My first serious effort at star photos.

[mikec]

Mr Felix try doing a search on the rule of 600 for doing star shots. It works really well and have done it many times myself. It does require knowing where infinity is on your lens but you can work that out easily enough even with the kit lenses.

Basically you;

1. Set f/stop wide open
2. ISO to 2000 to 4000
3. To calc the shutter speed take the focal length then calculate 600 / focal length
4. Focus to infinity
5. Ensure you've got mirror lock up on and are either using timer or a shutter release

[Mr Felix]

MikeC,

One thing I did do was activate the live view to stop the mirror shake.

Point 3 is handy to know.

Thanks.

[arthurking83]

Mirror lockup isn't so important with very long exposures(Eg. > 10 sec exposures), and if you don't have a remote of any kind, then locking up the mirror is a redundant setting anyhow.

Some cameras feature a setting called exposure delay, which is a pseudo mirror lockup(MLU) setting, whereby when you press the shutter with one action, the first stage is to raise the mirror, the camera waits about 1 sec and then makes the exposure. For a short focal length this can work very well, as in general an 0.5s delay is sufficient to stop camera shake caused by the mirror.

Does the 550D have liveview feature?
If so, the best way to find the point of focus for an infinity setting such as stars is to use liveview.
The other issue with infinity focus is the weather/temperature of the time.
It shifts as the temperature changes. This is why most lenses will focus past infinity, to compensate for this.
So while focusing to the infinity mark on the lens may work one day, it's not guaranteed to work the next.
With a very very wide angle lens this is less of an issue.
Best aperture setting to use is the most open setting, that gives the sharpest, most contrasty rendering of the scene .. not so much stopped down to get a deeper DOF.
If this 18-135 lens is the main lens you want to stick with, have a look at any test/report on how this lens works at various aperture settings, specifically looking for the aperture setting where it peaks in terms of sharpness(but watching for other aberrations such as CA and suchlike) and stick with this value.
All ISO and shutter speed settings should really be calculated around this value.

[William]

Quote Arthur : Mirror lockup isn't so important with very long exposures(Eg. > 10 sec exposures), and if you don't have a remote of any kind, then locking up the mirror is a redundant setting anyhow.

Morning Arthur, I'm confused about this , On my old 30D I rarely use a remote on my Sunrises, I regulary take 20 -25 sec shots, I set Mirror Lockup, set Timer and with the lockup activated it gives a 2 sec delay , The mirror is definately up cause you cant see anything through the viefinder at all , Remember I dont have Video or live view and I do only use it on a short focal lenght 11mm to 12mm , Maybe the newer cameras have this pseudo function - Cheers Bill

[Mr Felix]

Ok, I'll ask first.



I took a "nice" picture of the moon through some trees.

Should I put it here, as it is a image of the moon (and/or and wooden tower) and not stars as the topic is?

[ricktas]

Ok, I'll ask first.



I took a "nice" picture of the moon through some trees.

Should I put it here, as it is a image of the moon (and/or and wooden tower) and not stars as the topic is?

If you want to post it to ask questions relevant to this thread, then yes, post it here. If you want to post it just for CC on it, post it into the relevant Member Photos Forum

[Mark L]

I didn't want to use higher ISO settings as they give noise and I am not wanting to start learing about that just now.

See am's post, #16. ISO 3200, not to much niose.
I've had to force myself to learn not to be to worried about pushing ISO up if that's what's needed.

[Mr Felix]

Hi again.

Dunno if I am just stupid, or am missing something.

My picture was 18mm and of Orion.
It was 75 seconds.
Ok, low ISO.

Gerry's picture was so much brighter.

His was F1.4 for 4 seconds.
High ISO.

Ok, I read 3200 isn't a "high" speed for night shots.

I guess there was a lot more "exposure" in Gerry's shot than mine?

[ameerat42]

Mr Felix.
(BTW, where's Gerry's pic? In another thread?)
I see you're trying to get your head around this type of photography, and that's good. No self-deprecation is needed: there are some tricky ideas in it.

A couple of points for your next efforts at star photography.
1. "The stars" - but not the moon, sun, and planets - are regarded as "point sources of light" for most earth-based pursuits. That means, no matter what "magnification" you view or photograph them with, like say, a 2000mm telescope, you can never resolve them past a point. (Most un-ideal optics, though, will smear the "point" out somewhat, not to mention what the atmosphere does and adjacent pixels on a sensor.)
BUT, it also means that they respond well to large diameters of glass. That is, the wider the diameter of the objective lens the more light it will collect. This holds for any means of "observing" the stars. You can even see more stars when you use a pair of binoculars than you can with the naked eye. That's because the eye lens is much smaller than those of the binoculars.

2. If you have a lens with fairly large aperture - that is, area of glass, you will get a much brighter image than with a smaller aperture. You may not then have to worry about increasing your ISO to extremes, say, 3200, but you might get by with much less, like even ISO100. But this depends on how bright the stars are that you want to photograph. For example, going from f/2 to f/1 (how nice if...), or from f/4 to f/2, this represents a doubling of lens diameter and a X4 of glass area. That means four times the amount of light will reach the sensor, reducing the need for high ISOs.

3. When your lens is of short focal length, say f=18mm, they are often also of "fairly high" maximum aperture, like about f/3.5 or f/4. This means that when you divide the focal length by that ratio, f/3.5 or f/4, you end up with a very small aperture to let the starlight in. For the examples, the apertures will be about 5 or 4.5 mm. It is in these cases when you have to bump up your ISO, and so introduce noise, and so have to remove it in PP, and so lose potential information. It becomes a bit of a compromise.

4. Star trailling is a problem when you D N'T want a picture of star trails. Stars appear to wheel across the sky more quickly near the celestial equator (Orion-ish) than near the celestial poles (S. Cross-ish, Polaris in N Hemisphere). 15 sec of exposure just showed incipient trailling in my f=24mm shot of Orion above, and no detectable trailling in my S Cross shot (some other thread) using the same exposure time and f=16mm. Of course, the two factors are involved in this comparison, but it's all I've got.

5. Serious non-trailling star shots require the use of a tracking (equatorial) mount, and all that's required to do that sort of stuff.

And lastly,
6. I feel like Arthur King after this.

Am (?)

[Mark L]

^Thanks Am, feeling like Arthur, I found that a useful post (yes I learned some things).

Mr Felix.
(BTW, where's Gerry's pic? In another thread?)

Posts #5 and 6.

[ameerat42]

Ta, Mark L. I was whizzing down MOST PROBABLY before the screen fully appeared and didn't see them . Now I can. (Talk of being observant!)

Then to answer Mr Felix, yes, they got more exposure because of the higher ISO used.

[Mr Felix]

Mark L beat me.

Yes, thanks Ameerat.

I shall hae to wait until another clear night and when I am out in the country to try again.

[jjjnettie]

It's a pretty steep learning curve, this night sky photography.
Best tips I can give for tripod based work is....
1. if you don't have a remote timer, use your built in timer, set it for 3 seconds to give the camera time to settle after pressing the button.
2. for short exp. 30 secs or less, make use of your ICNR
3. ISO 800-1600 is best. Though ISO 3200 will give ok shots.
4. If the region of sky you are shooting in, has no bright stars to focus on, swing around to a bright star and focus, then gently bring the camera back to the region you are going to work on.
5. To frame your shot, set the camera up to ISO 6400 or higher and take a couple of test shots. Then don't forget to change back to the lower ISO. LOLOL
6. Always knock your F stop up a couple of notches, your stars will be sharper and it should tame any coma inherent with the lens.
7. It's OK to have slight trails. You're shooting fixed objects from a moving planet, it's inevitable . Pin point stars are only to be expected if you're using a EQ mount with guiding.
8. If you want to end up with a bright picture with plenty of detail, you will need to stack your images. Take as many photos as possible, fill your card even. Reframing as you go, so the object you are shooting stays in frame. Then put all those photos through a program called Deep Sky Stacker.
9. If you have any questions at all re. astro imaging, just PM me.

[Mr Felix]

Thanks for that.


Shall try those ideas as soon as we get some clear weather.

Sydney has been terrible for night shots recently.

[Mr Felix]

Recently I tried some more night shots pointing as far south as I could.

I didn't know exactly where the south celestial pole is/was, but I tried.

Alas I still got a lot of problems focusing on those little blighters!

Even putting it on live view so the screen at the back of the camera was the display and setting MANUAL FOCUS, the lens's focusing system is touchy to say the least.
Only a SLIGHT touch and the star goes in/out of focus like that!

Is there a way to "cheat" with this?

My only thought was to build a "venere" thingy which gives me a thing to turn and it is geared down to turn the focus ring so SLIGHT adjustments are possible.

How you people with "normal" lenses manage such fine focusing on stars?

(Maybe I've just got a dicky lens with a fickle focus ring?)

[ameerat42]

Well, Mr Felix, for star shots can I hazard a guess that you are using a fairly wide lens? Perhaps 30-50mm range. Does it have a short focus "throw"? That is, hardly any turn between closest and infinity?
Yes, they can be touchy. But you can try to focus on a largish, brightish distant object, like the moon (hopefully setting and not very full), or a street lamp. If your lens goes "past" infinity, swing it back and forth so that you end up with the sharpest image. You can only go from there. And I seem to remember that you have a late-ish Canon camera. Does it allow a magnified Live View? Use that to you advantage, like on the bright distant objects.

All of this is in Manual focus mode, of course.

Otherwise - and I have only heard about this - you set your lens to AF, focus into the night sky (and hope it has focused at infinity), then switch back to Manual focus.
Good luck.
Am.

[Mr Felix]

Well, honestly: No I am using the 18-135 which came with it.
Or maybe the 90 - 300 Canon lens.

Stabaliser off, manal focus.
(the 90 - 300 doesn't have stabaliser anyway)

I try to zoom in on the actual star I want to see.

Like Mars was in clear view but when I too the shot it was a red line.
I accept that was the rotation.

So I went to the southern cross and tried to get the diamond part (the main 5 starts) in the shot.

As "good" as it was, I feel it was our of focus.
I shall upload a image when I can.

I tried a few more times, which is when I realised HOW sensative the focus ring is.

I sat there for a while with the torch, tripod and other things but had little sucess.

I shall try the wide angle idea but the 18-135 at 18mm is the widest I have.
Well, acually it isn't. I bought one of those wide angle converter things. But: Didn't have it with me.
D'oh!

Ah, well. More things learnt.


So, let's say Jupiter is up. Or Saturn. Ok, a 135 isn't going to really going to let me see the rings, but it is a "big" object.

I want to have it in the picture as the "main" thing. Sure the long exposure will bring in other fainter stars which make it more than a "white spot on a square of blackness", but the MAIN thing woudl be Saturn/Jupiter.

Focusing on them would be painful the way I have things now.

I'm guessing I need a bigger lens?

[ricktas]

most lenses go past infinity. So in manual focus turn focus ring right out to infinity, and then bring in back, just a touch, a wee bit, not much at all. Generally that will give you a good focus.

[ameerat42]

For planetary detail - like, disc and bands on Jupiter, rings of Saturn - you would really need a quite good, stably mounted, preferably tracking telescope. For "telescope", substitute lens at least f=1000mm.
Then you would have to attach you camera to it in one of several methods, usually prime focus, afocal projection, eyepiece projection.
After all that you will start to get a big(gish, relatively speaking) image of the said big object.

Anything less than that, like f=135mm, will only give you varyingly bright/coloured dots. This is OK, because many astro shots are wide-field and are taken to show various dispositions of the stars/planets in the sky at the time.

Focusing will not necessarily get any easier no matter what optical system you are using. Again, if your camera has magnified Live View, then this is what you should try to use. But, do not zoom in to focus and then zoom back out to a wide view, as this may change the actual focus.

From experience, about 15 seconds exposure at f=18mm focal length is about as long as you can go without getting any (just noticeable) trailing. (And this gets less as you move nearer the celestial equator.) So you will have to open up your aperture to maximum (what, f/4?) and maybe give it an ISO of about 400 but not any more than that. Once you nail that focusing you'll be 1/2 way there. Bonus: make that 3/4.

In summary: Focusing, there's no easy way. Once you get it right for that lens (at that focal length), make a note of it.
Am.

[Mr Felix]

Well, here is the effort:

I am not sure if the focus is as good as it can be and there is some rotational distortion visible.


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