step-down wide angle converter on large size filter thead


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runaway1991

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#1
hi everyone,

i'm actually using a sigma 24-70 f2.8 with a super big filter thread size of 82mm.
it's hard to find a wide angle converter (WAC) for 82mm and even if shops were selling it,
they were really reaaaaaaaaally expensive.

so i tried to post a wtbuy in B&S looking for 82mm WAC but to no avail,
guess not many people are using it..

so i was wondering,
if i can get a WAC for a more common filter thread size with a step down ring,
(i.e. 72mm WAC with 82mm - 72mm step down ring)
will i actually see black spots at the edges ?

something like this :
http://www.flickr.com/photos/celticsong22/2651294216/

i'm fine with a little vignetting, but i don't want it to be absolutely black.

thanks for reading !! :)
 

Octarine

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#2
Get a proper ultra wide angle lens, e.g. Tokina 11-16. Most of these converters are not worth the money and the image quality suffers. Distortions and Chromatic Aberrations are the common flaws of these adapters. On top you will get heavy vignetting. Is it really worth it?
 

Blur Shadow

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Sep 17, 2005
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#3
It's gonna be a lot of trouble for really disappointing results. I suggest getting a dedicated ultra-wide angle lens.
 

Rashkae

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Nov 28, 2005
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#5
Remember, you can also rent instead of buying...
 

runaway1991

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#6
many thanks for your opinions guys,
really appreciate it :)

i'd love to get a 10-22mm EF-S,
just that i'm having quite a tight budget (i'm only in JC2)
so i'm willing to spend only about $120..

i've considered another option which is to get a 18-55mm kit lens..
(2nd hand kit lenses are about $120)

but then i calculated 18mm won't beat the (0.45 x 24mm) 10.8mm i'll get with the converter.
and the converter is easier to carry around then a kit lens
PLUS i get to keep the f2.8 aperture with the converter..

so yep!

:( GAH.
no hurry to get my converter or kit lens just yet,
i'm just considering which option will give me a better value with my $$$..
 

runaway1991

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#7
well here are some comparative pictures between 11mm and 18mm :

~11mm (with wide angle converter)



~18mm (with kit lens)



i think it's quite a lot of difference,
not to mention i get to keep f2.8 with the wide angle converter..
 

pinholecam

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Jul 23, 2007
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#9
Just look at the edges of the 11mm. Its totally rubbish (no offense intended). Its noticible even with the small image size posted.
Sorry bud, but I've been there, done that, so just hope to share what I found.
My own findings were that these things were never meant for DSLR lenses. On a compact (esp. prosumer), which uses the better center portion of the converter and where you can stop down a lot (ie. f8 or higher), it can be good enough. On DSLR lenses the issues are :

1. Vignetting (at the end can't use it at 18mm)
2. Poor edges

Maybe if you can find some sort of humongous UWA adapter that effectively makes the DSLR lens use only its center portion it would work. Then again, this giant of a lens would not be cheap :D





well here are some comparative pictures between 11mm and 18mm :

~11mm (with wide angle converter)



~18mm (with kit lens)



i think it's quite a lot of difference,
not to mention i get to keep f2.8 with the wide angle converter..
 

runaway1991

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Apr 25, 2009
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#10
ah thanks..

i went down to peninsula today and the largest they had was a 77mm 0.5x vitacon.

[size=+2]$180![/size]

GAH.

maybe i'll just decide to get a basic kit lens after all :S
(though i'm still seriously very very reluctant!)
24mm on my 1.6 crop body is waaaaaaaaaaay too tele for me.
 

pinholecam

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Jul 23, 2007
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#11
ah thanks..

i went down to peninsula today and the largest they had was a 77mm 0.5x vitacon.

[size=+2]$180![/size]

GAH.

maybe i'll just decide to get a basic kit lens after all :S
(though i'm still seriously very very reluctant!)
24mm on my 1.6 crop body is waaaaaaaaaaay too tele for me.
24mm is wide. During film days, 28mm was already considered a good wide angle focal length. Even when I have a 10-20mm, very often I am using it at 12-18mm. Look at it this way. From the sample pictures you posted again. In terms of aesthetics and composition, what did that 11mm add to the picture compared to the 18mm (almost nothing). ;)
 

Octarine

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#12
i went down to peninsula today and the largest they had was a 77mm 0.5x vitacon.
[size=+2]$180![/size]
GAH.
Most likely only worth 20% of that, at maximum. Don't get conned. Even 17mm on crop body is sufficiently wide for most purposes. Night86mare once had a nice write-up about the empty space most people create with UWA, missing it to fill with a subject :)
 

runaway1991

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Apr 25, 2009
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#13
ah yes actually i find the 18mm on the kit lens wide enough for most of my uses :)
but i shrug at the idea of having to bring an extra lens around and having to change lenses when i'm out and about.. rather just screw-on the WA converter and, voila !

and i don't get to keep my f2.8 :S

anyway i just got a basic kit lens yesterday night,
will use it for awhile first and see if it suits me :)

thanks again, everyone !
really appreciate all your comments :)
 

Octarine

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Jan 3, 2008
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#14
but i shrug at the idea of having to bring an extra lens around and having to change lenses when i'm out and about.. rather just screw-on the WA converter and, voila !
and i don't get to keep my f2.8
DSLR is a concept where the lens is selected according purpose. If your purpose is UWA then get the right lens. Concerned about changing lenses? Dust is there anyway, doesn't matter whether you change lenses or not. Planning your shots properly helps preventing any rushing in changing lenses.
There is even a Tokina lens with f/2.8 - but I don't see the need for this wide aperture, unless you want wide angle shots handheld. For everything else you can step down and / or use a tripod.
 

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