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PostPosted: Tue Jul 24, 2007 9:10 pm 
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I got my Tamron SP 500mm mirror-lens back from testing at PhotoZone.de and finally the moon was up in the sky. So I mounted my trusty old Manfrotto 055pro with my gear and made a series of shots from the moon.
I ended up with f8.0 (fixed) ISO 200 and a 1/125sec. This was my first surprise: I was starting with 1/2 sec shutter speed (you know the lens has no auto-exposure on the D80).
As to WB: You know I'm an automatic-fan, and that was it - pretty much dead on. Second surprise.
Although the 500mm is like a 750mm in a 35mm-film camera still the moon was only 1/4 hight of the pic (clickable). Third surprise.
Image
And the fourth surprise? Well, two pics of 9 were sharp enough to show a 100% (1191x842) crop, so here is the link to it (clickable):
Image

What do we learn from this:
- You would need a 1500-2000mm lens to capture the moon full size on an APS-C sensor cam
- The moon is brighter than you might think, but that's only logical: the sun is shining brightly onto the surface.
- don't use the flash. It simply doesn't help :wink:

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Last edited by Thomas on Fri Jul 27, 2007 3:14 pm, edited 6 times in total.

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PostPosted: Tue Jul 24, 2007 9:14 pm 
Aww man need this for the lunar eclipse on 22nd August :)


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PostPosted: Tue Jul 24, 2007 9:49 pm 
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Yep, both the Sun and the Moon are smaller than they look - just half a degree in arc, so yep, you're looking at massive focal lengths to fill the frame with either.

This of course equally applies to shots where you like to see the Sun's disc in the background of a shot at, say, sunrise or sunset...

The other thing to watch out for is at much longer focal lengths, the effect of the Earth rotating will see these objects move across the frame quite rapidly, so unless you have a tracking mount, you'll need a sufficiently quick shutter to freeze the motion!

Gordon


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PostPosted: Tue Jul 24, 2007 10:09 pm 
extender 2x = 1000mm ;)

but there is a 1200mm canon lens.... with would equal to 1920 mm on a crop frame sensor, with the 2x extender would equal to ... 3820mm

the largest picture of the moon i saw was from a 3000mm telescope, but now that you can get near 4000.... that would be awesome. of course the 1200 lens is about 75 000- 90 000 :P

Image

Image


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PostPosted: Tue Jul 24, 2007 11:39 pm 
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Oh yeah, the Canon 1200mm! I knew I had one of those somewhere!

Image

Only kidding - this was securely screwed down at Photokina, although it does prove I have more than one shirt...

Seriously though, something around 500mm with a 2x converter is a nice focal length for this kind of thing - my Televue Genesis telescope is a 540mm f5.4, so with a 2x converter gives an equivalent of 1620mm with a Nikon DSLR or 1728mm with a cropped Canon DSLR.

Gordon


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 Post subject: Mooning
PostPosted: Tue Jul 24, 2007 11:45 pm 
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Thomas wrote:
two pics of 9 were sharp enough to show a 100% crop

Nice going. I guess that the other seven were affected by atmospheric distortion - the same effect that causes stars to "twinkle".

Cr4zYH3aD wrote:
there is a 1200mm canon lens.... with would equal to 1920 mm on a crop frame sensor

Hmm. On the other hand you could, for $21000, buy a Takahashi BRC-250 on a Takahashi EM-500 Temma II mount

Image.

Of course it then makes sense to add a full frame 11 megapixel colour CCD sensor to this setup such as the STL-11000MCM for an additional $8500 and then you too could achieve pictures like this.

The only trouble with this equipment list is that one has still only spent around one fifth of the price of that 1200mm Canon lens. On the other hand, if the paparazzi had to lug that lot about we might have a lot less nonsense in the press!

Now, what did I do with those lottery tickets? :?

Bob.

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Olympus OM-D E-M1 + M.Zuiko Digital ED 12-40mm f/2.8, Lumix 7-14mm f/4, Leica DG Summilux 15mm f/1.7 ASPH, M.Zuiko Digital 45mm 1:1.8, M.Zuiko Digital ED 75mm 1:1.8.
Leica D Vario-Elmar 14mm-150mm f/3.5 - f/5.6 ASPH.
OM-D E-M5, H-PS14042E, Gitzo GT1541T, Arca-Swiss Z1 DP ball-head.
Astrophotography: TEC 140 'scope, FLI ML16803 camera, ASA DDM60 Pro mount.


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PostPosted: Fri Jul 27, 2007 3:18 pm 
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Well Bob, unfortunately there is nothing automatic on my Tamron SP 500mm. And I was simply not used to focus correctly, so I sort of bracketed the moon and that gave the 2 out of 9 sharp ones.

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PostPosted: Fri Jul 27, 2007 4:46 pm 
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Hi Tom,

My own brief trial run a week or two ago showed how difficult it was to focus, even using a bright star. Unfortunately, one of the cons with the EOS 400D (there, I said it again!) is that you can't change the focus screen. I have ordered a Canon Angle Finder C which includes a switchable 2.5x magnification.

Image

That should help with the focussing, if only to save me craning my neck in order to be able to look through the camera viewfinder with the camera mounted on top of my telescope.

This morning I received a LPS-P2-FF "front filter" which will allow me to cut out a deal of the stray light from the local sodium street lights. This filter has a slight colour cast to it but they also sell a clear dust-protector filter which could be of interest to those who have to change lenses in dusty environments. The drawback is that these filters can't work with lenses that protrude into the camera body.

Once I get the angle finder and a few clear moonless nights it will be play time.

Bob.

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Olympus OM-D E-M1 + M.Zuiko Digital ED 12-40mm f/2.8, Lumix 7-14mm f/4, Leica DG Summilux 15mm f/1.7 ASPH, M.Zuiko Digital 45mm 1:1.8, M.Zuiko Digital ED 75mm 1:1.8.
Leica D Vario-Elmar 14mm-150mm f/3.5 - f/5.6 ASPH.
OM-D E-M5, H-PS14042E, Gitzo GT1541T, Arca-Swiss Z1 DP ball-head.
Astrophotography: TEC 140 'scope, FLI ML16803 camera, ASA DDM60 Pro mount.


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PostPosted: Fri Jul 27, 2007 5:15 pm 
Quote:
LPS-P2-FF "front filter"


I like the idea of the clear filter for dust elimination though it is another piece of glass and its kind of pricey for the sake of keeping dust out. Still i was surprised to see they fit the D40's


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 Post subject: DP-FF Front Filter
PostPosted: Fri Jul 27, 2007 7:16 pm 
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Brate wrote:
kind of pricey


Absolutely, at £80/€120/$160 dust would have to be a real problem in your working environment to justify buying one. Even then, with a DP-FF filter fitted the seal isn't hermetic.

Bob.

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Olympus OM-D E-M1 + M.Zuiko Digital ED 12-40mm f/2.8, Lumix 7-14mm f/4, Leica DG Summilux 15mm f/1.7 ASPH, M.Zuiko Digital 45mm 1:1.8, M.Zuiko Digital ED 75mm 1:1.8.
Leica D Vario-Elmar 14mm-150mm f/3.5 - f/5.6 ASPH.
OM-D E-M5, H-PS14042E, Gitzo GT1541T, Arca-Swiss Z1 DP ball-head.
Astrophotography: TEC 140 'scope, FLI ML16803 camera, ASA DDM60 Pro mount.


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PostPosted: Sat Jul 28, 2007 11:38 pm 
I should consider a small telescope for shooting astophotos instead of an expensive lens. And it helps to shoot not only the moon and the sun but also star clusters, galaxies and nebulas...

That was also the first cause to buy a good DSLR (it's the only kind of camera that fits perfectly on a telescope).

Of course till know, i managed to buy only the camera, but the next step is a telescope (god help us.... :shock: )

Gordon you mentioned above about 2x teleconverters on telescopes? Does it really works with telescopes? i didn't know that!


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 Post subject: Small telescopes
PostPosted: Sun Jul 29, 2007 12:07 am 
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Hi Constantinou,

I have a Televue Pronto similar to

Image

The scope is on a relatively cheap German Equatorial mount and is motor driven. With the camera attached in place of the diagonal and eyepiece one can certainly get some nice shots. For instance the Pleiades fill the frame perfectly.

That said, this setup is a bit betwixt and between in my view. The optics and camera sensor are not really up to deep sky work where light gathering power and low noise are paramount. In any event for the long exposure times it would be necessary to manually tweak the guidance using an off-axis eyepiece and I'm not geared up for that.

As a result I have decided to have a go at some big sky shots with the my Canon 400D mounted on top of the Pronto to take advantage of the guidance. My two zooms cover from 24mm to 200mm at f/4 so it will be a good test of their optics. There will be zero scientific value in the photographs (I suppose I could hunt for comets or novae but I don't have the patience) but if I enjoy myself then it might be worth getting a fast prime at my preferred focal length.

By the way, unless you use a solar filter of some sort on the telescope objective lens I would be very loath to point the telescope at the Sun. Not only a quick way to go blind but a pretty sure way to start a fire inside your camera!

Bob.

_________________
Olympus OM-D E-M1 + M.Zuiko Digital ED 12-40mm f/2.8, Lumix 7-14mm f/4, Leica DG Summilux 15mm f/1.7 ASPH, M.Zuiko Digital 45mm 1:1.8, M.Zuiko Digital ED 75mm 1:1.8.
Leica D Vario-Elmar 14mm-150mm f/3.5 - f/5.6 ASPH.
OM-D E-M5, H-PS14042E, Gitzo GT1541T, Arca-Swiss Z1 DP ball-head.
Astrophotography: TEC 140 'scope, FLI ML16803 camera, ASA DDM60 Pro mount.


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PostPosted: Sun Jul 29, 2007 1:14 am 
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Yep, I use a 2x teleconverter with my Televue Genesis all the time when photographing the Sun or Moon. As Bob says, though, you WILL need a solar filter when photographing the Sun.

Just because a 2x converter will work on my particular scope though doesn't mean it will on all of them! With telescopes, it's often a case of switching various extension tubes around until you get an image which will focus at the required point. Then further experimenting to see if your particular combination of parts is being overly detrimental to optical quality.

Luckily, I've the 2x teleconverter I use seems to be quite happy mounted between the camera body and the tube which allows the DSLR to fit on the scope.

Gordon


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PostPosted: Sun Jul 29, 2007 9:40 pm 
thanks for the infos guys...when i buy a telescope we will get in touch for more infos on this subject. now i can only tell all i know from what i read

I'm aware for the using solar filters when viewing the sun. i don't own a telescope as i said but last year when the total solar eclipse occured near my country, i equiped 2 pair of binoculars and my 35mm camera with Baader AstroSolar filter. i wished i had a telescope back then but i was not so lucky... :cry:

BTW Bob nice scope :wink:


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