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12-12-2010, 09:59 AM   #1
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Help/advise regarding Sigma 30mm

Hello,

I'm looking into buying a secondhand Sigma EX 30mm f/1.4 lens (or something similar), however I'm too new into photography and therefor need a bit help and perhaps some advise.

I own a Pentax K-x and currently have the 18-55mm and 50-200mm kit lenses.

What I'm looking for:
A wide angle lens - somewhere between 20-35mm. Lower is better.
A fast lens - preferably f/2.0 or faster (I have no experience with such lenses, but judging by the pics I've seen, I'd say this is what I want.
Sharpness (edge sharpness doesn't matter too much. Depends on how "bad" it is)

Type of photography:
Indoor/low light - preferably without use of flash.
"Artistic" shooting with lots of blur/shallow DoF.

Budget:
About 625USD.

I found the mentioned lens which will cost me about 375USD including shipment. I'm assuming this is older than the HSM lens that can be seen on Sigma site. What are the differences? Is the price OK? And how is the quality for this particular lens (I've seen a number of posts about the dodgy quality of Sigma lenses).

Also, what will work and what wont? I'm thinking in terms of AF, and whatnot.

I've been provided with these pics:


100% crop:


12-12-2010, 03:19 PM   #2
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Well, those don't appear to be astounding sample shots, but the price sounds like it's about in the ballpark. I'm not too familiar with the going prices of the various models, but you can see the Lens reviews sections right here for some details.

Here's the version you're looking at, I think:

Sigma 30mm F1.4 EX DC Lens Reviews - Pentax Third-Party Lens Review Database


This thread may end up getting moved to the Lenses forum, you'll probably get more answers there.

I understand the HSM feature isn't on the Pentax versions of that lens anyway, so you don't need to worry about that, afaik, ...whether or not the newer version is better in other ways, that's best left to those with firsthand familarity with those models.

Also, btw, don't overlook the new DA 35 2.4: not what I'd call a terribly fast lens, but the image quality's great, and they're cheaper and smaller and lighter, which could be a nice combination.

I also like my Sigma 28/1.8: it's even bigger than the 30, but it has qualities that are useful to me personally for it. (like, good for film, is particularly nice with sharpness across the whole frame (as is the new 35) ..which is a very good attribute for me personally, because of my style with wider lenses: I like to put my subjects over there. ) Twill do, at least till I can lay hands on the Pentax Limited 31, which is very expensive but smaller and awesome.


Anyway, hope that helps. There are quite a few options out there within your budget that are quite nice.
12-12-2010, 04:40 PM   #3
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Thanks for the reply - I'm aware of the lacking HSM feature on the new model and I don't think it would be of too much concern to me.

The thread you're referring to was actually one of the pages that convinced me consider this lens - I narrowed my list down to FA35, DA35 and this Sigma 30mm. I prioritized the Sigma because of the extra speed, which would (should) allow me to take better photos in low light, but also do fun shots with shallow DoF. The price of the new DA35 is however very appealing and that only complicates the decision making :P

I haven't been able to locate any nearby shops who has any of these lenses. None in the entire country, actually - and that further complicates it because I can't get any first hand expression.

I found a Sigma 30mm @ 300USD + shipment, and I think I'll go with that. It seems to be cheap enough to be worth the "risk". This owner could show many pics he had been taking and they looked great (all down scaled though and most likely shopped to some degree).
12-13-2010, 02:06 AM   #4
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It's a great lens, made especially for the purpose you'd like to use it. Quite sharp wide open, stopped down to f/2 it's razor sharp. For the intended use you don't have to worry about the extreme corners and borders, those will be out of focus anyways. (and to be honest, DA* 16-50 is also quite soft at extreme corners and borders wide open).
This is my indoors low light lens, I use it mostly in f/1.6 - f/2 range for DOF and fast shutter speeds. Sometimes for creative reasons (very shallow DOF) or when it's very dark I use it wide open.

12-13-2010, 07:20 AM   #5
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Thanks for the input. I appreciate it. I've placed an order for a brand new HSM model and I should (hopefully) receive it tomorrow.

Wouldn't mind a secondhand model, but the ones I did find are gone now.
12-13-2010, 11:10 AM   #6
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QuoteOriginally posted by Zafar Iqbal Quote
Thanks for the input. I appreciate it. I've placed an order for a brand new HSM model and I should (hopefully) receive it tomorrow.

Wouldn't mind a secondhand model, but the ones I did find are gone now.
I'm confused. A couple of posts up, you say that you are aware of the lacking HSM on the new model, and then in this post, you say you have ordered a new HSM model. This lens does not come in HSM for the Pentax mount. Some retailers mistakenly list it as having HSM. Not a big deal to my mind. I had one of these and really liked it.
12-13-2010, 03:51 PM   #7
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It's a nice lens and at f4 it is amazingly sharp in the centre of the frame. It does suffer from CA and border softness but for most applications that's not a deal breaker. What I found more annoying (on my K20D) is that the AF was unreliable but maybe I was not being realistic - in low light AF is often useless.

Here's one at f1.8:


Last edited by DanielT74; 12-13-2010 at 03:59 PM.
12-14-2010, 02:50 AM   #8
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QuoteOriginally posted by DogLover Quote
I'm confused. A couple of posts up, you say that you are aware of the lacking HSM on the new model, and then in this post, you say you have ordered a new HSM model. This lens does not come in HSM for the Pentax mount. Some retailers mistakenly list it as having HSM. Not a big deal to my mind. I had one of these and really liked it.
Sorry for the confusion. I'm still aware that I won't be able to use the HSM thingy. I found a national dealer with the lens in stock by chance, and prefer to purchase this way over buying from someone on the other side of the world - but even better: I'll have full warranty on it.

DanielT74: Thanks for the pic. I've been concerned about how "bad" these softer edges would be, but I think I'm pretty sure now that it's well below what I personally would label as being bad. To me some softness adds character to the images, depending on what kind they are, so I'm all in for it tbh - and by the time I'll be longing for overall sharpness will probably also be when I'm ready for another lens

12-16-2010, 04:41 PM   #9
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I've been playing a bit with the Sigma and the initial impression was rather good. But I was at first doing somewhat up-close shots. When I later shot over longer distances 2-3+ meters I noticed that the lens had problems focusing correctly. The light here is somewhat dim and it seems that plays a role. I can easily imagine places being darker than where I am, but places many ppl would like to take photos from such as parties, cafés etc - I currently can't imagine coming home with a good night of shooting. Looks like the fail ratio is very high. Any ideas?

Edit: The retailer called me after I wrote to them - he mentioned I can have the lens calibrated free of charge (covered by warranty), so that's what I will be doing now.

Last edited by Zafar Iqbal; 12-17-2010 at 04:56 AM.
12-18-2010, 06:11 PM   #10
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Following shot was done out of curiosity: http://www.r4ptor.dk/zi20101219_6125.jpg

I did 4 and all look identical - front-focus issue (or os it "back"? I haven't fully worked those two out yet) which should be eliminated after I let professionals calibrate the lens, but notice that the focus is also horizontally shifted. Is this related to calibration as well?
12-18-2010, 08:18 PM   #11
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Looks like some minor decentering (to the right and in front of the ideal focus point) but nothing too egregious...
12-23-2010, 12:39 PM   #12
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The lens is defective and needs to be sent back to the dealer. Whats a good alternative to this lens?
02-13-2011, 01:09 PM   #13
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I haven't received the replacement lens yet and I'm starting to lose patience. Are there any other good alternative worth looking into OR how about on the other end of the scale - long focal lenses with large aperture? They will likely be a lot more expensive, but I'm thinking It might be worth it.

Can't say exactly what I'm after - I like the non-distorted look from longer lenses. Shallow DoF is a big plus too for both artistic and low light reasons. I'd like something sharper than my kit lenses too.

I don't plan on shooting too much wild life/nature or similar stuff, but I wouldn't mind being able to do so though.

No Sigma lenses!
02-13-2011, 04:49 PM   #14
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just to clear something up - the camera uses the its focus mechanism to focus on a subject. that is, it turns the focus ring on the lens to bring a subject into focus and if the lens is truly defective the camera will fail to lock focus.

however, when it comes to focusing in low light for the most part it's the camera that will have issues, not the lens.

so chances are, in dim light, at F2 or faster, the camera might have problems focusing regardless of which lens is attached. although things like focal length and distance to subject will affect focus speed.
02-13-2011, 05:26 PM   #15
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QuoteOriginally posted by pb_red Quote
just to clear something up - the camera uses the its focus mechanism to focus on a subject. that is, it turns the focus ring on the lens to bring a subject into focus and if the lens is truly defective the camera will fail to lock focus.

however, when it comes to focusing in low light for the most part it's the camera that will have issues, not the lens.

so chances are, in dim light, at F2 or faster, the camera might have problems focusing regardless of which lens is attached. although things like focal length and distance to subject will affect focus speed.
Sorry but that is not the case here.
The Sigma 30mm and the 50mm have a known issue with focus accuracy especially at close focusing distances. This issue happens with Canon, and Nikon mounts, not just Pentax. The lens can be adjusted by the local Sigma service center. Using the camera's AF fine adjustment doesn't really clear up the issue. I've had several friends who experienced the issue first hand and got it cleared up by the local Sigma service center. The difference after recalibration is definitely noticeable.
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