html

I couldnt at the time, and now I dont use my DSLR for that any more But thanks. Id prefer to get a camera that does not need a hack to disable it though, as the debug menu is not meant for end customer use. Not saying that I have not used a bunch of features Im not supposed to, but that is also how I bricked my router

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[geoffcole]

are you a native english speaker?

Lets see --- this is the posts more or less in order.

1. Someone asks if K5 can turn of DFS, because his K7 cant.

2. I ask why he wants to turn it off.

3. Someone says that it saves time.

4. I say that - OK then you can take only one dark frame.

5. Someone says - not with K7.

6. I say - we already know that.

7. You say - are you a native English speaker?

Can someone explain what the & &%¤ post #5 and #7 adds to the discussion? I am not a native speaker and I must have missed some of the finer meanings of those posts.

1. 5 and #7 do not add anything to the discussion. IMO they're coming from someone who is loosing track of what is being said and (perhaps inadvertently) taking the discussion off topic.

Getting back to what the OP said and what he said in another post a few months ago, he takes a lot of images in the 'magic hour' at sunset and sunrise, and dark-frame subtraction hinders his ability to capture the moment in in these fast-changing, low-light conditions -- thus his interest in finding out if the K-7 and K-5 can be configured to not perform dark-frame subtraction.

--
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[Roland Karlsson]

Getting back to what the OP said and what he said in another post a few months ago, he takes a lot of images in the 'magic hour' at sunset and sunrise, and dark-frame subtraction hinders his ability to capture the moment in in these fast-changing, low-light conditions -- thus his interest in finding out if the K-7 and K-5 can be configured to not perform dark-frame subtraction.

And - it is possible to turn it off for K-7 - in the debug menu. I dont know if anyone have any info regarding K-5.

Just remember that if you take one black frame to use with several photos - you need a software that can do the black frame subtraction before doing RAW conversion. Otherwise you get ugly artefacts around all hot pixels.

--
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[José Ramos]

So many people talking about something they only know in theory, and which they never experimented with in the real world.

I discovered that I do not need DFS with my K10d because, as soon as I open the RAW image in AdobeCameraRaw, it automatically removes every hot pixel in the image, leaving me with a clean image to work with.

Now you understand why I want to be able to turn DFS off in a new Pentax camera? Every brand allows it, why not Pentax?

If this isn't possible, than I'll just move one and change brands in December.

--
José Ramos
http://www.joseramos.com (nature/landscape photography)

 

[cr0100]

Just remember that if you take one black frame to use with several photos - you need a software that can do the black frame subtraction before doing RAW conversion. Otherwise you get ugly artefacts around all hot pixels.

Adobe's RAW converter (like what comes in LightRoom) takes out the hot pixels for you without having to do DFS at all.

If you shoot RAW, and use LightRoom (or PhotoShop) the dark frame is nothing but a waste of time.

-Charles

 

[KitTP]

Just remember that if you take one black frame to use with several photos - you need a software that can do the black frame subtraction before doing RAW conversion. Otherwise you get ugly artefacts around all hot pixels.

Adobe's RAW converter (like what comes in LightRoom) takes out the hot pixels for you without having to do DFS at all.

If you shoot RAW, and use LightRoom (or PhotoShop) the dark frame is nothing but a waste of time.

-Charles

Dark Frame Subtraction (aka Long Exposure Noise Reduction) does more than correcting for hot pixels. It also helps correct for the thermal noise arising from sensor heating after X minutes of continuous exposure.

Each sensor has its own noise characteristic, and the noise also varies with exposure time.

I'm not sure how well or accurately off-camera software can correct for that.

 

[Deeb]

I would love to see the DFS disable option in the new K-5. Being able to turn DFS off in my K10d is the only reason I still have it. In fact, I carry two tripods to a location to do star shots to mount both my K20d and K10d. I use the K10d to establish the parameters that are optimal while the light (and star position) changes, taking half the time to get the result. Then, I shoot with the K20d with the same settings, and the K20d will produce a better image-without the lighter smudge of electronic interference in the upper left-center edge of the frame that is present in the K10d image. Noise still has to be dealt with in post processing.

Like many, I am still on the fence as to whether I will buy the K-5. The ability to disable dark frame subtraction is just one the factors that will help me make that decision.

 

[Nass]

Jose, I've been asking about this too, some say it is and others say it isn't. Falk is planning to test a > 30s B exposure on Sunday when he's there, that should give us the definite answer. My purchase also depends on this, I'll let you know.

Whoever said it's possible to turn off DFS in debug, it's not, even using [DISABLENR] 1@ in sysparam.

Landscape (ND crowd) and astro use this. We need to use this. Thank you.

 

[Roland Karlsson]

I discovered that I do not need DFS with my K10d because, as soon as I open the RAW image in AdobeCameraRaw, it automatically removes every hot pixel in the image, leaving me with a clean image to work with.

Interpolating away hot pixels does not equal DFS. If that hot pixel happens to hit a faint star - then that star is gone. But with DFS it will be there.

Now you understand why I want to be able to turn DFS off in a new Pentax camera? Every brand allows it, why not Pentax?

If this isn't possible, than I'll just move one and change brands in December.

I agree that it is a disadvantage to not being able to turn it off.

But ... it is also an advantage to make a camera as simple to use as possible. And fewer settings is a way to do that.

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[Nass]

But ... it is also an advantage to make a camera as simple to use as possible. And fewer settings is a way to do that.

Roland.

a) What is the basis of your info that it is possible to turn off DFS on the K-7, do you have any actual evidence? Because no, It's not actually possible to turn off DFS in debug in K-7. You are misinformed. I've been in touch with him and plenty of others and have personally gone deeper into the K-7's DFS debug setup than that entire site. No, using sysparam doesn't remove it. There are other variables and it's bound up with 1600 bulb ISO in some way that I don't care to brick my camera trying it. I've had a technical note in with Pentax about this for 12 or so months.

b) Regarding your point about simplicity. There are also buttons for f stop, shutter speed and ISO. If we take those away it'd make the camera "simpler". How would you feel?

c) Suggest going back to the OP's question, which wasn't one asking for opinions whether it's right but asking facts of whether it's possible. Thank you.

Now on the upside, it looks like the K-5 might have answered our prayers, which would be peachy. Let's wait for Sunday's testing.

 

[Roland Karlsson]

a) What is the basis of your info that it is possible to turn off DFS on the K-7, do you have any actual evidence? Because no, It's not actually possible to turn off DFS in debug in K-7. You are misinformed. I've been in touch with him and plenty of others and have personally gone deeper into the K-7's DFS debug setup than that entire site. No, using sysparam doesn't remove it. There are other variables and it's bound up with 1600 bulb ISO in some way that I don't care to brick my camera trying it. I've had a technical note in with Pentax about this for 12 or so months.

I am probably wrong then. But ... on the Russian hack side for Pentax debug mode activation it said something I interpreted as it was possible - and so did others. But I have to admit that I have not tried it.

b) Regarding your point about simplicity. There are also buttons for f stop, shutter speed and ISO. If we take those away it'd make the camera "simpler". How would you feel?

Dont be absurd.

A point and shoot without settings is NOT easier to take good images with than one where you can manipulate major settings like shutter speed. Its much harder.

But - e.g. being able to choose different JPEG resolutions and qualities does not help taking better images now when we have flash cards with several gigabyte of space - just do the best quality you can - and thats enough.

c) Suggest going back to the OP's question, which wasn't one asking for opinions whether it's right but asking facts of whether it's possible.

It was I that asked why he wanted to do it. A legitimate question IMHO.

Now on the upside, it looks like the K-5 might have answered our prayers, which would be peachy. Let's wait for Sunday's testing.

Personally I hope they have fixed the 1/100 blur problem. That is what I dislike the most with my K-7.

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[Nass]

b) Regarding your point about simplicity. There are also buttons for f stop, shutter speed and ISO. If we take those away it'd make the camera "simpler". How would you feel?

Dont be absurd.

Exactly. And to us this is absurd too =). To us, this is really really really really important, and you know... we're big boys and girls... we're not p&s neophytes... if it's ok we're more than capable of making our own informed choices about the tools we'd like to have available rather than being constrained because it makes a camera nice and simple?!?!

Falk's findings - yes. I wonder if he'll bug them about it on Sunday .

 

[Roland Karlsson]

Exactly. And to us this is absurd too =). To us, this is really really really really important, and you know... we're big boys and girls... we're not p&s neophytes... if it's ok we're more than capable of making our own informed choices about the tools we'd like to have available rather than being constrained because it makes a camera nice and simple?!?!

Falk's findings - yes. I wonder if he'll bug them about it on Sunday .

You are of course entitled to any opinion you like. My original question was genuine. I did not know why you wanted to turn it off.

Personally I would be more interested in being able to choose if I have an IR filter or not, if I have an AA filter or not or if I have micro lenses or not. A camera where one or more of those filters are optional would be very interesting. And a camera with live view and where the IR filter is optional would be terrific!

Hmmm ... an optional Bayer filter would also be cool.

I would also appreciate a camera where the shutter can be slightly delayed after closing the aperture - so I can use my older lenses with slow closing of the aperture.

And I would like the camera to move the aperture during exposure to simulate smooth bokeh. And of course - I want to be able to access the aperture plane so I can even better affect the bokeh.

Then I want a script language engine (like the Kodak compact cameras had) where I can program what the camera shall do when taking images. Then I can do my own bracketing sequences and other fun stuff.

And then I want a sweep panorama mode that works for RAW and a sweep HDR mode that also works for RAW.

etc etc etc ...



--
Roland

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[Nass]

Exactly. And to us this is absurd too =). To us, this is really really really really important, and you know... we're big boys and girls... we're not p&s neophytes... if it's ok we're more than capable of making our own informed choices about the tools we'd like to have available rather than being constrained because it makes a camera nice and simple?!?!

Falk's findings - yes. I wonder if he'll bug them about it on Sunday .

You are of course entitled to any opinion you like. My original question was genuine. I did not know why you wanted to turn it off.

Personally I would be more interested in being able to choose if I have an IR filter or not, if I have an AA filter or not or if I have micro lenses or not. A camera where one or more of those filters are optional would be very interesting. And a camera with live view and where the IR filter is optional would be terrific!

Hmmm ... an optional Bayer filter would also be cool.

I would also appreciate a camera where the shutter can be slightly delayed after closing the aperture - so I can use my older lenses with slow closing of the aperture.

And I would like the camera to move the aperture during exposure to simulate smooth bokeh. And of course - I want to be able to access the aperture plane so I can even better affect the bokeh.

Then I want a script language engine (like the Kodak compact cameras had) where I can program what the camera shall do when taking images. Then I can do my own bracketing sequences and other fun stuff.

And then I want a sweep panorama mode that works for RAW and a sweep HDR mode that also works for RAW.

etc etc etc ...



--
Roland

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QFT.

Do you really want to do that? Adding new functions might not make a camera as simple to use as possible!

 

[Roland Karlsson]

Do you really want to do that? Adding new functions might not make a camera as simple to use as possible!

hehe

Its a difficult balance between a minimalistic and a feature rich product.

Maybe I want both.

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[Nass]

Jose, it looks strongly from one person who has tried k-5 at Photokina with B at > 30s that the answer is yes, it can be switched off. He was able to take another within 1 sec. Hopefully Falk will confirm on Sunday. Happy days.

 

[Roland Karlsson]

Jose, it looks strongly from one person who has tried k-5 at Photokina with B at > 30s that the answer is yes, it can be switched off. He was able to take another within 1 sec. Hopefully Falk will confirm on Sunday. Happy days.

OK - nice.

And if they have fixed the 1/100 second shutter blur I will be happy also.

And if I then can put the K5 shutter in my K7 then I will be more than happy.

The latter I am not willing to bet on though.

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