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ProfF

Member Since 26 Jun 2009
Offline Last Active Mar 02 2014 04:51 AM
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Posts I've Made

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

23 December 2013 - 01:10 PM

I am not sure if I understand the graph, but I assume the y-axis is capacity and the x-axis is time (it would help to have a scale :-)

 

Anyhow, just wanted to report that after ~12 dives with the modified flash I have many TTL shots that came perfect on and some that did not. I am not sure if this is due to my errors (e.g., positioning of the strobes) or due to the flash output capacity. I did not hold a careful comparison.

 

Here are two examples, shot with TTL with the 10uf mod and two external strobes (Sea & Sea YS110a + DS-Y1, both set on TTL). Didn't change the exposure in development from RAW

 

 

Attached File  PC120586.jpg   406.68KB   42 downloadsAttached File  PC131061.jpg   318.53KB   38 downloads

 

In some cases I had to set the exposure higher in Lightroom. So the mod might be under-exposing in some situation.

 

Regarding my earlier comparison, I did repeat a similar test with a full housing, and it seems that having the fiber-optic cable in the right positioning helps... and the results are better. 

 


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

09 December 2013 - 06:14 AM

Jock,

 

I am not sure. Actually, I was surprised to see this. I just revisited the YS-D1 manual (I usually don't shot TTL, so never checked this option), and it seems that maybe I should have used the Slave-TTL rather than the normal TTL mode (which assumes preflash). I don't think the E-PL3 pre-flashes.

 

Nir


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

07 December 2013 - 09:04 PM

As an E-PL3 owner, I thought I will give it a try. I modified one of my two strobes, and indeed got a much weaker light. To test the effects on TTL, I did a semi controlled test (see attached pictures). My conclusion is that there is little difference between the two strobes when using an external strobe in TLL mode. The differences are mainly at the extereme ranges of apartures.

 

Setup:

 

E-PL3, Olympus 60mm lens, T 1/160 throughout.

 

External strobe YS-D1, set on TTL with the TTL dial on 0. The strobe was on the right of the camera facing so that the edge of the beam was on the object. The strobe was connected with fiber optic cable. I was holding the other end of the cable about 2cm in front of the camera strobe. I checked that the hand blocked any light from that strobe (you can also see that from the shades in the images).

 

I varied the strobe setting of the camera and aperture, as noted in the attached picture. I converted the images from raw to jpeg without any adjustments.

 
 
Attached File  Untitled-1.png   273.48KB   41 downloads

 

 

My conclusion is that the camera changes output by modifying duration of the flash. The modified strobe had slightly lower exposures throughout the test. 


In Topic: DIY LCD magnifier - optics question

25 September 2013 - 06:45 AM

I am aware that lenses lose between 1/2 to 3/4 of their power due to differences in refraction index. I am thinking of sandwiching a diopter lens between two clear ones (UV filter). If I can get this contraption to be waterproof, the diopter should not lose its power, as far as I understand. (This how Subsee lenses are built.) The optics are terrible with cheap filters, but since it is only a viewfinder, this will not show in the final images :-)

 

I am wondering if there is a way to make the diopter power adjustable. Any ideas?


In Topic: 3D Printing a port

18 May 2013 - 11:27 PM

If you have a lathe, why not produce one from metal (aluminum)?