Can I get a re-cap?

[toilandtrouble123]

Evening all!

Just wanted to pick people's brains (again, sorry) about tweaking the setting on my Canon 350 D, and having a second go at constellation shots and star trails.

This is what I've got so far:

Constellation Shots/Night Scenery

-Increase exposure time to around 20 seconds, and take multiple shots of same exposure time

-Keep ISO at 800, because any higher I will run the risk of noise and getting washed out by the LP

-Turn off noise reduction on custom functions, and take my own "dark frames" instead (will be using a black t-shirt over the lens as camera doesn't have a lens cap!)

-Lowest f/number that I can get down to, which is f/3.5 as I only have the standard 18-55mm lens the camera came with#

Star Trails

-Lower ISO to 200

-Noise reduction off and lowest f/number, same as above

-Instead of taking one long exposure, taking shorter exposures then stacking them together how long should these exposures be for star trails??

Have I missed anything?

Cheers

Nat xx

[IanL]

-Turn off noise reduction on custom functions, and take my own "dark frames" instead (will be using a black t-shirt over the lens as camera doesn't have a lens cap!)

Not sure that a black t-shirt would be a good enough option. It wouldn't be that opaque.

I would recommend using a few layers of kitchen tin-foil over the end of the lens (even a plastic lens cap is not necessarily opaque to IR, and the IR filter built in to the camera will not block 100% of it, so your darks wouldn't be totally dark). A metal lens cap would be even better, but if you don't have one make sure the foil seals all the way round the edge (use some tape if you need to ) and there are no pin holes.

Also at the very least block the viewfinder at the back using tape/tinfoil (most Canons have a rubber widget that you can slot in to the viewfinder but I don't think it is light tight). You might even find it beneficial to wrap the body in foil if you think light is leaking in through gaps in the body (but this is not usually an issue).

[toilandtrouble123]

Ok, I'll do that on my front door step, before I bring it back in.

However, eerie thick ground mist has appeared out of the blue, so very quickly trying to make a dew shield for the camera lens, but an inquisitive little kitten is making the job rather difficult lol!

Are the above settings ok for what I what to do tonight?

Nat xx

[IanL]

They sound like a reasonable place to start experimenting from, I'd expect you to get something useable from that. I don't know how long you will be able to expose the non-star trails for, but at f/3.5 you may be able to get away with more than 20s; personally I'd go for a range of exposures, starting with a bunch at 20s and then do some more at 40s, 60s until you start to see obvious trailing or the LP starts to get too bright.

As for the star trails, it really is just down to LP in the end. Stop exposing when the background looks like it will begin to wash things out.

An ISO in the 200-400-800 range is reasonable in both cases. You'd only need to go down to ISO200 for longer exposures if you have bad LP, and actually 400 or 800 with a shorter exposure might be better.

Don't forget to do your darks at the SAME ISO settings and exposure lengths as the lights, so you may need several sets if you are changing either or both.

[Jessun]

It all sounds about right to me, but it's obvious here on SGL that the DSLR guys/gals do a fair bit of experimenting. As IanL points out a t-shirt is most likely not enough for the darks though. Some literally seal the whole camera and take them IN THE DARK. Photon hunting is by necessity turning to photon phobia!

Luckily you can do darks later - weeks, or even months later - so long as you take them at the same ambient temperature. Many keep a dark library for different temperatures, and as the CCD ages they replace these darks every few months or so.

You'll pretty quickly get a feel for how long an exposure you can do - everything you can imagine comes into play here. Target, temperature, seeing and vis, LP, tracking accuracy etc. Experiment and post back!

/Jesper

[toilandtrouble123]

Ok cheers. I'll post my pre-processing and post-processing photos on here after work tomorrow.

Many Thanks

Nat

[redneon]

Am I wrong in thinking that for star trails you don't want to stack? I'm new to this myself so I'm probably wrong but if you stack images in DSS doesn't it attempt to correct any alignment differences between the images? Or is the point that you don't use DSS but manually stitch the photos together yourself in PS?

[toilandtrouble123]

I was advised to try that method to avoid being washed out by LP, like I was for my first attempt. I was given a link to a star trails tutorial, but it's on another topic page

Nat xx

[JamesF]

For the star trails I'd follow the instructions here:

http://www.startrails.de/html/software.html

James

[redneon]

Just out of interest, how are you making the dew shield? I should probably make one myself. Stupidly, I've never really done anything to protect my camera from the elements before.

[toilandtrouble123]

sweet! cheers James, you a life saver, as always! However, now I can't even see down the end of my street > it always happens to me

damned fog fml

Nat xx

[toilandtrouble123]

Just out of interest, how are you making the dew shield? I should probably make one myself. Stupidly, I've never really done anything to protect my camera from the elements before.

I glugged a can of fosters (I could tooth ache cos it was really cold straight out the fridge, smooth I know) Cut it in half, then made a sort of "opening flower" effect by cutting on end into strips and bending them outwards, andcovered the sharp edges with tape. Now I'm going to sacrifice an old threadbare black "hair dying" towel, to line the inside (literally all the pile from the towel has gone, so less risk of fibres getting on the lens. Now I gotta figure out how to keep the mini upside down lamp shade thing (yes it looks like a inside-out upside-down lamp shade lol) in place on the lens.....and the damned kitten keeps trying to eat the sellotape, which is distracting.

There's got to be an easier way, surely..

In the meantime, what to have, wine or fosters

[JamesF]

sweet! cheers James, you a life saver, as always! However, now I can't even see down the end of my street > it always happens to me

damned fog fml

I feel your pain. I've not had a decent night's observing since 9th December and I have new toys to play with. Frustration is running high

James

[JamesF]

There's got to be an easier way, surely..

There so is:

http://www.ebay.co.uk/itm/LC-58-centre-pinch-camera-front-lens-cap-58mm-for-Pentax-Sigma-Canon-Olympus-etc-/121042374609

(just the first example I happened to find. There may be cheaper ones. I think "the size is right" (as I'm sure they used to say on television).

James

[JamesF]

Just checked, and it is 58mm for my 18-55mm kit lens.

James

[toilandtrouble123]

must be ok for me too, as I use the same lens as you x

[JamesF]

I have on my desk an aerosol can of ink-jet fixative spray with a push-on lid (no, not for those mornings when a strong coffee just won't do the job . It just struck me that it looks just about the right size to fit over the lens. I'm sure other aerosol cans must be of similar dimensions. Fix a dark one (or any colour one covered with your dark towel) over the lens with a bit of tape and you could well be sorted.

James

[toilandtrouble123]

Ahhhhhh... you genious! I shall rummage around through the halloween decs and costume box, cos I bought some black-coloured hairspray (I turned my housemate into peppy le pew the warner bros skunk) and the lid was black. I've now got bored with doing a "Blue Peter" job on my dew shield for my camera, I'll carry on with it tomorrow now. But thanks for the tip James!

Nat xx

[IanL]

There's got to be an easier way, surely..

Just be careful okay. No doubt someone will come along shortly and tell you to cut out a piece of (ideally black) foam camping mat, roll it in to a tube and fasten using sticky velcro pads or duck tape. DO NOT LISTEN TO THAT PERSON.

Everyone "in the know" used a piece of black foam yoga mat. This results in the photons being more relaxed just as they enter the lens or telescope, and thus it makes tracking them easier.

[JamesF]

Ah, that's for a dew shield though, not a lens cap.

James

[toilandtrouble123]

I havent got the idea from anyone, just opened the fridge, saw my beer, and *light bulb*! It's going ok, I'll post a pic when it's done!

[toilandtrouble123]

Ah, that's for a dew shield though, not a lens cap.

James

Needed a lens cap and dew shield for my dslr tonight. mist has almost completely cleared, will head out in the next hr or so, and carry on with my dew shield tomorrow. I got no money to buy any mats like a yoga mat, hence using a beer can as a frame for an old towel

[IanL]

Ah, that's for a dew shield though, not a lens cap.

James

Yep but in post #3 there was a dew shield in the offing too, just ensuring everyone is aware if the issue. I'm going to write a paper about it sometime I think.