Monday, October 22, 2007

Sun without spots

My first decent attempt to photograph the sun... This time it did not have any visible spots, image was taken at 20th October 2007. Used equipment were: Baader solar filter foil, Nikon 300/4,5 tele lens and Samsung SHC-721A surveillance camera. This final image was stacked from separate frames with Registax, approximately 250 frames were used.
After taking the original AVI clips, some problems were really visible. Below is one frame captured from the clip. Below and above the sun, the brighter area is visible. This may be due to blooming affect on the camera. Also narrow darker vertical "stripes" are visible. This particular camera has menu, but I have not found any blooming related adjustments there. Looks like this type of camera is not very suitable for high contrast targets...

Wednesday, October 17, 2007

SC OTA for planets, order placed

Today I have placed an order of SC OTA, to be used for planet photography mainly. I would expect, that there is good package for many years to come:

Celestron C8 OTA with XLT coatings
William Optics SC Grayford focuser
TeleVue 3x barlow (1.25" size)

Now I have couple of weeks and endless hours of waiting the package to arrive. Just like a small child waiting for the Santa Claus to visit :-)

Wednesday, October 3, 2007

Nikon EH-6 secrets, part1

Opening the covers of the EH-6 power supply, exposes parts with high voltage. So there is actual risk of electric shock, dangerous to your health. I have checked information in this article. I do not take any responsibility of the actual information, the correctness of information, or misusage of it. If you have any feedback, please inform me.

This "cracking project" started when I bought a external power supply for my Nikon D200 camera. The only available model was the EH-6 supply (by Nikon, that propably explains the price tag). For astro photography there also was a need to use D200 directly from the "non-Nikon" DC supply. The current / voltage specs needed for that were same as in EH-6, i.e. 13.5V 5A. Also there was a need to know pin purpose for low voltage connector (that mates the D200 body).

So I decided to "sacrifice" my EH-6 product quarantee, and open the covers... There was most propably SMPS -type power supply inside (based on the small size of heat sink and the high voltage electrolytic capacitor). On the left side, low voltage output cable connects to Nikon D200 (red / black wires).

I measured the DC voltage on the output. It was 13.66V, when supply was not connected to D200. After connecting supply to camera and swithing on it, the voltage dropped to 13.65V. Red wire carries the positive voltage (I call it as "VCC") and black wire is for the ground connection ("GND"). After measuring the voltages on the secondary side of EH-6 supply, it looks that pins have following purpose:

The "NC" stands for "not connected". This is because I did not found any voltage on this pin. I measured the resistance also towards the other pins, no connection found. If this "NC" pin has some other purpose, that I do not know (if you have info, please let me know). The respective pins on the Nikon D200 body are:

Again the "NC" pin was named on the D200 body. This is a pin that I am not sure, where is used to (if you have info, please let me know). The following is a situation where I feed D200 power from the external adjustable DC supply. Voltage reading (13.58V) is on the upper left, and current (0.29A) on the right. Typically the camera drains 0.3A, when swithed on and back TFT display is on. During long "bulb" exposures, the drawn current was about 0.6A. This is two times the "average" value. Current drain is especially important factor (if the camera is used only by batteries)

What I will do with my EH-6 supply ? For the moment, I'll leave it like it was. If I am not able to find the Nikon specific power supply connector electronics stores, I propably need to cut the secondary wire in half. And to install some suitable good quality two-pole locking connector there inbetween. That would allow to use EH-6 and leave also possibility to power D200 with suitable "non-Nikon" DC-supply.