Digital's Advances?

Remember that I'm clueless, so don't beat up on me too much. I didn't see on the site if Infared photography was possible on Digital SLR technology? First, I don't know if it would be effective underwater or not for some expression, and wether digital had the capability of doing it?

Also, one other uneducated question. I don't know the term for it, but I'll describe what I mean. When some photographers take a picture of the clear sky at night focusing on the stars and they allow the shutter to remain open for a long time, they get the stars to be captured moving and a trail comes through on the photograph. I realize they are stationary and it takes a long, long time with stars. But does digital have this capability? And then can digital capture the same movement underwater? Like instead of capture a fast moving animal crisply in a perfect still shot, but instead slower capturing more movement over a longer distance (even if slightly blurred or not)?

Does this make sense? Do I need to elaborate more? Sorry for being so inept in terminology.

To the Moving stars:

Yes this is possible if your camera offers you that long shutterspeeds you need for stars.

Here a quick do it your self example: Go into a dark room (or try this at night). Light a candle. Set a long Shutter speed like 4" (shutter priority). Aim on the flame so that it is a small spot on the picture. release the shutter. move your aiming during this 4" but keep the flame inide the frame. Have a look at the result.

Simon

Remember that I'm clueless, so don't beat up on me too much. I didn't see on the site if Infared photography was possible on Digital SLR technology? First, I don't know if it would be effective underwater or not for some expression, and wether digital had the capability of doing it?

 

Also, one other uneducated question. I don't know the term for it, but I'll describe what I mean. When some photographers take a picture of the clear sky at night focusing on the stars and they allow the shutter to remain open for a long time, they get the stars to be captured moving and a trail comes through on the photograph. I realize they are stationary and it takes a long, long time with stars. But does digital have this capability? And then can digital capture the same movement underwater? Like instead of capture a fast moving animal crisply in a perfect still shot, but instead slower capturing more movement over a longer distance (even if slightly blurred or not)?

 

Does this make sense? Do I need to elaborate more? Sorry for being so inept in terminology.

The sensors in digital cameras are sensitive to infrared, so the cameras are manufactured in a manner that prevents infrared from reducing the quality of the image. It is possible to use them for infrared photography, but it may require camera modifications. Eric has played with this and offers this web page on the subject. Infrared is not very interesting underwater, though, as its penetration is very poor.

Regarding astronomical photography, I'm no expert but most of this is done with digital imaging sensors. The new Canons have a reputation for great quality at very long exposures, so they would be a candidate for this type of work. Again, though, I don't think this will be successful underwater except under very calm, clear conditions. There are fine examples of long exposure photography in underwater caves, but in open water I'm afraid the diffused glow of ambient light will be all you capture. Might be worth a try, though.

Yes, you can do infrared with DSLRs. I've seen it done in person, but I didn't pay much attention. The image came out quite nicely, though.

Yes, DSLRs can do long exposures. Star trails require extremely long exposures, often measured in hours as opposed to seconds and minutes. Long exposures with digitals do suffer more noise.

As far as motion blur underwater, it's no different than film. Same types of exposures. The problem is the same; subject motion blur vs. camera shake blur. Keeping an underwater camera motionless is much harder than on land. I've seen interesting shots using slow sync and rear curtain sync. Personally, they never appealed to me, but it is definitely possible.

Thanks for the Infared leads, that is very helpful!

Can you also point me to information on capturing bioluminescence underwater, from the range of the smaller agitated individual capture to larger fields.

Thanks again!!

I've found infrared with DSLRs to be pretty bad (the hot mirror filters used are very effective at removing most IR in light before it hits the sensor). I use a modified Nikon Coolpix 990, myself. It has had its hot mirror filter removed and replaced with glass approximating the same optical properties as the removed filter.

I've found older 2.1MP digicams to be much more sensitive to near IR than 3+MP cameras are.

I played with this with my Canon 10D recently:

The shutter times required are very long due to the IR filters inside the camera, 4-8 seconds (depending on ISO and f/stop etc) in bright daylight. Interestingly they're about the same in the shade (again on a sunny day). The aforementioned hot spot is also a problem.

Eric if you can post any information on getting a modified or modifying a consumer digicam for this purpose that would be very interesting, even if just as a novelty.

Sean: what filter did you use?

Here's a site that talks about removing the hot mirror filter in a Coolpix:

http://www.abe.msstate.edu/%7Ejwooten/came...mera/lense.html

It will be mirrored at my site soon, but it's there for now.

--

As a comparison to your 4-8 second exposure, here is a 1/135sec exposure at f4.4 with my modified Coolpix 990:

http://echeng.com/photo/infrared/gallery03...151002_6440.htm

(if you can't see the photo below, click above)

File: 030329_151002_6440.tif

File size: 335KB

Camera Model: E990

Date/Time: 2003:03:29 15:10:02

Shutter speed: 1/135 sec

Aperture: 4.4

Exposure mode: Program

Flash: Off

Metering mode: Multi-segment

ISO: 100

Focal length: 8.0mm

Image size: 675 x 506

White balance: Auto

User comments:

"An near-infrared action shot! Justin, Stanford foothills (modified Coolpix 990, #87 filter)"

I used the Hoya RM72 IR filter. I bought the 62mm for $75-ish; the 77mm (which fits most of my lenses) was close to $300!! So instead I bought some step-up rings, much cheaper, and with the focal crop there's no problem using the smaller filter.

The above shot was out of the camera and the auto-leveled in PS. I didn't convert to B&W because I liked the false-color effect.

Interesting site on the digicam mods. I wonder how easy it would be to mod, say, a Canon S30, which can be had mighty cheap complete with an u/w housing...

The modified coolpix gives a near b&w look with filters that block out all red light (like the #87 that I like to use). They are *slightly* green tinged out of the camera. I tend to convert them to b&w, which basically "cools" down the out-of-camera look a bit.

Here's a shot straight from the camera on auto-exposure, with a histogram in the upper-left hand corner of the frame (not converted to b&w or anything). You can see the green tinge in her hair.

File: 030507_145912_6473.jpg

File size: 671KB

Camera Model: E990

Firmware: E990v1.0

Date/Time: 2003:05:07 14:59:12

Shutter speed: 1/125 sec

Aperture: 4.9

Exposure mode: Program

Flash: Off

Metering mode: Multi-segment

ISO: 100

Focal length: 10.9mm

AF mode: AF-C

Image size: 2048 x 1536

Rotation: none

Image quality: NORMAL

White balance: AUTO

Sharpness: AUTO

I've just moved this to the Gallery because we're no longer just talking about Digital SLRs.

Couldn't help but throw some really basic IR pictures in. I had been wanting to get into IR but didn't want to spend money on filters until I knew I would like the outcome. I have a SonyF707 camera which takes night shots (via IR). The problem is that in daylight, the pictures are washed out which is why you need some filters. Instead of buying a filters, I looked around my desk for something that would suffice.

The following shots were taken with the F707 in nightsot mode with a 5.25 inch floppy filter. I took a floppy disk, cut it to fit in the lense, and took the pictures. The portion of the disk I used was te magnetic portion and not the spindle. The results aren't great, but I haven't played with the pics and the cam was set for full auto.

Oh well, just my 2 cents worth, literally

You had a 5 1/4" floppy on your desk?!? You must work for the Dept of Motor Vehicles or some equally cutting edge agency

Hey that is I nice tip, I think i'll sarch for my old 5,25" disks in the basment next weekend.

Simon