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04-02-2014, 02:16 AM   #1
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Pentax K-50 and Sigma EF 610 DG ST Flash.

Hello Everyone,

I've recently updated my DSLR from, K-X to K-50. I've also got my hands on a Sigma EF 610 DG ST flash.

I am looking at doing some indoor photography - portrait stuff. I am also maybe getting some slave flash units and umbrellas. I believe the flash I have does not trigger other flashes so will need some kind of trigger (unit that will sit between K-50 and Sigma Flash) and no doubt a receiver (or two) and slave flash(s), umbrella(s) that will essentially do what I am looking for?

I'm new to this side of photography so any advice, pointers and suggestions most welcome on what equipment I should be looking for - I am not looking to break the bank so aiming for functional rather than top-of-the-range until I feel comfortable.

Thanks for your advice in advance.

jaq1967

04-02-2014, 03:34 AM   #2
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QuoteOriginally posted by jaq1967 Quote
Hello Everyone,

I've recently updated my DSLR from, K-X to K-50. I've also got my hands on a Sigma EF 610 DG ST flash.

I am looking at doing some indoor photography - portrait stuff. I am also maybe getting some slave flash units and umbrellas. I believe the flash I have does not trigger other flashes so will need some kind of trigger (unit that will sit between K-50 and Sigma Flash) and no doubt a receiver (or two) and slave flash(s), umbrella(s) that will essentially do what I am looking for?

I'm new to this side of photography so any advice, pointers and suggestions most welcome on what equipment I should be looking for - I am not looking to break the bank so aiming for functional rather than top-of-the-range until I feel comfortable.

Thanks for your advice in advance.

jaq1967
Before you go off the deep end and spend money you may not have to make sure you check out the lighting forum on this site, it will provide you a lot of useful information regarding Pentax.

Pay particular attention to this thread there are two new flash systems released recently. https://www.pentaxforums.com/forums/125-flashes-lighting-studio/253216-cactus...sh-review.html

MAC on campus has an excellent series of video's about using bare flashes for balancing ambient and flash. It's a good place to start without investing hundreds in equipment that you may or may not use, the information in these videos easily transfer to studio work and diffuser uses.

I've found you tube very useful to better understand using flash in ambient light and in studio, in particular MAC on CAMPUS. If you're going to shoot using flash with Pentax beyond camera mounted flash (P-TTL) you will have to learn how to use both camera and flash in manual mode.
04-02-2014, 06:12 AM   #3
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If you're using off-camera flashes with triggers it is cheaper to buy either old auto autothyristor flashes or cheap Chinese autothyristor flashes.

Careful about the Sigma as it might not work correctly if you use it with the K50. Pentax slightly changed the flash protocol so third party lenses need to have their firmware updated in order to work with new Pentax cameras.
04-02-2014, 10:34 AM   #4
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QuoteOriginally posted by Deni Quote
If you're using off-camera flashes with triggers it is cheaper to buy either old auto autothyristor flashes or cheap Chinese autothyristor flashes.

Careful about the Sigma as it might not work correctly if you use it with the K50. Pentax slightly changed the flash protocol so third party lenses need to have their firmware updated in order to work with new Pentax cameras.
That's might be the reason why an old Sigma AF 28-80 lens won't work with my K-50 but is happy on my K-X.

I liked Pentax for being backward compatible but seems like they are less backward compatible as they use to be. Not good, as some of the old stuff is perfectly functional at the fraction of the price!

Thank you (...both) for your advice and help.

Jaq

04-05-2014, 10:43 AM   #5
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You're wrong about the compatibility. It's the 28-80 that does not adhere to the specifications .
04-05-2014, 11:53 PM   #6
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QuoteOriginally posted by sterretje Quote
You're wrong about the compatibility. It's the 28-80 that does not adhere to the specifications .
Yes... I am wrong. Why? Because I'm an idiot! It would have helped if I moved the switch on the lens to 'A'. It worked on the K-50 after that! Beats me how it worked on the K-X without it switch to 'A' but I ain't gonna worry about that. Life's too short! Lol...

---------- Post added 04-06-2014 at 07:56 AM ----------

QuoteOriginally posted by sterretje Quote
You're wrong about the compatibility. It's the 28-80 that does not adhere to the specifications .
Besides... How do you figure the 28-80 AF not adhering to the specs if indeed the AF is OLDER than the K-50?!? Surely that's not a possible conclusion if prior to the K-50 it worked with all other models?!?
04-29-2014, 03:31 AM   #7
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jaq1967, just one comment from me re: your flash. Unless I'm mistaken, it can only be used at full and 1/16th power in manual mode. Which might limit your ability to use it in the way you want, off-camera. (P-TTL can work remotely though). It's one of the reasons I bought the Super version, although I don't really use mine on manual much.

Just wanted to flag that before you go off and buy kit!
01-21-2015, 11:24 PM   #8
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Hi all,
Following up on that thread as I have the exact same configuration: K-50 & EF-610 DG ST.
I have not been through extensive tests yet (no time) but being new with the external flash elements, I have some doubts the P-TTL protocol is working properly currently... It seems the flash is always shooting at max power.
Is there a way to confirm everything is fine? Is there any known issue between these two products?

Thanks.
A flash newbie that needs some help!

01-22-2015, 10:56 AM   #9
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QuoteOriginally posted by newbanall Quote
Hi all,
Following up on that thread as I have the exact same configuration: K-50 & EF-610 DG ST.
I have not been through extensive tests yet (no time) but being new with the external flash elements, I have some doubts the P-TTL protocol is working properly currently... It seems the flash is always shooting at max power.
Is there a way to confirm everything is fine? Is there any known issue between these two products?

Thanks.
A flash newbie that needs some help!
You might have done better opening a new thread either here or in the accessories portion of this site. I don't know own your model flash, but can give you a list of bullet points to chew on:
  • Did you buy your flash new when you got your K-50? There are some reports of Sigma from as little as four years ago not working with current generation Pentax P-TTL.
  • Are you sure you are using the correct mode on the flash? I have found the Sigma user interface to not be very user friendly. Be sure you are in P-TTL mode
  • Are you using the flash on-camera or off-camera. I don't believe that the EF-610 DG ST supports off-camera P-TTL.
Lastly, you may want to confirm that you have the Pentax version of the flash.


Steve
01-22-2015, 12:59 PM   #10
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QuoteOriginally posted by jaq1967 Quote
Besides... How do you figure the 28-80 AF not adhering to the specs if indeed the AF is OLDER than the K-50?!? Surely that's not a possible conclusion if prior to the K-50 it worked with all other models?!?
I know a bit about interfaces and protocols (not Pentax specific) and a little about reverse engineering. Below is an example as to why it might not work.

Pentax has a specification for the serial interface. It will, amongst other things, specify the the voltage(s) of the signal that is used for communication with the lens. As there is no power contact in the KAF mount (except for the PZ contacts that are often not used), this signal on the serial interface is also used to provide power to the lens electronics.

The Pentax specification will (just as an example) state that the a signal level below -2V represents a logical '0' and a voltage level above +2V represents a logical '1'.

In an older Pentax camera, these levels might be -3V and +3V respectively. It's within the spec (-3V is 'better than' -2V and +3V is 'better than' +2V). Sigma measured the voltages on the older camera, saw the plus and minus 3V and designed their lens electronics around that.

In a K50, Pentax decided to change the voltages on the serial interface to e.g. -2.5V and plus 2.5V. It's still within to the specification of plus and minus 2V. So the Sigma lens now gets lower voltages and the lens electronics basically can't power up as it requires those plus and minus 3V voltages to work. The Pentax lenses however were designed to work with the plus and minus 2V and will still be working.

A reason why Pentax lowered the voltage on the K50 might be that power consumption goes down with voltage.

Note1
I have never analyzed the Pentax interface and protocol, so I don't know the exact details; the 3V numbers are just examples; it could also have been 0 and 3V or whatever.

Note2
This problem is similar to battery powered equipment that is designed for an internal power of 5V and is therefore powered by 4 alkaline batteries (4x1.5V = 6V); trying to power it with e.g. 4 Ni-Cd batteries (4x1.2V = 4.8V) might cause it not to power up.
01-22-2015, 06:32 PM   #11
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QuoteOriginally posted by stevebrot Quote
You might have done better opening a new thread either here or in the accessories portion of this site. I don't know own your model flash, but can give you a list of bullet points to chew on:
  • Did you buy your flash new when you got your K-50? There are some reports of Sigma from as little as four years ago not working with current generation Pentax P-TTL.
  • Are you sure you are using the correct mode on the flash? I have found the Sigma user interface to not be very user friendly. Be sure you are in P-TTL mode
  • Are you using the flash on-camera or off-camera. I don't believe that the EF-610 DG ST supports off-camera P-TTL.
Lastly, you may want to confirm that you have the Pentax version of the flash.


Steve
Hi stevebrot. Thanks for the advice: I did no want to open another thread as it would have been an identical title. But I'll know better next time .
With regards to your questions:
- I bought the flash few months after the K-50. I did some extensive reading on the web and did not find any warning on the compatibility (but this does not mean there's no issue),
- Indeed, it is in P-TTL mode when using it (this flash has really no user interface beside a switch with 4 positions: OFF, P-TTL, Manual low power, Manual full power),
- Using the flash on-camera. This flash does not support off-camera indeed (from what I read anyway).
And yes, I confirm this is the Pentax version .

I'll do some more testings over the weekend to try to understand exactly what's going on... I'll keep you posted.

Thanks
01-22-2015, 07:20 PM   #12
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QuoteOriginally posted by newbanall Quote
I bought the flash few months after the K-50.
If you bought it new, you should talk to Sigma or the store from which you bought it. If you bought it used, it may be old enough to not support the K-50.


Steve
01-22-2015, 08:28 PM   #13
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QuoteOriginally posted by stevebrot Quote
If you bought it new, you should talk to Sigma or the store from which you bought it. If you bought it used, it may be old enough to not support the K-50.


Steve
Yup. Checking with Sigma as we speak as bought new.
Thanks again.
01-25-2015, 04:31 AM   #14
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Did some more tests over the weekend, and the P-TTL seems to work fine when using the Sigma 18-200 lense, but It seems not to work at all with the DA35mmAL prime lense...
This could be a normal behavior, but I do not quite understand where this could be coming from.
Any clue around here?
Thanks
01-27-2015, 09:53 AM   #15
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QuoteOriginally posted by newbanall Quote
Did some more tests over the weekend, and the P-TTL seems to work fine when using the Sigma 18-200 lense...
The key word here is "seems". How are you testing? With the same subject, same ambient light, same aperture, and with the 18-200 at 35mm, both lenses should result in similar exposures. What happens with the built-in flash?


Steve
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