Images from Utö, Messier 27

Another image from trip to Utö... This time one planetary nebula (Messier 27), as wide angle image. It is visible in image upper left corner, as green dot. Difficult imaging indeed, conditions were windy and I had to struggle keeping my tripod on the ground. Image taken with Nikon D200, Nikkor AF-S G 50mm, at f/1.4, single 8s exposure at ISO2500. Unfortunately sensor produces lot of noise :-(

Nikon DSLR battery project, converter specs

This battery project, requires some additional electronics. Main purpose is to keep output voltage stable as the input voltage changes (depending on the amount of 4S LiPo cell discharge level).

There is many options and manufactures to look at... First I will check what local stores (like YE, Partco and Elfa) are selling. I will make later decisions, what voltage converter to use. Because of efficiency requirements, converter module based on the linear technology, is not an option here...

requirements:

-typical input voltage 14.8…16.8V DC

-output voltage 12...13.5V DC

-output current 6A continuous

-efficiency bigger than 80%

-input low voltage cut-off @ 14V => 4*3.5V for 4S LiPo

-output short circuit protected

-preferred as PCB model

-small size recommended

-small heatsink usage - ok

Seawater bow at Utö

My company photography club made a trip to Finland archipelago / Utö, at October 2012. There I got captured few images, related to optical phenomenon. Origin of seawater bow is same as in normal rainbow, light is reflected inside of seawater droplet.

Nikon DSLR battery project, 4S LiPo testing

Project test continues with 4S LiPo battery (Orion 14.8V 6400mAh). Only D200 camera was powered. I used four diodes as voltage dropper (1N3879 switching diode). This solution is only temporary, more sophisticated one would be low loss switch mode voltage converter....

camera setup
***************************************
Nikon D200
300/4.5 lens (at max aperture)
raw images used
ISO800
menu: high ISO NR, off
menu: long exposure NR, off
"M" mode used
bulb exposure selected
camera at room temp, approx +23C

exposure setup
************************
MC36 trigger used
delay 10sec
exposure 60sec
interval 62sec
no limit in image count

Results (27th Oct)
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Diodes heat up a bit during testing, without heat sink used. Test was stopped, when voltage per cell approx at 3.5V level (some cells were 3.2/3.3V, two last at 3.6V, slightly uneven discharging). Totally 472 images were taken. It corresponds to three times more images, than in 3S LiPo 2100mAh test setup.

Utö nightsky, milky way

In the the beginning of October 2012, we had a company's photography club trip to Utö. It is a small island, in southern Finnish archipelago.

Expected clear sky there, for astro imaging. Expectations were not completely fulfilled. Occasionally sky was clear and milky way visible. Definitely a place, where you need to visit again some day...

Milky way, Utö 10/2012

Nikon DSLR battery project, 3S LiPo testing

I put the Orion 3S 11.1V LiPo cell (2100mAh version) to test. Nikon D200 is directly fed with this battery, no EN-EL3E used at battery slot. Small fuse of 2.5A is used in series to protect camera... I made the test without MB-D200 battery pack.

Power cord I took from my Nikon EH-6 AC supply. A sacrifice to science was made, and wire cut with scissors :-) Starting voltage at 3S LiPo battery, was 12.4V. I will at least run test down to 11.1V, maybe even a bit below that, if D200 still operates correctly.

Settings in the camera, were following:
 ****************************************
Nikon D200
300/4.5 lens (at max aperture)
raw images used
ISO800
menu: high ISO NR, off
menu: long exposure NR, off
"M" mode used
bulb exposure selected
camera at room temp, approx +23C

exposure setup
************************
MC36 trigger used
delay 10sec
exposure 60sec (1min)
interval 62 (1min 2 sec)
no limit in image count

Results (23rd October)
*******************************
Sequnce was run, until voltage under load was 3.5V per cell (overall 10.5V). Totally 145 images were taken. There is capacity increase noticed, when compared to 48 images with single EN-EL3E  and 91 images with dual EN-EL3E (with MB-D200 battery grip).

Results (24th October)
*******************************
Orion 3S Lipo battery was charged again. Now it took bit longer than last time, approximately 75min to full charge. Test settings were same as above, totally 149 images taken.

Nikon DSLR battery project, LiPo charging

Both batteries are now charged, all went OK as expected. No heating was noticed in the battery, when touched by hand. During 4S LiPo charging, charger itself heated (not still too hot to touch).

Following figures below, show the main data during charging. 3S LiPo was charged with full current (2.1A). Even it was defined higher current - 5 Amps - for the Orion 4S 6400mAh LiPo, approximate value was 3.3Amp.

Charging data for 3S 2100mAh LiPo

Charging data for 4S 6400mAh LiPo