maybe the 20D does not use the mechanical shutter for exposures under 1/250 (the stated maximum), this is what the D70 does. not sure if the 20D has the necessary electronics to do that though
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DSLR features what do you actually use?
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Posted 1 year ago #
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maybe the 20D does not use the mechanical shutter for exposures under 1/250 (the stated maximum)
yes, I was thinking that was the other possibility...
Posted 1 year ago # -
This might help explain FP (Focal Plain) high speed sync for flash units and cameras.
Sorry to go off topic, but this will explain how it's done and what the limitations are (limited distance). This is something the Nikon D700 etc can manage and I imagine many others too.
* As I say, raeding the camera's manual helps refresh the grey matter. On line tutorials are great too!
Posted 1 year ago # -
well it appears i may have been wrong then
can't say i've ever really paid enough attention to shutter speed when using a fill flash
i thought that auto FP ust extended the sync to 1/320 but it actuall enables unlimited exposure albeit with reduced output
Posted 1 year ago # -
20D doesnt go faster than 1/250th with the onboard flash at least. Or at least mine doesn't with the latest firmware etc.
this says different
That says exactly what I said? (smaller pixel size, higher pixel density G6 has much higher diffraction limit.
Posted 1 year ago # -
We're talking about flash units attached to the hotshoe.
If in any doubt, Google FP High Speed Sync canon 20dPosted 1 year ago # -
unlimited exposure
i mean unlimited shutter speed of course
Posted 1 year ago # -
That says exactly what I said? (smaller pixel size, higher pixel density G6 has much higher diffraction limit.
no, it says the smaller the pixel site the worse the diffraction!
Posted 1 year ago # -
20D doesnt go faster than 1/250th with the onboard flash at least. Or at least mine doesn't with the latest firmware etc.
No, not with the onboard flash. Look at my picture on page 2, info clearly shows 1/1250 sec and the flash fired! You simply need a flash with the capability of high speed sync, I thought it was just the 580exII but I also see that the link from above says other canon flashes sync to high speeds.
down side is that due to such high speeds the light ain't going to travel very far!
Posted 1 year ago # -
simon, you're right, my mistake! Still, it doesn't seem to make noticable difference. I'll take some samples to see!
don - I said onboard flash.
down side is that due to such high speeds the light ain't going to travel very far!
In 1/1250th light will have travelled 240km
But in seriousness, I thought most full-power flashes took about 1/1000th for complete discharge?
Posted 1 year ago # -
Still, it doesn't seem to make noticable difference. I'll take some samples to see!
one might question the possibility, f/64 for a 10mm lens would be an aperture of 0.15mm, which is smaller than a full stop!
Posted 1 year ago # -
one might question the possibility, f/64 for a 10mm lens would be an aperture of 0.15mm, which is smaller than a full stop!
One might, but creating electromechanical machines capable of such small motions is fairly simple and commonplace these days. It may well be limited earlier than that in reality though and just allow the user to attempt it.
Posted 1 year ago # -
Full stops are massive....the printheads that the last company I worked for make have nozzles put in them that are 0.036mm diameter....
Posted 1 year ago # -
the printheads that the last company I worked for make have nozzles put in them that are 0.036mm diameter....
I don't think the comparison is apt as the maximum aperture is likely to be around 5mm so it's asking a lot of the blades to accurately close so small!
Posted 1 year ago # -
Still don't think it's mechanically that much to ask, but for the price of the camera I suspect it's not capable of going that small. I wonder if it's a "fake" F, working as an electronic shutter adjustment instead.
Posted 1 year ago # -
Yeah - sorry. I was just being facetious or something.....
Posted 1 year ago # -
In 1/1250th light will have travelled 240km But in seriousness, I thought most full-power flashes took about 1/1000th for complete discharge?
They do, but in high speed sync you're only discharging a portion of the energy stored in the capacitor that fires the flash. This takes less time. The downside is the strobed effect can look weird in the certain situations, and the power of the flash is massively reduced.
FYI The D70 could sync at high speeds without the need for a strobing flash because at higher speeds it used a electronic shutter on it's CCD (i.e. it there isn't a physical shutter it just sampled the ccd at the appropiate moment.) 20D etc uses a focal plane shutter so above 1/250 or (1/300 on the 1D) your stuffed.
In a lot of situations this isn't actually a problem as you can use a slower shutter speed and use the flash to freeze the action (as it has a very short duration under 1/1000 s). Just stop down a couple of stops and the meter for the flash on the subject.
Posted 1 year ago #
Topic Closed
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