Those annoying spots...

[VACaver]

Taking what I hoped to be some nice shots while caving, I download them at home and find that there are spots all over. At the risk of sounding stupid, I assume these are dust particles reflecting the light from the flash.

After seeing really nice cave photos, are the spots digitally removed or am I missing some technique?

Thanks.

[ian mckenzie]

The spots might be flash reflections off water droplets (mist) in the air. They are easily removed using the Clone Stamp function in Photoshop.

[VACaver]

Thanks for the reply. Now all I have to do is figure out how to work Photoshop

[NZcaver]

Generally speaking, using a remote slave flash can help to eliminate those spots too. Plus it gives you more light in your shots, and some different lighting options.

For somewhere around $60, you can get a Firefly slave like those often used by cave photographers. You'll still need a separate flash to connect it to. A cheaper way to improve your caving "snapshots" might be to get a $20 mini slave flash like this from Ritz Camera -

http://www.ritzcamera.com/product/531660769.htm

When using a digital camera, just be aware that it probably fires 2 flashes in quick succession. The first one sets the white balance, and the second illuminates your shot. Most slave flashes (like the Ritz one) will go off with the first flash instead of helping to light your shot. Check if your digital camera can be set to fire its flash only once, and if so you'll be fine. If not, you can maybe hunt around for a different slave unit that can be set to "ignore" that first flash - they do make these.

Have fun!

[Dave Bunnell]

More thoughts:

I would expect dust to produce more discrete spots, and water vapor to produce more of a fog. You could also have gotten some dust on the lens.

Reflections from dust in the air or fogging would be reduced by off-camera flash. If you are using the oncamera flash to trigger remote ones, turn it down to its lowest power.

In any event, its always a good idea (assuming this was digital) to zoom in to highest magnification after taking your photo to look for stuff like this, and especially to verify focus.

Finally, the best photoshop tool to remove spots, if you have the CS or CS2 version, is the spot removal tool. Much easier than the generic clone stamp.

[itabot]

These spots?

Check if your digital camera can be set to fire its flash only once, and if so you'll be fine. If not, you can maybe hunt around for a different slave unit that can be set to "ignore" that first flash - they do make these.

Do you know of any places that sell a flash that will ignore the first flash?

I use a digital camera that has the pre-flash that you can't turn off. It has an external flash that attaches to the camera. You can turn the camera flash off and only use the external, but I don't know if the external has the pre-flash. I haven't used it yet.

[Dave Bunnell]

Yeah, those look like reflections off dust to me and the off-camera flash should eliminate those.

As for slaves for use with digicams that have pre-flash, Firefly has just introduced a new version (firefly3) of their popular slave unit that has this feature:

http://www.fireflyelectronics.co.uk/pag ... tm#BF1SPEC

They are much pricier than the firefly2, 60 pounds or about $90 on the website direct.

Peter Jones (pjcaver@gwi.net) is the USA distributor of firefly, I don't know if he has them yet or not.

As for flashes with built-in slaves (much less versatile because the sensor can only point one way), Vivitar has one called the DF200 for about $70 street that has varipower levels and a GN of 92 at ISO 100. There are also lots of small flashes with these slaves but many are quite weak.

Happy shooting.

Dave

[NZcaver]

...It has an external flash that attaches to the camera. You can turn the camera flash off and only use the external, but I don't know if the external has the pre-flash. I haven't used it yet.

I doubt the external flash gives you a pre-flash. Since you have the ability to turn off the built in flash and use the external one - do that. That's what I do with my Olympus C-5050 zoom. Hold the flash out at arms length, connected to the camera by a cord. You can also use a regular slave flash or two as well if you choose.

Dave is quite right about the limitations of some of the cheaper slave flash units. The one I mentioned should be used just as a fill-in flash, at best. The slave sensitivity is only good for a relatively short range, but it does have a 360 degree sensor on top. It can also be manually fired if you are doing a time exposure. Another alternative to the big-dollar Firefly slave can be found here -

http://www.caves.org/phpBB2/viewtopic.php?t=457
I got a couple recently. They seem great, but I haven't used them underground yet - that will be later this month.

[itabot]

As for slaves for use with digicams that have pre-flash, Firefly has just introduced a new version (firefly3) of their popular slave unit that has this feature:
http://www.fireflyelectronics.co.uk/pag ... tm#BF1SPEC
Dave

So this is a "slave unit" that you would attach to a flash?

I doubt the external flash gives you a pre-flash. Since you have the ability to turn off the built in flash and use the external one - do that. That's what I do with my Olympus C-5050 zoom. Hold the flash out at arms length, connected to the camera by a cord. You can also use a regular slave flash or two as well if you choose.

I have the Olympus C-4000 Zoom. I don't have the external flash yet. How well does it work. Does it light up a pretty big area?

[Dave Bunnell]

Yes, the Firefly connects to any flash with a hot shoe on it.

I wouldn't spend the bucks for the dedicated Olympus flash if your main interest is cave photography. You pay a lot for dedicated features and autoflash capabilities, but mostly you just want a good generic, variable power flash like the vivitar 285, or sunpak 383, all about $75 or so mail order or shop for used ones on ebay. I get all my strobes there now, usually for half the cost of new or less. The cat's meow, for twice the cost, is the Sunpak 120j. Bare flash capability like a bulb and high power but still uses 4aas...and probably still cheaper than the Olympus dedicated flash.

Dave

[NZcaver]

...I wouldn't spend the bucks for the dedicated Olympus flash if your main interest is cave photography. You pay a lot for dedicated features and autoflash capabilities, but mostly you just want a good generic, variable power flash...

Right on! After seeing the ridiculous price of dedicated Olympus flash units, that's exactly what I did...

Don't waste money on a $40+ Olympus flash cable either - just get a generic one from a camera shop, eBay, etc.

[rcoomer]

In order to get rid of the spots, you will need to either get the flash off your camera completely, such as on an off camera cord, block it with an infrared filter (old piece of developed film leader), or use a flash with an adjustable head.

The reason for the spots is that the flash is reflecting back into the camera lens from dust particles in the air from a flash that is pretty close to being inline with the lens. So any flash firing from the vicinity of the camera will do this, slave or not. If your on camera flash fires to trigger a slave, it will still cause spots.

So you either have to use an external flash on a cord long enough to get it away from your camera, mine is about 3 feet long, or use slave flashes away from the camera. To trigger these slaves, you will need to fire the front flash either from the cord, or aim it at the ceiling or some other direction so the slaves will see it but it will not reflect back to the camera. You can also block it with a piece of developed but not exposed film. That will stop the light but allow the infrared through to trigger IR slaves.

If your camera is capable of long exposures, just use open shutter techniques. Set your camera on a tripod, turn out all lights, open the shutter for at least 5 seconds or on bulb setting and then fire the flashes by hand anywhere you want as many times as you want as long as your shutter is open.

[NZcaver]

In order to get rid of the spots, you will need to either get the flash off your camera completely, such as on an off camera cord, block it with an infrared filter (old piece of developed film leader), or use a flash with an adjustable head...

The infrared flash filter idea works great with regular film cameras, but may or may not cause a problem with digital cameras. Digitals pick up IR light, you see. Try turning on your digital camera screen, point your TV remote at it, and push a button. Neat trick, huh? Having said this, you'll probably still get good results with a digital and IR flash trigger IF your other flashes fully illuminate the shot, particularly in the foreground. Just thought this should be mentioned, that's all.

...The reason for the spots is that the flash is reflecting back into the camera lens from dust particles in the air from a flash that is pretty close to being inline with the lens. So any flash firing from the vicinity of the camera will do this, slave or not. If your on camera flash fires to trigger a slave, it will still cause spots...

Agreed. However when I was using an old crappy snappy digital, I found my extra slave flash did eliminate most - if not all - the dust spots in my shots. Even with the built-in flash firing as well. These days I do exactly what you recommend - use the 3 foot cord at arms length, often use slave flashes, and use a tripod for time exposures.

[itabot]

So you either have to use an external flash on a cord long enough to get it away from your camera, mine is about 3 feet long, or use slave flashes away from the camera.

I've looked for a longer cord. The Olympus cord is pretty short. Do you know where to get a longer cord? If it's just wires, can you splice it, and make even longer?

[rcoomer]

The infrared flash filter idea works great with regular film cameras, but may or may not cause a problem with digital cameras. Digitals pick up IR light, you see. Try turning on your digital camera screen, point your TV remote at it, and push a button. Neat trick, huh? Having said this, you'll probably still get good results with a digital and IR flash trigger IF your other flashes fully illuminate the shot, particularly in the foreground. Just thought this should be mentioned, that's all.

Actually I don't believe they are much more sensitive to IR than normal film. Normally to capture IR you need an IR filter to eliminate all other light or a sensor/film that is only sensitive to it, The IR is there anyway, it's just not noticeable in the full spectrum. Have you ever seen an IR flashbulb? It's just a coating to filter out the rest of it's light and only allow the IR through. Most digitals have a filter over the sensor to limit the IR they see. . . that's why IR exposures are generally pretty long unless on digital cameras you have a night shot IR mode on your camera. The built in slaves on the Canon flashes are IR based I believe, definitely not radio slaves.