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Ecumenical portrait…

On Thanksgiving eve, there was an ecumenical prayer service at Santa Cruz in Buda, TX. Last year we took a group photo of the various local ministers, so we were asked to come again and do the same.

I didn’t recall exactly how we had it set up last year, but this year, I used two umbrellas above and on both sides of the camera. Right behind was a bare flash aimed away to a strip of wall to provide some additional diffuse light (or that was the hope). Here is the setup photo:

The result was:

I mentioned that I didn’t recall how I set up last year because I got a nasty, bright specular reflection off the window around the shadow of the woman 3rd from the right. I ended up having to paint in some dark blue from another pane (at about 11 o’clock from the bright area) to make the bright spot go away. You can still see some of that reflection on the lead between the panes.  At full size on the screen and printed on 8×10, it looks ok.

I was asked by a local reporter if I would provide a copy of the image to her.  I didn’t see it in the online edition of the Hays Free Press, but she sent me a link to her blog posting.

Posted by by david

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Small studio…

DIY Photography is a site I read often. I’ve even written two articles for it.

Today there was a posting about utilizing a small space as a studio. A very good read. Much of it is similar to what we’ve been doing in the living room. The biggest difference is that he’s using studio strobes and we don’t have as many different light modifiers. The biggest item we do not have are grids to limit the increase the directionality of the light. I have been wanting to make some grids but have not fully settled on the best way to DIY that.

They key is to move the lights up close to the subject to take advantage of the fall off from the inverse square law.


Posted by by david

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DIY Radio Popper building blocks…

In perusing the web, I stumbled upon an interesting blog posting where an RF remote flash trigger was modified to send the Nikon CLS flash pulses to create DIY Radio Popper equivalents. That blog posting points to several other related postings. All very interesting… [Radio Poppers are extend the range of Nikon’s CLS system to non-line of sight using a radio link.]

After mulling it over for a while, I decided rather than purchase a boxed up pair of RF modules to modify, I would just order a bare set of RF data link modules, the phototransistors, and IR LEDs. The first pair of RF modules were a huge disappointment because there is too much chatter on the receiver end with no valid transmission, making them useless. A new pair was ordered with a better receiver module but it has not yet been received.

In the mean while, I wired up one of the phototransistors to see how well I could capture the Nikon CLS pulse train. I lifted the basic scheme from here, copying the high pass filter which filters out the contribution from ambient light. I wired it up thusly:

The resistor values are different than in the other posting I found because I did not have a full box of resistor and capacitors to pull from; I had to use what was on hand. Here is a photo of the breadboarded setup:

Here is a scope trace of part of the Nikon CLS pulse train measured at points A and B in the schematic above:

The yellow trace is from point A, the blue trace is from point B. The 330 Ohm resistor, R1, does very well at keeping the ambient office lights from contributing much to the signal in the yellow trace. The ground level in the blue trace dips below zero with successive pulses. The output at point A is probably sufficiently clean to drive the transmitter module.

The new receiver module should have an RX3310A superheterodyne receiver chip on it. It looks like the module set was designed to operate up to 4800 baud, so I suspect that the timing caps on the receiver module may need to be changed to better capture the pulses from the CLS train, since they’re flashing at about 8kHz.

More to come after the new RF link module set comes…

Posted by by david

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