FLash problems using radio triggers

[ksporry]

Hi Guys,

Hmm, just noticed there is no section on flash or a section on technique discussions. Guess this is the second best place then (or third best perhaps...):
I have an issue with off-camera flash.
I am using a Canon 5Dmk2 and an EOS 580EX II. I want to set up the flash off-camera and I use a Pixel Knight (TR-332) radio trigger to trigger the flash.
When I have my subject set up, I set the flash on the left side and have some halogens overhead ( room lighting). The camera is positioned on the front of the subject.
I set the camera on P (setting Av seems to somehow make the camera expose based on ambient lighting). I tried M, which also works as long as I set the shutter fast enough (eg 1/60). The flash is set up as master with wireless enabled and TTL.
With this setup somehow the image shows a horizontal triangle in front of the focus point where the flash seems to expose the subject, with the rest of the subject ambient exposed. This occurs with the flash head pointing up and the white reflection card pulled out, with the wide angle refractor pulled out, but also with the flash directly pointing at the subject (regardless if it is direct flash or via the refractor).
This does not occur when I mount the flash on the camera (in this case a proper exposure occurs, regardless if I use the refractor or not).
Does anyone know what's going on and how I can correct this?

See attachment...

[The Crofter]

I know am getting on a bit but where is this triangle ?.

I have taken a lot of flower pics at 1:1 and always use the camera on manual (Shutter 1/60th) and adjust the exposure using the flash output, ambient light and lens aperture. Using P mode does not give me the control I need and you will always be fighting the camera. That may help your workflow but no idea if it affects your problem. On another site someone recommended placing the flash in different locations to isolate problem angles so that is good advice. Not sure if the picture you posted is representitive of what you are trying to photograph but from what I can see you will have a lot of problems with getting good DOF so prerhaps changing the composition would help.

You can easily post to this site using the "upload attachment" tab and follow the instructions.

[ksporry]

Added an attachment...

It's not the angle. I tried changing the angle but without any effect, and nothing is blocking the flash. I'm wondering if it is an issue with the flash settings and using it off-camera. I wanted to use it off-camera with E-TTL.

As for the subject, these are test shots only. The camera shoots at 1/60th.

[bez]

long time since I used 'studio' flash - all sounds very complicated
... not very helpful, but natural light (or at least continuous) is always easier because you can see exactly what it's doing

[ksporry]

True...
But I'd like to get into studio stuff a bit more, and as it happens, a friend of mine asked me to help out taking some product shots, so I started doing some practising.
Tonight I'm on a photography course so I will ask my teacher the question...

[bez]

Studio flash is of course mostly mains powered. Way back in my working days we used Strobe Equipment, and most of the time just a single light source for table-top product photography – either the Fish Fryer (3’ x 2’) or the huge Swimming Pool (6’ x 4’) which were effectively large very heavy metal & perspex soft boxes on stands, powered by a huge 10,000 joule cabinet on wheels. The built-in modelling lights gave a good idea of what the flash is doing.
Today's soft boxes are mostly lightweight fabric construction

Interestingly I found one of these antique monsters on eBay
http://www.ebay.co.uk/itm/7ft-strobe-FF ... 0711580886

[ksporry]

right... I hoe you are not suggesting I drop my Canon flash light for that monster, are you?

[bez]

A good general rule is never use more light sources than you need (double shadows ) Fill can be supplied by white card or mirrors. Reflective objects are the most tricky.
Unless you’re going for dramatic theatrical lighting, aim for the traditional 19th century softness of a large studio window.
Small table-top objects such as jewellery and watches (particularly on black velvet) will tolerate more than one light source ... ooh, it all takes me back 30 years

[ksporry]

I think I know what's been happening. I made some further test shots and spoke to my photography teacher, and considering that the batteries of my radio triggers are running empty, it might be that they have enough power to keep working, but the signal is degraded and slow, resulting in a delayed trigger (the flash seems to trigger when the 2nd curtain is going down, whilst the flash is set up to sync at 1st curtain.). SO my next step will be new batteries and try again...

[bez]

Although completely irrelevant to your problem, I’m just looking for an excuse to post this - a straight scan on the Epson V700 from a 10x8 Ektachrome (those are 2p coins on the corners) The only lighting is the Fish Fryer



Circa 1979 - subject is unsurprisingly the Sheaffer pen. Camera is a Sinar Norma, can’t exactly remember the lens but probably the Schneider 240mm Symmar.

[ksporry]

Nice pic, indeed irrelevant to the post, but confirming the need of a "techniques/criticism" section in the forum.

I found out the real problem with my triggers.
These triggers have a special setting for the 5D series cameras of Canon. I used them before, so I assumed the setting still held. However, it may have reset after I changed batteries. Shouldn't do such a thing but nevertheless, it's posisble this happened, because I could have sworn this setting was enabled.
Anyway, I checked the settings and the radio triggers were NOT set to the 5D, so I switched them and voila, they work!
Problem solved, next patient...