Calibrating Time Lapse Images.

[TheDecepticon]

I think I have asked this before, however the search function doesn't seem to work for me.

What format do you normally shoot your time lapse frames in? RAW or Jpeg? My camera is a bit noisy so I am trying to do RAW. How then, do I calibrate the frames with at least darks?

I think I will have to get that book Mike was talking about.

Thanks.

[White Rabbit]

You just turn on icnr in the camera and let the camera dark subtract on its own. You don't need too take flats.

[iceman]

You wouldn't take flats or darks for timelapse images.

[White Rabbit]

And always shoot raw, its far more forgiving. If you don't set something quite right before the shoot. Raw format will allow far more flexibility when it comes to fixing it.

[iceman]

If you're just getting started though, I'd recommend shooting small jpeg.

It's easier, you fit more on your card, and processing is so much quicker.

Once you get more experience, switch to RAW.

[gregbradley]

I don't think you'll be able to use ICNR unless you are using a really fast F1.4 lens. I've been using 30 seconds at ISO6400 at F2.8. So that's really cranked up. With 10 second gap between shots. You'd need 35 seconds between shots if you used ICNR (it doubles the exposure).

You could set high ISO noise reduction on if noise is a problem.

Greg.

[alexch]

I suggesting shooting RAW (I always do, 32GB memory cards are not that expensive now). If you need to recover some shadow detail after the file is written RAW gives you 12 or 14 bit data to work with, JPEG has only 8 bit of lossy compressed data per pixel.

As far as darks, for timelapse work you want to avoid long exposure noise reduction done in-camera (ICNR, LENR) because it will make long gaps between your shots when it is taking a dark frame and the final video will look jerky.

The biggest benefit of calibration is the removal of hot pixels which stand out in time lapse. I used to convert RAW to TIFF, calibrate the TIFFs in DeepSkyStacker with a master dark frame made at the end of the imaging run. Then adjust curves in the TIFF files and save as JPEG for video rendering. Now Nikon Capture NX includes a hot pixel removal algorithm in RAW files only and I don't do the dark calibration any more. Adobe Camera RAW converter found in Photoshop and Lightroom also removes hot pixels when it opens RAW files, so here is another pro-RAW argument.

Hope it helps,

Alex

[White Rabbit]

I use ICNR all the time with exposures of up to 30sec, so 1min between shots, they dont look jerky. Of course you need shoot for longer but there is no problem with using ICNR.

I'll post a link to a TL with 1 min intervals.

[alexch]

It may look ok close to SCP with ultra-wide lenses and higher frame rates, however the gaps will become apparent if you want to slow the video down to 16 or 12 fps or use 35mm lens.

Why throw data away at the time of shooting if it is so easy to subtract dark frames afterwards in DeepSkyStacker or let Adobe Camera Raw or Nikon Capture NX2 remove hot pixels without dark frames?

Alex

[White Rabbit]

Mmm, I've never though about using DSS to subtract darks for time lapse. How do you dark subtract darks from 1000 light frames?

[alexch]

Open 1000 images in DSS, select them all and choose to "Save a calibrated file for each light frame" in set Alignment to "None" in stacking settings. Then set star detection threshold to 98 so it does not waste time finding stars.
After processing all 1000 frames you will have dark subtracted frames beside them.

[RB]

Do you use the RAWs or jpgs ?

[alexch]

Actually I remembered now, DSS was leaving some artefacts (black dots) after hotpixel removal. I had to create a master dark in DSS and then subrtact it in Photoshop using Magic Wand and Median Noise filter in an action.

It became much easier when Nikon Capture NX2 introduced "Astro Noise Reduction" (Hot pixel removal). If you use Photoshop or Lightroom to open your RAW files then it removes hot pixels automatically.

[White Rabbit]

Thanks for the info, I'll give it a try.

Andrew I always raw.

[RB]

If you use only RAWs then ICNR has no effect on RAWs.
It's only applied on the jpgs.

RB

[alexch]

I think we refer to ICNR as long exposure noise reduction (dark frame subtraction or LENR) here and it is definitely applied to RAW Nikon files. I just tested it again and exposure time ws doubled and the dark frame is subtracted from NEF file when LENR was on.

My impression was that Canon DSLRs work the same way.

Cheers,
Alex

[RB]

Alex I was referring to Canon since White Rabbit is using Canon gear.
And yes ICNR is refering to long exposure noise reduction or In Camera NR.

I don't know about Nikon or how it handles it's RAWs but I understand that Canon RAW files do not get ICNR applied to them, only the jpgs do.

So if he's shooting in RAW only and not using the jpgs then it's a waste to have ICNR on when it doesn't get applied to the RAWs.

Andrew
:)

[Octane]

Hrm, Andrew, I think ICNR is applied to the RAWs in Canons. At least my testing would show as such.

H

[RobF]

I'd respectfully ask for evidence that ICNR is NOT applied to RAWs Andrew. That's not logical, and really quick google suggests not correct?
(Happy to be educated though if I've always mid-understood this?)

[RB]

I'm off to bed because I've got a big day tomorrow.

I'll get back to you on that tomorrow night when I return though because I always understood that Canon RAWs had nothing applied to them and this was confirmed to me by Burt (Avandonk).
I did try a couple of 30 sec shots last night on the 5DII when I got home but haven't had time to examine them yet on my main computer.

Andrew
:)

[iceman]

I'm pretty sure ICNR is also applied to RAWs. At least that's my experience too.

[alexch]

I think what Bert referred to was the notorious "hot pixel removal" algorithm that Nikon applies to the RAW files. It can remove faint stars if your guiding is on a pixel level (not applicable to time lapse frames on a stationary tripod) and there is no way to turn it off. Canon does not alter RAW files unless told so.

LENR (ICNR) though is a conscious menu setting which should affect the RAW files because it is meant to subtract the dark current noise. I am sure both Nikons and Canons apply LENR(ICNR) to the RAW files.