Attempting Mars at 6400 mm...;-)

[liquidstone]

With the skies briefly clearing over Manila after weeks of cloudy/rainy weather, I hurriedly took out my Sigmonster, put all my TCs at its end, and tried to find Mars through the semi-opaque VF.

I couldn't find it at full zoom, and only after great difficulty at minimum zoom (300 mm x 8 = 2400 mm). After locating it at 2400 mm, I slowly zoomed out to 6400 mm, and it's surprising how the red planet jumps out of view with each minute movement of the zoom ring. I realized later that 10,240 mm equivalent AOV is barely about 1/4 of a degree.

Here's the best crop out of seven shots before the rainclouds reclaimed the skies. About the only "detail" I resolved is that it's "half-Mars" (as in half-moon) tonight over Manila.



Controlling shake at 6400 mm is not an easy matter, and the crop looks featureless because of this movement. At least I think I got an idea about the exposure values needed, and I still have relatively fast shutter speeds (1/160 sec ISO 400, or 1/320 ISO 800) to play with in the next few nights' attempts.

Anybody want to share their Mars shooting tips or pics using a conventional SLR lens?

Cheerps,

--
Liquidstone
http://www.pbase.com/liquidstone/top25

 

[Besim]

Hi liquidstone,

I think other than using mirror lockup there is not much else you can do. Locating it at 2400 mm without any aid like a little finderscope attached to your main lens (like what you get with telescopes) is already quite impressive.

The best way to photograph planet is via multiple exposures using a webcam or a dedicated CCD attached to the focal point of the lens. You take ~ 800 exposures, most of which will be useless due to atmospheric turbulence, and use some stacking software like Registax to stack them together, averaging out the noise and bringing out the features. Even if you had a decent tracking telescope with a T-mount and you connected your SLR to it for a long exposure through a neutral density filter, the results will be much worse than multiple exposures combined. If you want to see decent detail on Mars (and the ice cap is not very visible at this moment in time), you will need to stack at least a few hundred exposures together.

Also, the pixel density of a typical SLR is not high enough to get a big enough image of planets, unless you use very long focal lengths. A webcam is a different matter.

Photographing deep sky objects like galaxies and nebulae is another matter, and there you will have good success rate with longer exposures, but to shoot anything interesting, you need a polar mount that tracks the sky by compensating for the earth's motion so the object stays stationary on your sensor plane. And even then, it is a very involved process to align the polar mount accurately enough for an exposure longer than a few minutes without seeing trails.

Having said all this, there are quite a few enthusiasts doing this stuff with excellent results. You will need to spend some money towards the cause, though.

Besim.

Controlling shake at 6400 mm is not an easy matter, and the crop
looks featureless because of this movement. At least I think I got
an idea about the exposure values needed, and I still have
relatively fast shutter speeds (1/160 sec ISO 400, or 1/320 ISO
800) to play with in the next few nights' attempts.

Anybody want to share their Mars shooting tips or pics using a
conventional SLR lens?

Cheerps,

--
Liquidstone
http://www.pbase.com/liquidstone/top25

 

[liquidstone]

Thanks, Besim, for the explanation - very well said.

I do realize the limitations of my birding gear at this application. However, I believe this setup can still improve a bit if I can control shake better. The pics won't turn out anywhere near as good as stacked images with telescopes, of course.

I hope I can minimize shake by switching from gimbal head to gear head and get Mars nearly as "detailed" as this shot of Jupiter with the Sigmonster + 5.6x worth of TCs.

Hi liquidstone,

I think other than using mirror lockup there is not much else you
can do. Locating it at 2400 mm without any aid like a little
finderscope attached to your main lens (like what you get with
telescopes) is already quite impressive.

The best way to photograph planet is via multiple exposures using a
webcam or a dedicated CCD attached to the focal point of the lens.
You take ~ 800 exposures, most of which will be useless due to
atmospheric turbulence, and use some stacking software like
Registax to stack them together, averaging out the noise and
bringing out the features. Even if you had a decent tracking
telescope with a T-mount and you connected your SLR to it for a
long exposure through a neutral density filter, the results will be
much worse than multiple exposures combined. If you want to see
decent detail on Mars (and the ice cap is not very visible at this
moment in time), you will need to stack at least a few hundred
exposures together.

Also, the pixel density of a typical SLR is not high enough to get
a big enough image of planets, unless you use very long focal
lengths. A webcam is a different matter.

Photographing deep sky objects like galaxies and nebulae is another
matter, and there you will have good success rate with longer
exposures, but to shoot anything interesting, you need a polar
mount that tracks the sky by compensating for the earth's motion so
the object stays stationary on your sensor plane. And even then, it
is a very involved process to align the polar mount accurately
enough for an exposure longer than a few minutes without seeing
trails.

Having said all this, there are quite a few enthusiasts doing this
stuff with excellent results. You will need to spend some money
towards the cause, though.

Besim.

--
Liquidstone
http://www.pbase.com/liquidstone/top25

 

[Hauxon]

The fact that Mars is now closer to earth than it will be for the rest of your lifspan ignites the "nerd" in me. I did spend a long time with a telescope looking at it few days ago. The only bad thing is my longest lens is only 50mm Hope you can get a better shot.

Hrannar

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

 

[Another birder]

By a country mile, the best amateur planetary shots Ive seen are taken with cheap webcams attached to telescopes. Hundreds of shots are then averaged with astro software to get a final result.

--
'Your ideas intrigue me, and I'd like to subscribe to your newsletter'

http://www.pbase.com/timothyo

 

[hollis_f]

About the only "detail" I resolved is that
it's "half-Mars" (as in half-moon) tonight over Manila.

That's confusing. As Mars is almost at opposition, surely it should be very close to being 'full Mars'? In fact, planets further from the Sun than we are can only ever be full or gibbous, never showing a half pahse like this.

Here's a link - http://elvis.rowan.edu/marswatch/images/marswatch.php?s=2005-10-23&e=2005-10-29 to some images taken on Oct 23rd with a proper telescope. They show Mars in the full phase.

I'm not sure what could have caused your image to look like that, but I'm sure it's not supposed to.

 

[danmurrelljr]

You can't take a "half-Mars" image of Mars, not from Earth anyway. The geometry of the solar system is such that planets outside of Earth in solar orbit will always present a fully lit face to us. Only Venus and Mercury can be seen in phases from Earth.

Right now, Venus will be to the west trailing behind the Sun after it sets, whereas Mars is off to the east after sunset. Venus will be blindingly white, and Mars will be orangish. You may not be able to get a good shot of Mars with your setup, there just isn't as much light as with Venus.

--
Dan Murrell
http://www.flickr.com/photos/danmurrelljr/

 

[Petteri Sulonen]

(NT)

 

[liquidstone]

The planet I just photographed exactly matched your description - "to the west trailing behind the Sun after it sets."

My bad......:-(

You can't take a "half-Mars" image of Mars, not from Earth anyway.
The geometry of the solar system is such that planets outside of
Earth in solar orbit will always present a fully lit face to us.
Only Venus and Mercury can be seen in phases from Earth.

Right now, Venus will be to the west trailing behind the Sun after
it sets, whereas Mars is off to the east after sunset. Venus will
be blindingly white, and Mars will be orangish. You may not be
able to get a good shot of Mars with your setup, there just isn't
as much light as with Venus.

--
Dan Murrell
http://www.flickr.com/photos/danmurrelljr/

--
Liquidstone
http://www.pbase.com/liquidstone/top25

 

[Hauxon]

Mars will be orangish.

To my eye's it's pink.

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

 

[Besim]

Hmmm, correct indeed. Looks like it is, although feature-wise it wouldn't be that different taken under the same conditions lol!! Just tint it slightly reddish and clone the dark part from the light one, and you have Mars hehe!!!!.

Mars should be quite high in the sky after 8pm or so this month. Opposition is on November 7. However, being an outer planet does not necessarily mean that it will be 100% round, not for Mars anyway. this week, though, it should be 100% round.

All this talk about Mars has whetted my appetite. I will try to get my telescope out of the closet and try some webcam photography this week I think!

Besim.

The planet I just photographed exactly matched your description -
"to the west trailing behind the Sun after it sets."

My bad......:-(

 

[liquidstone]

Just got out and tried to capture the brightest "star" to the east - it's very close to 90 degrees (about 70 to 80 degrees) above our eastern horizon at about 10 pm, Manila time.

I guess this is now the best that my equipment and technique can do at this subject. I shot over 30 pics using my geared head. The "star" was speeding so fast upwards thru the VF, that even if I place it at the bottom, I only have a few seconds to focus before it leaves the VF at the top.



I think I have more confidence in shooting the moon...;-)



Cheerps,
--
Liquidstone
http://www.pbase.com/liquidstone/top25

 

[liquidstone]

... it could just be my imagination, but I think the dark surface markings of Mars are just barely discernable at the lower half of each crop. ...;-)

--
Liquidstone
http://www.pbase.com/liquidstone/top25

 

[Besim]

If you took your 30 or so photos within a time range of 4-5 minutes, and provided you always used the same FL, try stacking them all together. If there is a hint of surface features, they should at least show up slightly.

Here are some I took with a webcam:

Venus



Jupiter



Saturn



This one of the moon was taken with my 300D connected to my Meade ETX105 telescope using a T-mount adapter:



Besim.

--
Liquidstone
http://www.pbase.com/liquidstone/top25

 

[mever]

Would someone please explain how do you use a cheap webcam to photo planets?
Thank's
Marty Everhard, SLC UT
--

 

[Fish_eye]

try this:

http://groups.yahoo.com/group/QCUIAG/

 

[Arglebargle]

Interesting, my friend has started doing astrophotography and the moons of Saturn all look like they are crescent to half, but your logic does seem totally reasonable. Perhaps it is the light bouncing off Saturn and illuminating the moons?

 

[liquidstone]

... especially Jupiter and Saturn.

If I could only find Saturn, I think I'll give it a try too and hope to at least make the rings distinguishable.

If you took your 30 or so photos within a time range of 4-5
minutes, and provided you always used the same FL, try stacking
them all together. If there is a hint of surface features, they
should at least show up slightly.

Here are some I took with a webcam:

--
Liquidstone
http://www.pbase.com/liquidstone/top25

 

[Todd Walker]

... especially Jupiter and Saturn.

If I could only find Saturn, I think I'll give it a try too and
hope to at least make the rings distinguishable.

That should be pretty easy with your setup. Even my little ETX90 brings out the rings pretty nicely.
--
Todd Walker
http://www.toddwalker.net
http://www.twphotography.net
http://www.pbase.com/twalker294

 

[Daniella68313]

how did you manage to get 1/160s at ISO 400 and effetive F72? was it that bright?

would you not get a better result with your camera hooked to a telescope?

I have no idea what is the equivalent focal length of a telescope (average one).



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