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11-12-2010, 12:45 PM   #1
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TTL Flash Pop-Up and Dedicated, Help Explain How It Works?

I have a ZX-5n and a SuperProgram and know that they both support TTL flash. However the manuals do not explain how TTL really works. I did a search and found nothing on the issue.
-If I buy an AF500FTZ will it do TTL on the SuperProgram?
-Does the camera need to be in Program Auto to use TTL?
-Will the pop-up flash on the ZX automatically adjust to lighting in M or Av modes?
-In TTL mode will the camera meter for flash or do you just select an aperture?

11-12-2010, 01:13 PM   #2
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QuoteOriginally posted by FlannelSpoon Quote
I have a ZX-5n and a SuperProgram and know that they both support TTL flash. However the manuals do not explain how TTL really works. I did a search and found nothing on the issue.
-If I buy an AF500FTZ will it do TTL on the SuperProgram?
-Does the camera need to be in Program Auto to use TTL?
-Will the pop-up flash on the ZX automatically adjust to lighting in M or Av modes?
-In TTL mode will the camera meter for flash or do you just select an aperture?
Hi.

I'll let someone else go into the details, but you can check out Michael Butkus Jr.; Trenton State College, College of New Jersey, Chinon Cameras, K-Mount, Ricoh cameras, UPS, power outages, swinning pool liners, camera instruction manuals, electronic flash manuals, hand held light meter manuals, insturction guide for lots of manuals.

Basically, the way TTL flash works is to have a sensor somewhere inside the camera which cuts off the flash output when there is sufficient light for a given setting: (often by a reflection off the film itself) it's similar to the old 'auto' flash which would do the same via a sensor on the flash itself.
11-12-2010, 05:25 PM   #3
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QuoteOriginally posted by FlannelSpoon Quote
I have a ZX-5n and a SuperProgram and know that they both support TTL flash. However the manuals do not explain how TTL really works. I did a search and found nothing on the issue.
-If I buy an AF500FTZ will it do TTL on the SuperProgram?
-Does the camera need to be in Program Auto to use TTL?
-Will the pop-up flash on the ZX automatically adjust to lighting in M or Av modes?
-In TTL mode will the camera meter for flash or do you just select an aperture?
TTL works through a light sensor aimed towards the film. At the start of the exposure, the film is revealed (first shutter moves away), then the flash is triggered.
This sensor monitors the amount of light reflected by the film, and the camera shut the flash off whenthe desired amount is reached.

The AF500FTZ will work on any TTL body, fr the SuperProgram to the *istDS2.

TTL flash is operating in every camera modes, so it will work in M, Program, AV, whatever. So, yes, the Pop-up flash of a ZX will work in TTL in any mode.

How the camera meters the ambient with flash on depends on your camera. It usually varies from one mode to another (Tv, Av, etc), and then you can choose 2nd curtain too, which will often force the camera to try to meter for the ambient first.
11-13-2010, 12:29 PM   #4
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Thanks for the response. It's all clear now.

11-14-2010, 07:46 PM   #5
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When looking at Pentax flashes, I believe that the "T" in the suffix indicates TTL mode, so the AF-500FTZ will work with a TTL camera. The Z indicates it has a zoom reflector to vary the angle of flash coverage. The F, I believe, indicates that the flash head tilts/swivels. The AF just stands for "Auto Flash".

The 500 indicates the guide number in meters. Actually, you must put a decimal point between the two zeroes. Its guide number is 50 for ISO 100 film or sensor setting. IOW, if you know the distance from the camera to the subject is, say, 10 meters, divide the guide number 50 by 10 to give an aperture of f/5 (or as close as you can get). Of course, the TTL system relieves you of all that math. To convert the guide number into feet, simply multiply by 3.3. So, the AF-500FTZ has a guide number of about 165 in feet. Divide 165 by 33 feet (10 meters) and you still get f/5.

The naming convention still holds. The new flashes, AF360-FGZ and AF-540FGZ, are both P-TTL flashes, indicated by the G in the suffix. The guide numbers are 36 and 54, respectively.

Note that current Pentax dslrs do NOT have the internal light sensor that would allow them to use a TTL flash. They require the pre-flash (the "P" in p-ttl) to meter the flash with the mirror down, then the real flash with the mirror up, to make the image. A few of the first Pentax dslrs supported TTL, but from at least the K100 on, they have been P-TTL only.
11-15-2010, 05:07 AM   #6
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QuoteOriginally posted by noblepa Quote
Note that current Pentax dslrs do NOT have the internal light sensor that would allow them to use a TTL flash. They require the pre-flash (the "P" in p-ttl) to meter the flash with the mirror down, then the real flash with the mirror up, to make the image. A few of the first Pentax dslrs supported TTL, but from at least the K100 on, they have been P-TTL only.
Last DSLR to have this was the *istDS2...

Note of interest for those still using TTL : you can use some Nikon flashes as true TTL slaves... Search for my thread on this if you're interested.
11-18-2010, 08:23 AM   #7
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QuoteOriginally posted by noblepa Quote
When looking at Pentax flashes, I believe that the "T" in the suffix indicates TTL mode, so the AF-500FTZ will work with a TTL camera. The Z indicates it has a zoom reflector to vary the angle of flash coverage. The F, I believe, indicates that the flash head tilts/swivels. The AF just stands for "Auto Flash".

The 500 indicates the guide number in meters. Actually, you must put a decimal point between the two zeroes. Its guide number is 50 for ISO 100 film or sensor setting. IOW, if you know the distance from the camera to the subject is, say, 10 meters, divide the guide number 50 by 10 to give an aperture of f/5 (or as close as you can get). Of course, the TTL system relieves you of all that math. To convert the guide number into feet, simply multiply by 3.3. So, the AF-500FTZ has a guide number of about 165 in feet. Divide 165 by 33 feet (10 meters) and you still get f/5.

The naming convention still holds. The new flashes, AF360-FGZ and AF-540FGZ, are both P-TTL flashes, indicated by the G in the suffix. The guide numbers are 36 and 54, respectively.

Note that current Pentax dslrs do NOT have the internal light sensor that would allow them to use a TTL flash. They require the pre-flash (the "P" in p-ttl) to meter the flash with the mirror down, then the real flash with the mirror up, to make the image. A few of the first Pentax dslrs supported TTL, but from at least the K100 on, they have been P-TTL only.
a quick note on naming conventions the AF500FTZ and AF300FTZ while supporting TTL flash do not support Auto Flash as they do not have any sensor for auto mode.
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