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10-19-2012, 11:39 PM   #1
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what am i not getting here? noob alert flash and k5

I am trying to understand how to use my k5 and the af360 flash.

I have the flash on the hot shoe and I have it off. Put the camera in tav give it some random values 125 and f 4.5, take a picture of my room, camera sets iso to 12800.

Next turn the flash on , same 125 and 4.5 flash on pttl mode, take a picture, the camera still sets iso to 12800 result overly exposed photo.

Does the camera not know there is a flash???

10-19-2012, 11:58 PM   #2
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Why do you want to use TAV mode with a flash on board? Have you tried the same thing in Av mode or manual mode? I just tried your settings with my K-5 and a Metz flash. In Tav I get blown out pictures and auto high ISO. In Av mode I get perfectly exposed pictures.

Best of all is to use manual mode when using a flash. (or sometime I use X-sync mode)

There are plenty of tutorials around on the net about using flash, but none of them will mention TAv mode, because that is a Pentax exclusive feature. There are many threads on this forum about using your Pentax gear correctly. I have never read of anyone using TAv mode for flash.
10-20-2012, 12:18 AM   #3
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QuoteOriginally posted by wizofoz Quote
Why do you want to use TAV mode with a flash on board? Have you tried the same thing in Av mode or manual mode? I just tried your settings with my K-5 and a Metz flash. In Tav I get blown out pictures and auto high ISO. In Av mode I get perfectly exposed pictures.

Best of all is to use manual mode when using a flash. (or sometime I use X-sync mode)

There are plenty of tutorials around on the net about using flash, but none of them will mention TAv mode, because that is a Pentax exclusive feature. There are many threads on this forum about using your Pentax gear correctly. I have never read of anyone using TAv mode for flash.

i come from canon and yes there are many things about pentax i don't get yet. will keep reading and trying
10-20-2012, 12:24 AM   #4
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when trying av or m mode the camera "meter" is that what that is?, kept blinking and showing -5 yet when firing the picture was exposed just fine.

what is the use of that meter? I understood the ideal is to make it show "0" but in this case by doing that either increasing aperture or reducing shutter speed I got overly exposed photos.

10-20-2012, 03:55 AM - 2 Likes   #5
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QuoteOriginally posted by Vindemiatrix Quote
when trying av or m mode the camera "meter" is that what that is?, kept blinking and showing -5 yet when firing the picture was exposed just fine.

what is the use of that meter? I understood the ideal is to make it show "0" but in this case by doing that either increasing aperture or reducing shutter speed I got overly exposed photos.

The light meter built into the camera is measuring the light coming into the lens from the room interior while you are composing the shot and the flash isnt firing.
In TAv it boosts the Auto-ISO to give the metering in that situation. (In your case 12800 - your room is pretty dark, much darker than my hotel room here)

Get out of TAv mode & get Auto-ISO off because its useless for flash.

In M-mode for example having the same lighting f4.5 1/125 at a lower ISO like say 100. The light meter will measure the light when the flash isn't firing and say that it's more than -5 under. (That's because it is.... Without the flash its about -8 stops underexposed in this example).

When you use the flash in P-TTL inside your roomspace dont worry about what the light meter in the camera says. The whole scene lighting will be taken care of buy the flash. Point it up to bounce it of the ceiling and fill most evenly.

In P-TTL When you press the shutter, the flash fires a pre-flash. The meter in the camera meters the light from this pre-flash and then the camera then works out how much light the flash need to output to expose the scene correctly according to this and then tells the flash to fire that amount of power and then it takes the shot, hopefully correctly exposed.


P-TTL is OK but its like any computer controlled device, its not foolproof. You can trick it with uneven lighting, like pointing at bright highlights or mirrors, or even glass surfaces that reflect back to the lens.

A mode on the flash is kind of the same except you set the aperture and ISO on the flash and it uses its own light meter to give the correct lighting.
If you set your camera ISO and Aperture to the same as the flash then you'll theoretically get the same result as what P-TTL calculated.

Manual mode in the flash is the most consistent. It just fires at whatever level you set it to, but you are the one that has to do the maths first.
Or you could just guess like I usually do.
10-20-2012, 06:27 AM   #6
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Or, you could just put the camera into P mode.
10-20-2012, 09:06 AM   #7
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QuoteOriginally posted by steve1307 Quote
The light meter built into the camera is measuring the light coming into the lens from the room interior while you are composing the shot and the flash isnt firing.
In TAv it boosts the Auto-ISO to give the metering in that situation. (In your case 12800 - your room is pretty dark, much darker than my hotel room here)

Get out of TAv mode & get Auto-ISO off because its useless for flash.

In M-mode for example having the same lighting f4.5 1/125 at a lower ISO like say 100. The light meter will measure the light when the flash isn't firing and say that it's more than -5 under. (That's because it is.... Without the flash its about -8 stops underexposed in this example).

When you use the flash in P-TTL inside your roomspace dont worry about what the light meter in the camera says. The whole scene lighting will be taken care of buy the flash. Point it up to bounce it of the ceiling and fill most evenly.

In P-TTL When you press the shutter, the flash fires a pre-flash. The meter in the camera meters the light from this pre-flash and then the camera then works out how much light the flash need to output to expose the scene correctly according to this and then tells the flash to fire that amount of power and then it takes the shot, hopefully correctly exposed.


P-TTL is OK but its like any computer controlled device, its not foolproof. You can trick it with uneven lighting, like pointing at bright highlights or mirrors, or even glass surfaces that reflect back to the lens.

A mode on the flash is kind of the same except you set the aperture and ISO on the flash and it uses its own light meter to give the correct lighting.
If you set your camera ISO and Aperture to the same as the flash then you'll theoretically get the same result as what P-TTL calculated.

Manual mode in the flash is the most consistent. It just fires at whatever level you set it to, but you are the one that has to do the maths first.
Or you could just guess like I usually do.
Thank you for such a comprenhensive reply. I tought the camera "knew" what the flash was doing before firing. The light meter was confusing me big time.

I downloaded the flash manual but it isn't much help.

I am trying to figure out how to use the flash in wireless mode with the pop up flash. I want the external flash to be in the exposure not the pop up, so do i have to set the build in flash to master or control? I'm guessing control?

thank you again
10-20-2012, 09:39 AM   #8
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go to pentax uk forum search for matmattic's flash guide... buy it from him... best resource out there. Pentax should buy it from him and include the pdf with every flash sold in the english speaking world.

10-20-2012, 01:26 PM   #9
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QuoteOriginally posted by Vindemiatrix Quote
I am trying to understand how to use my k5 and the af360 flash.

I have the flash on the hot shoe and I have it off. Put the camera in tav give it some random values 125 and f 4.5, take a picture of my room, camera sets iso to 12800.

Next turn the flash on , same 125 and 4.5 flash on pttl mode, take a picture, the camera still sets iso to 12800 result overly exposed photo.

Does the camera not know there is a flash???
Being curious, I tried this out on my K-30. Basically, flash doesn't "work" in Tav mode despite the camera manual implying otherwise. In my case, I tried both the built-in flash and a 360AFZ with the same result: ISO didn't change when turning on either flash.

Here's how I think Pentax set up flash for it's modern cameras (with built-in flash):

In P mode:
1) speed gets set to the slowest feasible for the recorded lens focal length
2) next, ISO gets set to 400
3) next, aperture gets set appropriately from above parameters
4) next, if with aperture wide open there isn't enough light then it raises ISO above 400
or
4) if there's more than enough light, camera choses a faster shutter speed (up to 1/180)

5) if still more than enough light, not sure if the flash power is reduced, ISO lowered, or aperture reduced

I didn't go through the whole same exercise with a 360AFZ instead of the built-in flash but am *guessing* it's the same.
10-20-2012, 08:27 PM   #10
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QuoteOriginally posted by Vindemiatrix Quote
Thank you for such a comprenhensive reply. I tought the camera "knew" what the flash was doing before firing. The light meter was confusing me big time.

I downloaded the flash manual but it isn't much help.

I am trying to figure out how to use the flash in wireless mode with the pop up flash. I want the external flash to be in the exposure not the pop up, so do i have to set the build in flash to master or control? I'm guessing control?

thank you again
Cool, no problem, thanks for the thumbs up.
I'm trying to learn about flash technique myself. I paid for a learning course in my local photo club but I've already missed week 1 of it as I'm working O/S.

I agree the flash manual is pretty useless & confusing, the camera manual is better with some info on external flash.

You are right about the the setting of the pop up flash in the custom menu "flash in wireless mode". pop-up flash Master or Control.
In Control mode in theory the built-in flash doesn't contribute to the exposure.

That's the mode I leave it in, I'd light to understand how to use just 1 light works before having 2 flashes.
10-20-2012, 08:38 PM - 1 Like   #11
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If you really think about it; TAV mode is to let the camera choose the best ISO when you have tried to fix Aperture and Shutter. Therefore, given the situation when the lighting is minimal indoor, it will go to bump the iso to get the proper reading. If you want to TAv mode in flash, you can limit the range to 100-400. However, the best mode to use is M mode.
10-21-2012, 01:42 AM   #12
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Demonstration of P-TTL in the various shooting modes:
https://www.pentaxforums.com/forums/pentax-k-5/191116-some-insight-into-flash...ml#post2020805

Flash ain't rocket science. Basic thing to remember is that you're dialling in the shot that you'd like to be able to make if only you had enough light. The purpose of the flash then becomes making the shot possible. TTL flash takes the guesswork / calculation out of the process.
10-21-2012, 05:29 AM   #13
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Above is a good, succinct answer.

My suggestions - set pTTL on flash, set M mode on camera, choose aperture you need for desired DOF, set shutter to 1/125 to start and change if necessary. Let the flash calculate the rest - just shoot.
10-21-2012, 05:51 AM   #14
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any time you use flash you have two lightsources, the flash and the ambient... you choose one to b your main and the other as fill. from there it gets real easy to understand... then you have to know how to set the camera and flash unit to get it to do what you want it to do.

I prefer to work in all manual for flash....
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