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ChrisRoss

Member Since 13 Feb 2016
Offline Last Active Today, 04:06 AM
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Posts I've Made

In Topic: Olympus PT-EP13 Underwater Housing issues and cleaning

14 June 2019 - 07:44 PM

The EM-1 MkII is excellent - great AF, significantly better than the EM-5 MkII.  C-AF plus tracking actually works well and is my default AF option underwater for both wide and macro.  Sensor wise you have a few more MP but performance is not a huge leap above the EM-5 II, certainly noticeable but not a big step forward.


In Topic: Wider option for A7RII

14 June 2019 - 07:31 PM

The fish eyes work fine with the 140mm dome, you can also use the ultra compact little Zen 100mm dome.  You would need to get recommendations on the extensions to use probably from Phil as the combination is not listed in Nauticam's port chart, also whether to use a N85 or N120 port.  You would probably only want the huge 230mm dome if you were doing lots of over/unders.

 

Based on the Canon port chart the Canon 8-15 needs 20mm more extension than the Tokina 10-17.  Based on the Sony N85 port charts the Tokina 10-17 plus metabones needs a 50mm n85-N120 adapter with the metabones, so it follows that the Canon 8-15 would need 20mm more which is a 70mm n85-N120 adapter - I would ask to confirm that.    You would also need a recommendation for a zoom gear.


In Topic: TTL Converter for Nauticam GH5 Housing

14 June 2019 - 04:43 AM

In theory that's the way it should work, it will depend on a number of things including having good quality cables to transmit the signals and if the LEDs are strong enough to trigger the  YS-D2s reliably. 

 

Sounds like you are wanting to shoot stills - the EM-1 MkII will definitely trigger your YS-D2s using the little accessory flash it comes with and the AF is really first class, can't compare it to a GH5 not having used one, but I've been really happy with my EM-1 MkII and the little accessory flash has served me well. Plenty of examples on my website in the link in my signature.

 

I thought I wanted to shoot TTL  as well when I first started, but very quickly switched to manual, setting the flash at 1/64th power to trigger my strobes.  Results were hit and miss particularly for wide angle where the flash was never powerful enough.   To be honest I don't have to change power very much except when going between wide angle and macro when I need to turn it down a stop or two and any errors in exposure are 100% correctable in Raw.  At 1/64th recycle is instant and I'm never constrained by waiting for it to recycle and doesn't really impact battery life as I can do 3- 4 dives on one battery.


In Topic: Beginner question: Mininum focusing distance

13 June 2019 - 11:51 PM

What I find can happen with the contrast detect AF systems is they "look through" the subject to focus on what is behind if it has more contrast than the subject or if the subject is a little small.  Generally though I look for two things focus acquisition and the subject becoming more defined or snapping to focus.  The minimum focus distance is measured from the sensor plane and as stated above you are focusing on a virtual image, which is closer.  You can use this to Visualise  how far away you can focus:  https://oceanity.com.au/tools/virtual-image-calculator/ 

 

For a 6 inch dome (with a 3" radius of curvature ) at 20cm object distance from dome the virtual image is 8.1cm from the dome, which is as low as the calculator goes.  I would estimate the virtual image is 5cm from the dome with an object 10cm from the dome and it really should be able to focus on that.  If you were focusing on coral maybe the back of the coral head with coral branches against clear water had the better contrast and it focused there.  Just because it locked focus does not mean it focused on what you wanted to focus on.

 

Based on my Oly 12-40 which has the same more or less min focus distance you should be able to focus maybe 5cm from the port surface.  You could try assigning focus peaking to a function button and confirm it's peaking around the thing you want to focus upon?


In Topic: Olympus PT-EP13 Underwater Housing issues and cleaning

13 June 2019 - 05:46 PM

If the buttons are leaking you will probably find the housing is beyond repair, these types of housing are not made with servicing of o rings on the buttons in mind.  A suggested look in the classifieds for a second hand Nauticam housing - I had one and it was excellent - now upgraded to EM-1 MkII.  In the way of new housings you could purchase a Nauticam $US1450, Isotta $US1200 or an ikelite $US1049 .  You would probably need to buy new ports which of course adds to the expense, but the security of the vacuum system makes it worthwhile in my view.  Getting a second hand Olympus housing could see you in the exact same position in a year or two.

 

On the question of leaking buttons, this can be caused by salt crystals if you don't soak the housing and work all the buttons after each dive.