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A short fat well off crap cave diver. Likes wrecks
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Discussion Starter · #1 ·
OK: I have a Canaon ixus 750 in a Ikolite 60m housing with a Sea and Sea SY 110 strobe on a 500mm arm. I am using a wide angle lense

When i use the strobe I am finding it just bleeches out the subject. I tried it on min (which i asume is minimum power) but that didnt help.

Some pics were just a white out but others that were useable just had too much reflected lite.

Any help please an remember I am reeeeeeeellllyyy a novice at this.

ATB

Mark Chase

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"Look mate, the problem's between the user and the
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2,711 Posts
looks like shutter speed is too slow or appeture is wrong...

OR.....

are you using an auto setting on the camera? if so (and my assumptions are right) then it will be taking the shot without the knowledge of the strobe... hence you are providing too much light as the strobe fires with more umph than the internal one...

If thats right then you can compensate by going old school :D with the settings....

[assumption- fibre sync cord/optical trigger]
 

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aka Chimp 1 or Mavis...
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10,108 Posts
Mark,

I would set the camera up in manual and approximately the following settings:

ISO 100-200
Shutter: 1/20
Aperture: f6.7
Flash: Full Power

This image was taken with the above settings using a SS200 strobe on a 12" arm with the strobe directly above the dome port but slightly back from the 'film plane' at 50m last week. :D



If the image is blown out you have the following options - move away from the subject, increase the f-stop number (make the hole smaller) or turn the strobe down

If the subject is under-exposed, reduce the f-stop or get closer, or increase the ISO (but not too high or the image will be grainy)

The aperture varies the 'effect' of the flash, the shutter speed varies the ambient light in put. Shutter speed will not have a major effect on the overall lighting of the subject, it will show up as a moving ghost if too slow but 1/20-1/60 will be fine for pretty much everything you will shoot.


This was taken with 1/15, f5.6 (because he was further away) and ISO 400.

Finally, shot everything in RAW until you get the hang of things, you can make a semi-decent recovery in PS if you shoot RAW, shoot jpeg and you will have a much harder job of it.

HTH
 

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Open Wide
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Mark,

I would set the camera up in manual and approximately the following settings:

ISO 100-200
Shutter: 1/20
Aperture: f6.7
Flash: Full Power

If the image is blown out you have the following options - move away from the subject, increase the f-stop number (make the hole smaller) or turn the strobe down

If the subject is under-exposed, reduce the f-stop or get closer, or increase the ISO (but not too high or the image will be grainy)

The aperture varies the 'effect' of the flash, the shutter speed varies the ambient light in put.

Finally, shot everything in RAW until you get the hang of things, you can make a semi-decent recovery in PS if you shoot RAW, shoot jpeg and you will have a much harder job of it.

HTH
? shutter at 1 /20? Would you not struggle to capture anything moving with this long an exposure?

Does the Ixus do RAW?
 

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aka Chimp 1 or Mavis...
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? shutter at 1 /20? Would you not struggle to capture anything moving with this long an exposure?

Does the Ixus do RAW?
The strobe has an exposure of 1/10 000 second so you would have to be moving pretty quickly!!

You can set a higher shutter speed but the background will be really dark/black, if you have a slightly slower shutter speed you allow some of the ambient light to be captured but the flash freezes the foreground/subject. Obviously you have to have some semblance of bouyancy control/motion control so that you aren't swinging the camera around the scene :D

Nope, sorry the Ixus 75 doesn't do RAW. Mark, you will just have to make sure your exposures are a little more spot on!! :)
 

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Open Wide
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Ta, not got a strobe, so only familiar with ambient light, well in truth, very low light down a microscope photography! Anything below 1/100 and pictures of root canals become blurred, but too much above it and they are too dark. I could add a strobe to my set up for both fish and teeth, but gets expensive.
 

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aka Chimp 1 or Mavis...
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The shots I posted were from my 10th and 3rd (respectively) dives with a strobe. Up until then all my shots had been with ambient light (which to a certain extent) is why I use B&W to hide some of the noise.

In addition, using a 10mm lens also makes slower shutter speeds more acceptable.

Regards
 

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Open Wide
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Well they are bloody good.

When I put the ISO up above 400, it goes to 3200 on the underwater camera it's way too grainy. I prefer 400 and below for an acceptable image. But then you need light.

I guess a strobe will be next on the shopping list, especially for UK diving.
 

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A short fat well off crap cave diver. Likes wrecks
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15,343 Posts
Discussion Starter · #12 ·
OOOOOOOOOOOOOOOKyyyyyyyyy

Yes I have the Ixus set on Auto. The strobe i have tried to set to minimum but obviously that dosent work so Ill try manualy setting the camera

This is going to be interesting:(

So far I have only used point and shoot in blue water so its obviously going to be an up hill struggle to justifie the money I have spent.

ATB

Mark
 

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aka Chimp 1 or Mavis...
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10,108 Posts
OOOOOOOOOOOOOOOKyyyyyyyyy

Yes I have the Ixus set on Auto. The strobe i have tried to set to minimum but obviously that dosent work so Ill try manualy setting the camera

This is going to be interesting:(

So far I have only used point and shoot in blue water so its obviously going to be an up hill struggle to justifie the money I have spent.

ATB

Mark
You can practice most of this in the lounge with the lights turned off and the strobe set to half the power you would use underwater. Or rather whatever works in the lounge, double the power when you are underwater to take into account the absorbtion of the water and particulant. eg if you used 1/20, f6.7, ISO 100 and half power in the lounge, use full power or f4.5 or ISO 200 when underwater.

You can also use this to work out the placement of the strobe but as a starter I would put it above and behind the port (probably in the region of a fist height above the housing)

If you need any more info Mark, just drop me a line or post on here.
 

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aka Chimp 1 or Mavis...
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Mark Milburn
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I don't know the Ixus 750.

Basically the camera doesn't know you have a strobe attached unless they are connected by a wire (TTL).

So you have to tell the camera to work with more light.

The easiest way is to change the ISO to something low, like 100 or 80, it'll be running a lot higher normally.
 

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All hail the mighty ZOM
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The 750 is about the same as my 700.

Take it off Auto mode and set the exposure to -1 then try shooting again. You don't have all this manual kerfuffle all the photo spods are blathering on about, just a +/- exposure doo dah. The camera is setting itself up for light from the internal flash and you're blasting it with a load from the external strobe so you need to compensate for this by reducing the shutter speed which is what the - thingy does.

Also fit a diffuser over your strobe. I made a very effective one from a bit chopped out of an old Tupperware box held on with bungee.

Mind you I've not played cameras much recently. I did do a little 1 day course which helped tremendously. Generally you're better under exposing shots then arsing about in software to correct it. No RAW mode on the IXUS so shoot in max res, min compression mode, ISO 100 or 200. 400 has too much noise (unless you are GLOC in which case you cheat and use B&W to correct your kak-handedness ;))

If you need any more help in plain english rather than f-stop bollox then let me know.
 

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Mark,

a lot of what has been said before is true - the camera doesn't know about the external flash and calculates an exposure without taking the extra light into account sou you're certain to have parts of the shot over exposed.

If your camera supports manual and can show you an exposure histogram after the shot has been taken, then a little time spent learning how to do this will reap huge benefits. As you've already spent loads of cash another £25 is but a drop in the ocean - buy "The Underwater Photographer" by Martin Edge. Read it and practice in a pool.

Here's an example of what I was getting using an Oly 5050 and YS 90 external strobe using the auto settings:




I decided that digital was [email protected] and was going to flog the housing and go back to my Nikonos IV, but fortunately I saw the light :) and followed the advice in Martin's book. Using the same camera, in the same place (Sharm) but 6 months later, these were the result:










I no longer think all digital cameras are rubbish :) it was me :D

If you've still got my email from the gliding, drop me a line and I'm happy to chat about this.

Cheers, Chris
 
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