Shooting Saturn, any suggestions?

[Howard102273]

Hi, this weekend Saturn will be at its brightest this year. I want to take a snapshot. I use a 5D. Should I:

1) go for the largest magnification, which for me is the 100-400 @ 400mm, plus a 1.4x TC, but that makes the aperture very small (f/8).
2) go for the largest aperture, which for me is the 50 f/1.4.

I have no equatorial mount, so I can only boost the ISO.

Thanks in advance.
Howard
--
-----
cameras: 5D, D60, R2K
lenses: 17-40 f/4, 24-105 f/4, 100-400 f/4.5-5.6
24 f/3.5 TSE, 35 f/2, 50 f/1.4, Tamron 90 f/2.8 Macro
http://www.imagereservoir.com

 

[mattr]

Hi, this weekend Saturn will be at its brightest this year. I want to
take a snapshot. I use a 5D. Should I:

1) go for the largest magnification, which for me is the 100-400 @
400mm, plus a 1.4x TC, but that makes the aperture very small (f/8).

You will need all the magnification you can get.

2) go for the largest aperture, which for me is the 50 f/1.4.

Your lens has a horizontal FOV of about 40 degrees and your 5D has 4368 horizontal pixels. Thus one pixels covers 0.009 degrees or 0.55 arc minutes or 33 arc seconds. Saturn's apparent size is only 20 arc seconds. You are completely out of luck resolving it with a 50mm lens on the 5D.

I have no equatorial mount, so I can only boost the ISO.

You should be able to boost the ISO to get short enough shutter speeds. The problem with Saturn is the small apparent size not that surface brightness is too low.

Good luck ;-)

 

[Cal Dawson]

If you don't use the long lens (400) it will look like just another star....

Why not try all and check a few after shooting....
--
Cal

Put a Canon to your head, You deserve it....

http://funshots.smugmug.com/

 

[fred vachss]

Saturn's bright enough to get a good exposure with moderate ISO, but so small in angular field that you'll need as much magnification as you can get. Without a clock drive you'll need to keep the shutter speed up to something like 20-40s/(focal length in mm) to avoid trailing.

Other folks on these forums have MUCH better shots than this, but here's an example of what I got by just pointing a lens up at Saturn - and a good starting point for exposure. In this case 500mm + 2x + 1.4x at f/13 and 1/60s, ISO 800:

 

[Howard102273]

Hi, this is not a bad shot at all, at least now I have some concrete example. I bet if you stack multiple photos you will get even better results!

Thanks,
Howard

--
-----
cameras: 5D, D60, R2K
lenses: 17-40 f/4, 24-105 f/4, 100-400 f/4.5-5.6
24 f/3.5 TSE, 35 f/2, 50 f/1.4, Tamron 90 f/2.8 Macro
http://www.imagereservoir.com

 

[Alansworld]

2) go for the largest aperture, which for me is the 50 f/1.4.

Wow, every ring will be visible with a 50, don't you think? I should think Saturn would be indistinguishable from a dust spot.

--
Alan, Newbury, UK

 

[Another birder]

Telescope and a webcam Will give you the best results. No need to use an EQ mount, but you will need to use something like registax to stack the images.

By all means have ago with what you have, but I wouldnt expect anything other than a bright misshapen blob. You need a telescope in all honesty.

--
Canon 40D
FujiFilm F20

http://www.pbase.com/timothyo

 

[mmullen]

Here's a composite shot with a 40D and Televue Pronto (small refractor). I used a Canon t-mount and EF 2x II and EF 1.4x. It's a composite of about 10 or 12 images that I hand aligned in photoshop.

ISO 640 1/15 second and focal length somewhere around 1600mm and f/11.



--
Mike Mullen

 

[Lee Jay]

Telescope and a webcam Will give you the best results. No need to
use an EQ mount, but you will need to use something like registax to
stack the images.

By all means have ago with what you have, but I wouldnt expect
anything other than a bright misshapen blob. You need a telescope in
all honesty.

You have no idea how small Saturn is. This is a 100% crop at 1900mm with pixels of the same size as the 40D (5.7 microns), and Jupiter was around twice as large as Saturn will be! 400mm with 8.2 micron pixels on Saturn will just be not nearly enough.



--
Lee Jay
(see profile for equipment)

 

[Lee Jay]

In this case 500mm + 2x +
1.4x at f/13 and 1/60s, ISO 800:

So, that's 6.4 micron pixels and 1400mm - about 4.5 times the resolving power of the 5D+100-400L.

See that little "zoom out" button on the top-left of the image of Saturn above? Hit it twice to see about the best the OP can hope for.

--
Lee Jay
(see profile for equipment)

 

[ARShutterbug]

At a fixed distance, your larger-aperture lens is 400 f/5.6. Attaching a 1.4X Extender does not affect the objective aperture, because 400 f/5.6 is the same size as 560 f/8. You want to use the largest objective aperture that you have available.

I resolved the rings with a 400 f/5.6 objective, but the object was the size of a speck in the frame and required an enlargement to see anything worthwhile. It was interesting seeing that such a small lens could actually resolve any details like that. A 300 f/2.8 is much better, and better still if you can get larger objectives. This may be a good excuse for you to buy or rent a Canon prime lens. If you want to spend some money on an even-larger objective, get a large Dobsonian telescope. They are lightweight and inexpensive, and focusing will be much easier.

--
http://www.pbase.com/arshutterbug/

 

[derTeufel]

Sorry, I don't understand you. Are you implying that a 300 f/2.8 lens alone (with no TCs) will do better than a 400 f/5.6 with a 2x TC (800 f/11 effective) for photographing Saturn? That doesn't sound right.

--
-Teufel

 

[ARShutterbug]

Yes, and it is because 300 f/2.8 is faster than 400 f/5.6, which is the same as 800 f/11. At a fixed distance, the biggest problem is not the focal length of the lens, but the objective size and how much light it can collect. This is why people should be careful when buying cheap telescopes that advertise very long focal lengths. If you look at the objective aperture of some of these scopes, they are smaller than a 200 f/2.8, which makes viewing and imaging rather difficult.

If you have an unlimited exposure time available, you can get excellent results with a small lens. But when you actually want to view a distant object and image it within a limited time period, you must use larger-aperture lenses.

--
http://www.pbase.com/arshutterbug/

 

[fotomatt]

Don't expect it to look like the other posted photos with any ring detaail. For the remainder of 09 Saturn although bright is not that impressive as the rings are on edge. Sort of like a pencil poked through a tennis ball. Its a great time to check out the moons with a telescope without the rings in the way.

 

[fyngyrz]

Great answer; you started me thinking about this, now I have a spreadsheet that gives me the number of pixels to expect for all the planets, for all my applicable lenses, for my particular camera. Awesome. I might cobble up a web page out of this.

--
Photos: http://www.flickr.com/photos/fyngyrz/
Blog: http://fyngyrz.wordpress.com/

 

[Howard102273]

I think you are using the methodology of analyzing telescopes' light gathering ability here, which is not exactly applicable to taking pictures with a SLR.

For telescopes, you can change the eyepiece to get different magnifications, so the light gathering ability of the 'scope is critical (which is proportional to its diameter). For SLRs, since the sensor (think of it as the "eyepiece") is fixed, the magnification is solely dependent on the lens. Therefore, the lens magnification (which is proportional to the focal length) becomes critical. Of course, given the same focal length, the larger the diameter (aperture), the better the light gathering ability, the better chance of getting a low noise image.

Howard

--
-----
cameras: 5D, D60, R2K
lenses: 17-40 f/4, 24-105 f/4, 100-400 f/4.5-5.6
24 f/3.5 TSE, 35 f/2, 50 f/1.4, Tamron 90 f/2.8 Macro
http://www.imagereservoir.com

 

[Dilligas]

I might cobble up a web page out of this.

If you do, please share it with us. I know that I would find it helpful.

 

[Howard102273]

--
-----
cameras: 5D, D60, R2K
lenses: 17-40 f/4, 24-105 f/4, 100-400 f/4.5-5.6
24 f/3.5 TSE, 35 f/2, 50 f/1.4, Tamron 90 f/2.8 Macro
http://www.imagereservoir.com

 

[ARShutterbug]

The size of the objective is important, regardless of the type of photography. What you are doing is collecting light in a specific amount of time, because you have no tracking mount. Even if you did have a tracking mount, you will not be able to focus accurately with a small lens, for the same reason that its aperture is too small.

When you open the shutter, you have a specific time period during which you can collect light. After that expires, you will have too much motion blur to be usable. The "magnification" of distant light sources is irrelevant. You want resolution quality and the maximum light collection per unit time.

Here is what a sky shot looked like with the 50 f/1.4 lens at f/1.4. Ignoring the purple fringing and focusing difficulties, you may notice that only the bright objects are visible. You cannot "magnify" details from light that was never collected.



With a 200 f/2.8 aperture and a shorter exposure time, I was able to get this:



With a larger objective aperture, focusing and general viewing becomes much easier.

--
http://www.pbase.com/arshutterbug/

 

[fyngyrz]

http://fyngyrz.wordpress.com/2009/03/04/pixels-per-planet/

--
Photos: http://www.flickr.com/photos/fyngyrz/
Blog: http://fyngyrz.wordpress.com/