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12-20-2009, 11:27 AM   #1
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Strange "space" shots.

Well, I am a bit shocked to see someone presenting, at PPG, astrophotography shots of :
1. The "Seven Sisters"
2. The Andromeda galaxy,

using, for No. 1, a DA*300 F4 .... and for No.2, a DA*200 F2.8 !!!
No mention of telescopic attachment of any kind.
The pictures are great, by the way, but ...

Any thoughts on this?

I am not posting those pictures. because they belong to someone else, for fear of misrepresentation.

JP


Last edited by jpzk; 12-20-2009 at 11:34 AM.
12-20-2009, 12:08 PM   #2
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For a size comparison the Andromeda galaxy has an angular size of 4 degrees, a full Moon is only 1/2 of a degree.
12-20-2009, 12:23 PM   #3
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Hey JP,
can you please send me the link via pm,
i cannot find the shots.

THX
12-20-2009, 12:30 PM   #4
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QuoteOriginally posted by Deimo Quote
Hey JP,
can you please send me the link via pm,
i cannot find the shots.

THX
Hi Deimo,
I can't!
They were presented for "Voting", and once you go through the voting process, those pics will not show up again.
They were very good, to a point where you could actually see another galaxy next to the Andromeda, on the bottom right.

JP

12-20-2009, 12:31 PM   #5
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QuoteOriginally posted by Raybo Quote
For a size comparison the Andromeda galaxy has an angular size of 4 degrees, a full Moon is only 1/2 of a degree.
Hi Raybo.

The galaxy and the Seven Sisters were not on the same photo.

JP
12-20-2009, 12:32 PM   #6
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I haven't seen the pictures, but it seems plausible. Raybo is right about the scale of Andromeda. If you can get away from city lights with a good telephoto lens on a equatorial tracking mount, you should be able to get a nice pic. The DA* 200 should be up to the task. The "Seven Sisters" are the Pleiades star cluster that can easily be seen with the naked eye. You shouldn't even need tracking for that pic because they are relatively bright.

Last edited by PentaxPoke; 12-20-2009 at 12:43 PM.
12-20-2009, 12:47 PM   #7
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QuoteOriginally posted by PentaxPoke Quote
I haven't seen the pictures, but it seems plausible. Raybo is right about the scale of Andromeda. If you can get away from city lights with a good telephoto lens on a equatorial tracking mount, you should be able to get a nice pic. The DA* 200 should be up to the task. The "Seven Sisters" are the Pleiades star cluster that can easily be seen with the naked eye. You shouldn't even need tracking for that pic because they are relatively bright.
Well ... I am still not convinced.

How in the world would you be able to take a shot of the Andromeda Galaxy with "just" a 200mm telephoto lens? I mean: in this photo, you could really see the typical swirl of the galaxy, not something you would normally be able to pin-point with such short focal.
Please explain how this would be possible.

As for the Seven Sisters, that's ok, I'll buy that since it is true that we can see them with the naked eye already.


JP
12-20-2009, 01:08 PM   #8
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QuoteOriginally posted by jpzk Quote
Well ... I am still not convinced.

How in the world would you be able to take a shot of the Andromeda Galaxy with "just" a 200mm telephoto lens? I mean: in this photo, you could really see the typical swirl of the galaxy, not something you would normally be able to pin-point with such short focal.
Please explain how this would be possible.

As for the Seven Sisters, that's ok, I'll buy that since it is true that we can see them with the naked eye already.


JP
Although the Andromeda galaxy is large (8 full moons across) it is also pretty dim in comparison.
Long exposure (or a series of short exposures and stacking) and tracking will reveal the galaxy in all its glory!

12-20-2009, 01:14 PM   #9
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QuoteOriginally posted by Raybo Quote
Although the Andromeda galaxy is large (8 full moons across) it is also pretty dim in comparison.
Long exposure (or a series of short exposures and stacking) and tracking will reveal the galaxy in all its glory!
Alright, I understand.
This is not my stuff ... obviously, and thanks for the information.

JP
12-20-2009, 03:10 PM   #10
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QuoteOriginally posted by jpzk Quote
Well, I am a bit shocked to see someone presenting, at PPG, astrophotography shots of : 1. The "Seven Sisters" 2. The Andromeda galaxy,
using, for No. 1, a DA*300 F4 .... and for No.2, a DA*200 F2.8 !!!
No mention of telescopic attachment of any kind.
If the images show the stars as points, I'd say they'd have to be taken using an equatorial mount. It's easy enough to get images of faint objects even with the 1600 ISO of a K200D. The images below were taken with a 500mm f6.3 mirror lens on a tripod without an equatorial mount. As others have suggested, it's supposed to be possible to get good images by stacking, but I haven't tried this yet.

For some reason, today I can't insert images from my photo album on this site. But if you check my profile I've posted an image of the globular cluster 47 Tucanae and one of Jupiter. Jupiter is very bright, so I was able to use it as a focal reference.

Rob

PS The 47 Tucanae image is about 50% of the actual pixels while the Jupiter image is 1:1 on the pixels. With a shorter lens, the objects would be even smaller in the image.

Last edited by RobG; 12-21-2009 at 06:23 AM. Reason: updated image info
12-20-2009, 03:42 PM   #11
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QuoteOriginally posted by jpzk Quote
Well ... I am still not convinced.

How in the world would you be able to take a shot of the Andromeda Galaxy with "just" a 200mm telephoto lens? I mean: in this photo, you could really see the typical swirl of the galaxy, not something you would normally be able to pin-point with such short focal.
Please explain how this would be possible.


JP
I don't have a good example of my own, but this is a pic online from an excellent CD book that I own: "A Guide To Astrophotography with Digital SLR Cameras" by Jerry Lodriguss. The picture is M31 (Andromeda) taken with a Canon D20a, and a Canon EF 300mm f/2.8 USM IS lens. A polar equtorial mount with tracking was used as I mentioned above, to eliminate star trails. It is a composite which uses the modern method of stacking, in this case 57 images of 2 minutes exposure each, at ISO 1600 f/2.8:



Here is the page link in case the embeded picture link is broken or blocked:
http://www.astropix.com/HTML/SHOW_DIG/027.HTM

So as you can see, it is definitely plausible that one could get a fantastic shot of M31 with a good 200mm lens if the proper techniques are used. How does this image compare to the one you saw? Now as to the supposed PPG rules about "heavy processing"; Most pictures there are heavily processed with saturation and sharpness anyway, so I don't know if they would even check.

Last edited by PentaxPoke; 12-20-2009 at 04:02 PM.
12-20-2009, 05:58 PM   #12
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QuoteOriginally posted by RobG Quote
If the images show the stars as points, I'd say they'd have to be taken using an equatorial mount. It's easy enough to get images of faint objects even with the 1600 ISO of a K200D. .
Now I see why this was possible. There was no mention of that, but I see what you mean.
Thanks for the answer.
JP
12-20-2009, 06:05 PM   #13
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QuoteOriginally posted by PentaxPoke Quote
So as you can see, it is definitely plausible that one could get a fantastic shot of M31 with a good 200mm lens if the proper techniques are used. How does this image compare to the one you saw? Now as to the supposed PPG rules about "heavy processing"; Most pictures there are heavily processed with saturation and sharpness anyway, so I don't know if they would even check.
The image of the Andromeda galaxy at PPG was much less detailed and not as large as the one shown in the link you provided. I would say, the galaxy looked like only 25% of this one here you are showing.
About PP: right, there are so many heavily post-processed photos in there, which are ultimately accepted, that I wonder ...
jp
12-20-2009, 07:43 PM   #14
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QuoteOriginally posted by jpzk Quote
The image of the Andromeda galaxy at PPG was much less detailed and not as large as the one shown in the link you provided. I would say, the galaxy looked like only 25% of this one here you are showing.
About PP: right, there are so many heavily post-processed photos in there, which are ultimately accepted, that I wonder ...
jp
I think the PP policy is aimed at composite images or images where digital filters are applied such that the final image has little of the original information intact. For instance, I don't believe that they would allow Orton transformation since the final product is the result of merging two highly modified images.

Steve
12-21-2009, 08:48 PM   #15
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QuoteOriginally posted by stevebrot Quote
I think the PP policy is aimed at composite images or images where digital filters are applied such that the final image has little of the original information intact. For instance, I don't believe that they would allow Orton transformation since the final product is the result of merging two highly modified images.

Steve
We would have to ask PPG and get answers, that's the only way to find out for sure.
But, I am not worried; if people like what they see, so be it ... heavily PP'd or not.

JP
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