Waxing 3/4 Moon - Dig Rebel - (practicing for eclipse :)

[vwestervelt]

Got out in the backyard again last night.

Very cool evening, which minimized atmospheric distortion.

I hope the 27th is as clear! Though I'm concerned the moon will be too low in the sky during the eclipse....we'll see.

Images are greatly reduced. (60% for space.) email me for full image.

http://www.vernwestervelt.com/Astronomy/041023%2075%20Waxing%20Moon/waxing_34_moon_102304.htm

Vern

[tofuboy]

Very nice photos :)

[Tom W]

Good job, Vern.

I'm practicing a little myself, though I could certainly use more lens:

http://home.comcast.net/~trwilk3/Images/moon1200_Oct04.jpg

It looks like I overexposed a bit, resulting in some loss of detail.

[Lamium]

Those are beautifull pictures Vern, I can't wait to see the photos you'll make on the 27th

[vwestervelt]

Tom, Hi res images of a partial moon is VERY difficult to expose consistently across the entire surface.

The problem is, you're imaging a surface that spans the equivalent of "Lunar noon" to a "Lunar Dusk"...then the terminator into night.

Your photo clearly shows the challenge....near the terminator you're correctly exposed....but over towards "Lunar Noon" (created terminology :) it almost washes out the frame.

If you adjust for one, you end up having issues with the other.

I've found the best way for me is to try and fill the frame with as much of the surface as possible. This helps with cameras that "auto balance" as well as you have significantly less black in the frame. You really have to adjust exposure for the "lunar noon" portion of the landscape. It means you will lose some of the detail off the terminator with less exposure...but this isn't really a problem. (if you're wanting a specific crator or structure on the terminator for the shadow contrasts....just wait another night so you can correctly expose it....) The Lunar phase changes around 4% per day...so one day is enough to bring the object you're looking for into the right zone......

I'm using prime focus with an 8" SCT (2100mm) telescope. There are still challenges. Atmospheric distortion being easily the largest challenge. At prime focus the image is in almost constant motion (sort of like looking down a road on a hot summer day.....heat waves distort your image....) Since you're viewing through a very dynamic atmospheric layer..makes a high contrast consistent image a real challenge. For example, the image I have on this page is one set of over 100 frames. (at least the hobby keeps me in the yard :)

In the hi-res image (and if you look closely at the reduced size images) you can see areas that appear to be out of focus, even though other areas right next to it are in focus.....this is the atmospheric distortion I'm referring to. I have several examples of frames that were taken within a minute of each other....but if you try to overlay the two frames in photoshop...nothing lines up :)

To top this off, if you want a mosaic, you have to capture 2 frames in relatively close succession. Without Polar aligning your telescope, the field will "rotate" making the mosaic a bit more of a challenge.

I've only been going for the moon for about 4 years, so I don't claim to be an authority on the subject......but half the fun is just looking at it! :)

Now if I can only get clear sky's this week for the eclipse!

Vern

[vwestervelt]

Tom, something else.....

If you're not ajdusting your levels in Photoshop, you can bring out significant contrast and reduce your overexposed area's by lowering the halftones using the "adjust levels" slider....

I downloaded your image, with a halftone adjustment, you end up with only a couple of crater impacts that are solid white. it's a nice image!

What Lens? it appears to be 400 to 600mm?

[pcasciola]

Here's a shot I got of the moon last month when I first got my 300mm. I shot this handheld, just leaning the camera on the window sill. I'm not sure if I will have everything I need for wednesday to hook the 20D to my friends 8" SCT (t-mount, t-adapter and reducer) so I may just go with this lens on a tripod.

Moon shot with 300mm F/4L IS (http://www.casciola.com/pics/moon300mm.jpg)

[vwestervelt]

excellent shot for handheld. I'd say you have more than you need :)

I'm thinking of going with my F/6.3 focal reducer to do single frames. This will allow me to capture more images....albeit at less resolution.

excellent pic. That looks more than 300mm.

[Tom W]

Tom, Hi res images of a partial moon is VERY difficult to expose consistently across the entire surface.

The problem is, you're imaging a surface that spans the equivalent of "Lunar noon" to a "Lunar Dusk"...then the terminator into night.



Your photo clearly shows the challenge....near the terminator you're correctly exposed....but over towards "Lunar Noon" (created terminology :) it almost washes out the frame.

If you adjust for one, you end up having issues with the other.

Yes, its quite a range of exposure. Still, I probably could have reduced about 1/2-2/3 stops. I used spot metering, then bracketed a few shots. If I'm not mistaken, I raised exposure on this one about 1/2 stop before converting to JPEG. Should have left it alone.

I've found the best way for me is to try and fill the frame with as much of the surface as possible. This helps with cameras that "auto balance" as well as you have significantly less black in the frame. You really have to adjust exposure for the "lunar noon" portion of the landscape. It means you will lose some of the detail off the terminator with less exposure...but this isn't really a problem. (if you're wanting a specific crator or structure on the terminator for the shadow contrasts....just wait another night so you can correctly expose it....) The Lunar phase changes around 4% per day...so one day is enough to bring the object you're looking for into the right zone......

When it comes to taking images skyward, I am a bit lacking in equipment. I used my 100-400 zoom at 400 mm, f/5.6, along with a 1.4X Sigma Teleconverter. Filling the frame wasn't an option, though I was pleased to have autofocus with that combination.

I experimeted a bit at my friend's house during the summer when I had the 10D - I piggybacked his AstroPhysics scope and managed to get a few objects recorded. Since it was my first attempt, there were plenty of things that could have been improved, but that's what makes it fun. He was accustomed to polar-aligning and got the tracking very close, at least for the 2-3 minute images we took. But he's done astrophotography before, with film (and soon, a 10D as I just sold mine to him).


I'm using prime focus with an 8" SCT (2100mm) telescope. There are still challenges. Atmospheric distortion being easily the largest challenge. At prime focus the image is in almost constant motion (sort of like looking down a road on a hot summer day.....heat waves distort your image....) Since you're viewing through a very dynamic atmospheric layer..makes a high contrast consistent image a real challenge. For example, the image I have on this page is one set of over 100 frames. (at least the hobby keeps me in the yard :)

In the hi-res image (and if you look closely at the reduced size images) you can see areas that appear to be out of focus, even though other areas right next to it are in focus.....this is the atmospheric distortion I'm referring to. I have several examples of frames that were taken within a minute of each other....but if you try to overlay the two frames in photoshop...nothing lines up :)

To top this off, if you want a mosaic, you have to capture 2 frames in relatively close succession. Without Polar aligning your telescope, the field will "rotate" making the mosaic a bit more of a challenge.

I've only been going for the moon for about 4 years, so I don't claim to be an authority on the subject......but half the fun is just looking at it! :)

Now if I can only get clear sky's this week for the eclipse!

Vern

I hope for a clear sky as well - I'm about 15 miles out of downtown Chattanooga, so we have a reasonable level of "medium town" light pollution. I really wish I lived up on the mountain - its just that much less atmosphere to deal with.

Its a fascinating, and sometimes complex hobby. I guess I'm going to have to get a decent telescope and a sturdy equatorial mount.

[Tom W]

Tom, something else.....

If you're not ajdusting your levels in Photoshop, you can bring out significant contrast and reduce your overexposed area's by lowering the halftones using the "adjust levels" slider....

I downloaded your image, with a halftone adjustment, you end up with only a couple of crater impacts that are solid white. it's a nice image!

What Lens? it appears to be 400 to 600mm?

Right now, I'm using Photoshop Elements, but I can adjust levels and midtones after JPEG conversion. I haven't played much with this astro stuff, though I have a handful of lunar shots from my 10D. My mistake was shooting for the edge (dusk) detail at the expense of that "Noon" detail as you call it. I don't necessarily think either view is wrong, but I prefer what you did.

BTW, I was running a 100-400 + 1.4X converter for a total of 560 mm f/l.

[pcasciola]

That looks more than 300mm.

Don't forget, the 20d has 33% more resolution than a 10D/300D, so it's like a 400mm on one of those. Add the 1.6x crop and I'm effectively getting 640mm out of it compared with a full frame like the 1Ds.

I'd like to put the 1.4x extender on there too, for an effective 900mm. Ooh, that's tempting. Maybe I can pick one of those up before Wednesday.

[Tom W]

Here's one from back in June, right after I got the 100-400. Used the 10D. Got up early and cheated the sky to get the third quarter.

http://home.comcast.net/~trwilk3/Images/moon1200_Oct04.jpg

[Tom W]

That looks more than 300mm.

Don't forget, the 20d has 33% more resolution than a 10D/300D, so it's like a 400mm on one of those. Add the 1.6x crop and I'm effectively getting 640mm out of it compared with a full frame like the 1Ds.

That's a decided advantage as far as getting pixels down. The 20D is the long-range shooting leader these days.

I'd like to put the 1.4x extender on there too, for an effective 900mm. Ooh, that's tempting. Maybe I can pick one of those up before Wednesday.

I've successfully used the Sigma 1.4X with my 100-400L without trouble. Its a good alternative to the Canon if you're looking to save a buck or two, though it may not support all features (such as E-TTL II's "distance to subject") that the 20D uses. Then again, I'm not sure how useful a flash would be with that lens combination. :)

[vwestervelt]

Weatherman is forcasting thunderstorms for Wed night during the eclipse....bummer.

[billsh]

We must be using the same weatherman. We have bad weather forecasted as well. Maybe we could take up a collection and get a new weatherman. :twisted:

[pcasciola]

Yeah, and who scheduled this eclipse for Wednesday night? Don't these people know that some of us have to work the next day. :lol:

[tradkelly]

Very nice, all. Well, I don't have all the toys I need to get the resolution I'd like, and haven't been able to get ahold of my friend with a telescope for Wednesday... bummer. I have a question, for reference, though.

Procedure for using the RS cable release/timer with my 10D. I've not had much luck thus far. I did some good nighttime fireworks shots using manual settings, manual focus, 5-10 second exposure at F22 this July, but I can't seem to transition to the cable release. What settings would be a good place to perhaps start? I'm only using a 28-135mm lens, so I'm not going to get much out of them anyway, but it's decent practice (at 200mm effective).

TIA. Ya'll have fun out there tomorrow night!

[vwestervelt]

Trad,

I'm not sure about the 10D, I'm using the Digital Rebel.....but I think it would be the same.

As for the shutter release, you shouldn't need to use the timer if you have the release cable......just set your exposure time (if it's less than 30s...not sure if the 10D has more than 30s programmed exposure or not, with the Rebel it's 30s & then bulb....i.e. manual timing) and press the cable shutter button and it should properly open the shutter for the programmed time. (you are using a tripod for these I assume....)

The only alternative of an automatic exposure that is longer than the 30s would be using a computer cable & software that automates longer exposures like the one at www.dslrfocus.com. Other than that, I'm not completly sure what you're asking?

As for tomorrow night...I'm bummed, looks like thunderstorms here :(

Vern