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Filters - Worth trying?


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#1 MrFish

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Posted 15 March 2003 - 11:06 AM

I was wondering if anyone here uses filters on their digital SLRs. Would they benefit in any way in improving colour balance?
Dave Hopson
Fuji S2 pro, Ikelite housing, 60mm Nikon macro lens, DS50, Nikon SB-102

#2 craig

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Posted 15 March 2003 - 04:19 PM

I am doing it but it's too early for me to suggest anything too specific. I've done WA with FL-B's and UR Pro's (no CFWA). On my last trip I did macro with a variety of lighter filters. I also did one WA dive with a gel combination. I used the new Adobe RAW plugin to do my conversions and payed close attention to the WB settings I needed. I can provide more detail on my experiments so far if anyone would like.

I think the short answer to your second question is: (1) filters are of minor significance for macro work and probably not worthwhile, and (2) useful for WA as long as you carefully match the filter to the conditions and control strobe power properly, and (3) very useful for ambient light photography not shot close to the surface.

I have a Gossen Color Pro 3 meter that I use to measure filters and have a significant spreadsheet of numbers that I keep. I'm awaiting a transmissive spectrometer (a week late already) that I can use for full spectrum filter characterizations. My goal is to provide comprehensive information on any filter of interest to anyone underwater.
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#3 MrFish

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Posted 17 March 2003 - 01:44 AM

Thanks for the reply. It would be very interesting to see shots taken with and withou filters to see the effects they have, just not sure how this could be done.
Dave Hopson
Fuji S2 pro, Ikelite housing, 60mm Nikon macro lens, DS50, Nikon SB-102

#4 Alex_Mustard

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Posted 17 March 2003 - 06:12 AM

White balance control was the MAIN reason I decided to buy a digital camera. The technique works well with available light photography and enables you to take images that you just can't get on film.

Posted Image

This image shows four shots taken in the pool with my D100 by tuning the white balance with a grey card. The first shot shows my friend with the white balance in daylight. The second shot is with the white balance tuned with the grey card. Which has produced a much more "natural" result. Images c and d are autobracketed shots with plus one stop warmer and one stop cooler of white balance. These images were generated by the camera from the same frame and written to the card.

Since techniques for white balance tuning will vary between cameras there isn't much point in getting into it. Also different cameras offer different amounts of white balance control.

Alexander Mustard - www.amustard.com - www.magic-filters.com
Nikon D4 (Subal housing). Olympus EPL-5 (waiting for housing).


#5 craig

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Posted 17 March 2003 - 09:34 AM

White balance control was the MAIN reason I decided to buy a digital camera. The technique works well with available light photography and enables you to take images that you just can't get on film.

If you accept that a digital file is your final output, you can certainly get it with film. Simply scan it and adjust it. If you use RAW mode with your dSLR, you are bypassing custom white balance anyway. Ultimately, the dSLR imager has a fixed white balance just like film, it's simply easier to adjust WB. There's no superior capability that digital has over film. If you don't shoot RAW, WB comes into play but you're giving up quality. The only real way to alter color in ambient light photography is through filters (and, ironically, choice of film).

I don't have any true side-by-side comparisons to provide but I've got something close. Here are two shots of the same subject in the same area with the same camera on two different dives. I shot these in RAW and converted them in Bibble with WB processing disabled so you can see the true effects of the filters.

60mm, dome, no filter
Posted Image

70-180 @ 70mm, flat port, B+W FL-D filter
Posted Image

The magnification appears to be different because of the different lens and port, but working distances were similar. ISO was not the same so there is a different proportion of strobe vs. ambient, unfortunately, that's makes this comparison inconclusive.

What I'm trying to show is that the filter does some (hopefully most) of the white balance job. I've gotten good color right out of the imager in the second shot but not the first. With WA, greater working distances and stronger filters make a bigger difference. With macro the difference is easily corrected in PS.

For users of the new Abobe raw plugin, has anyone noticed that the tint control is generally always in the positive range? Using FL-D filters with macro fixes that.
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#6 craig

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Posted 17 March 2003 - 09:56 AM

Here is another comparison. I took a 5050z/PT-015 setup to loan out to others, so these two pictures were not taken by me.

With Hoya FL-D
Posted Image

No filter
Posted Image

These two pictures were converted with the Adobe CR plugin using a fixed WB settiing of 5000K, 0 tint. The differences are slight but you can see that the filter reduced green and increased reds.
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#7 Alex_Mustard

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Posted 18 March 2003 - 04:21 AM

Thanks Craig. Useful stuff. I learn so much on this forum!

For several years, with film, I have been using Wratten Gels. In blue water I have favoured 40CC red and 50CC red. These work well assuming a calibration of 4CC units per foot of light path from the surface to the subject to the camera. So I am still talking about very shallow work.

I have not tried the UR Pro or the FL-D (infact don't even know what that one is!). Do you reccommend trying these?

Alex

The only online versions of my filter work on film are in Underwater Photography Magazine Issue 1.Page 20/21

Alexander Mustard - www.amustard.com - www.magic-filters.com
Nikon D4 (Subal housing). Olympus EPL-5 (waiting for housing).


#8 craig

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Posted 18 March 2003 - 08:30 AM

Some manufacturers make filters to correct for flourescent lighting. FL-B filters are for indoor film and FL-D (and FL-W) are for daylight film. FL-B filters are unpopular because indoor film is unpopular, but they are good for underwater use. Every filter manufacturers' recipe is different, but the Singh-Ray FL-B is very much like the UR Pro CY filter only a little less strong.

The FL-D filters are much more like the green water filters. They have a pinkish appearance and remove predominantly green light. They will also have mild warming effect like an 81 series filter rather than an 85 series of the stronger FL-B's. Each manufacturer is different, with B+W being the mildest, then Hoya, Tiffen and Singh-Ray. I have measured all these and can provide actual filter values in each case.

As far as recommendations, and assuming the filter isn't removable, I like to Singh-Ray FL-B for WA, blue water as long as you aren't trying to do close focus. The gel equivalent is an 85B plus CC50M. I used that gel combination in my Sigma 15mm on my last trip and decided I'd rather have less warming, like and 85C instead. Switching to an 85C allows easier close focus. For green water or closer work, I like the Hoya FL-D. It is roughly the same as an 81C plus CC30M. Very similar to the UR Pro GR filter. The B+W FL-D is about half that strong, almost not worth bothering. If you like the red filters before, I think you'll like the Hoya FL-D.

Some people are concerned about image degradation with filters. Tiffen filters are gels sandwiched in green glass as are the UR Pro glass and Aquacolor glass filters. I've noticed quality issues in video at times that appear to be caused by the filter, so I am avoiding the Tiffen filters as well as all glass video filters. B+W, Heliopan, and most Hoya's are dyed-though glass. Singh-Ray, Lee and Hitech are resin. That's what I stick with. For video I've switched to the Singh-Ray FL-B. I've noticed that Amphibico has also moved away from the glass filters.
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#9 MrFish

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Posted 19 March 2003 - 01:22 PM

Thanks for the time and effort in your replies guys. I shall probabley try the FL-D filter.
I am right in presuming you mean a Flourescent day filter?
Dave Hopson
Fuji S2 pro, Ikelite housing, 60mm Nikon macro lens, DS50, Nikon SB-102

#10 craig

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Posted 19 March 2003 - 05:13 PM

FL-D means flourescent day. Each manufacturer's FL-D is different, though. Tiffen is strongest, then Hoya, then B+W.
I love it when a plan comes together.
- Col. John "Hannibal" Smith

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