Tom_Kline

It is not clear from the Sigma website: http://www.sigmaphoto.com/lenses/lenses_al...283&navigator=5 whether the tripod shoe is removable. Is it removable or can the lens fit into a port with it attached (SEACAM flat or macro port)? Thanks Tom

Cool shots! The filters you used for the pix in the first post must have functioned as a barrier filter such as used in fluorescence microscopy. With blue excitation the barrier filters are yellow. At depth, e.g., 30m, the ambient light is mostly cyan thus providing the excitation wavelength. The human eye to some degree adjusts for the ambient light much like with tungsten light so we see the fluorescence better than the camera. Try various filters to block the shorter wavelengths and viola' you've got the pix. Higher ISO would be useful too. Tom

MACRO! I have been using the 50mm macro with the RS for almost all my night dives for well over a decade, will use 60mm and 105mm macros with dSLRs. So I voted 'other.' At night one can get lots of creature pix (inverts in particular) so macros are most useful. I use an Ike SS200 with modeling light to focus and as my primary dive light. Tom

I too use the DUI harness with a drysuit and wish it had been invented decades earlier! On a recent trip to B.C. I added 8# (two 4# blocks) to an AL80 tank using an extra cam strap on a Hogarthian rig. Prefer to use steel tanks but they are not always available. With certain dry suits I have used ankle weights but they are not needed with my current rock boot equipped DUI suit. Tom

Any interesting new UW photo equipment at DEMA? Did SEACAM show their new remote control? Tom

Works well with 4GB cards too. Tom

Just back from a >1 month-long non-dive trip. Used a P2000 to store my images, which I managed to fill up; brought back remaining shots on 2 4GB CF cards. It worked well, never ran out of battery power. It was convenient to show pix to others but had to make sure they did not touch the buttons - the one on the bottom (facing holder) takes you back to the 'homepage' of the gadget and is easy to touch when holding the P2000. Scrolling for images on the HD of the P2000 is quite a bit slower than doing so on the CF card still in a D70 or D2H. The zoom function only works on jpegs, too bad. Improvements should include faster processor, larger drive, and better interface ergonomics. Hopefully 'Moore's law' will apply to this class of gadget. Tom

Wow!, you have some extraordinary photos here and in the other thread ! I guess I should not complain so much about our slow connections in Alaska, the gravel road of the information superhighway (there are a lot of gravel roads in Alaska). Tom

http://www.mydigitaldiscount.com/s.nl/sc.1/.f Above is the homepage for mydigitaldiscount, check out their Ridata sale prices, 4 GB 80x for 260 if you buy two . Tom

Thanks Mike! Actually the air temp was about 80 °F, I was in a t-shirt. I did get splashed a few times with the cold water, however, as the salmon were rather active, typical spawning activity! The difference between the air and water temperature caused the dome port to fog up rather instantly, like an ice cold drink on a warm day! Tom

Here is another example of fish sex - fisheye (10.5 mm) to fisheye (salmon) ! I just became operational for digital UW today, this being an example from today. Spawning sockeye salmon shot with available light: ISO 640 1/250s at f/11. I used the SEACAM Superdome (SD) port. That is a male in the center. He was chasing the female on the left side of the pic. That is a moribund spawned-out salmon in the background between the other two. Pacific salmon die after spawning. Tom

No bookmarks appeared to be working this morning, but now all seem to be OK including the one for the main page that did not work yesterday. The difference, in main page bookmarks, is one has www and one does not, both now work. Tom

Hi Eric, The main unusual thing I noticed was that the site was down for a while this evening. My bookmarked url for the main page is doa, now gets: This is the Pleskâ„¢ default page etc. instead, so made a new one. However, the old bookmarks for recent topics and the forum still work! Tom

Red-lined the attachment space, here is the other shot. Tom

I was down south in B.C just over a month ago diving in Barkley Sound for some warm-water diving . It is all relative. It was 55 to 61 F, which is not very cold for a dry suit. Not cold at all. I have seen numerous much colder divers in the tropics, mainly due to using wetsuits and loss of direct sunlight (night, cloudy and rainy etc). There were lots of black-eyed gobies, or goby-wons (re. obi-won), as I jokingly refered to them. Here is a pair of shots done with an RS (still on film), Velvia, and a single SS200. Note less DOF but focus on pectoral and dorsal in closer shot, that was as close as I could get to a goby-won with the 50, before they would spook. Tom

ps. forgot to mention that there are formulas for calculating the bellows correction factor, DOF etc. but are not to practical for UW use, one needs to know the total extension (tube plus amount due to lens focusing) and focal length and use a calculator. I recall one even includes pupillary magnification. One would need more input data.

In the good old days of manual focusing most macro lenses (e.g. 55/3.5, 105/4, and 200/4 Micro-Nikkors) only focused to 1:2 (half life size) so special extension tubes were sold to match to the focal lengths so as to yield 1:2 to 1:1 focusing range for some lenses. For example the Nikon PK-13 ring is 27.5mm long and was designed for the 55 whereas the PN-11 was for the 105. These two lenses also focused to 1:2 simply by racking out the lens elements, the extension tube carried this out for another increment equal to that intrinsic to the lens. When the 200 came out, it had internal focus (IF) and no extension tube came out for it. My recollection was the that the TC-300 teleconverter (TC; a.k.a. doubler) was recommended to bring the 200 to 1:1 but the PN-11 could be used too but less than 1:1 resulted. The IF enables lenses to compensate for lens aberrations induced by change in focus distance. This would be lost if an extension tube was used but would be conserved if a TC was used. The bellows correction factor (due to loss of light by the extension) was engraved on the barrel of some MF macro lenses, two scales on some for use with and without the 1:1 tube. With the advent of TTL metering and TTL flash, the bellows correction factor was all but forgotten since the metering system took care of it. Interestingly, the 50 macro lens for the Nikonos RS has an automatic compensation so that as the lens is focused to 1:1, it opens up a tad. Therefore, f/22 remains T/22, (T-stop, not f/stop) but the DOF is that of the compensated aperture, i.e., less DOF. I criticized this 'feature' in my review of the RS that I did for the AAUS a decade or so ago. This is good for some folks, but DOF is sacrificed as a result. The main problem of using an extension or TC UW is that one may have to use special lens gears; unless you have one of those ports that incorporates focusing and have a port extension tube that is the same length as your lens extension tube. Alternatively, you would have to do your dive at a fixed focus distance, like in the days of Nikonos (I to V) extension tubes and framers (remember them?). BTW, I believe the EOS Canon 50 macro lens only goes to 1:2 and needs a tube to go to 1:1 like many MF focusing macros. Tom

It all depends on how careful you want to be. I know of one diver who had to drive to Anchorage from Seward after (shallow) diving. There is a 3000 foot pass. He brought along a DAN O2 kit to breath off of. I seem recall that the volcano visitor center was at higher elevation from the contour lines on the map I was using to drive - I did not go beyond the black sand beach (the one east of South Point) that day. BTW when folks fly and dive from float planes, the pilots will fly under 1000 feet after diving as a precaution. This is also an issue for rescues here as all the operational chambers in this area are in Anchorage, and there are lots of mountains between the water bodies. The dive site, which I did from a boat out of Kona, where Capt. Cook was killed as I recall was quite good, if this is what you are referring to. It is very close to shore. Although the vis was not the best due to wind and waves (in Feb), there was a lava tube dive near the distal point of a lava outflow that was one of the most spectacular. In a lava tube cul-de-sac there were 3 moorish idols going around in a circle on vertical plane, as if they were in a clothes drier (at about that speed)! Tom

The trouble with adapting the RS lenses is the prism over-hang on the Nikons. There would not be enough clearance for both the lens and the housing wall-lens mount. There might not be enough room even with the camera cover removed. Although the RS lenses could be adapted to an EOS, becuase they do not have aperture rings this would make them problematic to use. The RS lenses were the first of the G type now being made for SLRs by Nikon! One would have to build a dSubeye to use the RS lenses at this point. Tom

Helge, Your drawing is conceptually not all that different from Seacam's. The Seacam S45 has more elements so yours might be a tad cheaper. They have 4 lens elements between the prism and housing, and 5 lens elements, not including the port, between the prism and eye. The best UW viewfinder I have used is that of the RS. The 15 degree off-set is great and ones eye can be off-axis a bit and thinsg are still OK. The next level down would be the finders used in medium format housings - they have the advantage of looking at a larger ground-glass. Tom

The UW housing shown in 2001 is the old 'Triton' housing made for Hasselblad by Hugy. If one really wanted these megapixels it might be better for now just to use one of the medium format housings in circulation and scan the film. Which Sinar? They make (made?) a special body called the Handy for the 47mm Super-Angulon that might be interesting UW (for just one shot per dive), but a view camera!!! However, I seem to recall seeing an old International Photo Technik magazine (Grossbild in German) a few decades ago with a view camera, probably a Linhof, UW in a plexiglass housing. Tom

Many of the on-going threads seem rather chatty already! A consideration is the global particpation and attendent time zone effect this has. Things that can be 'canned' and looked at later are therefore better. Tom

Be aware that going up to see the volcanoes requires an increase in elevation and plan your diving accordingly. We do not want anyone getting bent! Just the road to Southpoint from Kona goes up to about 1000 feet elevation if I remember right. Similar precautions for the other islands. For example, Haleakala (Maui) is about 10,000 feet! Aloha! Tom

Congratulations! from the frozen (though not at this time of year) north Tom

How about Louis Boutan's underwater pix from the 1890's? His self-portrait comes to mind. To TTL or not to TTL was not exactlly a concern back then ! Tom