¿is the foveon sensor good at long exposures?

Oh ok, thanks for your answer.

Hi Carlos,

Completing the answer above... yes, even shorter exposures come out noisy.

It's not the perfect camera for long exposure, but... I'm still here trying to squeeze something good out of it, there must be a reason :-|:-|

Carlosodze said:

Hi, i would like to know if long exposures (10min or so: lets say night landscapes,starts trails, etc)

come out to noisy.

Thanks!

Click to expand...

In answer to your question personally i would not recommend Foveon sensors for very long exposure work.

I have had reasonable results up to 90 seconds but after this length of time the images get too noisy for my liking which is a real shame.

I'm a great fan of the cameras/sensor but recently i have spent hours and hours trying to work with the problem but really long exposures are not possible with the current sensor in my opinion.

Maybe the next generation (Quattro) will be a significant improvement with it's redesigned sensor so i guess only time will tell.

As for camera IQ that's a different matter.

I have images and prints that were taken up to 30 seconds that i am really very happy with.

For Landscape work at exposure times less than 30 seconds the Foveon gives stunning results with good glass.

As for the maximum bulb time for long exposure work i have always thought it was 2 minutes as my SD!M closes the shutter at 2 minutes. (obviously i could be wrong about this)

If you can live with exposures of under 30 seconds the Foveon is a great camera IMHO.

Kind regards Lea.

No, it's just about the worst solution. Too noisy and deliberately limited in max exposure time. Foveon's strengths lie in strong light...

Canon, Nikon and other DSLR brands process, in-camera, the so called "dark frame". I noticed with my ex SD14 and actually with my SD15 that these two cameras don't process the in-camera "dark frame" so this is the reason that the images are noisy when you shoot at long exposures (> 30 seconds).

When you shoot with cameras above that process the "dark frame" the camera is busy for the twice the time it have used to make the shoot, because its in-camera software process the "dark frame". For example if a exposure of 60 seconds was used in the camera, after the shoot, the camera is locked for further 60 seconds, and meanwhile is not possible to make other shoots. The SD14, SD15, and maybe other Sigmas firmware and software, don't process the in-camera "dark frame", and when the shoot with long exposure is ended the camera is ready for another shoot.

I think that really long exposures are possible with the Foveon cameras with the help of Photoshop in my opinion, but we have to manually create the "dark frame" with Sigma cameras, we have to mimic the behavior of other brand cameras.

What is the "dark frame"? Is a digital image that contains only noise obtained in order to correct another image, is an image obtained with shutter closed and under the same conditions of sensitivity, temperature and exposure of the image that you want to correct.

How to obtain a "dark frame" image? This operation is simple: run the classic pose, then put the protective cap in the lens and take a second photo with the same parameters (sensitivity and shutter speed) that will subsequently subtracted from the first with the aid of Photoshop. Here is the link to the article on how to do this:

http://www.takegreatpictures.com/ph...tion-using-adobe-photoshop-br-by-chris-limone

or use this program that is completely freeware: Blackframe NR


Please pay attention to the fact that the dark frames, while taken at the same sensitivity and the same shutter speed may vary at different temperatures, showing greater disturbance to the higher thermal conditions. If you proceed in this way is good to record the ambient temperature and make sure that in poses in succession, the temperature of the camera's sensor does not vary significantly.

Alex

I never use darkframe NR in my cameras, can't be bothered to wait for the second exposure. This doesn't seem to cause any issues. I routinely shoot 2-4 minute exposures without being bothered by noise and occasionally up to 30 minutes without problems.

Most Foveon based cameras are reluctant to permit long exposures. For instance, my DP1 is limited to 15 seconds. I don't know what the limit is on other models (anyone?) but I think it may well be a couple of minutes. There is a reason for this - classic Foveon sensors are relatively noisy and this is really shown up in long exposures.

target5 said:

Canon, Nikon and other DSLR brands process, in-camera, the so called "dark frame". I noticed with my ex SD14 and actually with my SD15 that these two cameras don't process the in-camera "dark frame" so this is the reason that the images are noisy when you shoot at long exposures (> 30 seconds).

Click to expand...

This surprises me, but I cannot verify since I sold my SD15. I suspect that you have just hit a special case where the dark frame subtraction does not apply. For the original DP2 this happened when bracketing, but for single shots it is definitely done (and the difference is very visible). Maybe the extended bulb mode of the SD15 doesn't apply it or something?

Anyway, I did a quick test with my DP3M and it also applies dark frame subtraction after single shots as expected. The longer exposure, the longer subtraction is performed (with an hour glass showing on the screen).

Anyway, from my experience the noise isn't much of an issue within the regular limits of the camera (30s for a DP3M) as long as the subtraction takes place.