Hacking a Pentax 4P grip for the AF540-FGZ

MattMatic · 2007-07-18T12:57:01+0100

You may have seen one of these: http://www.bdimitrov.de/kmp/flashes/misc/grip.jpg It's a 4P, old style grip for the Pentax systems. It's very compact, has a great detachable camera plate and space for 8 x AA batteries inside. However, the hotshoe mount shorts out the extra pin on the AF540 and AF360 which makes the flash go a little AWOL. I had bodged a temporary solution by isolating the hotshoe with a piece of 35mm film (:P) Last night I finished a little modification job on the grip and thought I'd share the information ;) As usual - absolutely no responsibility taken for you reading this and messing up your grip or flash. This information is just to stop frustration for those that attempt to do this. Predrill This step is to make the hole in the plastic for the locking pin. I used a 1.5mm drill bit in a pillar drill to make a small hole that is in line with the left hand contact, and directly between the plastic and the metal of the hotshoe grip. (Make a measure with a piece of paper if it helps). The drill will probably just mark the metal and make a hole in the plastic. You'll do the metal hole in the next steps... Disassembly 1 ) Loosen the two silver screws on the mount joint (where the camera plate clicks in) and remove the silver band and clip from the grip. You'll need to also unscrew the AA battery cover (the big round cover at the bottom of the grip) 2 ) Remove the small black screw just in front of the hotshoe mount at the top. 3 ) Carefully peel back the texture from the rear half (the side with the red switch) and this will reveal three black screws. Remove these 4 ) Unclip and hinge out the front half of the grip. 5 ) Under the hotshoe you should see an earth tag - remove the small nut 6 ) Use a very well fitting jeweller screwdriver and carefully unscrew the four black screws in the hotshoe. DO NOT MANGLE the heads. Because the screws have been dabbed with a touch of glue/threadlock you have to be extremely careful - I had to scrape some of the green gunge off before unscrewing. 7 ) Having removed the hotshoe metal plate, you need to use a needle file to file out... 8 ) The corresponding hole in the metal for the locking pin 9 ) A large semicircle next to the front right screw hole. This ensures that the extra pin on the AF540 won't touch the hotshoe plate. I found it useful to slide the metal plate onto the bottom of the AF540 to see if I had the alignment right (taking into account the little bump of plastic that stops the flash from sliding right to the front of the metal). 10 ) While in there, I sliced off about one-quarter off the rubber pads that are in the AA battery bays. (The NiMH batteries I used wouldn't go in and let me screw the bottom plate on). 11 ) Reassembly was the reverse of the above - but fitting the metal plate back to the underside of the hotshoe was extremely fiddly :P With that complete I can mount the AF540 onto the hotshoe, screw in the 5P cable into the side of the AF540 and connect to the camera. Beautiful :) (I have some images which I'll posted later...) Hope that helps someone else fathom out what to do! (And if you have a 4P grip and want the job done, and can pay by PayPal, I could probably find some time to modify it for you... if you ask nicely!) Matt

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Mannesty Mannesty

7650 posts
21 years
Totana,
Spain.

Posted 26/04/2010 - 11:38 Link

Excellent instructions Matt, but I managed to do mine without taking it apart. I didn't drill the hole for the locking pin though.

I used a model making drill, like the Dremel, but with a fine and narrow grinding stone or glass etching bit, probably both. It did take awhile to remove enough of the metal to ensure the extra pin didn't short to the steel plate though.

I'll maybe revisit this and drill the hole for the locking pin. I hadn't actually thought of doing that because the locking pin is spring loaded and if the hole isn't there, it can't get stuck. It would give a bit better security to the fixing I guess.

It does make an awesome hammerhead gun though, which can still be used wirelessly if needed.

Peter E Smith - flickr Photostream

Edited by Mannesty: 26/04/2010 - 11:40