Rather than take a fixed approach to exposure, I'd suggest reading up on how a reflected light metre in a camera ' reads' light in a scene, and learning how to interpret the results using both the histogram and 'blinkies' indications.

This awareness will allow the photographer to make the necessary adjustments, both up or down, as each image requires. Optimal digital image exposure is something that needs consideration for each situation and changing light conditions.

Of course, the default camera meter exposure level will often get things into the right ball park, and processing adjustments can be easy later .... But I do think that the best IQ can be extracted when the camera exposure was the best it could have been.

The technique described earlier, of pushing up the brightness until the highlights hit the top, is related to the ETTR (expose to the right) approach, which should ensure that the bulk of image data captured falls into the top half of the sensors range (represented by the right hand half of the histogram). Unfortunately the dynamic range of so many scenes is too high to make this really practical, as even with clipped highlights a great deal of the image data still falls within the lower half .... This then leads to the inevitable 'shadow raising' in processing, if we keep the highlights within the upper limit.

Now automatic 2nd Curtain Sync with an autofocus lens and a P-TTL flash is looking increasingly attractive, and well worth the money!

There's some great contributions here .... Who needs to go out taking photos when there's all these calculations to do instead?

I'm thinking about it more .... It seems to me that one logical way to think about it is to convert the fraction to a percentage, then just add a zero to get milliseconds ..... Does that sound like it works? All I need now is a surefire way to convert fractions to percentages ......

1/30th anyone? .....1/90th? .......1/200th ?

Thanks, this is going to challenge my brain quite a bit, but I'll keep trying! Would you be able to show a few more examples in action, just to help get the formula ingrained?

Ok, so now we seem to have reached a point where some research and evidence is needed to determine what is this 'given speed', and how exactly to determine when it's not needed .

I'm starting to hope so .... although I wasn't the one here who wanted to use 2nd Curtain Sync with manual lenses ..... no doubt the OP has been well and truly put off it by now!!

No, you're right .... and a Millilitre is more than a pint, I think .....

I tend to agree with David there. Most of my longer telephoto shots (100-300mm), handheld, are shot at around 1/90th through to 1/500th sec, and I doubt that many would be usable without SR activated.

I don't see why there should be any correlation between the focal length inverse and SR being effective or not .... there is no relationship between these two conditions, surely .... ? I can understand that SR might become ineffective beyond a certain fast shutter speed, but I don't see any logic to it relating to focal length. I would haven thought that any SR would be an improvement, even if at the very longest lengths it can't prevent all the movement.

That does help a lot! Perhaps it should be converted into Litres also

Thanks Yves! That is going to be very useful for quite a few of us .... now, we all have to do our homework exercises to make sure we fully understand it

I'll start off with a few attempts, then I'll set a few examples for everyone to try and see how many they can get right !!

So .... 1/125th is 40ms ... there's a few easy ones I guess: 1000ms is 1 sec, so that means that 500ms is 1/2sec, 250ms is 1/4, 125ms is 1/8 .... etc

Let me try a few harder ones now .....

1/10 sec ..... (by Yves formula that should be) : 1000/10 = 100ms


1/60 sec ..... 1000/60=16.6666 .... ??? Huh? that doesn't sound right!!

I don't think I understand the formula ... please can it be explained again or differently

2nd Curtain Sync is a subset of P-TTL flash mode, and P-TTL needs autofocus lenses to function fully .....so there is no workaround for Manual lenses with the built-in flash, or a dedicated system flashgun.

As the technique involves delaying the flash output until the end of the exposure, you could find a Manual flash that has a programmable delay setting (e.g. Cactus RF60), and set an appropriate delay on the flash. You would need to convert the exposure time (in fractions of a second e.g. 1/25th) into milliseconds ....the millisecond figure is set on the flash, and you need to set it to occur around about the last 1/3rd or 1/4 of the exposure period. Obviously this is fiddly and rather experimental for all but quite long exposures, but you should be able to work out an approach that works for a range of exposure times.

I'm no mathematician, perhaps someone can give us a formula for converting fractions of a second into milliseconds ......? Come on you guys!

The K70 and KP are the camera models that have the features you mentioned. They both have a few different pros and cons that distinguish them, so it's a fairly personal decision. They both have Manual flash mode with 8 power steps ....but the situation with 2nd curtain remains the same I'm afraid.