Are all Oly flashes confused with close range RC?

Started May 24, 2012 | Discussions
veesah
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Are all Oly flashes confused with close range RC?
May 24, 2012

In a previous thread ( http://forums.dpreview.com/forums/readflat.asp?forum=1041&message=41460525 ) I found that the E-P3's flash controller signals were contributing to TTL calculations at close range and causing the camera to underexpose flash exposure when using the FL-300R.

Is this issue consistent on other Oly bodies and flashes? I'm wondering if it's related to the stripped down FL-300R or if it's inherent to all Oly RC gear.

Olympus PEN E-P3
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ginsbu
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Re: Are all Oly flashes confused with close range RC?
In reply to veesah, May 24, 2012

I commented in the other thread but may not have mentioned that my flash is a Metz 48.

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veesah
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Re: Are all Oly flashes confused with close range RC?
In reply to ginsbu, May 24, 2012

I commented in the other thread but may not have mentioned that my flash is a Metz 48.

Aah, then this is leaning towards a general issue in the Oly RC system..

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Guy Parsons
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Re: Are all Oly flashes confused with close range RC?
In reply to veesah, May 24, 2012

veesah wrote:

In a previous thread ( http://forums.dpreview.com/forums/readflat.asp?forum=1041&message=41460525 ) I found that the E-P3's flash controller signals were contributing to TTL calculations at close range and causing the camera to underexpose flash exposure when using the FL-300R.

Is this issue consistent on other Oly bodies and flashes? I'm wondering if it's related to the stripped down FL-300R or if it's inherent to all Oly RC gear.

Tell me again, what distance from camera to subject are you talking about?

Later (probably much later) I can experiment with my E-PL1 and FL-36R to see what happens - if I know a range of distances and the test setup to use (where flash is in respect to camera and which way the flash is pointed, at subject or at reflector aimed at subject?) .

Regards......... Guy

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veesah
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Re: Are all Oly flashes confused with close range RC?
In reply to Guy Parsons, May 24, 2012

Tell me again, what distance from camera to subject are you talking about?

Later (probably much later) I can experiment with my E-PL1 and FL-36R to see what happens - if I know a range of distances and the test setup to use (where flash is in respect to camera and which way the flash is pointed, at subject or at reflector aimed at subject?) .

Subject is about 3ft from camera. Flash fired at a wall behind camera. Underexpose the ambient and let RC TTL figure out appropriate flash exposure. For control, put FL-36R on camera and rotate backwards. For actual test, hold the flash pointed backwards about 1 ft in front of the camera (i.e. within line of sight of the on-board flash) but out of the scene.

Detailed test procedure is here: http://forums.dpreview.com/forums/read.asp?forum=1041&message=41572012

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Guy Parsons
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Re: Are all Oly flashes confused with close range RC?
In reply to veesah, May 24, 2012

veesah wrote:

Tell me again, what distance from camera to subject are you talking about?

Later (probably much later) I can experiment with my E-PL1 and FL-36R to see what happens - if I know a range of distances and the test setup to use (where flash is in respect to camera and which way the flash is pointed, at subject or at reflector aimed at subject?) .

Subject is about 3ft from camera. Flash fired at a wall behind camera. Underexpose the ambient and let RC TTL figure out appropriate flash exposure. For control, put FL-36R on camera and rotate backwards. For actual test, hold the flash pointed backwards about 1 ft in front of the camera (i.e. within line of sight of the on-board flash) but out of the scene.

Detailed test procedure is here: http://forums.dpreview.com/forums/read.asp?forum=1041&message=41572012

Sorry, didn't get that far into the other thread, have to go out now and will try my FL-36R when I get back in a couple of hours.

Regards......... Guy

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DrummerBL
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Re: Are all Oly flashes confused with close range RC?
In reply to veesah, May 24, 2012

I use RC flash (Olympus and Metz) very often, but I always shot it all manual...camera and flash. Usually two or three test shots and it's nailed. I love it.

Bruce Lehman

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Guy Parsons
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FL-36R test done
In reply to veesah, May 25, 2012

Back again from shopping.........

With E-PL1 and FL-36R:

Flash backwards on hot-shoe, RC control TTL, subject varying from maybe 1.5 feet to 3 feet all perfect exposure at varying focal lengths.

I always find that the slave flash works fine in the hot-shoe as stray light bouncing from the E-PL1 pop-up always gets to the sensor in the slave. Line of sight really only needed for the very distant slaves.

Room light a bit bright so I put camera on Manual with 1/160 second and f/22 (to really strain the flash and make the ambient exposure negligible). Wall behind at about 3 or so feet, wall painted a dull sandy colour and not white, so the conditions were a bit awful.

I could get correct exposure at all distances from the camera right up to closest focus with the kit lens.

All I can think of is that the smaller output of the FL-300R just does not allow bounce under the conditions you tried. Bounce off a ceiling usually knocks light down by about 2 or so stops, and bounce from behind the camera maybe more stops loss if the wall is a bit more than a few feet back, or a non-white colour. Maybe a big white reflector (say, one of those 4 foot springy disk reflectors, or a big sheet of white cardboard) much closer to the back of the backwards facing flash head would make a big difference.

Summary.... RC TTL does work at any distance, but some flashes may not be able to handle the light loss of bounce work.

Regards........... Guy

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Guy Parsons
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More... redid test
In reply to Guy Parsons, May 25, 2012

I turned on my brain a bit later and realised that my use of f/22 to dim the ambient was a bit wrong as the control flashes alone are so weak that at f/22 I could not get much exposure from control flash alone at all at a couple of feet.

So this time kit lens around 25mm and f/4.4 and subject (my hand) about 1.5 feet or so in front of the camera.

Case 1 (#393). FL-36R off, control flashes only make for a very underexposed subject.

Case 2 (# 396). FL-36R on, both control flash and rear facing bounce flash hitting subject, looks a bit bright on the LCD but was more like decent exposure when seen on screen and histogram, but with a tendency for highlights to be blown in the skin. That setup really needed the TTL to be wound back a bit.

Case 3 (#397). FL-36R on, but this time blocking the control flashes from hitting the subject with my other hand, this time the result is underexposed but does show skin texture better, a more workable result, should have TTL setting boosted a bit.

Left is control flash alone, middle is control flash and bounce, right is bounce flash alone and control blocked.

Holding my hand in the right place all the time varied a bit but from a few repeats this set of three shows what happens every time for me.

Sort of makes sense to me, at very close flash distances then timing does matter as it takes a very short time for light to bounce around but circuitry might take a bit longer to control it (more likely to over-expose at close distance). Haven't got a 20mm lens so can't duplicate what would happen at f/1.7

For me it was unexpected how underexposed the blocked control signal shot was.

Regards............ Guy

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Guy Parsons
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Invalid previous tests, possibly
In reply to Guy Parsons, May 25, 2012

Just now realised that to get RC control with R series flash in the hot-shoe the flash must be turned on and set to RC mode before putting in the hot-shoe. Otherwise turning off, putting flash in the hot-shoe then turning on stops me even accessing RC control on the flash.

Now I'm really confused as to what I did when. To make it a proper test with no mistooks I will dig out a side bar to make sure the flash is facing backwards without being in that hot-shoe. Also try and find a lens with bigger aperture......

A bit later.... 50/2 macro lens from 4/3 should do it.

First impressions are that the control flash does add to the TTL flash and have some effect on the exposure at 3 feet and f/2 being used. The trouble is that it's still too bright here in Sydney and will need to wait until the sun goes down and dims my room more. The f/2 lens needs more darkness at 1/160 sec.

Results so far seem better for both subject and wall distant behind when the control flash is obscured from the subject.

But be patient and I will wait for dark to do the sequence again properly

Regards...... Guy

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Guy Parsons
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Finally, yes, closeup RC TTL does get confused.
In reply to Guy Parsons, May 25, 2012

This time I did get it right.

Camera E-PL1 to bear 3 feet, camera to pale curtains 3 feet behind for bounce. Then 7 feet behind bear to sandy coloured wall. Lens 50/2 at f/2 and shutter at 1/160. FL-36R RC TTL mode on side bar with head facing back. Delay 2 seconds and I stood well aside for each shot so no bounce "shadows" from me.

417 = ambient light only

418 = RC control flash only

419 = RC control flash and FL-36R bounce

420 = FL-36R bounce and RC control forward aim obscured by scrap of aluminium foil so no contributory effect to exposure

So now that my test is set up properly then it agrees with your FL-300R finding, subject close enough with large enough aperture then the control pulses that trigger the slave flash to fire the initial TTL testing flashes do alter the output of the main slave flash when it fires again for the exposure.

Sorry about the earlier confusion, I now realise that I started with RC working in the hot-shoe flash but at some stage turned off the camera then on again so that action lost the RC and the "slave" reverted to plain vanilla TTL and confused the results for me.

Lesson: obscure the camera's control flash when in RC mode at closeup distances. especially if using large apertures.

Regards........... Guy

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veesah
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Re: Finally, yes, closeup RC TTL does get confused.
In reply to Guy Parsons, May 25, 2012

So now that my test is set up properly then it agrees with your FL-300R finding, subject close enough with large enough aperture then the control pulses that trigger the slave flash to fire the initial TTL testing flashes do alter the output of the main slave flash when it fires again for the exposure.

Sorry about the earlier confusion, I now realise that I started with RC working in the hot-shoe flash but at some stage turned off the camera then on again so that action lost the RC and the "slave" reverted to plain vanilla TTL and confused the results for me.

Lesson: obscure the camera's control flash when in RC mode at closeup distances. especially if using large apertures.

Thanks for taking the time to do this! Looks like this is a design issue of the Oly RC system.

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Guy Parsons
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Re: Finally, yes, closeup RC TTL does get confused.
In reply to veesah, May 25, 2012

veesah wrote:

Thanks for taking the time to do this! Looks like this is a design issue of the Oly RC system.

I don't see it as a design issue, just an issue involving closeup work with large apertures. Most things seem to be designed around normal consumer use with "normal" distances and smaller aperture lenses.

Once aware of that then it's easy to block the direct splash of the control flash onto the subject, or clip some sort of IR light low pass filter on the head so the visible light will not have an effect on the two pre-exposure TTL test flashes. In one case during the test I put an old white cotton glove over the pop-up flash head and that inhibited the direct control flash enough to give a more correct exposure.

In all my testing I was using a poor wall or curtain choice to bounce off, to me that was a more realistic way to test, and in doing so I did see that the "correct" final TTL exposure was about 1 stop lower than it should be, so for bounce then test shots need to be done to get the flash compensation correct. Next time if I persist I will try my 4 foot reflector disk set as white or silver about 3 feet behind the camera as the bounce aid and see if that improves things.

Maybe Oly needs to learn. On my old Nikon SB-30 flash that I sometimes use as a trigger device for simple slave operation (on Oly and Panasonic) is a built-in slide up black plastic piece that blocks visible light but passes IR light so the slaves trigger reliably without having any effect of the subject exposure. http://www.mir.com.my/rb/photography/hardwares/classics/NikonF5/Flash/SB30/index.htm and the tab for the pull-up IR filter is seen next to the tab for the pull-up wide angle adapter.

I do like the idea that floated through in the forum of the little clip-on for the FL-LM1/2 flashes that mirrors the direct flash up to a small upright white diffuser, some modification of that device as a home-made gadget for both the FL-LM1/2 flashes and the pop-ups would be nice.

As for my confusion when using the FL-36R in the hot-shoe as a slave, then I need to slip some tape on the contacts before mounting the flash to keep it in slave mode all the time.

Most things in photography, once you get out or the consumer normal range of operation, do require some extra fiddling.

Thanks for starting this thread as I did learn a lot in experimenting to get a result.

Regards.......... Guy

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