Opinions from experience please

[dolesorchard]

Buddy's has a digital photo shop where you can rent a camera at a reasonable price. My wife and I were there for two weeks in Dec. and we came home with 1200 pictures.

 

[Warren_L]

Enough with the pixel-peeping. The most important part of this equation is the soft fleshy thing looking into the viewfinder.

The OP, being both new to diving and UW photography is not likely worried about whether he is losing image sharpness at f/22.

To the OP, if you're still even reading this far into your thread:

Bottom line, get yourself a camera you're happy with, compact or dSLR. Be comfortable with your dive skills first and your ability to manage the rig in the type of environment you wish to dive in, and then learn and grow with your system. Understanding your limits and the limits of your rig will help you make the most of your shooting.

 

[bvanant]

Get the tiny housing for your video (again) and show your friends how the UW world looks.
Bill

 

[davelew]

Bill, A Nikon D3100 has around 2,200 to 2,400 lph (which is pretty typical of that class of SLR), A Oly zx-1 has, 2,200 to 2,400 lph... humm resolution is actually the same... The best P&S resolution is the G10, in low ISO at just over 2,400 (but sucked at any high iso).

...

I guess it is too much to ask, but I wish that anyone using a camera do some homework, learn a bit about the technology and it's good and bad points and actually compare identical images, and then make judgements.

Have you actually compared images taken with a P&S with a small sensor to dSLR images?

I would be really surprised if the images on an XZ-1 with ten million pixels that are 4 square microns were comparable to the images on a D3100 with 14 million pixels at 25 square microns per pixel, especially once you get out of an optics lab and into real life.

Physically larger pixels help with many things out in the field, but I'll focus on three right now: etendue, diffraction limits, and blur.

Etendue is a mathematically derived law that basically says bigger sensors will get more light. If you focus the light down from any reasonably close object, and focus it onto a smaller sensor, you will lose a lot of the light's intensity. I personally don;t trust all the spherical trigonometry used in the derivation of etendue, but people (many of whom know more math than I know) haven't been able to violate the laws of etendue in the last couple centuries, so there must be something to it. Wikipedia has a good description of etendue.

I agree with you about how diffraction limits affect sharpness, but missed a key point about how this is relative to sensor size. There's a reason you can't shoot f/32 on an XZ-1 or any other compact camera. At f/32, the smallest detail at the image sensor will be about 500 square microns. That's about a 1 megapixel image on the D3100 (usable, but you probably don't want to blow it up to poster size), but a 0.09 megapixel image on an XZ-1 (basically, a thumbnail image). There's a good description of the relationship of diffraction limits here: Diffraction Limited Photography: Pixel Size, Aperture and Airy Disks

Finally, larger pixels help with blur issues. If an XZ-1 moves by more than 2 microns while the shutter is open, you will blur the pixels. A D3100 can move by 5 microns and not have any blurring, because the pixels are so much larger. Larger sensors can also tolerate other causes of blur better than small sensors. Basically, errors are proportional to sensor size; an XZ-1 taking a photo with a 5 square micron defect in the port (or swimming in the water) will see the same amount of blur as a D3100 with a 25 square micron defect. The same also applies to alignment of the camera to the port, especially a dome port, where errors cause problems proportional to the pixel size.

The larger pixels from cameras with larger sensors (SLRs, EVILs, and large sensor compacts like the Fuji X100) help images in many ways. Larger sensors are better than smaller sensors in every way except for cost, weight and power consumption. that's why cameras like the XZ-1 have the largest sensors available in a compact-- if smaller sensors were better as you say, wouldn't the XZ-1 have the smallest sensor available in a compact?

 

[Puffer Fish]

Dave, Obviously I have. Cambridge is a great site to learn from...thanks for posting that.

I keep posting that small sensor camera's cannot use large f-stops, for exactly the reason you have pointed out...but they don't need them.

I took my initial photography training from Minor White, but later spent a lot of time with large format camera's. Sadly, large format cameras are an accidental casualty of the digital age, and even Medium format camera's have gotten stupid in price.

On land, for most purposes, a larger sensor is better, but when you shrink the working space down to feet instead of miles, things change. When you look at studio shots (which are done at a distance close to what one shoots underwater images at, suddenly, it becomes almost impossible to tell the difference, and if people don't know, many will pick the small sensor image as better.

That is because, if you have done your reading on that site, depth of field is better, so the overall focus is better. (dpreview has hundreds to look at, just download and print to at least 13 x 19 and do your own blind evaluation). I've done several with different people and up until the last couple of years, everyone could tell the difference.. today, most pick the smaller sensor.

Blur... well that is why they now all have anti-shake, and don't forget the tremendous differences between a focal plane shutter and a leaf.

Oh, and you missed perspective changes, larger is better there.. well if one has a perspective issue, which one usually doesn't underwater, but does on land.

Yes, larger sensor get more light (obviously). And that requires each sensor to be more sensitive... tremendously more sensitive to even work. Obviously, they have managed to work that out or they would not work.

Can I tell the difference in a good DSLR image over a point and shoot.. on land, yes. Underwater, if wide angle, yes. Underwater, if just a fish image, no, and I take images for large prints.

Lens that are used on any Dslr would not work on the really good point and shoot cameras... they are very different in design, and depend on equal parts software and special lens designs. A good P & S lens is around 10x more accurate over any slr lens.. and it has to be to take even reasonable images.

 

[davelew]

Sadly, large format cameras are an accidental casualty of the digital age, and even Medium format camera's have gotten stupid in price.

You can get a used Yashica-MAT for much less than the cost of an XZ-1, so not all medium format cameras have gotten stupid in price, but I agree with you that most are quite expensive for what they are.

As for DOF, I think the key problem is that f/stop doesn't account for different sized sensors. A given aperture will always give more DOF on a small sensor, more light on a large sensor, and more diffraction-limited resolution on a large sensor. f/1.8 on an XZ-1 is about equivalent to f/5.6 on an APS-C sensor like in the D3100 in terms of DOF, photons per photosite with a similar intensity of light entering the lens, and the effects of diffraction limited resolution on lph. That's because the sensor on a D3100 is about three times the width of the sensor on an XZ-1.

 

[nudibranco]

Me not making sense is nothing new, sorry.

There are two good things about P&S camera's over interchangeable lens ones:

1. Depth of field at a given field of view and F stop. The SLR people would tell you they have better control of depth of field, and they would be correct, except that they need to, because they have so much less of it.

2. The second is a bit more obscure. All focal plane camera's maximum flash sync at something between 1/125 to 1/250th (that I know of). I believe the micro four thirds are 1/160th maximum (to lazy to go look, sorry). If you want to cut out ambient light, you just have to increase the F stop. But, depending on the lens, after around F8, the image will degrade. By F16, you still have a nice image, but from an absolute quality point of view (not an internet image) one is now something below a really good P&S. And if you let ambient light in (assuming one is shallow and in clear water), then you are limited to the stop action of that 1/160th (which is not that good for really fast moving thing).

An LX-5 can flash sync up to 1/4000... the new fuji and the Oly will 1/2000. It varies with the canon's but they are at least 1/500th. Truth is, they need that because they don't have large number F stops, and they don't have those because they would make really crappy images. But for fast moving, underwater animals, you can freeze things that cannot be frozen with a SLR.

But you typically only get that with the higher end models...

It is not all good, by the way, as it can produce what I call the frozen fish look...

I cannot agree more and cannot understand why people fight this truth about having the ability to synch at higher speeds the strobes on the P&S cameras.

I see it all the time during daytime shots that blur that come with synch speeds that are around max 1/160 as on most EVIL cameras (although on the Olympus you can synch up higher in super FP mode and UFL2 strobes).

I will take any day an F2.8 with a 1/2000 shutter speed on a P&S than a F11 with 1/125 on the Aps cameras. My chances of getting subjects without blur are much higher (especially macro ones) and my strobes save a lot of power. With the better compacts like the XZ1 shooting at 100 ISO the quality will be mostly undistinguishable from medium macro to super macro shots as long as you use them correctly.

Too bad that the Supermacro on the XZ1 is basically useless unless Oly understands that for UW use we need to fire the external strobe and flash sync. I hope they will fix that in firmware.

One thing that also seems to be understated is the ergonomics of the camera/case combo. Quick one button WB custom setting for example (which I hear is more than a few steps on the XZ1) or having a case that can really show high res and bright displays at an angle for easier shooting or just a couple of dial modes that will just go to some user customizable settings. The Ricoh GX models seem very nice in this respect and I am not sure why nobody else follows that lead.

Anyway this thread is very valuable and thanks to all that are posting their experiences.!!

 

[AussieByron]

So the biggest advantage of a point and shoot is its ability to have a higher sync speed than a DSLR to capture fast moving fish. I believe that Bvanant has provided with his image of the Juvenile Drum shot with a DSLR which according to Puffer said would very hard to get a shot of without any blur from a DSLR.

Here is my example of which I believe most people would agree are fast moving skitish fish.

Anthias: taken on D80 ISO100, f18,1/80th

Even with a slow shutter speed of 1/80th I was able to capture all four without blur.

To be honest most of my macro work involves critters which are not fast moving and most of the time not moving at all. The issue of capturing fast moving small fish in macro photography would represent a very small percentage. The versatility of the DSLR with its broader range of DOF allows one to be more creative especially shooting subjects using shallow DOF. The ability to change between different lenses like between the 60mm and 100/105mm macro.

regards Mark

 

[bvanant]

Dave,

On land, for most purposes, a larger sensor is better, but when you shrink the working space down to feet instead of miles, things change. When you look at studio shots (which are done at a distance close to what one shoots underwater images at, suddenly, it becomes almost impossible to tell the difference, and if people don't know, many will pick the small sensor image as better.

Really? I guess that's why all those studio guys shooting catalogs are selling there Phase One backs.

Go to the DXo website and look at the sensor rankings. Better yet go to 404 ERROR PAGE
and take a look. Smaller sensors are not as good as larger sensors, period. New sensors are better than old ones and resolution makes a difference.

As for image quality, we do this test in our lab all the time. Same setup, same photo, same studio controlled lighting. Phase One back on an old Hasselblad wins, Canon 1ds MK III next, 5DMII next, 60D next, 7D next (sad to here since that's what I shoot) and our lowly G10 always at the bottom. If you are interested in image quality, then get a bigger sensor. There are many reasons to shoot little cameras, like size, cost, ability to shoot both wide and macro on the same dive, but image quality isn't one of them, sadly. If it were then guys like David Dubilet and Paul Nicklen would be shooting S95s for Nat Geo. They aren't and its not because they can't afford them.

Bill

 

[nudibranco]

I do not think it is very useful to say that larger sensors are better for image quality. Everybody knows that.

But in practical terms with the latest compact size cameras you can get fantastic images underwater unthinkable a few years ago. And if you are mainly shooting macro (like low viz waters) a camera like xz1 has very little to envy to the larger more expensive setups while gaining in just about everything else... The image quality result in this case is 95% of what you can get. It will not be the very best - but going back to what the original post is about-well the chances are that you can get much more success rate in underwater shooting with a compact size one than a DSLR or EVIL camera. Dubilet will likely want the very best and will use bigger sensors cameras but I doubt the majority of beginner or medium experienced photographers will need to go to 100% to see image quality that shows only in VERY large prints or sophisticated photoshopping.

I think photo composition and original shooting can go a lot further these days than quibbling about sensor size...