Jump to content

Recommended Posts

Tom,

 

Using a strobe AND a lens filter is very tricky ... the red correction from the lens filter for ambient light will make the strobe too red unless you use a filter on the strobe, to shift it bluer. As a beginner at this, I am sticking with "pure" available light (no strobe) until my use of filters in this situation is good, and then I may try to get fancy with the strobe. Craig (if I recall correctly) has previously posted on how filters nicely fit on some Inon strobes.

Share this post


Link to post
Share on other sites

Ok no strobe. Where do I start with my f-stop, ev and shutter speed?

 

Tom

Share this post


Link to post
Share on other sites

The easi4est answer is check the readings on your camera when you get in the water. If you put it in auto you will get a setting that will work.

If you put it in aperture priority it will then choose your shutter speed for you.

and then when you get used to it you can put it in manual and adjust all your settings for the result you want. :rolleyes:

 

i would like to know what filter pack you have as i have a oly 3040 in tetra housing and would like to know what sortof filter system ohter people use with it.

is there a web example of what you use ?

 

 

Giles

Share this post


Link to post
Share on other sites

Giles-

It is clear that there is a dearth of experience on this subject. To the extent I can I will add to this thread.

 

I wish I could find a refrence to the filter that I have. The bill of sale says Custom Filter SR-B 67MM (Underwater). The filter case is labeled Singh-Ray Marine Filter 67MM.

 

I have 10 diving days in Bonaire so I should be able to experiment with available light photography as well as take standard pics with my strobe. [iNON D180]

 

I will start in Macro, Auto, no strobe mode and see what happens at various depths and natural lighting conditions.

 

Tom

Share this post


Link to post
Share on other sites

Great shots !

 

Being a neophyte at the DSLR and Ikelight approach, I have a really basic (I am sure) question......

 

I have tried to do the same thing, using my D100 with no strobe, but the shutter will not trip underwater. Above yes, but once in the water, nuttin. I know I am probably missing some very obvious points, but I don't know enough to be dangerous. Any help would be appreciated !

 

mjleblanc

Share this post


Link to post
Share on other sites

You are probably trying to use a wideangle lens behind a dome port and the lens doesn't have a close enough focus to focus on the virtual image created by the dome.

 

The lens will focus fine above water, but when underwater, the water and port acts as a negative diopter.

 

Cheers

James

Share this post


Link to post
Share on other sites

Help!

 

Does anyone make colour correction filters that will fit on Sea & Sea equipment?

 

specifically

- DX 5000 (Nikon Coolpix 5000 housing) standard port

- Sea & Sea WA lens for MMIII and DX5000

 

If not, is it possible to buy larger filters, cut them to size and ...?

 

My local photo experts say "no" to both

:)

Share this post


Link to post
Share on other sites

I have noticed quite a big difference between CC filters and Fluorescent filters is in the cameras ability to auto white balance.

 

Fluor filters (specifically the UR-Pro series that I have used) tend to work really well on AUTO-WB (even when they actually don't look too good on the LCD screen when they are underwater). Whereas CC filters tend to need custom white balancing either in situ with a grey/neutral card or in RAW conversion in post processing.

 

This shot, for example, was shot on Auto WB and can out of the camera looking pretty much like this. The only way I can get such good colour balance straight from the camera with a CC filter is in situ WB.

 

birthday6.jpg

 

The obvious answer to this is that fluor filters are better. But I am not convinced about this because at certain depths the camera uses more extreme white balance (colour temp and tint) settings for the UR Pro than are needed for the CC filter. It is just that the camera (well my cameras D100 and D70) have found it easy to get the right white balance (in Auto) with the Fluor filter as opposed to the CC filter.

 

Alex

Share this post


Link to post
Share on other sites

Alex, I absolutely agree that FL filters are better for ambient light and I think that the camera agrees too! I think CC filters are OK for shallower depths and for complimentary stuff. FL filters are much harder for mixed light shooting though.

Share this post


Link to post
Share on other sites

Craig, I was hoping that you would add your thoughts.

 

Now we need a fluor filter that will work on a fisheye! (Not easy to physically fit them on with glass/sandwich FL filters).

 

Alex

Share this post


Link to post
Share on other sites

Nice color, Alex.

 

But I'd bet that if you saved your white-balance image and did a post-WB using the white from that image (as opposed to trying to find white on the image you're working on), you'd arrive at similar results...?

 

Or is that not the case? The reason for this is that the WB is so far off the scale that normal raw converters don't even offer the option for you to drag the sliders that far. One has to WB by clicking on white, and since it can be difficult to do so in the actual image you want to WB, you can take the settings from another, helper image.

Share this post


Link to post
Share on other sites
Craig, I was hoping that you would add your thoughts.

 

Now we need a fluor filter that will work on a fisheye! (Not easy to physically fit them on with glass/sandwich FL filters).

 

Alex

There aren't any that I know of. I've combined two gels for that purpose but it's very hard to do without the image going soft. It's be great to get some FL gels.

 

Nikon's 16mm has a lens cover that's easily adapted to take a front filter. With a DX sensor camera the corners aren't clipped too bad and they disappear with barrel correction. That doesn't help the 10.5 of course.

 

I think a tinted dome would be cool too. :D

Share this post


Link to post
Share on other sites
I think a tinted dome would be cool too. :D

 

What a great suggestion. That would be the ultimate UW photographic extravagance.

 

Alex

Share this post


Link to post
Share on other sites
Help!

Does anyone make colour correction filters that will fit on Sea & Sea equipment?

specifically

        - DX 5000 (Nikon Coolpix 5000 housing) standard port

        - Sea & Sea WA lens for MMIII and DX5000

If not, is it possible to buy larger filters, cut them to size and ...?

My local photo experts say "no" to both

:blink:

Kirk at URPRO can custom make them to your specs... at $$$. Another idea is to check out ikelite. They have a plastic filter cap for their bigger video housings which can be retrofitted. I have no idea how wide your WA lens is but that's a start.

Share this post


Link to post
Share on other sites

Hi Alex and Craig,

 

I've really enjoyed your posts over the past couple years! I regularly check this thread for any new info. After originally reading the thread, I tried a B+W FL-D in 2003 in Hawaii and got this photo.

 

diane-dolphins-976S7894-wetpixel.jpg

 

The interesting thing is the noise in the red channel, that gets worse towards the bottom. As I understand it, the idea of the filter is to cut down on the red channel plugging up? Do you think the B+W FL-D is too weak for the depth at the bottom of the photo (I was only 15 -20 feet down), but too strong for the light areas at the top (in the original RAW file, the light areas near the top are too pinkish)?

 

Looking at the channels on this jpeg is not a good representation, as i did some levels & channel mixing to make it look better on screen. But in the original RAW file, the red channel noise is so thick in the bottom half, that it's hard to get a decent print. The photo was shot with a 1Ds at ISO 400.

 

After all your experiences over the past year, what are your suggestions for the appropriate FL (or UR Pro equivalent) filter this type of natural light shot (wide angle, large subject(s), relatively shallow depth)? I love the colors you have achieved, and want to play with it some more, but the splotchiness of the red channel turned me off on the shots I've taken so far!

 

Also, I've read over on the Rob Galbraith site, that it's better to use a white card for custom WB with Canon SLRs. Are you guys using gray or white cards these days? Any suggestions on appropriate waterproof cards at this point?

 

Many thanks for all the valuable knowledge you (and many others) provide on this site!

 

Corey

Share this post


Link to post
Share on other sites

I don't think any filter change can help with the noise or splotchiness. What determines the right filter is the settings that are required to achieve good white balance. I've never used a white card with still photography though I have with video. Alex has done that and I believe it's a standard technique with him. With RAW you can adjust WB after the shot so a white card only helps with accuracy since sometimes there isn't anything white in the scene to help get the WB accuractely set. I'd think a wide angle shot like you've posted would be hardest to use a white card with.

 

Basically, what you are achieving with the filter is balancing white light back close to white as it enters the lens. In order to get a clean image from that there needs to be enough available light so that the camera can perform well even after the filter has removed a great deal of it. Stronger filters have little effect on the red portion of the spectrum so they won't cause the red channel to be noisier---the noise you see is always present but just stronger relative to the other color channels since the filter makes it so.

 

I order to avoid the image problems you see you may need to be careful with the perspective of your camera (shooting up/down, toward/away from the sun, etc), you may need better ambient light quality or clearer water, or you may benefit from higher ISO performance in your camera. A weaker filter will improve the situation but only at a proportional cost to color since you aren't getting an improvement in the red channel (you're just overpowering it in blue and green).

 

Careful application of NeatImage or Noise Ninja may be useful og you haven't tried those things.

Share this post


Link to post
Share on other sites

Craig, thanks for your input. I'm thinking that maybe I didn't phrase my questions very well. :blink: In a post from September 2003, CeeDave said:

 

"When there is excess blue-green light, the blue ( B ) and green (G ) pixels in the CCD array will tend to limit the exposure time (to avoid blooming), whereas the "not blue-green" ( R ) pixels will have low input and thus will be subject to noise. Inserting a red filter will block portions of the blue and green light. Thus, a longer exposure (or lower f-stop) can be used. This allows the red pixels to "fill up" better and avoids noise in the R without blowing pixels in BG." Now, here's the important part, to me: "This is fundamentally different from postprocessing the image, because if BG is blown/clipped or R is noisy, these are hard to repair without introducing artifacts. 'Precorrecting' the light balance with the filter better uses the dynamic range of all pixels, which can theoretically lead to a superior image."

 

That made sense to me, and seemed a good explanation for why a filter, during image capture, is a better solution than just adjusting WB later in the RAW converter. In fact, looking at the histogram of the image from my last post in ACR (showing each channel seperately), the bulk of the red channel pixels are farther to the left (underexposed... more noise) than the blue (farthest to the right) and green (most central) ones.

 

I always shoot RAW files, but I'm trying to figure out which filter, when used in conditions similar to the shot in my last post, would yeild the least red channel noise and would require the least drastic RAW conversion settings, without making the highlights too red.

 

I realize there is no perfect "one size fits all" solution, but I was just curious if you or Alex (or enyone else with experience in this technique) had any comments about which filters, in your experience (nearly 2 years after the start of this thread), have worked best for this type of situation (wide angle, blue water, relatively shallow).

 

Regarding the white card, I usually try to take a couple shots with one at the depth and lighting conditions I will be shooting in, so I can use it later in ACR to click adjust the white balance of the white card shot, save the settings, and load them as a starting point on other images from the shoot if AWB isn't yeilding a good starting point. I was using the white card in a set of Warm Cards, but I recently lost it and was curious what anyone else was using before I get anything new.

 

Thanks again for taking the time to answer, and for all your valuable input in these forums. Lurkers like myself have learned alot here.

 

Corey

Share this post


Link to post
Share on other sites

I think CeeDave's explanation is good, but keep in mind that the noise we're talking about is inherent in the imager. What makes the red channel noisy is lack of signal combined with excessive gain to fix the white balance. Ideally a filter will give you well exposed information in all three channels so if you're seeing red histograms that are significantly underexposed compared to blue/green then you could probably use a stronger one. Not all "noise" in the image is noise though. Particulates can appear as red noise too.

 

I made some recommendations on filter strength relative to depth in the original article so maybe you might revisit that. I think FL-D's are good to around 20 feet or so and FL-B's are useful deeper.

 

I think the way you are using the white card makes a lot of sense. I haven't done that myself but can't think of any reason not to do that.

Share this post


Link to post
Share on other sites

This is a very interesting thread. I have printed color negatives of UW shots and by filtration attempted to correct for blue (after the fact as it were). It is possible to remove the excess blue but one ends up with is a near black and white photograph. I think there will be a point of diminishing returns as a function of depth at a given location.

An interesting aside is that BBC does not use artificial lights when they shoot UW. They were here in Prince William Sound doing part of the Blue Planet series for the Discovery Channel. A lot of gear but no lights. The producer told me that lights were a no-no. Need to stay rather in shallow water - especially here.

Share this post


Link to post
Share on other sites
Particulates can appear as red noise too.

That's interesting... I hadn't thought about that or noticed that before. Are you saying that in your experience, you notice particulates in the water showing up more in the red channel than the blue or green channels? I remember the water did have some particulates in it that day, so maybe they are contributing to the splotchiness in the red channel?

I made some recommendations on filter strength relative to depth in the original article so maybe you might revisit that.  I think FL-D's are good to around 20 feet or so and FL-B's are useful deeper.

I remember reading that from the original article. But since the article was over a year and a half old, I was just curious if you had come to any additional observations in the past year. What you are saying makes sense though. I was using a FL-D on a 16-35mm lens at 16mm. I was at 15-20 feet. With the wide angle of view the lens provided, the water below me was deeper, and maybe needed a FL-B, and the water above me has less noise in the red channel, so the FL-D was probably fine.

Share this post


Link to post
Share on other sites

f10ab1b,

Your subject (in your avatar), a killer whale has built-in white- and black point targets! Have you used them this way?

Cheers!

Tom

Share this post


Link to post
Share on other sites

Tom, I tried, but then the whites were getting blown out and the blacks plugged up. :blink:

Corey

Share this post


Link to post
Share on other sites

Yes, I think particulates can do that. It seems to be more a function of excessive gain in the red channel causing posterization of red details. Theoretically a proper filter and good exposure would eliminate that but in deeper water no filter will be strong enough. I used to see that with video frequently where I'd shoot 80 feet deep and still get good color but with somewhat noisy or grainy footage.

 

Tom, filtering after the shot doesn't do the same thing as filtering before the shot. You're right about the diminishing returns but color can still be had at pretty significant depths. Filtering a negative is a lot like color balancing in photoshop. :blink:

Share this post


Link to post
Share on other sites

Roger on the filtering. Nevertheless if almost no red in ambient light is present, filtering will not help much. The concept of reducing the blue with a filter to keep from having to amplify the red later and so generate noise is a great concept but there must be depth limitations.

 

Hard to find true black and white even on a killer whale, same thing in topside shooting.

Share this post


Link to post
Share on other sites

Sponsors

Advertisements



×
×
  • Create New...