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Posts Made By: Wei-Hao Wang

May 2, 2005 11:01 AM Forum: Film Astrophotography - Imaging and Processing

Sheet film for wide fields

Posted By Wei-Hao Wang

Hi,

Probably Fujichrome Provia 100F is the only candidate in 4x5 format. Kodak E100S is also good but was discontinued two years ago. If you can find some E100S, you will like it.

Good luck!

Wei-Hao

May 27, 2005 12:13 AM Forum: Film Astrophotography - Imaging and Processing

Ronchi screen question

Posted By Wei-Hao Wang

Hi,

My guess is, film rail is still a better place to put the Ronchi screen.

If you attach one against the ground screen, the image of the Ronchi fringes will form right on the ground screen and will be extremely small to see. In this case, all you need is a good loupe or microscope to see the image. Using a Ronchi screen or not doesn't matter any more.

This is just my guess. You can still try it. It will be nice if this turns out working well.

Wei-Hao

July 13, 2005 03:36 AM Forum: CCD Imaging and Processing/Deep Sky

A Splash of Summer Color

Posted By Wei-Hao Wang

wow... very beautiful.
How about making a mosaic of this area?

Wei-Hao

September 28, 2005 10:23 AM Forum: Film Astrophotography - Imaging and Processing

reading list?

Posted By Wei-Hao Wang

The ultimate one would be "A Manual of Advanced Celestial Photography" by Wallis & Provin. This book is out of print but used ones can still be found on amazon. Another excellent online resource is Jerry Lodriguss' homepage: http://www.astropix.com/

November 15, 2005 03:46 AM Forum: Film Astrophotography - Imaging and Processing

m42

Posted By Wei-Hao Wang

Hi Jim,

How about taking a very long (e.g., 2 hours) exposure and a short (5-10 min) one and combine them together?

Wei-Hao

November 16, 2005 05:24 AM Forum: CCD Imaging and Processing/Deep Sky

Another M31

Posted By Wei-Hao Wang

Wow! I like the color.

Wei-Hao

December 31, 2005 04:47 AM Forum: CCD Imaging and Processing/Deep Sky

Anyone Image at Mauna Kea?

Posted By Wei-Hao Wang

Hi,

In short, it's dark enough at the VIS and it's a safe place to stay over night.

There are small star parties every day before 10pm. It's dark, but cars come and go. It gets much better after 10pm.

After 10pm, there are two light sources. One is the light from Hale Pohaku (offices and lounge for astronomers) to the north. If your telescope is near the north edge of the parking space at the VIS, trees may block this light for you but you may lose Polaris. The other light is the red light from the VIS. This could be easily blocked with your car.

Depending on the season, sometimes the inversion layer might go as high as 10000 feet. In that case, the summit may still have clear sky but the VIS doesn't. If you have a 4WD car, you can drive up to 12000 feet. There is couple of parking lots next to the road and is still far away from the summit. You can stay there over night without being harassed by the rangers. Over there, some people may have sickness but it won't be as bad as at the summit. Needless to say, the condition there is much better than the VIS.

Please feel free to ask me any questions. I will be very happy to help anyone to enjoy Mauna Kea.

Cheers,
Wei-Hao

February 2, 2006 12:52 PM Forum: Film Astrophotography - Imaging and Processing

Flatbed scanners and astro negatives

Posted By Wei-Hao Wang

Hi,

I use Epson 4870 to scan my astrophoto slides and negatives. It's great. Please see this: http://tinyurl.com/9vq8t

I'm not familiar with the Canon or HP ones but I believe they are equally good. The bottom line is, find one which allows you to scan the film (not the print) at 2400dpi or higher.

Cheers,
Wei-Hao

April 2, 2006 09:12 AM Forum: CCD Imaging and Processing/Deep Sky

new scope arrived

Posted By Wei-Hao Wang

Hi Tom,

Have you taken any pictures with your new scope yet?

As I know, traditional (spherical) Mak-Newt has coma. Although the coma is less than that of Newtonian, it still limits the performance of Mak-Newt for prime-focus photography, especially at F4. I'm very interested to know how your aspherical Mak-Newt performs.

Wei-Hao

May 14, 2006 09:34 PM Forum: Film Astrophotography - Imaging and Processing

M8,M20 & M21 Montage

Posted By Wei-Hao Wang

Hi Peter,

That's nice.

Have you considered using a coma corrector?
I heard Baader's MPCC works well on Meade SN.

Wei-Hao