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simonknee

Member Since 24 Aug 2008
Offline Last Active Jun 05 2014 02:05 AM
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Posts I've Made

In Topic: OM-D EM-1

31 January 2014 - 08:08 AM

Some more pics of the adapter in situ...

 

First the 50mm macro snout! You can see the control knob is nicely placed.

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The adapter is the correct length to allow full extension (close focus) of this lens.

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The gearing works correctly to allow manual focus but with the 50mm only allows fine adjustment since the oly gear has end stops.

Fine for photos since AF can do most of the work but I shall need to come up with a custom gear for video.

(n.b. it takes several full rotations to focus the 50mm infinity to close - and it is velocity sensitive too but you don't get much speed up on the knob)

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On with the dome - it actually goes on a few more mm than this pic shows and closes up the gap you see here.

But then you have to re-adjust the petals and I couldn't be bothered for this little shoot

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From above

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The lovely 8mm sitting where it should

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Now the 11-22mm with "customised" (draught excluder) gear from a 7-14mm.

A bit tricky to assemble as the knob has to stay in it's pulled out position.

But it all works as it shold which means the even larger 7-14mm would fit in this rig too.

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With dome and per-02 extender. 

I do not think this is at the nodal point at all and need to get a per-01 instead.

However there is no vignetting from the dome so it is worth testing in the water.

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And finally the lovely leak light showing I am leak free

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Simon


In Topic: OM-D EM-1

30 January 2014 - 09:14 AM

Look what arrived for me in the post today...

 

Attached File  IMG_20140130_170742.jpg   88.95KB   60 downloads

 

Thanks Alex, I'll let you know how it goes (not in the water for a couple of months mind you)

 

Also got the replacement vacuum indicator bits - doesn't look to hard to swap at all.

Includes two spare LED in case you break the existing one getting it out which is a thoughtful touch.

 

Simon


In Topic: Olympus PEN & OMD Flash mod to reduce recycling time & battery

27 January 2014 - 04:43 AM

Testing of resistance mod:

 

(my erratic exposure above F16 was down to the erratic closing of the aperture blades on my 50f2, I am now testing with my 11-22 @22mm as it is a happy snapper at all apertures)

 

So in an effort to increase the resistance of the tube (and use less power) I added some resistance.

 

I soldered in a 1ohm 5watt wirewound directly to the anode of the tube (pic later).

The flash still worked but this made little difference to recharge times.

There is plenty of power going through here which soon destroyed a 10ohm 1W carbon resistor (nice internal explosions).

So digging about in the component drawers I settled on a 6R8 (that's 6.8ohms) 22W wire wound resistor.

I will try and do the maths on what is a suitable wattage later - suffice to say please be careful if you try this, no fires please. 

 

When testing in the housing with a pair of Sea&Sea this shaved 1/3 off the recharge time compared to an original FL-LM2.

However reviewing the images from my resistive flash showed that as the aperture got smaller the exposure got brighter (tried another lens to confirm)

AT F10 exposure was the matched, at F22 it was approximately 1 stop brighter using the resistive flash.

I guess the mod upsets the pre-flash a bit and causes the EM-1 to think it needs more light.

So I stopped down the flash (on the EM-1) to match exposure and of course recharge time was even quicker.

The camera was able to keep up with the recharge of the S&S (YS110a & DS-01) on a dining room table test at least.

 

This is a double-edged sword for me since though it appears predictable it means there is more to remember to adjust which isn't really the ethos of TTL. Though adjusting flash exposure at the camera is much easier than in manual on each of the strobes.

 

Onwards and sideways

 

Simon

 

EDIT: As to this mod upsetting the pre-flash I did notice that the light produced by the flash dropped away more dramatically than the original as you moved down the full, 1/2, 1/4, 1/8 ... flash settings (tested on it's own out of housing). The resistor mod does appear to adversely affect shorter flash times (perhaps it causes a tiny start delay?). This does mean that there may be issues with short flash durations even in the housing - only UW testing will tell if these shorter durations are even needed.


In Topic: OM-D EM-1

24 January 2014 - 01:38 AM

Yes they do Karen, however the base of the ball also has the screw threads that the upper support bracket (silver metal in the pictures) attach to. With out this the handles are not as stable - it's not that bad though about 5mm flex if you push, I would be happy to use. So may want to ask Nauticam if there is an alternative top piece for the handles. The screw thread is large M8 I think but don't quote me on that.

 

Simon


In Topic: Olympus PEN & OMD Flash mod to reduce recycling time & battery

23 January 2014 - 10:42 AM

Screws are all underneath sticky tape. Flip the flash up and remove the bit of tape. You will find the ones you need to take the top cover off.

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