All Forum Comments
Comment by MattMatic posted on re: Pentax 50 f:1.2 at 15/02/2010 - 16:21
IrfanView can do it just fine
You use the Thumbnail view. http://www.irfanview.com/faq.htm#Q24
(It's not very intuitive, but it does work and very well!)
Matt
You use the Thumbnail view. http://www.irfanview.com/faq.htm#Q24
(It's not very intuitive, but it does work and very well!)
Matt
Comment by MattMatic posted on Adding EXIF data at 15/02/2010 - 09:44
It's not a silly question
When you use the Z-Pro 100mm graduated filters on a smaller lens mount, and especially with narrower angle of view (i.e. telephoto) then you pretty much lose the benefit of a graduated filter!
It's useful in that you can control how much ND there is by sliding the filter, but you do lose the benefit of a soft filter. Think of it this way - with a large lens and wide angle you get a full 0 to x-stop ND. If you stick the same filter on a 49mm thread lens, you'll get at most half of the graduation - either 0 to x/2-stop or x/2-stop to x-stop. Add to that a much narrower angle of view and you can find you just get straight ND.
I've hung on to my P sized ND-grads as well
Matt
When you use the Z-Pro 100mm graduated filters on a smaller lens mount, and especially with narrower angle of view (i.e. telephoto) then you pretty much lose the benefit of a graduated filter!
It's useful in that you can control how much ND there is by sliding the filter, but you do lose the benefit of a soft filter. Think of it this way - with a large lens and wide angle you get a full 0 to x-stop ND. If you stick the same filter on a 49mm thread lens, you'll get at most half of the graduation - either 0 to x/2-stop or x/2-stop to x-stop. Add to that a much narrower angle of view and you can find you just get straight ND.
I've hung on to my P sized ND-grads as well
Matt
Comment by MattMatic posted on Cokin Z Pro and Lee Filters at 15/02/2010 - 09:42
John,
AKAIK, Canon are easily popped. Apparently trigger voltages over 8V (IIRC) will blow the trigger mechanism.
They've probably just got a straight transistor output.
It's a tricky one - but easily fixed with the booster.
Matt
AKAIK, Canon are easily popped. Apparently trigger voltages over 8V (IIRC) will blow the trigger mechanism.
They've probably just got a straight transistor output.
It's a tricky one - but easily fixed with the booster.
Matt
Comment by MattMatic posted on X sync socket problem at 12/02/2010 - 20:34
Ok, test results in
Setup
* DC Power supply set at 5v (current limited to about 100mA just in case!)
* Various resistors
* Multimeter to measure DC volts
* Tested on *ist-D (probably same for K20D)
Results
* 1k - locks up as described
* 100k - perfect
* 10k - perfect
* 4k7 - perfect
* 2k - locks up
* 3k - perfect
So, it would appear that a current of more than about 2mA will lock up the PC socket/hotshoe - exactly as you suggested John
Suggestion
How about a little transistor booster:
* PNP transistor (e.g. BC327, BC547, etc, etc)
* Collector to ground (the outer of the PC connector)
* 100k between base and emitter (to turn off the transistor)
* 10k between base and the camera's PC centre (to limit current into the camera's thyristor)
* Take the emitter to the Flash's centre
(Basically you just want a high impedance input - greater than about 5k - to pull down a slightly larger current at the input of the studio flash. The Calumet's are 5v trigger voltage, so no big deal.)
You could probably blob that lot into a little adapter lead. If you've got problems, just let me know which jack size it is (and if it's mono), and I'm sure we could work out something
Matt
Setup
* DC Power supply set at 5v (current limited to about 100mA just in case!)
* Various resistors
* Multimeter to measure DC volts
* Tested on *ist-D (probably same for K20D)
Results
* 1k - locks up as described
* 100k - perfect
* 10k - perfect
* 4k7 - perfect
* 2k - locks up
* 3k - perfect
So, it would appear that a current of more than about 2mA will lock up the PC socket/hotshoe - exactly as you suggested John
Suggestion
How about a little transistor booster:
* PNP transistor (e.g. BC327, BC547, etc, etc)
* Collector to ground (the outer of the PC connector)
* 100k between base and emitter (to turn off the transistor)
* 10k between base and the camera's PC centre (to limit current into the camera's thyristor)
* Take the emitter to the Flash's centre
(Basically you just want a high impedance input - greater than about 5k - to pull down a slightly larger current at the input of the studio flash. The Calumet's are 5v trigger voltage, so no big deal.)
You could probably blob that lot into a little adapter lead. If you've got problems, just let me know which jack size it is (and if it's mono), and I'm sure we could work out something
Matt
Comment by MattMatic posted on X sync socket problem at 12/02/2010 - 15:56
Quote:
A typically quoted hold current for a small thyristor would be around 2 mA.
Perhaps that's what's happening then? Maybe the OP needs a high impedance 'booster' that can sink the current required on the studio lights.A typically quoted hold current for a small thyristor would be around 2 mA.
I'll try and measure the trigger current on my AF360, and setup some tests with different currents on the *ist-D and K20D. Hopefully should be able to do this later today...
Matt
Comment by MattMatic posted on X sync socket problem at 12/02/2010 - 10:31
Just metered my K20D... looks like the same as the *ist-D.
Now I'm puzzled
Perhaps it's the amount of current that is sunk through the PC/hotshoe connector that's locking it up? Using a multimeter will be taking microamps. Perhaps using an LED (and maybe with the studio strobes) they are drawing a larger amount of current (milliamps) and locking up the electronics.
I can test this tomorrow with the kit at work (assuming I get time)
If this is the case, then a little 'booster' would sort the problem out.
OP: Out of interest, were your studio lights 1/4" mono jack (i.e. like the big old headphone connector)? Or 3.5mm like newer headphones?
Matt
Now I'm puzzled
Perhaps it's the amount of current that is sunk through the PC/hotshoe connector that's locking it up? Using a multimeter will be taking microamps. Perhaps using an LED (and maybe with the studio strobes) they are drawing a larger amount of current (milliamps) and locking up the electronics.
I can test this tomorrow with the kit at work (assuming I get time)
If this is the case, then a little 'booster' would sort the problem out.
OP: Out of interest, were your studio lights 1/4" mono jack (i.e. like the big old headphone connector)? Or 3.5mm like newer headphones?
Matt
Comment by MattMatic posted on X sync socket problem at 11/02/2010 - 20:09
...I'll try and setup a test tomorrow with my K20D.
I'm still puzzled, because AFAIK, the trailing curtain sync is taken from the 'rising edge' of the sync pin - that wouldn't be possible if the sync latched (which it obviously does in your cases) - unless the trailing curtain is done in some other manner... (It's got me wondering!!)
Matt
I'm still puzzled, because AFAIK, the trailing curtain sync is taken from the 'rising edge' of the sync pin - that wouldn't be possible if the sync latched (which it obviously does in your cases) - unless the trailing curtain is done in some other manner... (It's got me wondering!!)
Matt
Comment by MattMatic posted on X sync socket problem at 11/02/2010 - 11:12
I've just been measuring my *ist-D (because it's to hand)...
* The hotshoe & PC socket are separate. There's no connection between the centre pin of either. So that's good
* The centre pin should be the positively biased pin. Measuring with a multimeter, I get about 700 Ohms when the shutter is open (ie flash is going off), and it goes open circuit when the shutter is closed.
* I'm not 100% sure about the thyristor comments above... the flash does need to know both the 'connect' and 'disconnect' moments from the PC cord. This allows a flash to do trailing curtain sync by deciding which 'edge' to trigger off.
Think I'll have to build something up to test these various ideas... and try it all out on the K20D to see if anything's changed.
Will keep you posted
Matt
* The hotshoe & PC socket are separate. There's no connection between the centre pin of either. So that's good
* The centre pin should be the positively biased pin. Measuring with a multimeter, I get about 700 Ohms when the shutter is open (ie flash is going off), and it goes open circuit when the shutter is closed.
* I'm not 100% sure about the thyristor comments above... the flash does need to know both the 'connect' and 'disconnect' moments from the PC cord. This allows a flash to do trailing curtain sync by deciding which 'edge' to trigger off.
Think I'll have to build something up to test these various ideas... and try it all out on the K20D to see if anything's changed.
Will keep you posted
Matt
Comment by MattMatic posted on X sync socket problem at 10/02/2010 - 15:39
Interesting though!
Matt