My 1st H-alpha pic

Meng Lee · Post by **Meng Lee** » Tue Jan 15, 2008 2:45 am

Hi, my first H alpha pic. Rosette Nebula

R200SS, with Baader H-alpha filter with ATIK 16 HR

cataclysm · Post by **cataclysm** » Tue Jan 15, 2008 2:03 pm

Good work Meng Lee! Yep, you can really go deep with narrowband filters, a real necessity for our light polluted sky. Btw, how long were the exposures?

Meng Lee · Post by **Meng Lee** » Tue Jan 15, 2008 2:15 pm

Hi,

Total exposures length is about 40 mins. Most frames are spolit because the rooftop was shaking with vehicles going by and i forgot to put the vibration supression pads and i was sleeping

. So only 40mins (5 min subs) worth of exposure is ok and 800mm will make a huge mosaic of rosette, hehe.

Post by **rcj** » Tue Jan 15, 2008 3:05 pm

good attempt! how did u solve the moisture issue for the 16HR?

Meng Lee · Post by **Meng Lee** » Tue Jan 15, 2008 3:19 pm

Hehe, actually the moisture wasn't resolved. Yesterday past midnight, humidity gets quite high, even the rooftop floor was damp and slippery. The screen starts showing white with dark hole in the middle, the camera window is moisted. It seems to moist up only on days like that, so I think that should be quite reasonable.

Post by **rcj** » Tue Jan 15, 2008 3:38 pm

so u managed to grab some exposures before the moisture set in? lucky chap!

Post by **perseid** » Tue Jan 15, 2008 4:33 pm

Great job. I can see a lot of detail in your image.

As for the dew problem, I was told by Jack of mallincam camera to do the following. (It may be applicable for your atik too). He told me to heat up the nose piece slightly and then quickly install the filters. This way the air between the sensor and the filter will be dry. Since this assembly is reasonably air tight, you may be able to do imaging a bit longer.

I have not tested out this method, but I am quite confident it will work.

Tachyon · Post by **Tachyon** » Tue Jan 15, 2008 4:52 pm

What about dew on the filter?

Meng Lee · Post by **Meng Lee** » Tue Jan 15, 2008 11:36 pm

Remus: Yah I shot before I saw fogging coming in from the edges, then i moved to eta carinae, i see fogging coming in. Actually half of the frames are thrown away because of the floor vibration. After setting up, I cannot put the pads on the tripod legs because the whole setup is impossible to be tilted to put the pads. I like the EQ-6 mount, it slew to rosette properly (and i only did 1 star alignment) and then slew to eta carinae properly. And R200SS is really a good imaging scope!

Perseid: I will try it out on a dry day and warm the nosepiece of the camera then seal it up somewhat.

Tachyon: there is no dew on the filter luckily.

Post by **perseid** » Wed Jan 16, 2008 1:05 am

Tachyon wrote:What about dew on the filter?

Most of the time, the dew problem only arise due to the cooling within the camera. This affect the optical glass which is next to the sensor. The filter is usually further away and didn't get much cooler than the ambient temperature.

If the filter does get wet, then I guess the telescope tube must be heated slightly before assembling the whole system.