Nikon D70 & Lense Challenge

[gterrell26]

Last fall I decided to upgrade from a point & shoot to get a housing for my Nikon D70. After choosing Ikelite I selected a port for the original kit lense (18-70mm AF-S). It seemed to work ok. On a recent trip the lense AF hung at a particular spot and I lost a day's worth of photo ops.

Heading on another trip, I decided to upgrade my setup with a Nikon 18-135mm AF-S and buy a new port from Ikelite. Seems like I didn't make a good decision. Got down to the Caymans and the camera would not auto focus underwater. In AF-C (continuous) it would hunt for focus continuously, in AF-S (single) it would not even operate the servo to attempt a focus.

Anyone had any luck with a Nikon 18-135mm AF-S?

Based on some other threads seems like the zoom route was a bad decision on my part. Still learning the difference between land and reef.

Greg Terrell

 

[sea2summit]

Dumb question but where you using a focus light?

 

[gterrell26]

I was not, but I was attempting this in 2-15 ft of water off Grand Cayman. I couldn't get the unit to focus on the boat ladder. If I lifted it above water I could focus on shore 1/4 mile and the boat 4 ft instantly without issue. Drop down 2' could not focus on the ladder.

 

[John Gulliver]

I was not, but I was attempting this in 2-15 ft of water off Grand Cayman. I couldn't get the unit to focus on the boat ladder. If I lifted it above water I could focus on shore 1/4 mile and the boat 4 ft instantly without issue. Drop down 2' could not focus on the ladder.

I have no experience of digital photography under water - I'm still using 35mm - but it sounds to me as though there simply wasn't enough light for the lens to focus. As suggested above, a focus light would probably have solved the problem.
As regards zoom versus primary lenses: There are many good zoom lenses on the market today and many good u/w photographers prefer a zoom lens for general use, simply because you never know what you are going to see during a dive and there are so many other factors that influence the quality of the image that minor differences in the quality of the lens are much less important under water than on land. Using Tokina's 10-17mm fisheye zoom, a friend of mine who is a semipro recently photographed a 10m whaleshark, a couple of big potato cod and a pair of mating spansh dancers on the same dive! That said, there are also many zoom lenses with mediocre optics, particlarly among those with a wide range. I suspect your 18-135mm lens may not be one of the better ones.

 

[dbh]

Assuming you are shooting it behind a dome, you most likely need a diopter to focus any closer than 4'. MOST of the time when you shoot a rectilinear lens behind a dome, you need a diopter....usually around a +2.

That being said, the 18-135 can be used underwater, but not optimally. The wide end works best in a dome...the other end works best in a flat port. If you want a zoom, the Nikkor 17-55 and Sigma 17-70 are successfully being used underwater. My personal favorite lens for underwater use is the 60mm Nikkor. I can shoot everything from the head of a big animal down to a nudibranch.

Both of these were taken with a 60mm:

HTH,
Dave

 

[Mariozi]

If you are shooting behind a dome dbh is really right.
Domes create an "illusion" to your camera... they bring the infinite to a distance roughly 2 times its diameter... so if your lens cannot focus that close, it will never see anything in focus.
Hence why you need the diopter.

Prime lens (not zoom) usually focus a lot closer, and in a dedicated dome port usually dont need the diopter. Some zoom lenses with "macro" function selectable like Nikkor AF-D 24-84/2.8-4 Macro, can work without the diopter in the macro mode inside a dome.

 

[gterrell26]

DBH & Mariozi... thank you! I am certain you nailed it. I guess my eyes weren't in focus when reviewing the Ikelite port chart. I missed the all important * on the 18-135 (and my previous 18-70).

I evaluated the EXIF data on pictures from the last 2 dives (18-70 on one and the 18-135 on the latter). I also setup a little test scene with the lenses, the body, and a tripod in my basement to evaluate min focus distance at various zoom lengths an sure enough there was strong correlation between the 12" min focus distance and the small number of shots that came out focused. I had AF problems with the 18-70 before but since its min focus is inside 12" for some focal lengths I had not made the connection.

Thanks again for valuable insight on diopters, dome port, and lense selections!

Greg Terrell
East Lansing, MI USA

 

[danclem]

Hi Greg:

I shoot with a D70s and D300, and thought a couple of other points might be worthwhile considering. I have much better luck underwater with AF-S, rather than AF-C, especially if there is any backscatter or turbidity in the water. We took a Stephen Frink class in Florida last summer, and the concensus was to pretty much avoid continuous auto-focus.

Also, remember that your focal distances will be different on land than in the water. If you want to nail focal lengths, try some pool time with a tape measure for experimenting. One of the other issues with larger lenses is that there is a larger column of water between you and the subject that can cause a number of problems. You generally want to get as close as possible, so your 18-135 is really pushing it on the large end.

My favorite lenses are the 60 mm mentioned above, a 12-24 with a 2x diopter for my dome port, and a 12-17 Tokina for really wide angle.

Have fun and good luck!

Dan