deep sky photography(singapore)

[michael]

Hi all,

i am not doing astrphotography.

I am wondering is here possible to take some deep sky photography? here sky is very bright, hardly visible +2 or +3 magnitude stars around HDB. I am not doing Astrophotography but intending to start on it, really confused that here sky is suitable for Astrophotography?

which location is batter for deep sky astrophotography? i am staying Bt-Batok west.

Need some comments.

Thank you.
michael

[mrngbss]

Michael, it is still possible to take great deep sky photos in Singapore. Meng Lee and rcj , catalysm , are some of the budding people here who images deep sky. rcj has also shot deep sky stuff from his balcony.

I'm sure they can tell you more on suitable locations.

[rcj]

Hi Michael,

I will try to answer your questions based on the following assumptions:

1) Pertaining to deep sky astrophotography only
2) Location is in Singapore or in any metropolitan city

It is DEFINITELY possible WITHOUT A DOUBT that deep sky imaging is NOW possible in a city. There are time tested examples from Hong Kong, London, Los Angeles, Singapore, etc to justify this fact.

The main idea is sensitivity of the imaging medium as technology advances. Last time, there was only film, where compared to CMOS and CCD chips, it was very slow, and thus deep sky astrophotography could only be done WELL in dark skies. It is possible to do it in the city, but the raw images will be plagued severly by sky glow from light pollution both extended and local sources.

Now, with the advent of CMOS chips with increasingly lower noise profiles, one can take mulitple exposures of the same deep sky object and then stack them together to increase the signal coming from the object while nullifying the noise profile (based on the random distribution property). Of course, the basic principle would stay the same, if you are under darker skies, you can expose with a longer duration (so as to get greater detail and depth of the structure of the object). But it does not mean you can do nothing under light polluted skies. You can, but shorter exposures. You can compromise this by taking more shorter exposures and stacking them. Although you can never get the depth and detail of images derived from darker skies GIVEN THE SAME IMAGING MEDIUM/SETUP, you can still get decent images. It is sometimes about the expectations of the imager involved as well. From my balcony, there are several sodium lamp-posts in full view while imaging, but still it is possible to capture non-eye-visible objects like the RCW nebulae catalogue, because of utiltising the multiple-exposure-stacking methodology. With the exisiting camera that you have (300D?), you could go for short exposures (5 minutes) but several of them, and then stack them with freeware like IRIS (Christian Buil) or premiere software like ImagesPlus (Mike Unsold), etc. However I would strongly advise you to start with a system that is manageable....manageable in the sense that it is flexsure free, no free-moving mirrors, and something that holds collimation well at all altitudes (from horizon to zenith), before it adds unnecessary frustration and difficulty/complexity to the learning curve. A refractor would do well in this regard. Nevermind if it is not an apo. A semi-apo or even achromat will do. One could start with narrowband imaging with a simple hydrogen alpha filter placed in front of the 300D. But note that you will need another telescope to guide and ensure that the primary image has pinpoint stars. So you will need a dual instrument platform (maybe two refractors, etc). One for imaging with the 300D, and the other to have a webcam/autoguider camera to train on a guided star near the field of view of interest to ensure that the mount is kept centered on the guide star for pinpoint star results. If this is quite a handful, you could start with a built-in camera with autoguider. This would save you on having another seperate guidescope taxing on the mount, but such a camera can be quite expensive. 2 cents!

[Meng Lee]

For me, a suitable location is anywhere with power and where I don't have to carry stuff for a far distance, hehe. NUS rooftop is such a place. JiaHao came over that day and said the light pollution is terrible. You can only see the full Scorpio on nights of very high transparency.

Let me give me own point of view.

1) For emission neb, you can use narrowband filters (H alpha, SII, H beta, OIII)
2) For other deep sky objects your only bet is short non-saturated exposures and stack (add, average, median) them, then remove the sky gradient. If the pollution is terrible, then individual exposures has to be shorter. BUT 60 x 1min is not the same depth as 10 x 10min. So if you are forced by pollution to decrease exposure time, then the number of exposures has to increase a few fold !!!!!!!!!!!!!

[michael]

Last time I stayed at Hougang 7th floor, I could see lots of stars there including deep sky object like GLB cl, Orion and some open clusters including some few nebs and dim andromeda. After I shifted to bt batok I barely can see all this. I thought Bt-Batok sky is more darker then hougang area. I have few telescopes now really useless.

I know high altitude is batter but I am living on the ground level. It is really bad that now I can’t see any deep sky objects. I really can’t enjoy as like I did last time at hougang area.
Now, I have to make a wheel trolley for my telescope to push any near dark place.

Actually I suppose to make large optics telescope. Can’t get enough courage to make because of the sky.

Hope for more comments on deep sky photography in light polluted city. It’s nice to read your views. I really enjoy it.

Thank you

[weixing]

Hi,
Are you sure you can't see any Deep Sky Object in bt batok??

The area (beside Tampines Central) I usually observe is not consider dark at all... the area was surrounded by light pollution sources... with all the HDBs around, interchange, MRT and a few shopping center at a few minutes walking distance away plus the forever on security light of the Mosque shine directly at me, but I still can see a lots of DSO and do my imaging there.

Also, I used to observe beside (10m away from the front gate) Tampines stadium even when the stadium was having a soccer match and I still can see quite a number of DSO using my previous 6" F5 Newtonian with all those floodlight on... in fact, I observe my first comet when the soccer match is on. So I think may be you should just bring your telescope out on a clear night and I think you'll be surprise what you can see.

Happy observing and have a nice day.

[Canopus Lim]

"Actually I suppose to make large optics telescope. Can’t get enough courage to make because of the sky. "

If you are only into visual, the larger the optics the better. It is even more important in light polluted Singapore. Most importantly is that you need to be able to find the objects first and after that use high magnification. For stars, star clusters, globs, planetary nebula and objects with high surface brightness, all these objects can be seen quite well in Singapore if one knows how to use the correct magnification and find the objects.

[Meng Lee]

Also, very high contrast optics and eyepieces help a lot. Wehn I look at M57 with C8 and my WO Megrez FD, the latter show the ring nebula much more clearly.

You can also consider getting a portable scope and carry it to dark skies. It may not be a giant scope but you can see a lot more when you go to dark skies. Examples would be: WO Megrez 90 or Mak 150. These are high contrast and portable scopes. The ultimate is Teleport 7".

Photographywise, sometimes, optical quality is more important than aperture.

[weixing]

Hi,

Wehn I look at M57 with C8 and my WO Megrez FD, the latter show the ring nebula much more clearly.

Hmm... Logic tell me it shouldn't be as 8" and 3.1" difference is too big... Did you use the same magnification??

Have a nice day.

[Meng Lee]

I used a lower magnification for the Megrez but the Megrez uses dielectric diagonal and Pentax XW eyepiece and C8 uses ordinary diagonal (prism) and generic plossl .