Tom_Kline

Hi Jean, We have plenty of liquid water now, but it is falling from the sky propelled by a pineapple express - massive low pressure systems moving north up the Pacific. A colleague noted a gust to 90 mph today as the weather station readout is in his office. We are having a 'warm' winter. The short days are presently at at an end. Cheers! Tom

In the 'gold old days' of film one could use a Nikonos with a framer. One could 'walk' the camera around the quadrat shooting 2 vertical and 2 horizontal format (4 shots in the quadrat total). Everything was done manually. Advantage = consistency. Same area in each shot. Helps during the analysis. Digital equivalents??? Getting ID quality fish shots will vary by species. Video (i.e., low res) may OK for some while you may need to collect a sample for others.

I am thinking of this lens for super vis conditions, semi- to mostly ambient light shooting so light would not be limiting (e. g., Molokini backwall, NOT here in Alaska!). Sounds like it could be OK. Since you were using the Canon CU lens, it would have to go on inside the housing. I can see using a diopter if you were using this lens on a dive and the situation arose where you would want to reduce WD, but it would have to be one an external one. BTW, nice worm shot! FL with 10" WD helped avoid spooking them?

This is the first I have heard of anyone carrying their lead inside their drysuit. I actually tried out two sets of ankle weights when using a Viking - no that did give me lead foot! With no weigths the feet had excessive bouyancy - a lot depends on the suit! Tom

James, What was your reason for using the diopter? Does not the lens alone goes to 1:1? How did you find AF? See Ryans post (#6) in this thread: http://wetpixel.com/forums/index.php?showtopic=7545 Tom

I have been using (rubber and tri-laminate) shell type dry suits since the 1980’s and agree that each one, and the parts and accessories (zippers, seals, dry gloves, hood, boots), presented its own learning curve. However, I am of the school that keeps the air in the suit to the minimum, has the exhaust valve in the minimum pressure position (counterclockwise in the suits I have used), and uses a B.C. for buoyancy control. I now use the DUI weight harness with rather negative steel tanks but back in the 80’s I used Al tanks, which required 44# plus ankle weights for underwear needed for temps that are typically in the 40’s (F) with a standard weight belt. I am presently use 32# plus ankle weights when carrying a 2# negative camera rig. It takes a number of dives to get proficient in a dry suit. Tom

Yup, if you want the full 180 degrees you will need a lens specifically designed for camera's sensing area. Therefore Canon needs to develop FE's for for both the 1.3 AND for the 1.6 crop factor cams if they want to keep everyone happy! Probably ain't going to happen. I understand the 15mm Canon FE works rather well with the FF sensor unlike their prime or zoom rectilinear WA lenses.

Excellent points!!! Now we know why they are called fish eye lenses! They are also good for photographing fish eyes (and snouts), see my avatar. Tom

I have had good luck to about 10 feet with ISO 100 with one SB104 or one SS200. Shooting moving fish with a 50 mm f/2.8 on an RS. I shot wide open. My tendency with the RS 50 lens has been either to shoot it wide open or closed down all the way according to whether I was doing macro or whole fish shots. The quality of the 50 is quite good at f/2.8 too, probably due to it being a water contact lens.

Tom, Maybe we need to know actual focal lengths to the nearest 0.1 mm? The marked FL’s are generally a rounded value. 1 mm makes a bigger difference now with such short FL's in use for the newer smaller formats. Tom

Hi Ryan, Too bad! Even with D2's!! The 70-200 with AFS is so quick, too bad we don't have this with a fast macro. I was hoping f/2.8 would do the trick. Maybe the problem is Sigma's implementation of AFS/USM??? Tom

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.

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

Ryan, which camera did you use with the 150? TIA Tom

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.

It would be great if the mass as well as any added displacement for each component (including internally-used rings - need mass even if displacement = 0!) for a given system was provided by the manufacturers. After adding the mass of the camera components (e.g., camera and lens), one could then calculate the net bouyancy. There are too many possible combinations to list them all.

Seeing just outside the frame works rather well with a Leica M or when using an 80mm lens on a Nikonos III (and using the N3 VF)! The reduced image size as opposed to seeing it more magnified may be even more (than with Leicas) of an issue UW, however. Also one needs to use a wider angle lens than one intends to shoot with to 'Leica-ize' your D2X. If one is running out of CF space and is using a zoom but not at the shortest FL, one could zoom back and switch to crop mode to be able to take more shots on a particular dive - a photographic J-valve of sorts (I am dating myself) Tom

The 18-70 D70 kit lens is inexpensive and lightweight. A number of great shots using this lens have been posted on this site. It seems rather versatile. Tom

I have been thinking about this myself given the field report on the Seacam D100 housing on Steve Frink's site. Hopefully the attachment came through, which came from the German boat show. It shows the Subal D2 housing with the extended VF but from too a high an angle or too short a focal length - however, it looks like it will be OK. A straight-on or lower shot would have been more conclusive. Too bad they did not show one of the premium finders on the Seacam D2 housing at the same show as these are the only pix (see Alex's post at the start of this thread) that have been posted of the housing thus far. Tom

Congratulations Alex! You may be the first person on the planet to take a D2X underwater. This is also a test of the new wetpixel interface! Cheers from Alaska! Tom

Some good pix taken with the D2X were posted on FM and then transfered to a web site: http://photo.neuroscuba.net/gallery/benhorned2x Check out the fine detail in the flower shot. Cheers! Tom

Isn't anyone developing multi-LCD projector programs? Either that or have a projector with a vast number of megapixels capable of showing multiple images at a time. Would be easy to go from one gigantic pic to many smaller pix. We may need to wait for the next generation, or two, computer to handle the data flow. As an alternate to using ppt, I have used Nikon View (I would think other programs could work too) in slide show mode (a button on the GUI). Put a collection of pix you want to show in a folder and away you go. I have not figured out how to reorder the slides, default appears to be alphabetic. Looks like an opportunity for a software developer for a real slide show program. Cheers! Tom

You may be a newbie but you have it figured out. The water-port-air interface is like a diopter. When in the pool I find it easier to read my watch while submerged (with a mask on)! I use reading glasses now that I am older. The min focus stays the same but because of the mag you get a bigger image, hence 1.33:1 with a macro lens capable of 1:1. For this reason it is easiest to consider a focal length mag of 1.33. A 100mm becomes a '133' mm lens. Cheers! Tom

By blow-up I mean crop!! T

A lot to respond to, which is posted below in the same order as above. Karl, I do not have an UW photo specific website. However, if you follow this link, there are hypertext links to some UW pix of mine from Prince William Sound. http://www.pwssc.gen.ak.us/shepard/docs/re...dal/diving.html They are small pix, which is good given the relative slow connection between here and the outside world. I frequently tell people that Alaska is on the gravel road of the information superhighway! (we have a lot of gravel roads here). The vis was quite bad at the location, so they look better small. ReefRoamer, CeeDave is quite right, think of it this way: 1:1 means that if you take a picture of a 30mm long nudibranch it will appear 30mm long in the image (film or sensor) plane of your camera. With a 24 x 36 mm (i.e., FF) you will be able to fit it lengthwise with 6 mm to spare. Because the Nikon DX format (for example) is 23.3 x 15.5 mm, a 30 mm will not fit lengthwise into the frame at 1:1. At half life size it would appear 15mm long in the image plane and would be able to fit with room to spare in a DX frame. At one half life size on a FF camera there would be a lot of space around it. To make one print from each camera in such way that the nudibranch is the same size (in the print), you would have to blow up the FF shot by 1.5 times as much compared to the DX shot. The smaller the sensor size the smaller the field covered at the same reproduction ratio. Shoot a coin at 1:1 on 35mm film and it appears large; on 4x5 inch film it appears small (at 1:1). BUT, if you laid the negatives (or transparencies etc.) side by side on a light table the coin images would be the same size and would be the same size as the coin itself. There would be just a lot of wasted film on the 4 x5. James, The Exif info in Nikon View does not show the focused distance on D70 shots (just checked). My guess is that what you are seeing is the same distance that you can read off the lens barrel, which would be the apparent distance. The Rolleimarin housing focusing knob had two scales, one for apparent, and one for actual distance. I gather former was to for guess focusing (they made an external metal frame-finder for the housing) when not using the focusing screen while the later could be used with a measuring tape. Bandit, I gather that the 5050 is a fixed-lens camera. It may zoom to a shorter focal length to achieve macro-range focusing, which means very short working distances. The 1.33 mag means that you do not need to even focus as close as 1:1 as inscribed on a macro lens barrel to achieve 1:1, so would have more WD. Racked out to 1:1 (as on the lens barrel), mag is 1.33:1 at the same WD as 1:1 in air (this WD has to include the space inside the housing in front of the lens as well as the port thickness; so distance from front of the port will be a bit less). Craig, I think I just answered your questions (first question -see reply to Bandit; second, the reply to ReefRoamer). It is still 1:1, just the format (senor size) is smaller!!!!!!