Has anyone used a 50mm lens for astrophotography? I recently purchased the Canon EF-S 50mm f/1.8 and find it's a great little lens. It lets in lot more light than I've been able to capture in not-dark-enough-but-ok-for-simple-astro-shot areas with my tele-macro but I can't seem to get the hang of the settings. I end up with blurry stars. I think I changed the f-stop from 2.8 as my original setting to 3.5, from memory, with ISO1600 for about 20s but it still looks like my stars are suffering from a bokeh effect.
Hoping to try it at 4.5 instead in the next couple of days, as recommended in an article I read, but does anyone have any experience using this lens or advice on better settings?
I know it's probably not the ideal lens for astrophotography but it was recommended as a simple starter lens for this purpose. I can see it has potential from the shots I managed to get, so I'm thinking it's more a question of my settings than the lens itself.
I am tossing up between my three lenses for my holiday, which includes a short trip to Atacama. I can only take two with me and I've pretty much decided on my tele-macro which is good for far away animals etc and I also know I can get decent (if narrow) star shots with it. My other lenses are the 50mm and my kit lens (18-55mm f/3.5-5.6). Haven't managed to get the hang of the kit lens for astrophotography either, but apparently it's supposed it be okay for landscape shots (obviously if you can get the right settings!).
I use a Canon 50mm f/1.2, but will be similar enough. I must say I have not done it for a while, BUT...
Put it in manual mode, and select B. Change the aperture to around f/3.2, and the ISO to around 1600 or so (some use higher), and the exposure to 15 to 20 seconds. Any more, and the trailing is obvious if not using a tracking mount.
I tend to use my Canon 28-135 USM more often for these kind of shots though. A good lens.
From your post I am assuming that you are new to astro imaging. I obviously have not seen any of your pics, but I tend to think that your star blobs may be due to poor focus. Assuming that your DSLR has Live View,
magnify a bright star 10x and then manually focus the star until it is as
small as you can get it; carefully move to your target without disturbing
the focal setting. Turn off LV, and take your shot.
The EF 50mm is a good lens for astro, but is exposure time limiting
if you are not using any form of tracking. you can only use exposure times
ranging between approx. 6 and 30secs before star trailing becomes obvious; the nearer you get to the poles, the longer the permissible exposure.
To get started and get some pleasing results I suggest you use the
18-55mm set to 18mm at f4. This focal length will allow exposures
ranging from 20-100secs [0 to 80 degrees declination]. Experiment
with settings as follows and see which you prefer.
18mm f4 ISO 3200 15-20-25 and 30sec. Try the same series of shots
using ISO 6400. Make sure noise reduction is enabled.
You may be forced to limit your exposure time because of skyglow
or other light pollution. If so, you will have to use multiple short
exposures, and stack them in your computer, but that may be a little
further down the track. In case you are not familiar with noise
reduction, the camera will do some processing for the same length
of time as the exposure you have just taken, before you get to see the results on the LCD screen.
I hope this helps; and I hope it wasn't patronising.
P.S. If your DSLR is an older model without Live View, focus on
something bright in the far distance, such as a street lamp. It is
unfortunate that DSLR viewfinders are smaller than the old film SLRs,
and the image is not as bright either.
raymo
Last edited by raymo; 08-10-2013 at 03:05 PM.
Reason: not finished
Bright planets (especially Venus and Jupiter) are good targets for autofocusing, as is the edge of the moon. You may find the camera focuses more easily if you use the centre point to focus, and turn off the other points.
Also, be sure to set the lens to manual focus afterwards so that you don't accidentally lose focus when setting up the camera for sky exposures.
The "Nifty 50" is an awesome little lens for the price.
I've used it a lot for astro imaging.
It's best to set it to F4.5 or even F5.6 for long exposures, it will sharpen up those stars and help reduce any coma in the corners.
As Dave just mentioned, focus on a bright star or planet before moving to the area you will be imaging.
I found that if you purchase an EL-CHEAPO (For me anyway) $250 lens that has a infinity setting on it you can get some nice shots without having the blobbed stars. There is also another trick you can try which I used before getting my new lens. Do some day time calibration (especially if there is no moon until later on in the night), select the most distant object you can see with your naked eye, then zoom as close as you can (if you have a zoom lens), then focus it until its as sharp as you can get it in manual, then note the settings and that should give you as close to infinity as possible for night time shooting. Note that if you intend in doing wide field aswell, you will need to note those settings aswell. If you don't mind a small nick filled with white-out on your lens casing, this is a good way or marking them !
try it on f4, 20secs might be pushing your luck-on a 1.6x sensor 10sec will be more like it
you say the stars have a bokeh efect -infinty focus isnt always right on -either focus in twilight - or focus on a street light some distance away
r u using liveview to focus the lens
dannat - I hadn't been using Live View for focusing. I hadn't really used either of the smaller lenses for astrophotography before, mainly the tele-macro which has an infinity setting. But I did try that last night and I think I'm getting somewhere.
raymo/naskies/jjjnettie - thanks for the focusing suggestion. I managed to focus on a bright star with the 10x on Live View and I think it turned out alright. Haven't downloaded the pics off my camera yet, so we'll see how they turned out!
raymo - I couldn't figure out if my camera has noise reduction (wasn't anywhere obvious anyway) and I didn't have the manual on me. I ended up going with a max of ISO 1600 because I ended up with just washed out sky with higher ISO (there was a bit of light pollution too, but it was a better location than my balcony!). I'll have to have a look at my camera manual on how to turn on noise reduction, and try those series' again. I get the feeling they'd probably work if I were in a darker location. I did take three or four exposures when I thought the stars looked focused to try stacking later on, but I know for stacking you usually need dark exposures etc. which I haven't read up on, so not really sure if it would work with just star shots? (And no, it wasn't patronising, I appreciate the help! )
LewisM - I tried similar settings (I think I ended up around f4, maybe higher, due to the light pollution) and you're right, they started going oval. I think the longest I could do before it was starting to show was about 13 sec. I used manual mode, as I usually do, but I'm not sure what you mean by "B" ...
jr_simpson - my tele-macro lens has infinity focus and I've taken some nice shots with it. Unfortunately I don't know how good it would be for landscape shots, even on Normal mode, as I've only ever been able to try it on landscapes that are relatively close to me ... I attached a shot I took with the tele-macro on Normal. Or do you mean another type of lens?
Thanks all; hopefully I will have a couple of decent exposures from last night to post soon!
Firstly, no good taking any notice of infinity setting on lens, as almost all
lenses can focus beyond it, so Live View is the way to go. To double check your focus after taking your first shot have a look at the result on the LCD screen when you magnify it.
Secondly, noise reduction. Turn camera to manual mode so all sections of the menu are available. In my 1100D it is in the last section. There is long exposure noise reduction, and high ISO noise reduction. Experiment with both
enabled, or either one on it's own. I generally get the best results with both enabled.
Thirdly, the B that Lewis mentioned stands for bulb. With the camera on manual turn the shutter speed wheel through longer and longer exposures until you reach 30secs, and the next click will then be B. In the B setting the shutter will stay open all the time the shutter button is held down.
You will need a shutter release cable, if you don't have one, in order to
avoid vibrations when touching the camera.[get one on ebay for a few dollars].
Fourthly, When doing fairly basic work, you don't need to worry about
dark frames; with noise reduction enabled the camera takes one after
every shot, and it also does some bias work. Some people over process
their shots, for instance, using bias frames when they don't need to.
And yes, you obviously have bad light pollution, so will have to take
more shorter exposures and stack them.
raymo
I usually have mine at f/4.0, I wouldn't want to go too far below that. I should try 4.5 and see what happens.
Personally and this is probably personal preference but I turn all of the in camera auto settings off, if you are taking lots of frames then those settings tend to use up your battery and make sure you shoot in RAW mode.
Thanks JB80! Yes, I've been shooting in RAW though somehow I managed to inadvertently select RAW+JPG last night and ended up with duplicates
Quote:
Originally Posted by raymo
Secondly, noise reduction. Turn camera to manual mode so all sections of the menu are available. In my 1100D it is in the last section. There is long exposure noise reduction, and high ISO noise reduction. Experiment with both
enabled, or either one on it's own. I generally get the best results with both enabled.
Thirdly, the B that Lewis mentioned stands for bulb. With the camera on manual turn the shutter speed wheel through longer and longer exposures until you reach 30secs, and the next click will then be B. In the B setting the shutter will stay open all the time the shutter button is held down.
You will need a shutter release cable, if you don't have one, in order to
avoid vibrations when touching the camera.[get one on ebay for a few dollars].
Fourthly, When doing fairly basic work, you don't need to worry about
dark frames; with noise reduction enabled the camera takes one after
every shot, and it also does some bias work. Some people over process
their shots, for instance, using bias frames when they don't need to.
raymo
Thanks raymo - I found the noise reduction in the end and it seemed to help. I live in the city and don't often have a chance to drive out to somewhere darker, so my shots still have light pollution, but they're looking a bit better. The foreground is discernible but not washed out and you can still see stars in the background, which is the effect I'm after. I used f4 and ISO 800 for 15sec on the 18-55mm lens when I was testing last night. I think I could go with a higher ISO when it's somewhere darker.
Is there any difference between using the 15sec setting and using Bulb setting for the same amount of time? I can't imagine how it would be different, but I could be missing something ... I was just using the 15sec setting. I do have a shutter release cable, though, it definitely helps!
Hi Romina,
No, there is no difference between 15 secs with or without B,
except of course that in the B setting you have to close the shutter yourself after 15secs.
If you have plenty of space on your card, it's a good idea to shoot
RAW+JPEG, because the JPEGS can be kept as back up.
raymo
Thanks raymo. I usually shoot just in RAW and then convert them into JPEG on my machine. I haven't started learning how to edit RAW files yet, but I've kept them all for later. Mainly I edit the JPEGs. Not a bad idea to shoot in both when there's space, though.
[Ok, so it looks like the uploader didn't work last night ... will add the images again tonight!]
So, here are some basic shots from each lens. Bear in mind there's a lot of light pollution where I'm taking them and my dad is also rebuilding the pergola, so there's a bunch of stuff in the way, limiting my access to standing next to the clothesline!
Having said that, does anyone have any recommendations on which lens to take based on the shots? I'm still undecided!
IMG_2152,54,59 are from the 18-55mm lens
and
IMG_2164,74 are from the 50mm lens
They're just unedited JPEGs, using ISO and long exposure noise reduction. Any thoughts?
Last edited by Shooting_Star; 16-10-2013 at 10:25 AM.
to me the first and third shots have the stars being pretty round whereas the others have elongated stars. I also have pergola/tree problems in my back yard!
