I got a Nikon 70-300mm lens as it was on discount. I want to know if I can do astrophotography with it? I want to maximize the use of the lens. I wanted to get a 34-300 mm lens, but it was expensive.

I own an N90. How can I do astrophotography or tele with my 70-300 mm lens? What are the lens' capabilities and limitations?

up vote 7 down vote accepted

To do astrophotography with a 70-300mm lens using a film camera is a challenge, but is possible. One of the limiting factors is the speed of the film you use. In general you need a very fast speed film to do astrophotography, especially with longer focal lengths such as 300mm. This is because as the Earth rotates on its axis, the stars appear to move across the sky and they do so much faster than most people think. Here are some tips on how to do astrophotography with your N90 and 70-300mm lens.

  • Stabilize the camera/lens You will not be able to take photos of any night sky objects, other than the moon, at shutter speeds that will allow you to handhold your camera. A sturdy tripod that won't blow around in the wind is the minimum requirement.
  • Use the fastest film you can find Something like Ilford Delta-3200 B&W film. It has an actual sensitivity of around ISO 1250 to ISO 1600, but can be 'push processed' to ISO 3200 and beyond. With an f/4-5.6 lens, 'beyond' is what you are looking at. When you have the film processed, be sure to tell the lab to 'push' the speed to around ISO 6400.
  • Use your lens' maximum (widest) aperture This will be the aperture setting with the lowest number. AT 70mm your lens probably has a maximum aperture of f/4 and at 300mm a maximum aperture of f/5.6.
  • Focus manually to 'infinity' You may have to do a little bit of preparation before it gets dark. Point your camera at an extremely distant object and focus on it. Make a note of the position on the lens' focus scale. You can also use the moon if it is above the horizon. Don't assume the infinity mark on your lens is absolutely accurate. It is probably close, but focusing on stars is critical. You should be able to verify correct focus in your viewfinder by looking at one of the brightest stars in the sky through your viewfinder. Fine tune if necessary, but if you get too far out of focus the stars will disappear as the light from them is spread out over too large an area.
  • Limit your shutter speed If your camera is on a stationary mount, divide 600 by the focal length you are using. That is the longest shutter speed you can use that will show the stars as points on an 8x10 print. Anything longer will cause them to show up as trails. For 70mm, that figures to 8 seconds or so. At 300mm, it goes down to 2 seconds. You can double the shutter speed for a 4x6 print (divide 300 by the focal length). Even with very fast film, you're not going to capture many stars at f/5.6 and 2 seconds. Be sure to point your lens at areas that have several bright stars, such as Orion, Canis Major, or Gemini.
  • Consider a tracking mount This will allow you to use longer shutter speeds than covered above and will allow you to capture much dimmer stars in your photos. Many telescopes have mounts that, when lined up with the Earth's axis, will track along the path stars take across the sky. Adding a motor that moves the mount very steadily at the same rate as the Earth rotates allows the telescope to stay pointed at the same spot in the sky's constellations. Many photographers will modify their telescope to allow them to attach their camera and let it 'piggyback' on the telescope. If the mount is made for a smaller, lighter telescope then the mount needs to be adapted to hold the camera instead of the telescope.
  • Use the darkest skies you can find Find a spot away from heavy light pollution to take your photos of the night sky. Also, unless the moon itself is your target plan your sessions at times before the moon rises or after it has set. The darker the sky the better your results will be.

Photographing the moon is entirely different than the stars. You can use ISO 200 film, an aperture of f/8, and a shutter speed of around 1/250th second when the moon is more than about 15-20° above the horizon. You'll still need a tripod for good results at that shutter speed and 300mm.

  • @Micheal Clark , very detailed answer.Thank you. Now i am willing to change my camera for anyone of nikon model D3100,3200,5100,5200 or 5300 along with a extra lens, which might serve me macro or astro photography. In ur opnion which one is good? or perhaps any other choice – Nofel Jan 8 '14 at 18:24
  • In general for astrophotography, the camera with the best high ISO/low noise performance is preferred. Of those you have listed, that is probably the D5300, but the D600 would be even better. Please note that if you use a camera with an APS-C sized sensor (such as all of the models you listed), you will need to divide: 600/(focal length x 1.5) to account for the narrower field of view provided by the same lens when using a smaller sensor. For more on why, please see photo.stackexchange.com/questions/30263/… – Michael Clark Jan 8 '14 at 18:40
  • @Micheal Clark , mainly i do photoshoots so in my spare time, i do some landscape and lately been fascinated by astrophotography too like vimeo.com/57130400 so, don't want to miss out any features of new camera i get. – Nofel Jan 8 '14 at 19:03

A 300 mm lens is not so very much yet. So that you know what to expect, here is my shot of the planet Jupiter with four of its moons. My lens is a Sigma 70-300 mm cheap lens, but for this sample it does not matter, the 300 mm focal length is in question here:

Jupiter in 100% pixels crop
^^ Jupiter and moons cropped to show 100% pixels inline.

Jupiter in full resolution photo
^^ Here the full resolution photo. Click here for full size photo (4912x3264).

My camera has a 16 MP APS-C sensor which effectively turns the focal length into equivalent of 450 mm on a full frame (or a film) camera. I only noticed after reading @MichaelClark's answer that Nikon N90 is a film camera, and while I have used my share of film I never ever took a shot at the starry sky at night :(

Jupiter is very bright, but its moons are not so. Tripod or other strudy support is a must.
Exposure settings on my digital camera: 1/5 sec - f/6.3 - ISO 400

To get as close with that N90 you'll need a teleconverter in between the 300mm lens and your camera. Then again, if you do your own developing to paper prints, you can magnify the image in your darkroom quite nicely and if exposure is right you'll end up with a better photo easily.

  • You were able to see Jupiter's moons with a 300mm lens? Fantastic! – Michael H. Jan 6 '14 at 15:38
  • @khedron - Yes the lens is a 70-300mm but on my APS-C sensor camera it equals a 450mm in its view angle. – Esa Paulasto Jan 6 '14 at 20:33
  • 1
    Understood. I've got the 55-250mm w/ APS-C, and never would've imagined I could see Jupiter's moons with it. 400mm effective vs. 480mm might make the difference, but it means it's worth trying. – Michael H. Jan 8 '14 at 0:29
  • were you able to see jupiter cloud bands at 300mm? – editinit Apr 21 '16 at 18:01

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