Taking widefield images on a static tripod

[ianpwilliams]

I'm going on a wildlife trip to northern Spain next October, and because we'll be in a remote location I'm hoping that I might be able to get some decent widefield astro shots at night, weather permitting.

Obviously I'll have my camera with me on the trip, with an image stabilising lens as well so I won't need a tripod. But I was considering hiring a really lightweight tripod just for astro shots (and taking my camera remote timer with me) in the hope that I could take some short, static widefield astro shots at night.

So really I'm wondering if it would be worth doing?

And what kind of widefield sub lengths could I get on a static tripod, probably using the default 1100D lens fully zoomed out?

And could anyone recommend a lightweight tripod to hire?

[Leveye]

I like to shoot wide field on a standard tripod at 16mm f2.8 at ISO 2500 for about 25 seconds. Works the treat as they say.

[ianpwilliams]

My default lens starts at 18mm, so would f2.8 at ISO 2500 for 25 seconds be good to try do you think? And is 25 seconds going to be the maximum sub length before getting star trails? I'd like to go minimum zoom in the hope of getting maximum sub length. And I won't have a huge amount of time when I'm out there so I'm hoping that I won't have to worry about changing the f value or ISO, just experimenting with longer subs until I get star trails.

[JonH]

Check out the 500-rule: http://www.exploringexposure.com/blog/2014/8/28/how-to-avoid-star-trails-with-the-500-rule

Google '500-rule for astrophotography' and you'll get lots of hits.

Hope this helps.

[Knight of Clear Skies]

I put together a quick guide to shooting with the kit lens that you might find useful, the kit lens is capable of some decent results. That's almost exactly how I got started with AP, a holiday to Menorca with my new (at the time) 1100D. I didn't have a tripod with me so I just laid the camera down on the patio, facing straight up. This is a 30 second shot at 18mm, f3.5 and ISO 1600.

[bogdog]

you should setup and shoot for 25 seconds @ high iso,then review your picture and zoom in and see how much movement you get,

then either reduce or increase by a second depending on results,always reviewing picture taken,when you finally reach a good number without trails

then reduce your iso to what your happy with and set off a run at the rquired amount of seconds knowing your going to be safe

better to waste 5 minutes getting it nailed than wasting a full night

[Astrosurf]

I'm sure you already know, but take lots of shots and stack in Deep Sky Stacker to increase data and reduce signal to noise.  Good luck!

Alexxx

[ianpwilliams]

Thanks, lots of useful info there.

Oh yeah I forgot that it would be worth taking lots of shots and stacking them, rather than just one. I have PixInsight so I should be able to do some decent processing of the stacked image. And actually I might as well stack in PixInsight too.

Would PixInsight, DSS etc successfully stack these images, given that the stars etc would be in different places in each shot due to no tracking being involved?

Also, would it be worth taking Darks, ie the same sub length but with the lens cap on? I may not have time, but just in case.

[happy-kat]

Static tripod just means you will crop more of the edge away on your final stacked image. But don't include stuff that doesn't move in your shot unless you are going to do creative cutting etc. In post processing. If there is foreground then I don't stack it is a one hit wonder image (i hope) instead.

Yes take darks and i also take a few bias frames (same as darks but with fastest shutter available).

Tripod why not get a slr gorrila pod (good for day time use anyway) and do use a intravolometer.

You want IS turned off on the lens.

The biggest challenge is getting focus right. I like to use the back button focus option in custom menus as this stops the camera focus creeping I find. Though I use manual focus at night.

Practice before your holiday so you don't get frustrated on holiday not knowing how to set camera up at night.

[Astrosurf]

A photographer astrobuddy said to turn down the exposure so the star you're focusing on becomes as small a dot as possible. That helps with focusing. 

[ianpwilliams]

There's no IS on the default lens so no problem there.

By intravalometer do you mean a remote timer? Because I do have one of those.

The SLR gorilla pod looks good, and cheaper than I thought (it is the bendy one at around £40 isn't it?). The only downside I can see with that is that because it's short, I wouldn't be able to check my shots very easily when taking shots to get the focus right, without lifting up the camera and tripod. Whereas with a taller tripod maybe I would be able to see the preview image without leaning right down. But then maybe lifting up the camera and tripod wouldn't be an issue?

The back button focus - what does that do? Is it some kind of feature where you have to hold the button down in order to change focus, preventing the camera from changing focus by itself?

I can practice at home if I buy a tripod, although with light pollution I doubt the results would be very impressive! I'm hopeful that the place we will be staying in will be very remote, which would hopefully give some great skies.

[happy-kat]

Take a google to read up on back button focus. It separates focusing from shutter release. I use option 3 in the custom menu from memory, camera is not to hand to check. I use it combined with Al Servo with burst. I don't bother changing back to basic button shooting whether action or still photos we leave it set like this all the time. The fingers get used to gentle touch to trigger just one shot.

My kit lens has IS there are two versions of the same lens I didn't know which you had.

The SLR zoom gorilla pod can attach to the back of a chair or a tree branch or anything really to get higher and is suitcase friendly. I have a ball head fitted to ours. It was just an idea.

[ianpwilliams]

OK I'll read up on back button focus.

And of course the gorilla can be attached to something higher up. And I have various adaptors for attaching my camera to a tripod including a ballhead, So yes, looks like that's the way to go.

As for lenses, I have the default non-IS 55mm lens which I planned on using with a tripod for astro, and I'll be buying a 250mm IS zoom lens which I plan to use for the distant wildlife without a tripod.

[happy-kat]

Have never thought about hiring a tripod is it a cheap option.

[ianpwilliams]

Not sure, haven't looked into it yet. But if I had the gorilla on the ground then I don't see why I couldn't pick up the camera and tripod together to look at the preview shots.

[ianpwilliams]

I've revisited this and I'm attempting to put a step-by-step together, based on the info in this thread and from the links. This is was I have so far:

 

Kit Lens Astrophotography

 

Aperture

 

1. Set to lowest available for the current focal length:

a) 18mm (18mm-55mm kit lens) - f/22

b) 55mm (55mm-250mm IS lens) - f/36

 

Exposure Length

 

1. Manual mode

2. Bulb exposure length

3. 500 Rule (500 / focal length):

a) 18mm = 27 seconds

b) 55mm = 9 seconds

4. 1.6 crop would be 300 Rule:

a) 18mm = 16 seconds

b) 55mm = 5 seconds

 

ISO

 

Use 800/1600/3200 ISO for imaging

 

Focussing

 

1. Set lens to manual focus

2. Turn off IS (if applicable)

3. Get rough infinity focus - turn all the way to the end (which end?) then back a tiny bit

4. Increase camera to maximum ISO and turn on Live View

5. Find a bright star, or a planet, or the moon, and have it one third away from the frame edge

6. Zoom in on Live View and then focus

7. Put some Blu Tak on the focusser ring to stop it from creeping

8. Change the ISO back to the imaging ISO

 

Framing

 

1. Make sure all tripod and adaptor joints etc are tight

2. Choose target - Milky Way ideally, if not then maybe Orion or Pleiades? Include the horizon where possible

3. Take some highest-ISO 10-second shots for framing the shot

 

Lights

 

1. Timer settings:

a) 10-second delay

b) 10-second interval (or 30-seconds?)

c) 1 shot if including horizon etc, otherwise as many as possible (for stacking)

 

Darks (if no foreground/background objects)

 

Take Darks only if photographing space with no background or foreground objects - take as many as there is time for

 

Flats

 

Worth taking flats? Maybe hold iPhone (it's plus size so may be big enough) to camera lens?

 

Bias

 

Just use library ones?

 

I do have some questions though, if anyone can help, which are as follows:

 

Would it be worth going with anything other than 18mm? The kit lens is 18-55mm, and the IS lens is 55mm-250mm, so maybe I could try 18mm with the kit lens and 55mm with the IS lens, which based on the 500 rule would be limited to 27 seconds and 9 seconds respectively (or 16 seconds and 5 seconds respectively for the 300 rule)? Should I keep it simple and stick with 18mm?

 

I would like to include background if I can, hopefully trees or buildings etc, rather than pointing straight up. Would including horizon objects change things at all?

 

Should I aim where there is an object e.g. Pleiades or Orion (should one of those be near the horizon assuming I want to include the horizon itself, although at 18mm I guess the object could be pretty high)? Or should I just aim anywhere? Or just aim for the Milky Way?

 

Longer subs if pointing closer to the North or South, correct? Is it worth trying to increase the sub length in this case, or are we just talking milliseconds?

 

Higher ISO means more detail but noisier image - is 800, 1600, or 3200 best? How will I be able to tell which ISO looks the best just by looking at the small screen of the camera?

 

Put some Blu Tak on the focusser ring to stop it from creeping - how would you do this?

 

10-second delay enough? Too much?

 

10-second interval enough? I normally do 30-seconds for deep sky imaging though, so maybe stick with that?

 

Darks not required if including horizon etc?

 

Just use library Bias?

 

Worth taking flats? Maybe hold iPhone (it's plus size so may be big enough) to camera lens?

 

It does look like I would be looking at the "300 rule" looking at this, as full frame adds up roughly to 500 in this table, but the 1.6 crop adds up to roughly 300:

 

Seconds Before Stars Blur
Focal Length	Full Frame	Canon 1.6 Crop	Full Frame Rule	1.6 Crop Rule
10	n/a	31		310
14	36	22	504	308
16	31	20	496	320
20	25	16	500	320
24	21	13	504	312
28	18	11	504	308
35	14	9	490	315
50	10	6	500	300
70	7	4	490	280
85	6	4	510	340

[RikM]

You are right about using the lowest aperture available, but the values you posted are the 'highest'. For the kit lens it should be  f/3.5 and the 55-250 should be f/4

 

[happy-kat]

Be mindful fastest aperature lens setting could likely be poor star shapes in corners. Sometimes to control CA you might stop down a bit.

Crop sensor is 400 rule. Though I always check the image taken to see if happy with star shape. Some trailing if you don't pixel peep can be acceptable.

Include foreground if you want but just be aware if stacking many images it walks and blurs a bit, but if you have the images you could be creative in photoshop.

Iso look at histogram that is what drives your iso selection for your shutter/aperature selected.

Practice before you go then you'll feel comfortable.

The longer the gap between images the more you will be cropping off if you are stacking as you are using a static tripod.

You don't have any library darks/bias as you don't currently use this setup, you can take those when back in room using same settings and but don't change the focus.

Flats I take by using my tablet screen as white screen and balance it on lens so it doesn't wobble.

Have an enjoyable holiday.

 

[ianpwilliams]

Knight suggests in his guide that poor stars in the corners is better than noise - "The aperture setting is something of a compromise, shooting wide open will result in distorted stars in the corners (coma) but this is preferable to a noisy image". Or do you think I should experiment with the aperture and try to find a balance?

 

I'll use the 400 Rule as a starting point then (22 seconds at 18mm) and decrease the sub length if I get star trails. Maybe I could try increasing it by a second or two as well just to see what I can get away with.

 

For the ISO, I'll set the aperture and sub length first, take a shot, check the histogram, and increase or decrease the ISO accordingly. Would I be looking to get a 50% peak like I do with my subs and flats here at home?

 

I'm certainly going to have a few practice sessions in the back garden before I go, because apart from anything else I won't have much time when I'm outside during the trip. It'll be dinner, then outside, then bed, because it'll be very early starts. So ideally during the trip I'll need to be able to get out there and get going straight away, especially if I'm taking Darks, Bias and Flats too. Although the ISO will be radically different in the dark skies on the trip compared to my light polluted skies here.

 

Seeing as I want to include the horizon if it's possible, I just assumed that there wouldn't be any point in taking many images and stacking them seeing as the sky would move but the ground wouldn't. But having said that, presumably I could take lots of images, stack them all together, and then just overlay the ground section from one of the subs on top of the processed stack? That would work wouldn't it?

 

For gaps between images, you're right that the longer the gap the more cropping I'll have to do, didn't think of that. But I'm also aware that if the sensor doesn't have time to cool between subs then that can cause issues too (more noise?). So which is more of a problem? Should I stick with shorter gaps and more noise, or longer gaps with less noise but more cropping?

 

I'll try taking Flats using my iPhone. Hopefully I can have the camera pointing straight up and balance it on the lens. I take it I'll be aiming for 50% peak like I normally do with Flats?

 

Will I get longer subs if aiming North or South, or will that be negligible?

 

And does anyone have any tips for making sure the focus ring doesn't move?

 

Also, I was considering making a makeshift dew shield for the camera, although I'm not sure if I need one. And actually I remember now that I have a lens hood, so maybe I should use that? Will it be needed?

 

[RikM]

I fix the focus ring with a small bit of masking tape.

I would advise not zooming in to check the trails. You will always get star trails, and you will always see them if you zoom in. The '500' rule is intended to minimise visible trails when viewing the full image at normal size. I use '300’ rule for Canon crop sensor cameras (500/1.6=312.5) and take that as a starting point. If pointing north you can go a bit longer, south you need to keep a bit shorter exposure. If using a stupid wide angle like 10mm, it doesn't much matter which way you are facing as you catch such a wide area of sky.

[happy-kat]

Maybe because this is a trip away would I bother with calibration frames, that is a tough one but I think I might take a few but realistically I might be more inclined to just take one hit images and enjoy the sky I am looking at. Put my effort into having fun perhaps take a torch and try to incorporate some light painting on the foreground. 

[happy-kat]

Just had an idea, I would also read up on taking sunsets you might see some crackers.

If I stop the lens down I just try 1 or 2 stops in it depends on what I see but wide open will give the most light capturing.

[ianpwilliams]

Yes I considered that myself. The images I've seen online must have been one-shot because the ground isn't blurry (unless they stacked multiple shots and overlayed one shot of the ground). Although if I'm going to be limited to 16-sec subs then it shouldn't take too long to take maybe 10 lights, darks and flats, and do bias indoors.

 

I take it that light painting is as described in that link ie waving the torch around for a few seconds during one of the shots? Although maybe that might only be worth doing if there's something in the foreground worth seeing?

 

It's also occurred to me that practicing in the garden will be tough, not just because I don't have the tripod here that I will be borrowing so I'll have to use a chair, but also because there are streetlights and/or building lights round most of the garden, so I'll have to point the camera upwards a little bit at least.

 

And without the light pollution filter the results won't be great. Although I suppose I could remove the light pollution filter from the camera/telescope adaptors and attach it to the end of the kit lens couldn't I? The kit lens does already have a Hoya filter attached to it (I can't remember why I bought that, but I'm sure it was someone on here who recommended it). Could the light pollution filter go on the end of that Hoya filter?

[happy-kat]

It's about practicing in the dark where the function buttons are and working a feel for finding infinity focus. Light painting, you might have an interesting tree or sculpture or something to light with your torch rather then wave it around like a light saber. Anyway just a thought.

[ianpwilliams]

So if there is something interesting in the foreground, would I have the torch pointing at it the whole time, or would that be overexposed?

 

Regarding the light pollution filter I'm hopeful that I won't need to use that on the trip, and I wonder if it will even be useful when practicing here at home, given the 16-sec or so subs?