Astrophotography

minimace

minimace

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Aaron
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I have got into astrophography recently, I have been using a 50mm 1.8 lens for Milky Way pics etc, and for trying to take pics pics of things further into space have been using a 55-250mm canon lens. I'm struggling with sharpness and can't help but think that it's the lens. Thinking about getting a 100-400mm mk1 L lens, but want to know how much difference it would make?
 
I'll tag @Jannyfox and @swag72 since they're among the best astro photographers on the board.

Personally, for the Milky Way, I use as wide as I can get hold of (in both focal length and aperture) or as long as possible (for Moon shots and similar), usually hand holding for flexibility. I don't do deep space stuff though - I lack the patience, expertise and specialised mounts that that really needs to do well.
 
Hi
Are all the other factors taken care of?
I.e... tripod/mount, shutter speed, mirror lock or delay, focussing lock, temperature etc etc.. ?
 
idigitize said:
Hi
Are all the other factors taken care of?
I.e... tripod/mount, shutter speed, mirror lock or delay, focussing lock, temperature etc etc.. ?
Click to expand...

Yeah, the lens is probably the last thing to look at given what you've said.
 
..... There's LOADS of things to take into account! Here's a couple of thoughts....

  • Temperature affects focus and so throughout the course of a night for example, good focus can become bad focus.
  • It's actually VERY difficult to get good focus... Many people use a Bahtinov mask over the front of their lens / scope to ensure best focus is achieved.
  • Mirror lockup does need to be enabled
  • You need a cable so that there is absolutely NO vibration going on.
  • Mount .... Mmmm. The sky moves at a surprising rate and so depending on your focal length you may find that you can only take surprisingly short exposures before you get elongated stars (Once they happen your target will start to look out of focus)... You can negate this to some extent by taking MANY exposures and then stacking them together in free software so that your signal builds up.
Hope that helps :)
 
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I've just seen you purchased a skywatcher adventurer so assume mount is taken care of assuming that is on a decent set of legs.
Still, make sure all the other factors are 100% dealt with before worrying about the lens.
 
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As a frustrated astro photographer, I would concur with lens quality. Changed from a oly 300mm zoom to a pany 400mm zoom, and photo quality improved no end. Probably in line with the relative cost of the lens!

As an ex land surveyor, (in the days of optical instruments), clarity of image depended so much on atmospherics. The scopes magnified the humid atmosphere mist and gunge..........

The more vertical the shot is taken, the less atmosphere the photo has to see through.....

Light pollution is also another bugbear.:(:(

Keep trying though..........:):)
 
I can't comment on Milky Way type shots but when you say 'further into space', what do you mean by that? Sara's the real expert here and as she says there are lots of things to take into consideration. Deep sky astrophotography isn't easy. I use the Sigma 150-600mm on a tracking mount (a proper driven mount you'd use to put a scope on, not a tracking head on a fixed tripod). I also use it for the Sun and Moon, which don't need long shutter speeds and a driven mount. Have a look at my Flickr Astronomy album if you want. The notes for each image tell you which were taken using just the lens. If this is what you had in mind come back and I'll try to help. It may be as simple as a focussing issue, although the answer isn't as simple as it is in daylight.............. But don't rush into changing the lens if you haven't got the basics right.
 
Yes I have now got a skywatcher and have a better tripod on the way. With the 55-250mm I find that pics are a lot sharper at say 55mm, as soon as I go past 150-200mm the images aren't sharp at all, that was what made me think it was the lens.
 
minimace said:
Yes I have now got a skywatcher and have a better tripod on the way. With the 55-250mm I find that pics are a lot sharper at say 55mm, as soon as I go past 150-200mm the images aren't sharp at all, that was what made me think it was the lens.
Click to expand...

Sounds more like technique to me.
 
You are probably right, going France in march in a area where there is very little light pollution, want to make sure I get everything right before I go!
 
As you go out in the zoom you will also be far more sensitive to atmospheric stability. There will just be nights where nothing ends up looking sharp even with the best lens in the world - it's not just the clouds that make this kind of thing hard from the UK!
 
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