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30D, DS125,160 not synching in Ikelite housing


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#1 emptech

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Posted 27 August 2010 - 10:34 AM

I like to use aperture preferred on the 30D for various reasons, mainly depth of
field and sharpness. Setting the cam for iso 800, using Ikelite DS160 and DS125,
strobes go off but the photos appear to have been taken with available light. I
took a photo into a mirror and see that both strobes are lit up.

I switched to shutter preferred, 1/200 sec, tried it again, and it works fine. I like
f22 and according to the tables, should be good for about four feet, and my shots
were well within that distance. I didn't try different f stops than 22.

With aperture preferred, the shutter speeds are quite slow, 1/50, 1/80, 1/100, etc,
resulting in blurred subjects, so the camera knows it didn't see the strobe.

I had this problem a couple years ago and can't remember how I solved it.

For now, I'll just choose shutter preferred.

I'm at Kona, Hawaii, diving on my third day here, first day, memory card errors,
changed memory card, should never have used a new memory card!

Second day, the flash problems, hopefully today I'll get some bugs out. Not new
to this, used Nikonos cams for years with strobes. Been using the 30D with a single
DS125 strobe but just added a DS160.

Jim

#2 Balrog

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Posted 27 August 2010 - 02:45 PM

I didn't think aperture priority worked with flash on Canon, not even the internal flash when used on land.

If you want to use automatic metering, set the camera to manual, choose your aperture, set the strobes to TTL and the Ikelite electronics will look after strobe power. You will also find that you can vary the non flash lit background exposure by changing the shutter speed.

You might also get crisper results at a lower ISO.

#3 Aussiebyron

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Posted 27 August 2010 - 08:04 PM

Hi Jim,

What lens are you shooting with? I use f22 and 1/200th when shooting with a 60mm or 105mm with the strobes in really close and the subject only a few inches away.

I agree with Balrog. Turn the camera onto manual and set the strobes to TTL and have the iso set to the lowest.

Regards Mark
Nikon D7000 with Aquatica housing called "Deedee", Tokina 10-17,Nikkor 60mm, Nikkor 105mm, Sigma 17-70, Ikelite DS161

http://www.flickr.co...s/22898788@N04/

#4 Andy Morrison

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Posted 28 August 2010 - 05:38 AM

The camera is trying to give you a balanced exposure between ambient light and your strobes, hence the slow shutter speeds when using a small aperature and lack of noticable strobe light. It's syncing fine I'm sure. This would explain why it appears to work better using shutter priority. It sounds to me like both modes are working as designed. Either shoot manual or set you camera to default to 1/200th of a second when using strobes, instead of auto, where it will pick the shutter speed. This should work with the Ike circuitry. I'd just shoot manual.

#5 bvanant

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Posted 29 August 2010 - 03:55 PM

The camera is trying to give you a balanced exposure between ambient light and your strobes, hence the slow shutter speeds when using a small aperature and lack of noticable strobe light. It's syncing fine I'm sure. This would explain why it appears to work better using shutter priority. It sounds to me like both modes are working as designed. Either shoot manual or set you camera to default to 1/200th of a second when using strobes, instead of auto, where it will pick the shutter speed. This should work with the Ike circuitry. I'd just shoot manual.

As I understand how AV priority with ETTL works, you select the aperture, and the camera sets the shutter speed as if there were NO flash present and then adjusts the flash for fill flash. This is why the guys at Canon suggest this is for weddings. In general in AV mode, only fill flash is calculated while the shutter speed is calculated on the ambient light.

Bill

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#6 emptech

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Posted 29 August 2010 - 07:37 PM

Followed advice from your responses, from this site and another. Shutter preferred worked but couldn't predict the desired f stop, went to manual, 1/200 @ f22, iso 800, seems to be happy.

Next improvement needs to be sharper photos, using a Canon 17-85mm lens with a +4 diopter. Kind of wish I'd be using a real macro lens, since most of my photos are within three or four feet of small targets. But, with a macro lens I'd be locked in and couldn't do wide shots.

Somebody suggested using an iso of less than 800 to get sharper photos, need to try that, unfortunately, after taking the shot, don't know how much of the strobe was used. Might try 400 for a few shots and look at the histogram?

Diving again in the morning, will work on some more shots.

Thanks for the comments and suggestions =

Jim

#7 secretsea18

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Posted 30 August 2010 - 04:56 AM

Followed advice from your responses, from this site and another. Shutter preferred worked but couldn't predict the desired f stop, went to manual, 1/200 @ f22, iso 800, seems to be happy.

Next improvement needs to be sharper photos, using a Canon 17-85mm lens with a +4 diopter. Kind of wish I'd be using a real macro lens, since most of my photos are within three or four feet of small targets. But, with a macro lens I'd be locked in and couldn't do wide shots.

Somebody suggested using an iso of less than 800 to get sharper photos, need to try that, unfortunately, after taking the shot, don't know how much of the strobe was used. Might try 400 for a few shots and look at the histogram?

Diving again in the morning, will work on some more shots.

Thanks for the comments and suggestions =

Jim


The problem with using ISO of 800 is that it increases the "graininess" of the image.

I am not sure what the "sweet-spot" ISO is for your Canon, but I usually use ~ ISO200, F8-40, 1/250sec for my Nikon (using all manual settings, including the setting on the strobe, too) doing Macro with my two IKE 125s, mere inches away from the subject, not feet away.

Closing down the camera distance to subject and ISO level will improve the sharpness of your "macro" images, and decrease any "crud" in the water column between you and the subject. If you are using your strobes on TTL, the camera will tell the strobe when to quench and exposure will be OK.

#8 whaleshark

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Posted 30 August 2010 - 07:03 AM

Hi Jim,

You've gotten some good explanations of why the strobes aren't providing enough light. The settings you're using are adequate for ambient light. There's enough light for exposure without much flash so the camera shuts the strobes down early. Take the camera out of program mode or aperture or shutter speed priority and use manual mode to control both shutter speed and aperture.

Set the ISO to your lowest setting, ie ISO 100. You should be able to tell how much light the strobes are providing by the color of your subjects in review. Subjects with in the range of the flash should have the full range of color. Everything beyond the range will be the color of the ambient light, blue for clear Caribbean water or green for temperate, California waters. If you use the histogram set it for RGB, not white luminosity and see how much red is in the scene. Red is the flash, blue and green is the water or ambient light.

Start by setting f-stop around f/5.6 or f/8 and a shutter speed to sync with your strobes. I use 1/125 sec with ikelite DS-125 strobes and an Olympus camera so you should be able to do the same, depending on the sync speed for your Canon. For close in or macro work stop the aperture down to f8, f/11 or even f/16. For wide angle reef shots open up the aperture to f/4 or f/2.8. If your shutter speed is 1/200 sec you'll get dark backgrounds on close-up work and it's faster than you need for wide angle shots. Try setting shutter speed to 1/100 sec, 1/125 sec or 1/160 max for most shots. If you want a dark background for close up or macro work, then set the ss faster, to 1/200 sec. A ss of 1/100 would be the minimum for most reef scenes to stop fish action but it may work for a wide angle lens (or even slower, like 1/80).

With my Olympus E-3 or E-330, and I suspect with your Canon, I have to set the camera to sync at one particular ss speed. If you choose one sync speed an then set the shutter speed for another setting, the strobes may not sync properly. Even if you can adjust ss after choosing the sync speed, you should be able to set the ss and leave it on one place, only adjusting the aperture as needed for subject distance.

Once you master using TTL in manual exposure mode you can advance to manual control of the strobes. Then you can do stuff like wide angle shots where you use 1/3, 2/3 or full strobe power to light up big fish in the foreground while setting the camera to expose for the ambient light in the background with wider apertures. I'm still learning to do this myself. But you should be able to get excellent results with your set-up using TTL and my suggestions above.

Good luck,
Dave

Edited by whaleshark, 30 August 2010 - 09:42 AM.

Dave in So Cal
Olympus E-3, E-330, C-8080, Olympus Zuiko Digital lenses: 7-14, 11-22, 14-54, 50 f/2, 50-200, Pan/Leica 25 mm f/1.4
Ikelite housing for C-8080 and E-330, dual Ikelite DS-125 strobes

#9 emptech

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Posted 30 August 2010 - 07:14 PM

I ended up shooting manual, the attached photo was shot at 1/125 sec @f22, iso 800, at "turtle heaven", Kona, Hawaii.
The puffer fish was deep in a hole, was unable to light up with both strobes, hence the shadow. I'd post the photo but a little confused, does wetpixel host the jpg or do I have to link to it from another site?

Problems solved as far as the strobes go, Canon seems to have a problem, just best to avoid aperture preferred.

Jim

Hi Jim,

You've gotten some good explanations of why the strobes aren't providing enough light. The settings you're using are adequate for ambient light. There's enough light for exposure without much flash so the camera shuts the strobes down early. Take the camera out of program mode or aperture or shutter speed priority and use manual mode to control both shutter speed and aperture.

<snip>



Good luck,
Dave


Edited by emptech, 30 August 2010 - 08:11 PM.


#10 Balrog

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Posted 30 August 2010 - 10:45 PM

... I'd post the photo but a little confused, does wetpixel host the jpg or do I have to link to it from another site?

Problems solved as far as the strobes go, Canon seems to have a problem, just best to avoid aperture preferred.

Jim


You can link images either way in this forum.
Upload to a site of your choice then link to the URL using the image button at the top of the post editor
- or -
Open up the attachment editor at the bottom of the page, then upload the image from your computer..

Canon don't really have a problem with aperture priority, it's just designed to do something different to what you think it should. If you read the manual, it's all pretty much explained.

#11 whaleshark

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Posted 01 September 2010 - 09:41 PM

I ended up shooting manual, the attached photo was shot at 1/125 sec @f22, iso 800, at "turtle heaven", Kona, Hawaii.
...
Jim

Jim,

Aperture priority will set the shutter speed for you based on the ambient light. Underwater there's usally enough ambient light for a correct exposure without flash so the camera sets the ss slow enough for correct exposure. It also shuts the strobe down early. But a slow shutter speed doesn't work underwater with moving fish, it doesn't sync with your strobe and ambient light is monochromatic (makes everything blue). That's why it's better to shoot manual mode, control f-stop and ss and let the camera control the strobe duration in TTL. With settings at ISO 100, f/5.6 and 1/125 sec, the strobe will usually provide lots of light, bringing out the full range of colors in subjects within the range of the strobe.

I can't see your photo yet. But assuming the exposure is correct you could adjust these settings for better results. Try shooting at ISO100. If this shot is exposed right, you could set ISO 3 stops lower at ISO 100 and use f/8, or 3 stops wider. This aperture should give you enough DOF and the lower ISO will give you less noise and cleaner images.

At f/22 the lens will likely produce some diffraction. This is true with most if not all lenses made for crop-sensor and FF DLSRs. Ansel Adams had no truoble shooting at f/45 (and 5 seconds on a big tripod) with his 8x10 format but with a smaller SLR format f/22 isn't the best option. It's not the sweet spot of most DSLR lenses. That sharpest aperture would be near the middle of the f-stop range, usually around f/5.6.

In TTL mode with the lower ISO you will get very close to correct exposure by choosing f-stops that are reasonably close for subjects within the flash range. If you're stopped down a little too much, you'll lose some shadow details. If you're too wide open, you'll blow the highlights. Watch the histogram in review for unwanted peaks at the extreme ends of the graph. Keep the peaks off of the shadow side and the highlight side of the histogram (either luminosity or the red channel in RGB). Adjust aperture as needed for the distance until you get exposure right.

My best advice is like what they used to say about film. Shoot with the same film speed until you know what it can do. For digital & flash, set the ISO to the lowest setting and leave it there. Leave your shutter speed at 1/125. Soon you'll know which f-stops to use for which distances.

Good luck and keep shooting.
Dave

Edited by whaleshark, 02 September 2010 - 04:40 PM.

Dave in So Cal
Olympus E-3, E-330, C-8080, Olympus Zuiko Digital lenses: 7-14, 11-22, 14-54, 50 f/2, 50-200, Pan/Leica 25 mm f/1.4
Ikelite housing for C-8080 and E-330, dual Ikelite DS-125 strobes