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Old Mar 19, 2008, 6:36 AM   #1
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i have a self imposed dilemma
i have been thinking lately of augmenting my lens collection
i have been looking at 2 wide angle lenses
Pentax 10-17 fish eye
Sigma 10-20 wide angle
not only is my dilemma which one do i want the most
as i have seen good images posted on here from both lenses
where should i purchase one from also
the Pentax fish eye here is $730 au
the Sigma wide angle $750 au
on line the lenses are around $270 au dollars cheaper
but are from overseas
even with delivery and tax they are way cheaper than here
but likely no warranty

i would have lba if i could make a decision

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Old Mar 19, 2008, 8:14 AM   #2
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I don't have either of the two lenses you are looking at (I have the DA 12-24). However, from what I understand, the Sigma is more like the 12-24 - it's not a fish-eye. So the first question is whether you want the distortion/round-the-world view of the fisheye or not (it can be used very effectively when done right. However, you have to de-fish by pp when you don't want it). If you have a choice one way or another, then the decision becomes much easier. I don't regret my decision to get the 12-24, so I would go with the Sigma, but you may be looking for something different than I was.
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Old Mar 19, 2008, 8:44 AM   #3
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I heve Sigma 10-20mm and I have to say it's very good lens. no visible distorsion at wide end, quite sharp at f8-f14, much softer at f22

But there's one thing you should know about: Sigma have QC issues and some of them are not properly assembled and can have some problems. I've just found out that mine is decentered, which means that one side of the photo is in focus while the other isn't. It can be fixed under warranty, I have to send it to Sigma and wait 2-3 weeks.

If you get VAT and Duty receipt from your online seller Sigma should accept any warranty claims, al least it does here in UK. so if you buy online and pay all Australian duties and taxes you should be fine.

hope this helps

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Old Mar 21, 2008, 10:50 AM   #4
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Comparing the lenses based on focal length and being a regular lens vs a fish eye, may not be the best indicators. They both cover the same focal length, pretty much, but with one being a fish eye and the other not, does create a very large difference in field of view.
  • The Sigma 10-20 has a field of view of 102 to 63 degrees wide[/*]
  • The Pentax 10-17 has a field of view of 180 to 100 degrees wide[/*]
So the overlap between the two lenses is actually 2 degrees in view. Obviously the difference is the fish eye effect. This is going to be realized in viewing the subject of the pictures. With the fish eye, in the photos that are not defished, but done with out the curve effect, the subject will essentially be pushed back (you get a real distance feeling in the photo). The appearance of subjects using the fish eye, will be pushed away from you (so that your able to gather more view from around the edges of the image (the real wide angle effect).

The rectlinear lens - even at the same focal length, say - 10mm, only has about 50% of the field of view of the fe (100 degrees vs 180 degrees), so when using both of them, on the same subject, the subject of the image, is essentially pulled in using the rectlinear lens.

Now the above was for normal shooting - say landscapes. Using the lens in the other direction - in a Macro environment, also shows some differences. I have found that the fish eye - is a pretty good Macro lens, for close ups. With a 9 inch focus distance, you can get really close, and it appears to be a more normal image because of the surrounding view is included, as opposed to a much more narrow view of the subject. The Sigma also has a 9 inch minimum focus distance. I really do not know how it would react. Now I do not have a corresponding rectlinear lens for comparison (I do really need to order the Pentax 12-24, since I have saved up for it).

Anyway, what ever you select - your going to have fun! - enjoy...
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Old Mar 22, 2008, 2:15 PM   #5
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Hi Gumnut,

I chose the DA10-17 as my ultra-wide zoom because of the increased angle of view captured as Interested Observer noted. I'm not much of a critical WA shooter, and wanted something that would give me maximum coverage, even if I had to defish the image, which will obviously distort the details of the image at the edges and corners.

Defished, it will give you about 135°. If you can frame your shot with the horizon in the middle of the frame, the normal FE curvature is hardly apparent. I like to crop shots like this to 16:9 and it gives you a very panorama-like effect with one shot. Also, the FE effect lessens as you zoom out to 17mm, and it becomes closer to a rectilinear, but not quite.

Any of the ultra wide zooms will give you a ton of DOF, so you can get some interesting perspectives. Another consideration might be that you cannot use filters with the DA 10-17 because of the protrusion of the front lens element and lack of filter threads, but on the other hand, I've found that it can render surprisingly deep blue skies on a clear day, almost like having a CP filter. It's also a very compact lens, and very well made, IMO.

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Old Mar 24, 2008, 4:02 AM   #6
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thanks for the replies
i am leaning to the fish eye for the extra degrees
and i have seen some good defishing in the forum
but the Sigma warranty thing is interesting
but still tossing up is it worth $270 to not have an Australian warranty

thanks again guys
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Old Mar 29, 2008, 7:38 PM   #7
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I think an ultra wide angle lens is more useful than a fish eye. I have the Sigma 10-20mm and it's great!!
If you really want images with a much wider angle of view, you should create panoramas with a panorama program such as PTGui, which is almost flawless in its stitching.
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