Digital & TTL-Flash Issue

Scout Pro · 01-18-2008, 10:43 AM

I recently purchased one of Moose Peterson's books and have got to the section on flash. He states that TTL Mode should not be used with DSLR like with our film SLR cousins. Rather he states to use a "standard" flash mode. Does this make any sense? if this is true, why?? Moose is a Nikonian so I am not sure if he is refering to Nikon DSLR's in general or all Digital cameras, etc.

I myself am a new student to studying "light" and how to manipulate, utilize, and understand its core elements, etc.

Any info on this will be greatly appreciated.

Thanks.

**Lowell Goudge** · 01-18-2008, 11:02 AM

Originally posted by Scout Pro

I recently purchased one of Moose Peterson's books and have got to the section on flash. He states that TTL Mode should not be used with DSLR like with our film SLR cousins. Rather he states to use a "standard" flash mode. Does this make any sense? if this is true, why?? Moose is a Nikonian so I am not sure if he is refering to Nikon DSLR's in general or all Digital cameras, etc.

I myself am a new student to studying "light" and how to manipulate, utilize, and understand its core elements, etc.

Any info on this will be greatly appreciated.

Thanks.

There are a couple of issues, I don't know what I actually believe, but I will tell you what people hav said.

TTL on film took light reflected off the film. The film has specific reflective qualities.

A DSLR has a UV filter in front of the sensor. This filter has different reflective characteristics, and some claimed it gave false readings with flash. Newer cameras use what they call a pre flash. Pentax calls this P-TTL. it makes a small flash before stopping down the lens, and opening the shutter, and calculates, based upon the results back, with the selected apature, the correct amount of flash. I believe it uses the same sensors as the normal metering in the view finder.

The Pentax DSLRs have used both. the *istD and DS are TTL capable, all others are only P-TTL

I have both *istD and K10D, and have shot flash photography with both. Personally, I never saw any issue with the TTL flash on my *istD.

What I suspect is that it really is about saving the cost and complexity of additional sensors. There is, however a very serious down side with P-TTL flash. It does not work for the moment with the origonal K mount lenses because the camera does not know the apature setting. I say for the moment, because if pentax would simply allow the user to enter maximum and minimum apature and leave the lens set to minimum, the camera could control the lens. It is all a question of some software development and desire.

The "standard" mode referred to in the article is what in most peoples vocabulary is "auto" mode, where there is a sensor on the flash that controlls everything. This is not as good in my opinion as TTL because you cant select the light the flash sees. That is why we went to TTL in the first place.

Scout Pro · 01-18-2008, 11:15 AM

Awesome information; exactly what I was looking for etc. In my own findings with using my K10D & the 540 Flash, is that I usually need to reduce flsh strobe by one increment value. In addition to this, I am still learning the basics of flash & light rules in general. I realize that operator error is a sure bet with most issues I am facing now.

01-18-2008, 10:43 AM	#1
Scout Pro Junior Member Join Date: Aug 2007 Location: New Orleans, LA Photos: Gallery Posts: 34	Digital & TTL-Flash Issue I recently purchased one of Moose Peterson's books and have got to the section on flash. He states that TTL Mode should not be used with DSLR like with our film SLR cousins. Rather he states to use a "standard" flash mode. Does this make any sense? if this is true, why?? Moose is a Nikonian so I am not sure if he is refering to Nikon DSLR's in general or all Digital cameras, etc. I myself am a new student to studying "light" and how to manipulate, utilize, and understand its core elements, etc. Any info on this will be greatly appreciated. Thanks.

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01-18-2008, 11:02 AM	#2
Lowell Goudge Site Supporter Join Date: Jan 2007 Location: Toronto Photos: Gallery \| Albums Posts: 17,888	Originally posted by Scout Pro I recently purchased one of Moose Peterson's books and have got to the section on flash. He states that TTL Mode should not be used with DSLR like with our film SLR cousins. Rather he states to use a "standard" flash mode. Does this make any sense? if this is true, why?? Moose is a Nikonian so I am not sure if he is refering to Nikon DSLR's in general or all Digital cameras, etc. I myself am a new student to studying "light" and how to manipulate, utilize, and understand its core elements, etc. Any info on this will be greatly appreciated. Thanks. There are a couple of issues, I don't know what I actually believe, but I will tell you what people hav said. TTL on film took light reflected off the film. The film has specific reflective qualities. A DSLR has a UV filter in front of the sensor. This filter has different reflective characteristics, and some claimed it gave false readings with flash. Newer cameras use what they call a pre flash. Pentax calls this P-TTL. it makes a small flash before stopping down the lens, and opening the shutter, and calculates, based upon the results back, with the selected apature, the correct amount of flash. I believe it uses the same sensors as the normal metering in the view finder. The Pentax DSLRs have used both. the istD and DS are TTL capable, all others are only P-TTL I have both istD and K10D, and have shot flash photography with both. Personally, I never saw any issue with the TTL flash on my *istD. What I suspect is that it really is about saving the cost and complexity of additional sensors. There is, however a very serious down side with P-TTL flash. It does not work for the moment with the origonal K mount lenses because the camera does not know the apature setting. I say for the moment, because if pentax would simply allow the user to enter maximum and minimum apature and leave the lens set to minimum, the camera could control the lens. It is all a question of some software development and desire. The "standard" mode referred to in the article is what in most peoples vocabulary is "auto" mode, where there is a sensor on the flash that controlls everything. This is not as good in my opinion as TTL because you cant select the light the flash sees. That is why we went to TTL in the first place.

01-18-2008, 11:15 AM	#3
Scout Pro Junior Member Join Date: Aug 2007 Location: New Orleans, LA Photos: Gallery Posts: 34 Original Poster	Awesome information; exactly what I was looking for etc. In my own findings with using my K10D & the 540 Flash, is that I usually need to reduce flsh strobe by one increment value. In addition to this, I am still learning the basics of flash & light rules in general. I realize that operator error is a sure bet with most issues I am facing now.