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02-20-2010, 02:56 PM   #1
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Request: pictures from Sigma 24/28mm f/1.8, Vivitar CF WA f/2, 31ltd, etc

After this https://www.pentaxforums.com/forums/pentax-slr-lens-discussion/89346-looking-...tml#post909176 thread in which I tried to find a better looking and sturdier feeling replacement for my Sigma Aspherical High Speed Wide 28mm f/1.8 I now have narrowed down my list of possible replacements to the Komine made Vivitar Close Focus Wide Angle 28mm f/2 and the newer version of the Sigma - the EX DG Macro (24 or 28mm). I have pretty much settled for the newer Sigma because of its 1:3 magnification and AF - normally I wouldn't mind MF only but this is intended to be my main lens secondary the 16-50 so AF is a plus.
The second contender is dismissed for now because it has only 6 non-rounded aperture blades while the Sigma has 9. Still if the bokeh is nice I'd be open to the Vivitar. I saw the Sigma can produce wonderful oof areas at wide apertures. But I'd like to see how it performs with more distinct light sources like candles and such. Does the bokeh remain pleasing (following general consenus of what is pleasing bokeh) or does is get edgy? The reviews on here imply it stays circular. I'm asking this because on my current Sigma it certainly gets rather edgy above f/2 (7 non-rounded blades).

What surprised me is that the Sigma seems to perform better than my F 1.7/50 wide open which is considered very useable.
Maybe my test was spoilt but the sand sharpness tests strengthens my observation. AF doesn't look like it's off on the Pentax so it seems to be true.

So, what I'd like to see are wide open or near wide open pictures of the listed lenses, preferably something like the good old newspaper test to judge corner sharpness, something at f/5.6 that shows maximal sharpness and bokeh the lenses produce wide open and stopped down.
The 31ltd. is not on my list of planned purchases it should just act as some kind of reference since it's generally considered as the best near-normal lens.

To give you some kind of measurement -
this is what the Sigma produces at f/1.8, subject distance 0,6m


Pentax F 1.7/50 wide open:


BIG center crops:
I would just post them here full size but not everone has a 42" display so I attached them as thumbnails.
Sigma's blown up to 110% to match the 50's FOV.

Sigma f/1.8


Pentax f/1.7


Sigma f/2.8


Pentax f/2.8


Sigma f/4


Pentax f/4


Thanks for your effort...




Last edited by Egg Salad; 02-20-2010 at 03:23 PM.
02-21-2010, 12:01 AM   #2
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I don't have any samples to show you right now, but I have the Viv CF 2/28mm. At least on my copy @f2 the corners are considerably worse than on your Sigma shot. I've converted my copy to M42 from a different mount but all the corners are equally bad so I don't think it's my fault
02-21-2010, 04:34 AM   #3
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Nah, if you say so this will be right. But it's allways hard to say why off-center sharpness is that weaker. As a FF lens even the corners should be good but you never know how much field curvature the lens exhibits (except when you have the means to do lab tests).
This is also the case with my Sigma: sharpness across the frame is great but even stopped down the background is less sharp than with both M 3.5/28 and 16-50.
Since the newer macro designated version has a bigger front element and is bigger overall I suspect it to have even a flatter focus plane.

But before I blindly buy one I'd like to see if this is really an upgrade in all respects.
02-24-2010, 12:44 PM   #4
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Because of the rather low resonance I feel like bumping this thread.
Still need something to look at.
I know there are only a few who own one of theses lenses but no one?

So- bump!

02-24-2010, 01:40 PM   #5
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I have the Sigma 28/1.8, but all my samples are with a full frame Canon. There were some 24/1.8 samples posted here a while back that were amazing. If you get a good copy, they're amazing lenses.
02-24-2010, 02:56 PM   #6
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Well, Canon FF samples are better than nothing.
If it looks good on FF it should be great on asmaller sensor.

I found a thread that has 10 sites of images but none of theme on a Pentax and also just web-sized.
Here: Sigma 24mm f1.8 EX DG MACRO - Page 10 - Canon Digital Photography Forums
02-24-2010, 04:09 PM   #7
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I have the Sigma 28mm f/1.8. It is my favorite. Here is a link to my photos: Stephen Merola's Photos

There are a ton from that lens in there, including a test I did for a forum member of standard street shots. Just run your mouse over the photos to find the "info" button, which will show the focal length. If ir says 28mm then that is the sigma....because that is the only 28mm lens I have.

Stephen
02-24-2010, 07:59 PM   #8
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A couple of older threads from this forum:
https://www.pentaxforums.com/forums/post-your-photos/41539-shallow-depth-fiel...mm-f1-8-a.html
https://www.pentaxforums.com/forums/post-your-photos/42469-cacti-succulents-s...mm-f1-8-a.html

A few with the 28/1.8 wide open on Canon 5D:




02-25-2010, 02:23 PM   #9
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Ok, thanks folks.
Don't have time right now. Will hopefully have some to look at them later.
02-27-2010, 02:38 AM   #10
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StephenMerola after looking through your pics there is only one question left - why don't I own it yet?
It's far too great not to have it.

Now, how is the AF performance? Nikon and Canon users show mixed opinions.
Is it different than a "normal" (Pentax) screw-driven lens?

Only problem now is finding one.
02-27-2010, 08:19 AM   #11
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I think the AF is fine. Most of the normal distance shots were AF. The only time AF is a bit less reliable is at very close focus distances, but I usually manual focus macro stuff anyway.

You should know that to switch this lens (and many other Sigmas) to AF or MF requires the switch on the camera and lens to be moved. This is so the barrel does not move when auto-focusing.
02-28-2010, 05:39 AM   #12
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Rather pointless question as I already decided to get myself one but I need to disturb you another time: You said AF isn't that reliable at closer distances so MF is the better choice. So how does focusing feel on this lens? It has only ~45 rotation for a big distance span.
On my older Sigma it's pretty insensible and except from the gears inside without any resistance - so no fun.
02-28-2010, 08:50 AM   #13
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I think the feel of the focus is pretty good and I never noticed a problem with making small adjustments. The 45 degree rotation is pretty small but the focus ring is nice and smooth on my copy. I use it for close focus stuff often and never had a complaint. Hope this helps.
02-28-2010, 11:25 PM   #14
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Ah, it seems you're settled on one, anyway. I did grab some shots for someone on another thread (I think it was you,) but I thought that was settled already.

Anyway, I'm very happy with my Sigma 28. Pretty flat field of focus, too: AF's, I think, quite good, on the center nine AF points on my K20d: the two side ones seem to be too oblique somehow, pretty much refusing to focus at all if you manually-select either. The good news there is that the nearest point to those gets it right anyway.

(I didn't think to try auto AF selection, come to think of it, but I don't use that normally, anyway)
03-01-2010, 01:17 PM   #15
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Yes, for some time it was about even between the Vivitar and the Sigma. But the Sigma got me because of its convienience - it's going to be my normal lens which is kind of a main lens, so AF and all of todays merits are not only welcome but somewhat necessary to me.
If it was another FL I wouldn't care.
Besides it has something else I'll value very much: 9 blades and so a much smoother blurring than the Vivitar with its 6 blades.

As said before I would just keep my current Sigma but it's bokeh isn't very nice with certain lightsources and still important to me - it feels cheap (also the case with the Pentax F 1.7/50).

On Ebay there is an auction running for a Sigma 24mm f/1.8 Macro. Not 28mm and so slightly too wide but if it stays comfortably priced I'll buy it anyway. Not like there were tons of them around. That's actually the first I've found since the end of 2009.
Luckily for me the seller only ships within Germany so there isn't that much competion (at least I hope so).

Of course pictures are still welcome. I've seen a lot on Stephen's page but not much up close.
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