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Newbie to strobes - overexposing issues

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Hi there, I was wondering if anyone might be able to help me out with an overexposure issue I'm having with my BRAND NEW Inon D2000 (it's my first strobe, so please forgive the dumb questions!).

 

My camera is a fully automatic little Olympus mju1020 which doesn't allow much manual control of anything. I've been running some test shots on land with the strobe and the fiber optic connection and have found the images are exposing nicely. My problem is when I block the internal flash (I've been using black electrical tape with a pinprick hole to allow the optics to detect the preflash), all the images turn out hugely overexposed! I'm not sure if it could be something to do with the camera trying to brighten the images because the preflash is virtually blocked and it's not receiving the information it needs to expose correctly? I know that Inon does a tape that blocks out all visible light but allows IR wavelengths - not sure if this could be a solution, or if it's something else entirely? I've been using the strobe in Low sTTL and dialing the EV down to '5 o'clock' (about 7) as recommended by the manual.

 

If anyone can shed some light on this I'd really appreciate it. Hopefully it's just something I'm doing completely wrong :D

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Hi there, I was wondering if anyone might be able to help me out with an overexposure issue I'm having with my BRAND NEW Inon D2000 (it's my first strobe, so please forgive the dumb questions!).

 

My camera is a fully automatic little Olympus mju1020 which doesn't allow much manual control of anything. I've been running some test shots on land with the strobe and the fiber optic connection and have found the images are exposing nicely. My problem is when I block the internal flash (I've been using black electrical tape with a pinprick hole to allow the optics to detect the preflash), all the images turn out hugely overexposed! I'm not sure if it could be something to do with the camera trying to brighten the images because the preflash is virtually blocked and it's not receiving the information it needs to expose correctly? I know that Inon does a tape that blocks out all visible light but allows IR wavelengths - not sure if this could be a solution, or if it's something else entirely? I've been using the strobe in Low sTTL and dialing the EV down to '5 o'clock' (about 7) as recommended by the manual.

 

If anyone can shed some light on this I'd really appreciate it. Hopefully it's just something I'm doing completely wrong :D

 

Hi,

I'm not familiar with your camera, but I'm sure this isn't your problem.

The fact your images are being over exposed by the strobe means its syncing / firing on shutter release. Simply to much light is hitting the subject. (sorry for stating the obvious :))

I would try the strobe on manual and dial down the power (darken as I think it appears on the dial). The camera shutter speed doesn't matter, this will only affect the ambient part of the exposure. Try to match the aperture or bracket the flash to find what your happy with.

Hope this helps.

 

Andy.

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Thanks for the suggestion Andy, I'll give it a go ASAP.

 

What I'm a bit confused about is why the TTL function seems to be "working" ok when the internal flash of my camera is uncovered, but is wayyy out as soon as I cover up that flash. I know next to nothing about the intricacies of strobes or cameras and I just can't figure out why it would happen! I'm positive that it's a user error, but if anyone else has experienced (and resolved) something similar with the D2000 I'd love to hear from you.

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Hi,

 

I'll try and help!

 

The fibre optic sensor on your strobe picks up the ammount of flash that the camera is using to acheieve correct exposure and effectively replicates it. In order for it to do this, it must be able to "see" the cameras flash output. I'm not sure where you are sticking the tape, but if it is on the cameras flash itself, there is not enough camera flash getting through and hence the strobe if firing at full. Most fibre optic kits have a flash reducer that attaches externally onto the housing-with the end of the fibre optic "inside"-so it can pick up the flash.

 

Hope that helps.

 

Adam

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Hi,

 

I'll try and help!

 

The fibre optic sensor on your strobe picks up the ammount of flash that the camera is using to acheieve correct exposure and effectively replicates it. In order for it to do this, it must be able to "see" the cameras flash output. I'm not sure where you are sticking the tape, but if it is on the cameras flash itself, there is not enough camera flash getting through and hence the strobe if firing at full. Most fibre optic kits have a flash reducer that attaches externally onto the housing-with the end of the fibre optic "inside"-so it can pick up the flash.

 

Hope that helps.

 

Adam

 

Ahh that makes so much more sense now! You're right - I did have the tape on the camera body itself. So I'm guessing now I need to figure out some way to block my camera's internal flash while still letting enough light through to my fiber optic cable. I have a fiber optic mounting block from reefphoto that just sticks to the outside of the housing http://reefphoto.com/index.php?main_page=p...roducts_id=4023 but that's all I received with the kit. Would really appreciate recommendations from anyone! :D

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Ahh that makes so much more sense now! You're right - I did have the tape on the camera body itself. So I'm guessing now I need to figure out some way to block my camera's internal flash while still letting enough light through to my fiber optic cable. I have a fiber optic mounting block from reefphoto that just sticks to the outside of the housing http://reefphoto.com/index.php?main_page=p...roducts_id=4023 but that's all I received with the kit. Would really appreciate recommendations from anyone! :D

 

Hi Emma,

 

The mounting block is what you need to use to allow for adequate pick-up of the camera's flash discharge by the strobe, via the FO. You may need

to put some tape on the housing around the mount to reduce any light leakage going forward and potentially causing backscatter. The tape over the

camera flash has simply reduced the effective output which the strobe would have replicated on the pre-flash which I guess is then giving feedback to

the strobe to do a much bigger discharge than really needed.

 

If you have the Olympus housing it looks like you'll need to remove the flash diffuser first before sticking on the FO Mounting Block.

 

 

Cheers,

Jim.

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Thanks so much Wetpixellers, you've come to my rescue again.

 

I put black electrical tape all around the front corner of the housing and left a small window where the FO cable was fixed by the mounting block. Working wonderfully now! This is all still a mystery to me so thanks everyone for being patient with me. (Hi again, Jim!).

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Looking forward to seeing some well exposed pics of Handfish and Red Velvetfish :D

 

Cheers,

Jim.

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