Jump to content
Sign in to follow this  
videodan

Expodisc White Balance Filter

Recommended Posts

Anyone want to share ideas on how to make an Expodisc work on the Amphibico EVO for the A1 (wagsy?)? I'm open to ideas, and have a mini grinder.... :P

 

Thanks

Edited by Texas diver

Share this post


Link to post
Share on other sites

Update - more info: When the W/A lens arrived, it wasn't 67mm on the outward side (away from camera) but on the inward side. Ah, communications - how difficult they can be sometimes! Anyway, I took the cap that came with the housing, and cut a hole in it and mounted the 67mm Expodisc so that works fine for when I won't be using the W/A lens. Now I have to work on something for the W/A lens. Tommorw I'm ordering the 4x4 overnight to see if I can get something rigged up before we leave.

 

Does anyone know if it makes any difference whether the Expodisc is turned one way or the other? I would suspect that it has to be put in front of the lens in the expected direction but don't know for sure.

Edited by pablo

Share this post


Link to post
Share on other sites

Pablo I would say for sure it matter which way around it is because the whole point is that the little prisms gather light from a wide angle, and they will only work properly the correct way around. The frame on my 4"x4" also says which side should face the camera.

Share this post


Link to post
Share on other sites

Pablo, as Nick says, you must have the clear prism side of the Expodisc facing your subject. The Expodisc must be in front of the color correction filter, then you manual white balance through both simultaneously, remove the Expodisc, and begin shooting through the color correction filter. Also, white balance toward the sun for wide angle shooting, and right on your subject for close up, and rebalance often while descending. Experiment and let us know how it worked. I wish you good luck, and have a great trip to Tahiti.

Dan

Share this post


Link to post
Share on other sites
Anyone want to share ideas on how to make an Expodisc work on the Amphibico EVO for the A1 (wagsy?)? I'm open to ideas, and have a mini grinder.... :D

 

Thanks

I've been looking for a way to mount the 4x4 Expodisc on my EVO for a few days now. But I haven't come up with a good solution.

 

What I think I'm going to do instead is order the 82MM Expodisc and just snap it on to the front of the port to WB.

 

Since the 82MM filter is 3.228" and the vertical dimension on the port is 3-3/8th", a small plastic piece glued in place should provide enough friction to hold it in place temporarily. Maybe something with a little ridge/dimple to snap it under. Should be able to make something with the Moto-Tool pretty easily. There's almost 1/2 in of black plastic on the top/bottom of the lens port to glue it to that isn't seen by the camera through the port.

 

I also plan to order the discontinued "Classic" Expodisc as it has a plastic housing as well as a nice little lanyard that should keep it nearby while shooting.

Edited by sjspeck

Share this post


Link to post
Share on other sites

sjspeck-

Please keep us posted with the results of your modification. I was wondering if there was a way to use the slot where the white plastic lens protector is inserted, but I think it is bigger than 4x4.

 

Vic

Share this post


Link to post
Share on other sites
sjspeck-

Please keep us posted with the results of your modification. I was wondering if there was a way to use the slot where the white plastic lens protector is inserted, but I think it is bigger than 4x4.

 

Vic

That was my original plan but the 4x4 Expodisc is too thick. It actually would fit in the slot if it were thinner. Without the frame. See my previous posts here. And it would be impossible to widen the sides of the slot without a lot of grief.

 

So the only way to use it seems to be a flip down and there's not a lot of material on the top to secure it to since the slot is there. Unless you lengthened the arm of the flip down so you could screw it to the back of the port. But there's other screws back there already and Amphibico gas fills the port so that's not something I want to attempt.

 

I also thought about using some little u-shaped aluminum clips that would fasten to the outside edge of the metal frame of the Expodisc and be the right length so that when pushed into the slot from the top, they would hold it tight against the very front face of the port. But I don't know if you could drill into the Expodisc frame without shattering one or more of the elements while trying to attach it to the clips. And welding it seems like a really bad idea.

 

But then I thought of my new idea which seems simpler - and about $100 cheaper. I'll probably order it now and get around to it later next week, this week is too busy. Will post a picture if/when it's done.

 

I'm also thinking that a piece of velcro on the outside surface of the Expodisc with it's mate on the top (or bottom) of the inside lip of the port will be sufficient to hold it in place.

Edited by sjspeck

Share this post


Link to post
Share on other sites

Here's my post on the Tahiti trip so far as the Expodisc stuff goes. Equipment: Sony HDR-SR1, Ikelite 6038.90 housing with Ikelite W/A lens. Pictures shot last week off Moorea, French Polynesia.

 

= = = = =

 

The first shot shows, on the left, the 82mm standard Expodisc I fixed up for the regular port (I just glued this one to the poly cap and you can spot where the sealant against the plastic cap was coming un-stuck on the left half but the filter itself didn't leak), and the stock "cap" model Expodisc that I got for land use. You just squeeze the two buttons (only one is visible from this angle) and snap the filter on or off. The part showing below it is a standard filter adapter to take the SR1's 30mm filter receptacle size to the 37mm of the most-appropriate Expodisc size.

 

For the second picture, I propped up the housing under a box, with W/A lens mounted (didn't have the base on it at the time) and showing the 4x4 Expodisc that was cut down to a 3 5/8" diameter and mounted within 2 aluminum rings I had a local shop fabricate for me. (The black lanyard is the CC filter on the W/A lens.) Before assembling everything with the 6 stainless steel screws/bolts/lockwashers I sealed all including the screws themselves, and then added a wiring terminal connector under the one bolt of the screw that I deliberately chose to be longer. Then I ran a small piece of line through the sleeve - the part you'd normally crimp - and tied a knot while making a loop on the other end that was large enough to slip the whole assembly through for attachment to the housing. If you get a terminal that's made for, say #10 wire like this one, then it's plenty strong enough to hold the whole cap; I didn't even worry about it hanging around when I was in the water (did note it float up into the bottom of the FOV once though). It was easy to slip the cap on and and off to do a W/B, although not as simple as the flip-up arrangement inside a housing like others have done. Unfortunately, this fancy one leaked for some reason. I guess I didn't coat something properly when I was assembling it the night before we left. I intend to dissasemble and redo it in the hopes that another attempt will seal it properly. The cost to have a machinist make the rings on short notice was about $175 so it wasn't cheap, but it did make a solid arrangement that doesn't look bad. The 4x4 filter cost $160 at B&H, although if you use this round configuration (v. rectangular) you could buy the $105, non-cap 82mm version like in the first shot and get the same effective filter exposure area while saving $55.

 

For anyone who wants to get the poly caps, here's a good source that is helpful, inexpensive, and has a lot of sizes from small to large: Alliance in Santa Fe Springs, CA: 800-847-0486. I bought a small batch of them to mess around with, from 3", 3 1/2, 4, to 4 1/2, etc. They cost from $3.50 to $5.25 each plus nominal shipping.

 

= = = = =

 

Then I have 4 shots taken with the camera after using the Expodisc for MWB. They were all taken from between 40 and 60 feet (sorry I can't be more precise). Since I don't yet have any HD editing software I shot in SD video. These were poor diving conditions: 30-40 feet of visibility, lots of junk in the water due to rain runoff and surge, and cloudy skies. The second dive was even worse that the first since there was more runoff by afternoon and the visibility lost another 10 feet from what it had been.

 

Given that we got in only two dives and that I was happy just to get the camera/housing operations all working and MWB done with the Expodisc, I didn't try to do comparisons like WB with a slate and then the Expodisc for the same shots like I had originally planned. I was glad to get things recorded after all was said and done although I know that makes the shots less valuable for comparison. But using the Expodisc the color reproduction is pretty true to what my eyes saw. (There is no PROC on any of these pics - just frame grabs saved as JPG files.) No lighting was used.

 

I have to say that I really love the SR1 and the hard disk type of operation. It's fast, easy to throw away junk shots, easy to save off, holds a monstrous capacity (6-7 hours of HD, 10-12 SD), and worked flawlessly. I do wish the "One-Touch" MWB were a button instead of a menu choice, but it was workable. It has a lot of nice features and is an excellent camera. And my land shots were really nice too so far as I was concerned.

 

PAUL SHARP

(My wife often calls me "Pablo" so that's why I selected that nickname/username.)

post-8563-1170131918_thumb.jpg

post-8563-1170131953_thumb.jpg

post-8563-1170131990_thumb.jpg

post-8563-1170132007_thumb.jpg

post-8563-1170132028_thumb.jpg

post-8563-1170132046_thumb.jpg

Edited by pablo

Share this post


Link to post
Share on other sites

To my eye they look on the warm side, particularly the last 3. The one of just coral looks like my footage looks if I've white balanced then ascended a few metres without white balancing again. Personally if I was using those in a project I would reduce the red.

 

When my Locline bits and pieces arrive I'll make a holder for my Expodisc, do some comparative tests and post them here.

Share this post


Link to post
Share on other sites

It could very well be that I did ascend since the white balance in one or more of the shots. Would like to say, though, that the water was very brown due to the muddy runoff that was spilling gradually out of the reef entraces into the diving areas. And the reproductions - given that I don't have a computer monitor that is color balanced and all that kind of fine-tuned technical stuff - the raw shots reproduced very well to match what the "monitors" between my ears saw. If they were colder they would not represent what I saw.

 

I'm not that up to date anymore on various aspects of the video world (I go back to the old 2" tape hardware days!). I used to work as a sound/audio engineer in Hollywood and although I worked primarily in film that included video shoots at times. I was more up on video technology and such in those days but it's been quite a while, so I hesitate to suggest that my opinions amount to a lot in today's field. I do note, however, that a certain small portion of those responding to the Expodisc stuff in the forums here seem to like things colder than others. And it could be that using the Expodisc might actually require some re-balancing fo the filter components they're using in order to make it more true in an U/W environment. I've only had these two limited dives and was just happy, after all was said and done and all the setup and prep I went through to get to the point of the red "REC" lamp showing! - to just let the camera roll for two dives and see that I ended up with visible footage.

 

It was interesting that beyond not even having any rinse tanks, the dive operator and divemasters didn't seem to have any clue about what would be required to set up a video system. I told them in advance that I needed to stop around 10 feet for a minute and remove the W/A and filter and make sure the bubbles were cleared from the lenses (wet lens and wet filter) and set up W/A focus (getting it set and the locked to start with), and then to stop at the bottom long enough to do an initial MWB. Nevertheless they dropped on down the anchor line straight away and wandered off without me and I was left to locate and join them once I had things set up. I suppose this is something others have all adjusted to long ago but it was an interesting first experience for me. (When my wife was with me, as my partner she naturally hung around until I got those things done.)

Share this post


Link to post
Share on other sites

Pablo, as long as you're happy, that's all that matters. Everybody has different tastes as to what looks like good color. Only the one who actually did the shooting knows for sure, and frame grabs do no justice compared to how the footage looks on a good HDTV. With your camera/housing combo manual white balancing is a chore, and you are not as likely to re-balance as often as people with "one touch" balancing would. I will not shoot without the Expodisc now, because of the great color balance I acheive with it, and the ability to get great white balancing far deeper than without it. My footage is excellent by anyone's standards, and far better than before I had one. I had to recapture some older tapes, and I cringe at the difference in color balance on some of the older stuff which is still great by most people's standards, but not up to par for me anymore. So tell us more about Tahiti, would like to hear about it.

Dan

Share this post


Link to post
Share on other sites
sjspeck-

Please keep us posted with the results of your modification. I was wondering if there was a way to use the slot where the white plastic lens protector is inserted, but I think it is bigger than 4x4.

 

Vic

Got my Expodisc yesterday. The 82MM metal one. Placing it in front of the lens on the outside of the EVO port it's almost a perfect fit. I cut the top off one of those stick-on cable clamps and that takes up the gap nicely. The piece of cable clamp also has a hole in it for a screw which catches part of the Expodisc outer ring, so it "snaps" in yet you can easily pop it out. The piece is just under 1/8" thick.

Share this post


Link to post
Share on other sites

To SJSPECK: Seems like the EVO port is an oval one, then? It will be interesting to see what kind of results you get.

 

DAN: I posted a Tahiti trip report in the "Crazy Dive Stories and Trip Reports" forum. I tried to add in all the details about the trip (besides camera tech stuff, etc.) there. If you have any additional questions from what's there please feel free to ask.

Share this post


Link to post
Share on other sites

Hey sjspeck

 

Do you mean it just slid into the slot at the front?

Great work. :blink:

 

evo4.jpg

Share this post


Link to post
Share on other sites
Hey sjspeck

 

Do you mean it just slid into the slot at the front?

Great work. :blink:

No, it's too wide for the slot. It's just literally on top of the port and the piece of the clip secures it in place. You can see it at the top of the port in this photo:

http://www.scubaboard.com/gallery/showphot...00/ppuser/25243

Edited by sjspeck

Share this post


Link to post
Share on other sites
To SJSPECK: Seems like the EVO port is an oval one, then?

It will be interesting to see what kind of results you get.

The EVO port is actually rectangular. The 82MM Expodisc completely covers the lens opening in the port. So it should work fine. See the photo Wagsy provided or the one in my previous post. Edited by sjspeck

Share this post


Link to post
Share on other sites

SJSPECK can you provide some pictures of the cable clamps and how they attach the filter? The installation looks very good. Have you had a chance to try it out underwater yet?

 

Thanks,

Vic

Share this post


Link to post
Share on other sites
SJSPECK can you provide some pictures of the cable clamps and how they attach the filter? The installation looks very good. Have you had a chance to try it out underwater yet?

 

Thanks,

Vic

There's only one "clamp" and it's visible at the top of the photo - the white piece between the port wall and the Expodisc. Right now it's just sitting there but it will be stuck and epoxied to the port wall unless I find something better in black. It's a friction fit between the clip and the metal ring of the Expodisc. So it doesn't attach to the Expodisc at all. The bottom surface of the Expodisc just sits on the bottom lip of the port.

 

Attaching it to the top means that it won't be visible through the camera, notice how your red filter doesn't flip all the way up. So the camera's not seeing the entire port either.

 

The clip is made by Wire Slips and is called a cable clip. All I did was remove the two holding tabs and it fit perfectly. PM your address and I'll send you a couple. Photo: http://www.scubaboard.com/gallery/showphot...00/ppuser/25243

 

I just got it Friday and there's not a lot of water in Arizona.... :D

 

I have no doubt that it will work though, the Expodisc snaps in and is held firmly in place. I smacked the housing hard repeatedly and it didn't move. There's a little nub on the clamp that also holds the Expodisc firmly in place and keeps it from shifting side to side.

Edited by sjspeck

Share this post


Link to post
Share on other sites

Pablo, please don't think that I was criticizing, I was merely giving you some feedback based on what I'd think if I'd shot that footage myself. And I am perhaps over-sensitive to "warm" footage after years of reducing the red in footage that was shot shallower than my last MWB.

 

Like you say, the water is a different colour in different parts of the world. "Correct" white balance is totally subjective anyway. One could argue that we should white balance against a perfect white at depth to "reveal" the colours we would see if we lifted the reef to the surface, while another could argue that we should white balance against a perfect white at the surface to show the "truth" that most of the warm end of the spectrum has gone at depth. And in a way they'd both be right.

Share this post


Link to post
Share on other sites

No problem at all, Nick. I appreciate the great input from long-time people in the highly-experienced end of the spectrum. Heck, I'm not even shooting in HD yet until I sort out the AVCHD and editing software stuff.

Share this post


Link to post
Share on other sites

Finally got around to trying an Expodisc with my L&M Bluefin / Sony Z1P.

 

Unlike others who've tried the Expodisc in place of the flip macro or flip CC filter inside the housing, I didn't want to sacrifice either of those because I use them both on just about every day time dive I do. So instead mine flips down outside the housing. This also saved me getting another UR-Pro filter.

 

A 4" x 4" standard Expodisc (not the "warm" one) mail-ordered from Adorama in the US is mounted in a rectangle of white dive slate. Naturally a load of gaffer tape keeps it from falling apart. The "hinge" is made of 3 strips good old sticky-back velcro and gaffer tape. Three strips of the soft side of the velcro are stuck to the top of the 80-degree port. A single "tab" of velcro at the bottom of the slate holds the slate down during the white balance procedure, and up at other times by velcroing it to my LCD shade.

 

I need to zoom in to something like 80 on the scale of 1-99 for the Expodisc to fill the field of view. It gets partially flooded between the elements of the Expodisc during use, and there may be a little difference in functionality from having it dry and internal, but I doubt it's much different. And the elements are all plastic, so I don't see much danger in them being wet.

 

If I was to use this much I would want a better hinge system on top such as something using press-studs because on one dive it actually fell off as I jumped into the water. However I'm not sure I'm going to be using it often as I'm not overly impressed with the results, which I'll put in the next post...

post-3234-1173978423_thumb.jpg

post-3234-1173978449_thumb.jpg

Share this post


Link to post
Share on other sites

OK, so armed with my shiny new external Expodisc, I set about a WHITE BALANCE GIANT TEST.

 

The first round of tests was in 17m of clear blue water at the Burma Banks. The shutter was 1/50 and the gain 0dB on all shots. I left the iris on auto to try and even up the brightness of the various tests, and that sort of worked.

 

Anyway here are my own comments on the results:

 

1. No CC filter, auto white balance

Well it's very monochrome bluish green as expected but F6.8 is a much smaller iris than the other results with the CC filter in.

2. CC filter, auto white balance

Shows what a CC filter by itself can add but iris needs to open to F3.4 to compensate.

3. CC filter, manual white balance on the scene itself

A bit wishy washy and blue for my liking but that's not surprising with a lot of pale brown coral in the scene

4. CC filter, manual white balance on a white fin well lit by the sun (bottom right in pic)

This has been my regular method in recent years but it's definitely too red here.

5. CC filter, manual white balance zoomed in on the sun (bottom left in pic)

I like this result

6. CC filter, manual white balance zoomed on palm of hand (centre bottom in pic)

This is my favourite result of all. I think the slight pinkness of skin throws back the reds in the result a bit. After this test, this is how I started white balancing for the rest of that trip.

7. CC filter, manual white balance on Expodisc aiming towards sun

Too brown! Browner than just pointing at the sun without the Expodisc.

8. CC filter, manual white balance on Expodisc aiming at the scene

Still too brown, and surprisingly similar to the other Expodisc results, indicating the amount of averaging that the Expodisc is doing and that it doesn't seem to matter too much where you point it.

9. CC filter, manual white balance on Expodisc aiming at distant horizon

Basically the same result as aiming at the scene.

 

So for blue water I'm not really that impressed with the results of my Expodisc implementation. I will try to post the tests from greener water tomorrow. I'll also try and analyse the results more scientifically using the scopes/histogram in Vegas and/or Photoshop.

 

If you want the full size 1920 x 1080 JPEG of each white balance test you can download them here.

post-3234-1173980319_thumb.jpg

Share this post


Link to post
Share on other sites
OK, so armed with my shiny new external Expodisc, I set about a WHITE BALANCE GIANT TEST.

...

 

I definitely prefer the "Hand" one also -- followed by the "Sun" Wb

Share this post


Link to post
Share on other sites

I liked the handjob as well...

 

Dive safe

 

DeanB

Share this post


Link to post
Share on other sites

Dude!

 

Your housing has quite a bit of build up on the metal already, have you found a solution for rinse water yet?

 

i'd go for the hand and sun too

Share this post


Link to post
Share on other sites
Sign in to follow this  

Sponsors

Advertisements



×
×
  • Create New...