Advice for shooting in RAW then white balance in post.

[cburdick1]

Good afternoon,

I originally posted this in the "Tips and techniques" section, but I probably should have put it here. I'm heading to Maui in a week and will be diving a bunch while there. I've revieved some advice on my current setup (Canon 850is powershot w/ CDHK hack in Canon Housing) and have decided to save my photos in RAW format and white-balance using PhotoShop Essentials.

Obviously, I'd like to get good pictures right off the bat, so any suggestions as to technique would be appreciated.

For instance, flash on or off...if I have the flash turned off, the camera wants to shoot longer exposures, so do I force it to do shorter exposures by changing the exposure settings in CDHK? This stuff sure gets complicated.

Thanks!

 

[vondo]

Good afternoon,

I originally posted this in the "Tips and techniques" section, but I probably should have put it here. I'm heading to Maui in a week and will be diving a bunch while there. I've revieved some advice on my current setup (Canon 850is powershot w/ CDHK hack in Canon Housing) and have decided to save my photos in RAW format and white-balance using PhotoShop Essentials.

Obviously, I'd like to get good pictures right off the bat, so any suggestions as to technique would be appreciated.

For instance, flash on or off...if I have the flash turned off, the camera wants to shoot longer exposures, so do I force it to do shorter exposures by changing the exposure settings in CDHK? This stuff sure gets complicated.

Thanks!

You can use the flash for close in subjects (a few feet at best). Don't use it for subjects longer than that. Don't adjust the exposure to shorter times just because you want a shorter time, your shot will be underexposed. RAW will let you fix underexposure of a stop or less, but not more than that without problems.

I'm not saying don't use manual settings, but don't use them this way.

 

[Byte Me]

I generally carry a white card with me, attached to the camera housing and every time I shoot a different direction (where the lighting has changed) I'll take a picture of the card, then in post processing I use that as my white reference for all pictures up until the next time I run across a picture of my white card. I use Adobe camera raw and bridge for post processing and it's very easy to do this way. Just select all pictures you want to set WB for, click on the eyedropper for white and click on the white card in the picture. Bam, done.

Although on my last dive my white card cracked and I lost it so now I'm looking for a freebie white card I can use! Anyone have ideas there?

Also, I shoot Nikon above water and Oly under. But this isn't a manuf specific issue.

 

[M_Bipartitus]

...
Although on my last dive my white card cracked and I lost it so now I'm looking for a freebie white card I can use! Anyone have ideas there?

Buy some self-adhesive laminating sheets and laminate a sheet of card-stock. It might not last forever, but you could add stuff on the back (setting table for manual strobe, maps of common divesites, a dive table...) Something like this should work.

Amazon.com: Fellowes 5221501 9x12 Glossy Self Adhesive Laminating Sheets - 10-Pack: Home & Garden

 

[Byte Me]

Buy some self-adhesive laminating sheets and laminate a sheet of card-stock. It might not last forever, but you could add stuff on the back (setting table for manual strobe, maps of common divesites, a dive table...) Something like this should work.

Amazon.com: Fellowes 5221501 9x12 Glossy Self Adhesive Laminating Sheets - 10-Pack: Home & Garden

NICE! Easily replaceable, multiple functionality, cheap! Awesome!

 

[bperrybap]

My wife and I have the same setup you do canon 850is and we did a 3 week trip in
Indonesia in Sept/Oct 2008.

(I'm actually a CHDK developer and have my own version of CHDK
that I modified with certain menu preferences)

I Played quite a bit with raw on the trip and took most of the pictures in raw.
So after a few thousand photos I can give some feedback on using the camera
and its use with CHDK vs normal mode.

I'll start of by saying that I think that the normal underwater mode is no good.
You don't want to use that. It will leave your photos way too blue.
Use manual mode with custom white balance. I've done a few posts on this
with sample pictures.

Here are some tips/cautions.

- Canon underwater mode is not very good, don't use it.

+ Manual mode with custom white balance when set correctly usually
generates as good a photo as a CHDK RAW mode.

- If custom white balance is done without the flash and the flash fires
for the real photo, the jpeg photo will be VERY red.
+ If you are shooting with CHDK, you can still recover the image.

- CHDK eats up the battery faster. This is because instead of saving
a single 1-2M file you are now saving a 1-2M file *and* a 10M file for the
raw image.

- when taking lots of raw photos, the battery can heat up and cause
fogging. I never had fogging when not using CHDK but I did
with CHDK. I think it is because
of the extra data saves that eats up the power and causes the heat.

- On my dives we took quite a few photos and I'd get about
1-2 dives with chdk and 3-4 dives without per battery charge.
It depended on how many photos and how much flash was used.


- Don't go over a 4gb card with CHDK. Yes you can do it but then there
are complex booting issues and getting your photos to a PC
is very difficult because the card has to be partitioned and windows
doesn't support multiple partitions on removable media like a SD card.
If you do have a big card you have to swap partitions between boot and data
each time you go back and forth between using it on your camera and
on getting the photos to the PC. It is a real pain, and quite complicated.

- When opening the case small amounts of water drops tend to get into
the camera.
This is the one area that I would have to ding canon on. Look closely
the next time you open your camera after it has been wet. If you look
closely you will see that the way the o-ring works can allow a tiny
bit of water to seep around to the inside of the oring once you open
the case. Also the way the case opens
it very often drops water droplets into the case or on to the camera.
This adds unwanted moisture to the inside of the case on the next use.

- The preview you get on the screen after taking a picture or when reviwing
the photo is the jpeg not the RAW image. You cannot view the RAW images
until you process them. It can be done in CHDK by generatng a jpeg but
its real pain and it won't be as good as what you do on host s/w.

- macro mode goes out much further than you think.
Many times you need macro mode rather than normal mode.
I think macro mode goes to like 20 inches. Which means that at
12-16 inches you need to be in macro mode.


Overall I was happy with CHDK but I don't think it is needed all the time.
Sometimes I would turn it off and just shoot in manual mode.

If you can easily do white balancing then you may want to shoot plain manual instead
of chdk raw.

I used a slate for the white balance card and it works great.
I did have major issues trying to white balance when a flash was needed.
For some reason the white balance screwed quite often. I think it was because
the distance from the slate to the camera was different than the final image
and so the color correction is way off.

For the Caribbean I wouldn't mess with CHDK. There you simply point the
camera at the white sand and do the white balance. It is simple and works
great.

The reason I went with CHDK in Indonesia was that that there is no
white sand there and I wasn't sure that I'd want to constantly do white balance
with the slate. It really wasn't that bad.
There were a few times that the RAW images really saved the day.
I was able to recover some flash photos of a beautiful cuttle fish.
The jpegs were no good. So it definitely is useful.

Below is a link to my wife's web page about our recent
trip to Indonesia and all the photos were taken with canon 850is with
no external flash. Just canon housing.

Bill and Terrie in Sulawesi/

Direct links to some of the photo albums:
(there are many more on the main trip report page)
Bunaken_Underwater_Favorites/
Sulawesi Diving/
Lembeh_Underwater_Favorites/


--- bill

 

[lmorin]

I always use CHDK underwater (and never use the underwater white balance feature of the camera). It never causes fogging. Fogging can only happen if there is moisture already in the case. For that reason, I never open the case outside my room (which is usually lower humidity than outside), especially not on the boat/shore between dives.

If CHDK is used, white balancing during the dive is not necessary, either with a flash or without. Picasa is a free, downloadable viewer that is very efficient, both for viewing and basic editing of most RAW format files, including those of Canon. Picasa automatically corrects for white balance. Files usually require a bit more tweaking after that, but not much more. Most of it can be done in Picasa. The problem with Picasa, at least for me, is that it only allows edited files to be saved in JPG format. They look pretty good when saved as the edited version of the RAW file, but I'd like to be able to save them as DNGs for compatibility with PhotoShop.

 

[String]

If you dont have a strobe id leave the flash off. If using raw dont waste time with white balance underwater, its a complete pain having to do it whenever you change depth, sun goes behind a cloud and so on. Keep camera on cloudy and just use the eye dropper on white sand, grey tank or whatever in photoshop later to instantly correct it.
The massive advantage of RAW is you dont have to mess with WB underwater.

 

[cburdick1]

OK. I'm going to shoot RAW and WB with Photoshop essentials. I'll have to mess around with my ISO to keep shutter speeds quick, but besides that I think that I should be good.

To all of you, a sincere "thank you". I'll post a few pictures when we get back.

 

[bperrybap]

If you dont have a strobe id leave the flash off. If using raw dont waste time with white balance underwater, its a complete pain having to do it whenever you change depth, sun goes behind a cloud and so on. Keep camera on cloudy and just use the eye dropper on white sand, grey tank or whatever in photoshop later to instantly correct it.
The massive advantage of RAW is you dont have to mess with WB underwater.

I disagree with not using the built in flash.
It depends on what you are shooting , the lighting and water conditions.
The built in flash works quite well in fairly clear water
as long as you use the included diffuser and the distance is only a few feet or less.
Without the diffuser you will get a large shadow from the barrel of the housing
that is very obvious in the images.

Manual white balance is not that bad on the 850is once you program the
print button to set custom white balance.
Hold up the slate, point the camera at the slate,
push the print button. Done. white balance set.

But I agree that it is nice to not have to do white balance when shooting
RAW.

For shooting movies, you will want (need) to set the white balance.

--- bill