second curtain flash sync on k5

Hello

I've been using my k5 for almost 4 years now but it is only now that I discovered that the option for 2nd curtain flash sync is disabled if non A lens is attached to the body. I do have one AF lens and a few manual A lenses and a non pentax external flash but I often times want to use 2nd curtain sync on my non A lenses
My question is Is there a work around on this? Also I am contemplating on buying another apsc pentax body.
My considerations are efficient focus peaking with tilting lcd and manual flash control for manual lenses addressing my flash issues on k5 and of coarse no known mechanical or hardware issues.

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.

[quote:3496ace15f="McGregNi"]

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

1/25 sec in millisecond would be 1000 divided by 25=40 ms.

The formula would be 1000 multiplied by 1 divided by 25 were 1000 equals 1 sec, 1 equals the part of second you want out of 25 parts of a second.

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

If it helps 5,000 milliseconds is how long it takes to drink a pint of beer

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

Did you remember to subtract the number you first thought of ?

Isnt there a phone app ?

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

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!!

Or driven to drink!

1/25 = 40ms, as I wrote, not 1/125.

And yes, 16.6666... equals 1/60 sec. Just multiply 16.666... by 60 and you'll get 1 sec (1000 ms.).

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?

http://convert-to.com/conversion/time/convert-milli-sec-to-second.html

These conversion sites don't list shutter speeds such as 1/15th second etc.

I've just done this quickly on a spreadsheet. Needs checking
Rounded off to 3 places

Shutter 1/Shutter Milliseconds
1 1.000 1000.000
2 0.500 500.000
4 0.250 250.000
8 0.125 125.000
15 0.067 66.667
30 0.033 33.333
60 0.017 16.667
125 0.008 8.000
250 0.004 4.000
500 0.002 2.000
1000 0.001 1.000

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