Advice/Tips please: 50mm f/1.8

[Immaculens]

Night-sky newbie here!

I attached my nifty-fifty the other night and took various 35 second exposures, typically at f/2.2, ISO400 - bulb - remote shutter release

But in Live View using manual focus (10x) I was unable to get the focus I wanted - I had it turned all the way... to infinity I guess - and it seemed like it could have been sharper yet

If anyone else has done shots with their 50mm f/1.8 please share your successful settings... I imagine I was getting star-trails after about 8 seconds or less. 40 secs certainly showed the beginnings of trails.

I guess I will go back to using my 15-85mm - likely at 15mm f/3.5

Thanks for any tips. A processed shot with the above (top) settings is attached

[the jimmy]

Originally Posted by Immaculens

Night-sky newbie here!

But in Live View using manual focus (10x) I was unable to get the focus I wanted - I had it turned all the way... to infinity I guess - and it seemed like it could have been sharper yet

Focusing all the way to infinity is to far, you'll need to back off ever so slightly

[Immaculens]

hmmm... strange - I was trying to make the star - during manual focus - as small as I could and it seemed it was in the process of getting small but then I could not turn it further...

also - is it recommended I use my 50mm over the 15mm?

less exposure time...

[James33]

Your exposure time is too long using a 50mm lens on a crop body camera, unless you are using a tracking mount. It's causing the stars to start to "trail" due to the earth's movement.

Go back to your 15mm, start at 30 sec exposure max, use f/3.5 and ISO 1600/3200 if you can swing it. And what I do for focus is use manual focus in daylight and focus on infinity. Once you find the spot you can mark it on your lens so you don't have to hunt for it.

Hope this helps

[Immaculens]

Originally Posted by James33

Your exposure time is too long using a 50mm lens on a crop body camera, unless you are using a tracking mount. It's causing the stars to start to "trail" due to the earth's movement.

Go back to your 15mm, start at 30 sec exposure max, use f/3.5 and ISO 1600/3200 if you can swing it. And what I do for focus is use manual focus in daylight and focus on infinity. Once you find the spot you can mark it on your lens so you don't have to hunt for it.

Hope this helps

Thanks - yes - the exposure on the 50 was way too long - considering that for 15mm it should not be past 22 seconds

I'll be selling my rarely used but excellent 15-85mm and getting other toys like the G12 (got it already), new 40mm STM (selling the 50), and its hard to believe I'm writing this - the 18-55 IS... But, that will give me 18mm for the rare times I use it...

Thanks for the reply - cheers ~

[Nature Nut]

When I have used my nifty fifty for some night shots, I focus to infinity then back off a hair.Some, if not most, lenses today will allow you to go just past the infinity mark by hair. I found I prefer using a wide angle lens better for the most part though.

[Immaculens]

wide would be my preference also - I was just surprised I could not manually focus on stars with my copy of the 50...

[A.S.I.G.N. Observatory]

Originally Posted by Immaculens

1. I had it turned all the way... to infinity I guess - and it seemed like it could have been sharper yet

2. I guess I will go back to using my 15-85mm - likely at 15mm f/3.5

1. Every lens has it's sweet spot. It is usually just back a fraction from infinity and it's something you have to, feel" for rather than a set place.

2. Correct. That would be MUCH better.

The longer you go in focal length, the shorter your exposures will have to be to avoid star trails. Otherwise, get a mount that tracks.

Baz.