Old 12-10-2013, 10:04 AM
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Carl is offline
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lens for astronomy landscapes

Hi all
2 questions:
Q1. Which will give me a better sharper images
Canon EF 50mm f1.4 USM $450
Canon EF 50mm F1.8 II $130 Cheap but seems to be popular

Q2. Anyone purchased these on the web market ie DWI or similar
Carl Rainer
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Old 12-10-2013, 10:15 AM
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Nightscapes have different requirements from a lens than terrestial in my opinion.

F1.4 is usually unworkable in nightscapes as almost always lenses have bad chromatic aberration wide open at F1.4 unless its the new Zeiss Otus 55mm for $4,000.

I had the cheaper 50mm Canon and 2 Nikon 50mm versions and I found the Nikon and Canon to be indistinguishable in a loose test.

What is also handy is an aperture ring so I like my old Nikon 50mm F1.8D for that in case you end up wanting to use the lens on an astronomy CCD at some point. Aperture control then is important but you can always use step down rings to gain that smaller aperture if needed.

Unless you mainly want it for daytime imaging and want the subject isolation F1.4 can give then the cheaper one should be plenty good.

Sharpness at night is far less important than no distortions and no chromatic aberration. All lenses seem sharp at night! Chromatic aberration and coma is what stands out.

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Old 12-10-2013, 10:38 AM
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naskies (Dave)
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The Digital Picture has an extensive database of test charts shot with virtually all Canon lenses under identical conditions. Here's a comparison of the two you're looking at on a full-frame camera at f/2.8:


You'll notice that below f/2.8 both have nasty aberrations even with black lines on white background - stars will be horrible.

The two lenses are worlds apart in build quality, focusing speed, manual focusability, and bokeh (background blur - very harsh on the f/1.8). The f/1.8 version is popular primarily because it's cheap and provides great value - image quality and f-ratio that normally costs many, many times its price.
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Old 12-10-2013, 11:50 PM
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Thanks guys
Just got back in after doing some tests.
I borrowed the Canon Plastic 1:1.8 50mm from work. Maybe its been knocked around by the photographers at work, boy did it feel and manually focus cheaply. Not that impressed with the image.

I suppose I'm trying to weigh up the quality between the 2 50mm. Will one perform better under the stars than the other?

Also tested my Canon 16-35mm 1:2.8 L . When you shut down the aperture it's not too bad.

Some investigations to do.

Thanks for your help
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Old 13-10-2013, 12:20 AM
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Octane (Humayun)
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I imaged this with the piece of crap 1.8 lens.


It's a lot of lens for the $100 or whatever it costs. Mine acts as a body cap on the EOS-1V but I do use it occasionally. Being soft at f/1.8 renders soft artsy images.

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