Yashica 100DX Medical 100mm f4

I'm sorry to say that due to the unreliability and danger of blowing up my 70D again I'm having to retire this lens. It's been replaced by a spanking new Canon 100mm f2.8 IS USM L and Youngnou ring flash. Feel free to have a read anyway.

One of only two lenses that isn't a Takumar. I call this my 'Gyno' lens. It's actually designed for medical work, hence the name. Back in the day you would use a 35mm film camera, focus and shoot. The apeture changes as you focus which is actually also a sort of zoom. As you focus it zooms a little and the fstop goes up so at fully back its at f4 and at fully zoomed/focused in it's at f22. Sort of fool proof for doctors and dentists to use without any formal training. The things this thing as photographed in its time ah!! The mind boggles!

There is one very big note of caution regarding this kit. It consists of a control / battery pack that takes 12 yes Twelve AA batteries. This powers the built in flash and the little spotting light at the front. So back in the days of film and all mechanical cameras the fact that these flashes can pump out +400v back into the camera body after they are fired was of little worry to lumps of metal and glass. Roll forward to the wonderful electronic DSLR and those things have got lots of lovely shiny little bits of plastic and wire that will very happily go phoot at the slightest whiff of over 6v.

Thankfully there are a few solutions. One is to use a set of remote flash triggers as can be seen in the third picture below. Put a slither of plastic between the two triggers contacts and you have a remote action. These triggers can take a lot of current and are cheaper to replace than the camera. The other method is to give it to your electrical engineer brother, let him do a PAT test on it and install some jiggery pokery into the innards. Then not ask any questions since it's all magic.

With the remote triggers attached. A bit of a wedding cake but it works

This is a fantastic lens. I use my 70D crop with it and can sync at 320th perfect for moving things. The battery control box attaches to my waist, the curly coils connect everything together and I'm off to poke my gyno equipment into any bush.
I realy like the black background the flash gives. It has an Edwardian painting feel to it. The detail is wonderful and once you master the 'back and forth' focus method your in.
They can be quit expensive at between £150 and £200 however I managed to get mine for under £50 since it had been 'mucked about with'. Turns out there was nothing wrong with it. 


  1. Hello , How you trigger flash ? direct on 70D ? I try with radio trigger, also direct on spny A3000 and canon XTi , all 3 don't work, I measure 3,2v on flash shoe cord sync , secure to use on dslr , but it does not fire if I put the shoe in short circuit, fires normally.

  2. Hi Andre

    I used to use the two Yongnou rf603c remote triggers and they worked fine. See pic 3. If it works by short circuit there may be a problem with the shoe block unless you shorted it on the contacts there.

    The trigger is direct through the 70D hotshoe. I cannot see why yours does not fire. Whoever the flash does not fire in Live View on the 70D. Could that be it? I would not dare to use it direct on the 70D hotshoe even if you do measure 3.2v It's old tech that can blast out a lot of kick.

    You need 2 remote triggers with a piece of plastic between the two to isolate them.

    Hope this helps and let me know how you get on Andre



  3. Thanks for reply , I short circuit on shoe block contacts , I think this is ok , I will try buy this radios that you use or wein safe sync hot shoe, that I find this tip in another place. After I post my result, best regards

  4. Andre I've decided to not use this lens anymore. The flash was becoming unreliable and if it shorted again would blow up my 70D


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