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06-17-2018, 04:40 PM   #1
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Fake flash chip

Hi!

I'm fiddling around to make a round flash with a hood mount, to be able to install an angel eye to my lens, and use the hot shoe of my K-m as my main flash. I want this mainly because with my 18-200 i suffer from shadows (which i suffered too with the factory 18-55) and i feel like the angel eyes i installed to my computer makes almost as much light as the embedded flash, so i want to use the angel eye for focus purposes, and for the photo as well. I recall having read somewhere i can use both at the same time, but i don't care that much.

The issue comes where the hot shoe seems to rely on a digital communication, as i looked with but a multimeter and an oscilloscope, to sadly only get to the conclussion that the camera looks for a digital thing to answer, and if it doesn't, the camera just uses the embedded flash as always. No live voltage, no shutter signal, no nothing i could use as something. So my question is if there's any accessory for DIY purposes that let's me to retrieve both voltage and shutter signal faking a digital comunnication, or at least a main voltage, in order to use the hot shoe. I can always embed a secondary step up in my grip and a switch to light the led, but it will be much more confortable to do with the hot shoe if i can. If not, or if it's too much expensive, i'll end doing it pure DIY, but i don't lose anything by asking.

06-17-2018, 05:33 PM   #2
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Does the body have a PC Sync out for external flash? If not you can pick up one of those super cheap chinese flash triggers and use the PC out on that as a simple way to get a fire signal.
06-17-2018, 05:36 PM   #3
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QuoteOriginally posted by victormeldrew Quote
Does the body have a PC Sync out for external flash? If not you can pick up one of those super cheap chinese flash triggers and use the PC out on that as a simple way to get a fire signal.
Wouldn't that just fire as the flash does - once - not emit continuous light ?
06-17-2018, 05:45 PM   #4
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QuoteOriginally posted by victormeldrew Quote
Does the body have a PC Sync out for external flash? If not you can pick up one of those super cheap chinese flash triggers and use the PC out on that as a simple way to get a fire signal.
Not as a 3.5mm connector or a propietary one, just the hot shoe

QuoteOriginally posted by UncleVanya Quote
Wouldn't that just fire as the flash does - once - not emit continuous light ?
I don't know if an external flash does the same thing while focusing, just like the embedded one, but if there's not a flash that can do a focusing light, i'll just discard the idea and go directly for a step up module and some basic things to have it done. I'll have to look for a voltage limiter in order to have regulable light without worries about going through a "night on fire" but i'd like to look for this in first place.

06-17-2018, 05:50 PM   #5
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QuoteOriginally posted by CapitanXeon Quote
Not as a 3.5mm connector or a propietary one, just the hot shoe



I don't know if an external flash does the same thing while focusing, just like the embedded one, but if there's not a flash that can do a focusing light, i'll just discard the idea and go directly for a step up module and some basic things to have it done. I'll have to look for a voltage limiter in order to have regulable light without worries about going through a "night on fire" but i'd like to look for this in first place.
Yes - low light can trigger a focus light on some Pentax flashes. But I think that's a digital function not a passive "Dumb" trigger.
06-17-2018, 11:47 PM   #6
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As far as the communication is concerned, the center pin should be "dumb", no communication apart from the trigger voltage. That's how manual flashes work.

For the "focus" part, what you're trying to accomplish is called "focus assist light", and cameras usually have their dedicated one.
I don't think a manual flash can be made to do qhat you want.
Next best thing, I think, is to just rig another circuit in parallel to the one that connects to the hotshoe, that can be closed with a switch.
This way you depress a button, and the "flash" illuminates the subject while you focus, then you release it, fire the shutter and the flash fires.
06-17-2018, 11:54 PM   #7
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QuoteOriginally posted by LensBeginner Quote
As far as the communication is concerned, the center pin should be "dumb", no communication apart from the trigger voltage. That's how manual flashes work.

For the "focus" part, what you're trying to accomplish is called "focus assist light", and cameras usually have their dedicated one.
I don't think a manual flash can be made to do qhat you want.
Next best thing, I think, is to just rig another circuit in parallel to the one that connects to the hotshoe, that can be closed with a switch.
This way you depress a button, and the "flash" illuminates the subject while you focus, then you release it, fire the shutter and the flash fires.
I looked through it, and seems that if theres no communication, the trigger voltage doesn't deploy in order to avoid short circuits. Looks that this part is pretty sensitive and even an out of spec flashes (like old ones) can cook the camera by injecting +300v because potato.

My K-m uses the flash for the focus assist, so i may run a complete circuit for fixed light, just like a lamp instead a "flash" as is. I can combine both with that setup so i gues it's the way to go, and i can stack rings with consecutive sizes to enlarge light emission, just like this

I don think the consumption is going to be that much for a 1 amp step up, right?

06-18-2018, 12:04 AM   #8
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Yeah I guess... but since you're going fixed light, providing an independent power source (couple AAs?) should not prove too cumbersome, I guess?
If you weren't thinking about it from the start, that is.
06-18-2018, 12:33 AM   #9
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QuoteOriginally posted by LensBeginner Quote
Yeah I guess... but since you're going fixed light, providing an independent power source (couple AAs?) should not prove too cumbersome, I guess?
If you weren't thinking about it from the start, that is.
I actually had to craft a homemade battery grip since there isn't any available for the K-m, and i got to get stuffed inside 6600mAh of lithium so by power supply i'm not worried. Actually, the thing that could be unconfortable may be having a wire running the length of the lens, since i may need something like a bungee to route the cable by the left side of the camera and over the hot shoe, where it doesn't incomodate me. I recall something similar, that works by a wire somewhere, it can be or is a wet dream from a past me?
06-18-2018, 12:42 AM   #10
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QuoteOriginally posted by CapitanXeon Quote
I actually had to craft a homemade battery grip since there isn't any available for the K-m, and i got to get stuffed inside 6600mAh of lithium so by power supply i'm not worried. Actually, the thing that could be unconfortable may be having a wire running the length of the lens, since i may need something like a bungee to route the cable by the left side of the camera and over the hot shoe, where it doesn't incomodate me. I recall something similar, that works by a wire somewhere, it can be or is a wet dream from a past me?
Flashguns have worked by wire (for triggering, not power) for decades... it's still a wire running round the camera.
06-18-2018, 08:03 AM   #11
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Literally dozens of DIY blogs on how to make a ring light using the "angel eyes". Continuous lighting though. One uses a voltage booster to run off 4 AA batteries.

As far as the focus assist beam goes:

QuoteQuote:
All flashes except the Pentax AF200FG include a focus-assist beam which replaces the horrible subject-startling strobe effect Pentax built-in flashes use to provide AF assist. Additionally, Pentax and the higher-end Metz models provide a mode where the AF assist light is enabled but the flash doesn't fire — Metz calls this "spot beam".
Feature Comparison - Pentax P-TTL Flash Comparison
My Attempt at an DIY LED Macro Light - PentaxForums.com
DIY Macro Lighting LED Ring - DIY Photography
Making a focus assist macro light ring for manual lenses - StackRail.info
Inexpensive Ring Light Makes Macro Photos Easy | Hackaday
Make a 48 LED Macro Ring Light for SLR for $10

Do an Internet search on "DIY angel eye macro ring"

If you have continuous lighting you shouldn't need a low light focus assist.
06-18-2018, 08:12 AM   #12
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QuoteOriginally posted by Not a Number Quote
Literally dozens of DIY blogs on how to make a ring light using the "angel eyes". Continuous lighting though. One uses a voltage booster to run off 4 AA batteries.

As far as the focus assist beam goes:



My Attempt at an DIY LED Macro Light - PentaxForums.com
DIY Macro Lighting LED Ring - DIY Photography
Making a focus assist macro light ring for manual lenses - StackRail.info
Inexpensive Ring Light Makes Macro Photos Easy | Hackaday
Make a 48 LED Macro Ring Light for SLR for $10

Do an Internet search on "DIY angel eye macro ring"

If you have continuous lighting you shouldn't need a low light focus assist.
Yeah, i have gone through like tens of them, but none had integration with the camera as is. I think the first idea i had in mind, that was running the step up from the grip, it's likely the best idea, instead of fiddling around with digital protocold that likely won't take me anywhere. I gues that the pure DIY (you know, wire and buttons) are the way to go if you want reliable things!
06-18-2018, 08:35 AM   #13
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I guess I misread the original question.

If I wanted to do this, I would splice a small circuit into a wired shutter release and use the half-press signal to trigger switching on the 'focus assist' light (with a timer or latch to leave it on for a period) as well as operating the camera shutter as normal. Then the main DIY job is to rig up the button in a convenient place to use.


Alternatively a small touch sensor stuck to the shutter button could do a good job...a simple piece of copper for grounding through your finger would do it, or you could go high tech with capacitive but that's probably going a bit far.
06-18-2018, 08:48 AM   #14
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QuoteOriginally posted by victormeldrew Quote
...a simple piece of copper for grounding through your finger would do it, or you could go high tech with capacitive but that's probably going a bit far
LMAO, i'm definetely not going that far!
I'll look around next month or later, and i'll do just the "i'm a round flashlight" version. It's the most cost effective i guess.
07-13-2018, 09:09 AM   #15
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The Cactus V6II communicates with the camera in order to turn on its AF-assist light whenever the camera would have turned on the AF-assist light of a flash.

If you are electronically inclined, you might be able to use the voltage the V6II sends to its own AF-assist LED to control your angel eye. For the purpose of firing the angel eye whenever you take a picture, you could piggy-back on the sync-port of the V6II.
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