Canon 20D - 100 mm setup

[Jeff Toorish]

Guys, thanks for the feedback here is what I posted to Alcina elsewhere. Does it clarify what I am having trouble with? I want to stay auto with TTL functioning but I don't get the shutter speed I want when I select a higher number F stop?

Thanks for the input, my issue is not with the shutter speed although you are right to suggest I use a faster speed. I have an eTTL II connection between my camera (through the housing) and the twin strobes. Based on this I assume I can get the maximum DOF using something like F16 - 22. The strobe/TTL combo should give me well lit pictures and use an acceptable shutter speed automatically. Unfortunately the strobes do a full dump putting enough light on the subject but then the shutter stays open for up to 2 seconds. There is something in the camera setup that I am missing and I am hoping someone can help me figure it out.

Here's what I think is happening --just speculating because I don't know exactly what your set up is.

The e-TTL works to, essentially, shut off the strobes once the camera senses there has been enough light. That's the concept of TTL.

I think, again speculating, that by shooting at f-22, there is just relatively little light getting into the sensor. Remember, f-22 is actually 1/22, a very small fraction. I know I don't need to go into focal length theory, but essentially the little light sensor in your camera just isn't getting enough light to send the signal to shut off the strobes.

Also, by keeping your camera on automatic, you must be shooting at a very slow shutter speed --and all to increase the depth of field in a macro lens.

Like everything else, depth of field is a trade-off, especially so in low light underwater situations.

Can you drop the light output of your strobes? That way, you would be starting with less light to begin with (from the strobes I mean).

Honestly, what you are trying to do is something that auto/ttl was not really designed for. I'd bet if you played around with manual a bit, you could achieve what you want.

I'm not really sure this helped, and again, much of it is speculation based on what I believe is going on.

Jeff

 

[bigfrog23]

first off you can shoot in manual mode and still use TTL the only different between AV and M mode is that you get to pic both shutter speed and Aperture. IF you use Av mode, you pic the Apriture and the camera chooses the shutter speed but if you are in low light and pic an aperture of f22 the camera will then chose a slow shutter speed to compensate for the small aperture. the only way to keep this from happening is to go into the Custom Functions and go to set the flash sync speed from auto to fixed. When you do this it will keep the shutter speed fixed on a set shutter speed no mater if you are shooting f22 or f8 while shooting with a strobe it will use the power of the strobes to correctly expose the image. when you are not using a strobe it will go back to picking the shutter speed for you. you can try this quickly at home using the built in strobe on your camera.

instructions on how to set a fixed shutter speed in Aperture priority/AV mode
1. go to Custom Functions (C.Fn) hit OK
2. in the custom functions go to Flash sync. Speed in Av mode press ok
3. in this C. Fn menu press ok once to highlight this 0: Auto then change it to 1/250 sec. (Fixed) press OK accept the change

one side question :icosm02: do you shots come out way over exposed? :icosm02:also do your strobes fully discharge when you take a picture if so you are probably not getting TTL. if you are getting a TTL exposure your strobes should be ready for the next shot instantly there should be almost no recharge time.

those strobe are very bright and you should have no problem shooting at f22-32 with those strobe and a fast shutter speed

 

[victor]

My issue has to do with the setup in the camera. I have set the camera on Aperture priority to increase DOF and the strobes flash, however the shutter speed still extends for 1 or 2 seconds. I am not certain how to configure the camera to accept the high number opening (F16 - 22) and do so with a 1/60sec shutter using the strobes for the lighting needed.

No idea of how much experience you have so appoligise if I am stating the obvious.
This sounds like your TTL is not functioning properly.
The shutter staying open for 2 seconds implies to me that it is not recognising that the strobes have fired, also the fact that the strobes have done a full dump, I assume you get this from the recovery time, that the camera has not switched them off when it has received enough light.

My recommendation would be to do some tests in a dark room.

You imply that this setup works at low f stops e.g. f8 I would be surprised given the symptoms you describe.

Set up your camera with the 100mm lens and a flash on a tripod, set a subject about 12 inches away. Set the camera to the same settings as you would underwater.
Take pictures at all the available F stop settings without changing any other settings.

All these pictures should be correctly exposed. If these are not correctly exposed then this needs to be resolved first.

Now set up the camera in its housing, with a strobe attached, exactly the same camera settings, and repeat the process.

All these pictures should be correctly exposed. If as I suspect they are not then we can go from there.

 

[PapaBob]

Just a few comments.

Anything that Alcina advises you can take to the bank.

I have a 20D in an Ikelite housing with twin 125 strobes. When I invested in this rig I went through the 60mm efs vs 100mm prime debate and decided on the 60mm for the basic reason Alcina alludes to. In a previous life I shot a Nikonos III with a close up kit lens over a 28mm to get many of my fish shots. The 60mm does quite nicely in this department...

...and you can even get some people shots with it.

So, in addition to macro I get a good close up rig. Just remember that, due to a 1.6 magnification factor with the 20D sensor plus the additional water refraction, this is not a substitute for a wide angle lens and dome port.

Your camera is working fine in aperture priority. If you use a flash in Tv or Av modes the camera assumes it is fill flash and still tries to expose for the background. This is why you are getting the long shutter times in Av in low light or at high f-stops. The custom function (CF) work around, as already suggested, is to set CF3 to lock the shutter speed into 1/250 sec which is the only shutter speed option for this CF. IMO keep your UW macro to the program “P” mode or the manual “M” mode.

I drift dive in S Florida and my buddies don’t photograph so I generally do not have the time to set up and dial in a shot. I have found that Program mode and ttl works fine for these “dive by shootings.” I set my image review to show the histogram since it is impossible (for me at least) to see how good the shot was on the review screen. The Ikelite housing has a neat strobe controller and buttons built into the housing that let me increase or decrease the strobe power if the exposure is not right on. If you can spend the time with a subject, or are not mixing macro and close up like I do, by all means shoot manual and dial in your exposure by reference to the histogram in the review display.

As previous posters have suggested, depth of field is always an issue in macro. Because it is so narrow, try to be aware of the plane of the camera to the subject. The following is an example of how the angle of the camera affects DOF.

Notice part of the feather duster is in the focal plane but the angle of the camera cut a part out of focus. Sometimes you cannot get the angle you want without crawling on or digging a hole in the reef, which is of course verboten, so you just try to be aware and do the best with the situation given.

Another trick is to set your Custom Function #4 to option 3. This allows you to use the “*” button (second from right on upper right hand corner of the camera) to toggle the focus and leaves the shutter button to fire the shot. You can use single shot or Ai Servo (I use both but tend to prefer Ai Servo) and on the Ikelite housing this lets me toggle the focus on and off with the thumb control and fire the shot with the index finger control when I think I have the focus nailed. Because of the narrow DOF, focus is critical and a moving subject or camera will throw you OOF easily. Try to nail the focus with each shot and take several of the same subject if possible.

Hope this helps a little.

—Bob

 

[Scubapearce]

first off you can shoot in manual mode and still use TTL the only different between AV and M mode is that you get to pic both shutter speed and Aperture. IF you use Av mode, you pic the Apriture and the camera chooses the shutter speed but if you are in low light and pic an aperture of f22 the camera will then chose a slow shutter speed to compensate for the small aperture. the only way to keep this from happening is to go into the Custom Functions and go to set the flash sync speed from auto to fixed. When you do this it will keep the shutter speed fixed on a set shutter speed no mater if you are shooting f22 or f8 while shooting with a strobe it will use the power of the strobes to correctly expose the image. when you are not using a strobe it will go back to picking the shutter speed for you. you can try this quickly at home using the built in strobe on your camera.

instructions on how to set a fixed shutter speed in Aperture priority/AV mode
1. go to Custom Functions (C.Fn) hit OK
2. in the custom functions go to Flash sync. Speed in Av mode press ok
3. in this C. Fn menu press ok once to highlight this 0: Auto then change it to 1/250 sec. (Fixed) press OK accept the change

one side question :icosm02: do you shots come out way over exposed? :icosm02:also do your strobes fully discharge when you take a picture if so you are probably not getting TTL. if you are getting a TTL exposure your strobes should be ready for the next shot instantly there should be almost no recharge time.

those strobe are very bright and you should have no problem shooting at f22-32 with those strobe and a fast shutter speed

Bigfrog, thanks for the input, you were spot on. I should have read your reply before calling Ikelite.

In the meantime, once again Ikelite shows why they are a great company to deal with. I ended up calling them and speaking with Gale (sp), he was able to get the correct info and call me back with the solution in less than five minutes.

For anyone using a Canon 20D with a macro and Ikelite strobes you need only go to the "custom configuration" dealing with the flash sync speed, set it for 1/250 instead of "auto". When using the "aperture priority" mode you can set your F stop to whatever you wish and it will allow the photo to be taken at 1/250 with the strobes providing sufficient light.