Advice in choosing lens for night photography

Discussion in 'Photography Beginners' Forum' started by Normanaus, Dec 9, 2019.

  1. Normanaus

    Normanaus TPF Noob!

    Joined:
    Dec 9, 2019
    Messages:
    4
    Likes Received:
    5
    Can others edit my Photos:
    Photos OK to edit
    Hi,

    I am beginner to photography and very interested in taking night sky photos. I have Sony A6000 camera and considering purchasing a wide-angle lens. From the reviews I read and my financial abilities, I narrowed it down to three choices of Rokinon lenses. Can someone help me with choosing a right one?

    My understanding is that the larger the aperture , the more light will go in. I also read that longer lens will provide more detail and less noise- so does this mean 21mm f1.4 is a better option? It also has the most features to it.

    I also look at specs for each lens (links provided), it seems 12mm f.2 has almost identical features as 21mm f1.4. It is also shorter, which would make it easier to travel with. My primary reason for getting a lens is to shoot night sky, but secondary (and not as critical ) would be to use the lens during everyday travels too. Should I go with that one then? Also I am not sure as to how much difference between f1.4 and f2 there would be - isn't the difference manageable by using higher ISO settings?

    The 14mm f2.8 seems like a compromise between the 12 and 21mm, however I read that the wide lens it has will have be a challenge for putting filters on. So it would probably be my least favorite out of the three.

    Rokinon 12mm f.2
    Rokinon

    Rokinon 14mm f2.8
    Rokinon

    Rokinon 21mm f1.4
    Rokinon

    Any help, suggestions or ideas on other lenses would be greatly appreciated.

    Thank you


     
  2. Dacaur

    Dacaur TPF Noob!

    Joined:
    Jul 3, 2019
    Messages:
    90
    Likes Received:
    21
    Can others edit my Photos:
    Photos OK to edit
    The difference between f1.4 and f2 is that f1.4 let's in twice as much light. Litteraly. twice. as. much. So no, you couldn't manage that with s higher iso.
    Each "stop" larger on the aperature doubles the amount of light you let in. So f1.4 let's in twice as much light as f2.0, f2.0 let's in twice as much as f2.8, f2.8 let's in twice as much as f4.0. 1.4 let's in 4 times as much as f2.8, 8 times as much as f4.0, and 16 times as much light as f5.6......
    Basically, a 30 second exposure at f2.0 will look the same, brightness wise, as a 15 second exposure at f1.4...

    Now, as to your lenses choices, it's not as straightforward as it would seem.
    IMO, your budget is the biggest decider here. You have to decide if the benifit if the larger aperature is worth the cost.
    First off, Google the "500 rule" for astrophotography.

    Once you understand that, you will see that, yes, the 21mm f1.4 let's in twice as much light as the 12mm f2.0, but you can keep the shutter open on the 12mm lense nearly twice as long as you can the 21mm without getting star trails. Of course, the longer exposure will suffer from more noise, but the cost/benifit ratio of that is up to you to decide....

    If you also will want to use it for general photography, then the 12mm might be the way to go, as 21mm is likely already covered by your kit lense, as you aren't gaining as much adding a 21mm prime as you are adding a 12mm prime.
     
    • Like Like x 1
  3. photo1x1.com

    photo1x1.com TPF Supporters Supporting Member

    Joined:
    Sep 14, 2016
    Messages:
    861
    Likes Received:
    263
    Location:
    Austria/Europe
    Can others edit my Photos:
    Photos NOT OK to edit
    Hi there.
    There are a few things to consider when photographing the nightsky.
    The earth is rotating, so the stars are moving along the night sky. So there are "rules" that you need to understand and follow in order to not get star trails instead of sharp pinpointed stars.
    Read up on the 500 rule and the NPF rule. Basically they tell you how long you are able to expose without introducing star trails with a certain focal length. With the 12mm, you will be able to almost double the time of the 21mm. But then again the 21mm will let twice as much light in due to the bigger aperture, so these two are rather similar in this regard.
    The 14mm f2.8 however, allows for almost the same amount of time as the 12mm, but has a smaller max opening, only letting half the light in, so that will be the worst in this regard. But it is still very popular among night sky photographers from what I know.

    The longer lens won´t have less noise, but more detail because it enlarges the stars.

    Another thing to consider is that a wider lens will let you capture more of the nightsky in a single shot, which is really nice, because the milky way can cover the complete sky (depending on the time and the area you live in) Have a look at these examples.
    milkyWayFocalLengthComparison.jpg
    But you could always create a panorama made of multiple shots.
    milkyWayPano.jpg

    To get an idea of how much difference the various focal lengths make, let me suggest one of my videos. I created it to give people who are thinking about buying a lens some tips. Maybe that helps too.
     
    • Like Like x 1
  4. Derrel

    Derrel Mr. Rain Cloud

    Joined:
    Jul 23, 2009
    Messages:
    46,648
    Likes Received:
    18,043
    Location:
    USA
    Can others edit my Photos:
    Photos OK to edit
    The 12mm f/2 would be my choice for your aps-c camera.
     
    • Like Like x 1
  5. Normanaus

    Normanaus TPF Noob!

    Joined:
    Dec 9, 2019
    Messages:
    4
    Likes Received:
    5
    Can others edit my Photos:
    Photos OK to edit
    Thank you everyone so much for detailed responses!

    I googled the 500 rule, so if I was to use 12mm and 21mm lenses it would be:

    21 mm
    500 / 1.5 (Sony A6000 cropped sensor) x 21 = 16 seconds

    12mm
    500 / 1.5 x 12 = 28 seconds

    Now it was mentioned that the shutter speed can be "longer for 12mm lens without getting a star trail" - so does this mean that keeping shutter for longer time is a good thing? I am a bit confused - 12 mm longer shutter speed = more noise, but captures more image. 21mm shorter shutter speed resulting in smaller image but also less noise. So which one is then better? Would it not then, make more sense to have something that emits more light and produces more detailed images?
     
    • Like Like x 1
  6. Dacaur

    Dacaur TPF Noob!

    Joined:
    Jul 3, 2019
    Messages:
    90
    Likes Received:
    21
    Can others edit my Photos:
    Photos OK to edit
    You are right, it's better to get the same light with a shorter shutter time, because a longer shutter shutter time = more noise. I simply mentioned that because, depending on how your camera handles noise, the two lenses can take nearly the same picture, other than field of view, so the larger aperature of the 21mm is less of an advantage than it would seem at first glance, in my opinion...

    However, it's not always as simple as more light = the best lens for you. There are other things to consider.
    The 12mm lens will capture more of the sky in one shot, by nearly double... This can be good or bad depending on what you are after, as posted above, you can always take multiple pictures and stitch them together, but it would take 3-4 pictures with the 21mm to equal one with the 12mm. But of course, if you do the opposite by cropping the 12mm picture to the 21mm fov, you end up with a lower resolution picture...
    Youl likely already have 21mm covered by another zoom lens, however, a prime 21mm will always give better pictures... But still 12mm is probably not a focal length you have covered, and the 12mm would do double duty as a night sky lens, and a landscape lens, on the other hand, 12mm might be TO wide for many situations.....

    Helpful, right?
    If picking a lens were easy, we wouldn't have such a wide variety to choose from...
    Personally, I would go with the 12mm, but only because I already have a 24mm prime.
     
    Last edited: Dec 11, 2019
    • Like Like x 1
  7. Lonnie1212

    Lonnie1212 No longer a newbie, moving up!

    Joined:
    Sep 17, 2019
    Messages:
    225
    Likes Received:
    71
    Location:
    Springfield, Illinois
    Can others edit my Photos:
    Photos NOT OK to edit
     
    • Like Like x 1
  8. Lonnie1212

    Lonnie1212 No longer a newbie, moving up!

    Joined:
    Sep 17, 2019
    Messages:
    225
    Likes Received:
    71
    Location:
    Springfield, Illinois
    Can others edit my Photos:
    Photos NOT OK to edit
    What size lens do you have on your camera now?
     
  9. Lonnie1212

    Lonnie1212 No longer a newbie, moving up!

    Joined:
    Sep 17, 2019
    Messages:
    225
    Likes Received:
    71
    Location:
    Springfield, Illinois
    Can others edit my Photos:
    Photos NOT OK to edit
    Did your Sony come with the 16-50 lens? If so, many people would be content using that lens for astro photography. Your camera is also known to have excellent low capabilities.
     
    • Like Like x 1
  10. Normanaus

    Normanaus TPF Noob!

    Joined:
    Dec 9, 2019
    Messages:
    4
    Likes Received:
    5
    Can others edit my Photos:
    Photos OK to edit
    Thank you Dacaur!
    Will need to figure out, what I would prefer - stitching panoramas or taking all in one. This definitely gives me more things to consider.

    Lonnie1212
    Yes, my camera did come with 16-50 lens. The specs are as follow:

    • SPECIFICATIONS:
    • Optics/Lens:
    • Lens Type: E-mount 16-50mm F3.5-5.6
    • Lens Mount Type: Sony E-mount lenses
    • Aperture: f/3.5-5.6
    • Aperture (Max.): f/3.5-5.6
    • Aperture (Min.): f/22-36
    I tried it out for night photography before, but at the time had no idea what I was doing and whether if it was decent or not. That is what prompted me to read about night lenses.
     

    Attached Files:

    Last edited: Dec 12, 2019
  11. photo1x1.com

    photo1x1.com TPF Supporters Supporting Member

    Joined:
    Sep 14, 2016
    Messages:
    861
    Likes Received:
    263
    Location:
    Austria/Europe
    Can others edit my Photos:
    Photos NOT OK to edit
    In my experience, doubling the exposure time doesn´t nearly introduce as much noise as doubling the ISO, if that helps with your decision. It depends a lot on the temperatures you are shooting in. High tempertures being worse.
     
    • Like Like x 1
    • Agree Agree x 1
  12. Normanaus

    Normanaus TPF Noob!

    Joined:
    Dec 9, 2019
    Messages:
    4
    Likes Received:
    5
    Can others edit my Photos:
    Photos OK to edit


    Thank you everyone for your help, decided to settle on the 12mm f/2 lens.
     
    • Like Like x 4

Share This Page