Questions RE: Nikon D90 underwater...

[ameri180304]

So I'm new on the bus, I though I'd throw out a few questions. If anyone could address some or all, I'd appreciate it.

1. What is TTL Compatible when looking for a housing?

2. When on a budget, has anyone had a NiMar housing? Should I contemplate selling something to get an Aquatica? Significant difference between Nimar, Ikelite, Aquatica?

3. I see ikelite has video housings, I bought the D90 because it had video capabilities yet had the dslr picture option. Has anyone made videos with it? Do they look well? I tried looking on youtube had no luck.

4. What does this mean (Double Nikonos Bulkheads, vs. Single) and why would you need one or the other?

5. Can I have one flash positioned in the center when I get my setup, or must one buy two?

6. When doing video, do the strobes stay on constantly (like a lighting system) or do they just flash like the camera would?

My intentions and wants: Max depth 60feet, I only have open water not advanced cert. Most dives will be caribbean reefs and I'd like to do both pictures and video. Sorry for all the questions, but I guess if there was a place to ask -- this would be it ;-)

 

[Chuck Tribolet]

1. TTL compatible means you can use TTL flash. With the instant feedback
of digital, you really don't need TTL.

2. Also include Sea & Sea in your list. Be sure to include the total cost
of purchase including ports, synch cords, and flash. Adm. Linda was able
to get an Aquatica for her D40 for less than an Ikelite because she would
have had to buy new synch cords for the Ike. NiMar seems to have a
bad rep.

3. Video housings are for video cameras. To shoot video with a DSLR,
you need a DSLR housing that can push the video buttons. Most will.

4. Double Nikonos Bulkheads means that if you have two flashes you can
use two single flash cords. Single bulkhead means you need the expensive
and hard-to-find now double flash cord.

5. You can take pictures with one flash, you will get better pictures with
two.

6. You don't do video with flash, you use a video light that stays on
constantly while shooting, or no lights at all if shallow in clear water
(you do need to do white balanceing).


Chuck

 

[HerraduraDivers]

Chuck said everything,
i only add my experiences and thoughts of a D90 photographer.

The D90 has no autofocus while recording video due it's mirror/af-sensor system.
The only useful way is to use a wide angle or fisheye and set it to infinite to use the huge DoF they have.
You also may find a housing with a manual focus port to adjust the focus under water, but this will limit the choice of the housing.

Nimar housings have a bad reputation and not living in Italy you will be in troubles if issues occur.

Not being able/willing to spend 1000'ds of $$$ for a aluminium housing i would suggest a Ikelite,
they are worth the price and widely used. To get TTL with Ikelite you need Ikelite strobe(s) and
you can't use optical triggered slave strobes as the D90 strobe will not pop open and fire.

Get a quote from Reef Photo and Video, Optical Ocean Sales or Backscatter and/or Shop around for a used rig, you may find a bargain

Consider that a new Ikelite rig will be roughly:
1300$ housing, tray and 1 arm
300$ 6'' dome port for Tokina 11-17mm
800$ one corded strobe (Ikelite, S&S, Inon Z-240 + Cable
500$ Tokina 11-17mm WA lens
2900$ Total :shocked2:

Chris

 

[ameri180304]

Thank you guys for your responses, I appreciate the education on the matter Also, Ive had the Nikon DSLR for a few months and I love it... The smaller Macro lenses, are those the lenses of choice?

((Tokina 11-17mm WA lens)), or similar smaller mm lenses

Im assuming the lens that came with (18-55mm) wouldnt be recommended. It is AF-S, is that a bad feature when using it for diving? Hope my questions arent bothersome, lol. But again, thanks.

 

[HerraduraDivers]

In the times photos where made on 35mm film lenses where classified :
- lesser than 50mm (mostly 24mm), a lens was a wide angle lens Macro photography - Wikipedia, the free encyclopedia
- 50mm, was the "standard" lens as it has a FoV Field of View like the human eye
- more than 50mm (mostly 105mm), a telephoto lens Telephoto lens - Wikipedia, the free encyclopedia
Due todays crop factor on the D90 digital sensor and all other, -except full frame- sensors this values have shifted, but the principle is still the same.

Read both excellent articles above and you will understand the meaning of lenses and milimeters.

No, the 18-55mm lens is not very good under water, i have the 18-105mm VR lens and the corresponding port for it but i never use it as it is not good under water.

Most of underwater photography is made with WA (wide angle) or macro lenses.
AF-S is not a bad thing and the autofocus works very well on the D90

Chris

P.S. I love my D90 and think that she's a great camera for weight, build and image quality!

 

[John Gulliver]

1. TTL compatible means you can use TTL flash. With the instant feedback
of digital, you really don't need TTL.
Chuck

Perhaps not, but it's very useful IMHO. Under water, you often get only one chance to get the shot before the subject is gone and unless you are so skilled that you can be sure of getting the exposure right first time every time using your strobes with manual settings - I'm not - a good TTL system (like an Ikelite housing with Ikelite strobes) will save you a lot of disappointment. The manufacturers have gone to great lengths to give us this technology, so why not use it?

 

[marcaumarc]

I've had good luck so far with my D90 in the Ikelite housing and Ikelite strobes. It is pretty bulky, but it works. I think TTL is excellent to have for macro work. I have a few macro lenses, and I really like the 85mm that came out last year. I think Ikelite has a strobe now that also has a video light in it, so that might be worth looking into if you go with Ikelite.

 

[Viz'art]

Here is my take on TTL:

There is a law called the inverted square law that regulates light when it travels through air, the law state that whenever light travel it will lose strength, this can be measured by using the inverted square law, every time light will double its distance it will lose four time its strength, it does not matter what measuring unit are used (feet or meter), so for the sake of it, let’s take a subject located at 3 ft in wide angle and properly exposed it at, then if there is anything at 6 ft it will be getting 4x less light (and will be underexposed), if you light up the subject properly at 6ft. then you would need to go to 12ft to have 4x less light (and BTW, the subject at 3ft. is now getting 4 time more light and will be grossly overexposed).

In Macro, the same rule apply but the distance are radically shortened, a subject properly exposed at 3 inches means that if there is something at 6 inches, it now has 4x time less light, and let’s pursue this scenario a bit more, if the background is at 12 inches, then you will have 16x less light reaching it (that explain why many insect picture look like they are taken at night because the background is radically underexposed) and as mentioned earlier if you have any foreground at 3 inches (half the distance), then it gets 4x more light.

Now, you can break the rules, but not the law! Even if it is intended for top side photography taken through air and not for underwater where the density is +/- 800 times that of air, the basic principle that light falls off rapidly applies, it is just amplified and harder to quantify by the water visibility in which we are called upon to work in.

You probably noticed that in wide angle we were using much longer distance than in macro, the thing is, if you are exposing for a subject at 3ft, then you would need to move quite a bit in distance to influence the exposure, whereas in macro if you are shooting at a distance of 6 inches, then any small movement, like a few inches, will double or halves you exposure in no time, which is why TTL in macro and close ups is a real bonus and does make a difference in the number of keepers at the end of the day. As for regular wide angle photography underwater, well I could not care less for TTL, once you set aperture for your strobe exposure first and get your ambient light dialed in with the shutter after, you have definitely more leeway before a change in the strobe exposure is needed and if one is needed, this correction will be minimal (not so in macro where you can jump a stop or two in a matter of inches).

 

[Chuck Tribolet]

The D90 has no autofocus while recording video due it's mirror/af-sensor system.
The only useful way is to use a wide angle or fisheye and set it to infinite to use the huge DoF they have.

It would be better to set the lens at the hyperfocal distance (the
focus distance at which infinity is at the far end of the depth of field
for the chosen aperture.