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Old 09-08-2010, 12:00 PM
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Recommended wide prime lens on a budget.

Hi,
Just after some info on whats a good widefield prime for astro work.
Looking at primes between 15mm and 35mm and as I am on a budget, under $400-$500+. Canon, Sigma or other?
Any one recommend anything in this range? and any links or images taken with them. Was thinking of the EF 28mm f/2.8 but have heard that it`s not the best for astro work..
Thanks in advance
Gary
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Old 10-08-2010, 07:49 AM
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You could try trawling through the reviews here Gary to find your best option...
http://www.photozone.de/canon-eos

Doug
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Old 10-08-2010, 08:19 AM
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Those reviews are not very helpful for us (astronomers).
Poetic language used is very often misleading and based on this you can't possibly decide which lens is better or even adequate for astro-work.
The only relevant info for the lens quality may be in a form of MTF - and this is shown by manufacturers less often than snake's legs.

The only thing I can advise is, try to borrow from someone and perform a test on stars, then buy.

This page can be helpful..
http://www.astrosurf.com/~buil/50mm/test.htm
http://astrosurf.com/buil/us/10d/testopt.htm

I have a good experience with Canon 50mm F1.4 FD lens (but I had to mechanically modify it to fit my Canon 400D, and it is not too hard to do).
Also, I have Itorex 28mm F1.8 (originally for Pentax or Praktica, with M42 mount), it is very sharp when used at f2.8 or more - and very good for astro work (but 100% manual, of course).

All those were around $100 or slightly more (but well below $200, on ebay).
You may also try to have a look at www.rugift.com

Nikon lenses are considered very good for astro photography by many (and Nikon->Canon EOS adapter is very cheap on Ebay, as it does not have any optical and/or electronic elements, it just provides necessary mechanical interface between camera and lens).

Last edited by bojan; 10-08-2010 at 10:41 AM.
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Old 10-08-2010, 11:20 AM
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Quote:
Originally Posted by bojan View Post
Those reviews are not very helpful for us (astronomers).
Poetic language used is very often misleading and based on this you can't possibly decide which lens is better or even adequate for astro-work.
The only relevant info for the lens quality may be in a form of MTF - and this is shown by manufacturers less often than snake's legs.
The Photozone reviewers are pretty matter of fact as far as I can ascertain. In a number of the reviews they'll often state the glaring flaws in often hyped models without poetic language (whatever that's supposed to mean).
Their own MTF and CA lab tests (I don't believe they're printed verbatim from the manufacturers) have been extremely helpful to me.

Hand's on would be very nice before making a commitment though.
Cheers
Doug
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Old 10-08-2010, 11:38 AM
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Doug, actually, I didn't mean this particular site is "poetic" (like some others are).
Still, for astro-photography, even from there it is very hard to extract important information (like resolution at corners, which is essential for astro work).
Yes, hand's on is the best way to judge those things.

Last edited by bojan; 10-08-2010 at 11:48 AM.
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Old 10-08-2010, 01:07 PM
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Still, for astro-photography, even from there it is very hard to extract important information (like resolution at corners, which is essential for astro work).
Digital-Picture.com has a good test page (not stars unfortunately, but edge sharpness is discernible) where one can view edge versus centre comparisons for various different lenses. And, you can A/B 2 different lenses.
http://www.the-digital-picture.com/R...0&LensComp=100

Doug
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Old 10-08-2010, 01:10 PM
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Thanks Bogan and Doug!
I have trawled through the photozone tests some time back which helped me decide on the Sigma 17-70 zoom as a good budget choice for me. But for astro work it still doesn`t cut it ex the corners, even stopped down heaps it is only marginal. The reviews there are quiet good I find but without actually seeing what happens to stars ex in the extreme corners it is hard to put meanings to the figures.
I shall check out those links Bogan!
I also have a old 50mm f/1.4 lens and also find it excellent when stopped down below f/4. Just want something wider for big starfield shots and startrails.
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Old 10-08-2010, 01:11 PM
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Originally Posted by dugnsuz View Post
Digital-Picture.com has a good test page (not stars unfortunately, but edge sharpness is discernible) where one can view edge versus centre comparisons for various different lenses. And, you can A/B 2 different lenses.
http://www.the-digital-picture.com/R...0&LensComp=100

Doug
Ah thanks again Doug! shall check that out too!
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Old 11-08-2010, 12:03 PM
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That`s a great site Doug..
Doesn`t the cheap nifty fifty scrub up well! Might have to get one...
Also the 24 f/2.8 looks good.

Even the EF-S 18-55 IS performs really good for a standard lens..
Also the newer EF-S 15-85 3.5-5.6 looks really goodas well?
Anyone used these lens and have any good resolution shots with these or recommended these?
cheers Gary
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Old 11-08-2010, 01:14 PM
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Originally Posted by Garyh View Post
That`s a great site Doug..
Doesn`t the cheap nifty fifty scrub up well! Might have to get one...
Also the 24 f/2.8 looks good.

Even the EF-S 18-55 IS performs really good for a standard lens..
Also the newer EF-S 15-85 3.5-5.6 looks really goodas well?
Anyone used these lens and have any good resolution shots with these or recommended these?
cheers Gary
Hi Gary - yeah it's a good site to compare and contrast.
I find myself heading straight for the corner test shot to assess sharpness and CA first thing! That often sets the tone for any further enquiry into the suitability of that lens for astro imaging.

The 50mm f1.8 still looks really good for a $100+ prime.
Never tried an 18-55, but I did give the 17-85mm EF-S kit lens a go at widefield work - 'orrible+++
The 24mm looks pretty good even at f2.8 in the corners!!
Doug
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Old 20-08-2010, 06:41 AM
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Well after much looking at tests eg: I had to get a nifty fifty and managed to get a secondhand 24mm lens!
Look forwards to giving them some tests when they arrive.
Now I will be covered from 24mm to 200mm.
Now for a fisheye and a 300 lens like Dougs selling
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