Wednesday, November 19, 2008

Epoque DCL20 Wide angle lens review

Loose thoughts by Bjorn Landfeldt

So, I bought an Epoque DCL20 wide angle lens in New York a week back and had the opportunity to take it for a dive last weekend. Before I bought it, I could find no information about its performance on the web so it was a bit of a gamble whether to buy or not.

These are my initial thoughts without having had much time to really conduct experiments.

The lens is not very big, it doesn't really add much to my Ikelite and strobe arm setup for my G7, it adds a few hundred grams but that's pretty much it. The thread is so large and well defined it is easy to screw the lens on the port under water, I don't think there is much risk of damaging the thread with clumsy thick gloves etc.

The lens magnifies about 0.56 x so the angle is quite wide. My G7 has a 35mm equivalent of a 35 mm lens so I get about 19mm focal length (in 35 mm) with the Epoque attached. This is wide enough for the Ikelite standard port to get in the way and the result is vignetting (probably lots). I therefore also purchased the replacement port from Ikelite which is about 10mm shorter than the original port. There is a small limitation in the amount of zooming in one can do with this port because the lens eventually hits the port, but this is beyond the zoom when one can still focus in macro mode so I can't imagine it would be missed by anyone.

Above water one gets a bit of a shock when attaching the lens and taking a shot.

The first photo was taken without the Epoque at 35 mm (equiv.) and the second photo was taken at the same setting with the Epoque mounted. There were a couple of things I noticed straight away that worried me quite a lot.

First, there is obviously the barrel distortion to take into account. I was wondering what this would look like when taking photos under water. Second, there is significant softness around the edges (actually gradient from fairly much the center). Third, there is still a bit of vignetting happening. One obvious thing I noticed was the fact that the Ikelite housing has a pretty shoddy make. The camera is not centred in the lens barrel and when I first got the housing I had to cut of a lot of the light masking foam around the lens. With the Epoque mounted I get big black vignetting parts on the left side of the barrel and nothing on the right side. I lose quite a bit here since it means I have to crop much more to get rid of the vignetting.

So what happens under water?

I am pleased to say that my concerns are largely invalid when the lens comes in the water. First, I wanted to see what the coverage would be and how much distortion there would be so I took a few maximum wide angle photos of different things.

The visibility of the day was not too bad, probably about 8 or so meter (~24 ft) but there was a lot of particles in the water. The first photo would have been taken at about 3m from Taso and one can see that there is a lot of coverage at that distance and the diver is well defined since the distance is quite short.

Also, there is little evident barrel distortion in the photo. I then took some photos at closer distance and also tried to take some close up with the Epoque still attached. There was little evident distortion even at closer distances but closeups were heavily affected by the wet lens.

In the closeup of the snail one can clearly see how much blurring there is of the photo surrounding the snail. It doesn't look too bad in this specific photo, but it canreally make things bad.

So, all in all, I am looking forward to playing around much more with the lens and get a better understanding of what it can do and where there are limitations.

Saturday, November 8, 2008

Automatic BCD???

Loose thoughts by Bjorn Landfeldt

A pair of undergrad students presented the outcomes of their thesis work on an automatic BCD in early October at the UNiversity of Auckland (Mechatronics).

The (invention) is a control system for managing ascents and descents of divers using an embedded system and a control loop for the inflation circuit. Apparently, there is also what is known as a cruise control whereby the (pilot) sets desired depth and the circuitry maintains that depth.

To me this sounds like a pretty stupid idea for a number of different reasons such as:

1) Increased reliance on equipment, especially for new divers who might be in a very bad position if the circuitry fails
2) One more point of failure (actually several)
3) Need to bring batteries for the BCD on a dive trip (or do you hook it up to 240V and charge overnight?)
4)Costly circuitry and mechanical control components
5)Completely unnecessary, buoyancy is a necessary skill to learn anyway and it needs to be practiced

I wonder what George Irvine III would say? Unnecessary Crap perhaps!

Leisurepro shop

Loose thoughts by Bjorn Landfeldt

So, I finally got to go to New York and visited Leisurepro's shop. It is tucked away on top of ADORAMA photography run by the same owners. After one has been shopping for dive gear on their web site for a while, and experienced the massive range of gear they carry, the shop is somewhat of an anti-climax. I fully understand that real estate on mid - lower Manhattan is pretty expensive contrary to the impression Macy's gives. But, the 40 or so sqare meters of Leisurepro shopping experience is pretty dismal. In the shop itself there is nothing to look at apart from a handfull of items so one has to be prepared when going there. The idea is to shop on the web first, and print out a list of items to look at. Presenting the list to the staff and the stuff comes up from the basement if it is in stock. Then you can see the things you are interested in up close.

So, what's the verdict?

Leisurepro serves a purpose, cheap prices for gear when one knows what to get. However, the shopping experience is far from satisfactory, if one wants some advice or just to browse this is not the place, there are many dive shops that do a much better job at this. I guess you can't have everything.