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Need help on telescope equipments

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發表於 2008-12-29 17:33:30 | 顯示全部樓層 |閱讀模式
Hello Guys,

I always want to shoot some picture of Moon in High quality,
But I am not familiar on Telescope and astro photo equipments.
I found some stunning pic of Moon on the internet, such as this one
http://www.flickr.com/photos/grzesiek_k/410265592/
Big enough and in high details as this photo is my primary objective.
Can anyone who can give me some idea on the equipment that required shooting something like that?
What kind and which telescope can achieve such quality? Can they mount on my camera Nikon and Mamiya 645AFDII?
Thanks.

Wilson
發表於 2008-12-31 11:19:17 | 顯示全部樓層
Apart from the telescope and mount, how many hours would you like to invest on the learning process.

The moon picture you referred to is one taken during a total lunar eclipse, the exposure should be in the range of seconds and the focal length of the telescope should be about 1500 mm (if it is not a mosaic).  If my estimates are correct, you need a very sturdy tracking mount for taking the image.

If you want to take images of the "normal" moon, the exposure time can be much shorter (usually tenths of a second to hundredths of a second) but you still need a sturdy tracking mount for the telescope to get a crisp image.

The size of the moon image on the sensor/film plane can be estimated by the following formula

M = f/110

with M = diameter of moon image, f = focal length of telescope/lens.  So, a focal length of 1500 mm will produce a moon image about 14 mm in diameter which fits into the APS-C size sensor used in many DSLRs.

I would recommend you to join observation activities organised by HKAS or others to see what the "experts" are using.


CH Yeung
 樓主| 發表於 2009-1-3 11:13:40 | 顯示全部樓層
Hello CHYeung,

Thanks for answering. Apart from equipment, I am sure I will keep research on the knowledge. However, I prefer practical training, learn and fail rather than always talking on paper. I believe myself have knowedge in photography but not in astrophotography. So I might have some advantage in the practical learning process. The point is I don't know the astro equipment as well, I had joined some observation activities many yrs ago, but still can't get enough information on choice of equipment (brand/performance...) . I don't want to try and error on the equipment side because it is $. I need a first good set of telescope and mount for my starting point. So I am asking a shortcut from the experienced CHing here.    

can you suggest some equipment set (brand/model...) to me and so that I can figure it out. Thank you very much.
發表於 2009-1-4 16:18:47 | 顯示全部樓層
Dear Songallery,

There are several pieces of information that you have to supply before I can make a recommendation:

1. Do you have a permanent site for the telescope set? If not, how heavy can you carry and what is the distance that you have to carry the telescope set. The telescope itself can weigh from a few kg to tens of kg.  The mounting and tripod weighs about 10 to 100+ kg and it is the heavier the better.

2. What are you targets?  If you just want to take lunar images as shown in your example, a small good quality (80 - 100 mm aperture) refractor can do the job. If you want to image the planets or magnified moon images, you may want a larger, that means heavier, telescope.  With a heavier telescope, you need a heavier mount.  If you want to take images of deep sky objects such as star clusters, galaxies and nebula, you can use large aperture telephoto lenses or "relatively fast" telescopes.

3. What is the your budget?  The price of average amateur telescopes can varies from a few hundred dollars to hundreds of thousand dollars.  The price depends on the aperture, design and quality of the telescope.  The mount and tripod is as expensive or more expensive when compared to the telescope. Again, the price can range from a few hundred to more than 100k.

CH Yeung
發表於 2009-1-4 17:25:05 | 顯示全部樓層
I guess it's nice to start with your existing equipments.

Which lens do you have?
 樓主| 發表於 2009-1-4 18:39:19 | 顯示全部樓層
Dear CHYeung and oldfield
Thanks for answering.
1. I don't have permanent site for the telescope, that's mean mobility is a must. I think 1x kg may be my limit. I cannot sure at this moment. But If really need a permanent site, I can put to my old house in NT.

2.Major lunar, but I will try to shoot nebula like M42 or wide star field. I will not shoot very deep sky image at this moment.
So any advise on the good balanced combination? By the way, If I shoot wide star field or wider galaxies, can I shoot with just the camera and mount? Or still need something to guide?

3.My initial budget is about HKD 10K, hope can purchase a good balanced set of telescope mount. Quality/weight/cost. But I don't mind to pay a little bit more to get a better one rather than poor quality but cheap.  For the tripod, I have some Gitzo carbon fiber tripod. Can I use them?

To reply oldfield questions.
I don't have any equipments related to astronomy.
And here is my camera and lens.
135 DSLR Set
D700,
14-24 f/2.8,
35 f2,
50 f/1.4,
60 f/2.8,
70-200 f2.8,
TC-20EII (2x),

Medium format digital
Mamiya 645 AFDII
P45 digital back
35mm
55mm
80mm
120mm
210mm
and a mechanical body Cambo wide DS for super wide shoot on digital back.
What I can play with my exisiting equipments ? Thanks for help.

發表於 2009-1-5 10:30:54 | 顯示全部樓層
Prime lenses are usually great for astronomy, even if not, you can "close" them a few stops and they will work.

With your existing lens collection, you might want to try out some wide field and shorter exposure (say within a few minutes) on a tracked mount, since your longest prime lens is not very long, any decent tracking mount will do the job.  But of course, you will need to spend time to learn how to do a good polar alignment.

20kg is rather limited when astrophotography is concerned, but I guess you can take more with a good trolley.
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