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07-03-2011, 03:15 AM   #1
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Sigma 70mm f/2.8 EX DG Macro

Hi all,

I'm thinking about buying the Sigma 70mm f/2.8 EX DG Macro. It receives great reviews and I've seen lots of spectacular pictures on Flickr.

How does this lens, or a macro-lense in general, perform as a regular telephoto lens ? On my K-5 the full frame Sigma resembles a 105mm. Maybe this is a newbie question, but I have no experience with macro photography.

07-03-2011, 03:23 AM   #2
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The Sigma 70/2.8 EX is a great lens. It's razor sharp as a macro and also more than usable as portrait lens.

QuoteOriginally posted by vinni Quote
On my K-5 the full frame Sigma resembles a 105mm.
Yes, due to the APS-C crop factor, a 70mm will give you the AOV that a 105mm gives on a full frame camera. Still fine for portrait photography. Better, AFAIC, than a 100mm macro on APS-C.
07-03-2011, 03:52 AM   #3
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QuoteOriginally posted by Class A Quote
The Sigma 70/2.8 EX is a great lens. It's razor sharp as a macro and also more than usable as portrait lens.
Thanks for your reply! I took a closer look to your previous posts about this lens. Can't see any reason to NOT buy it. This would be my first purchase of a new lens. Until now I've only used M or A lenses on my K-5.

One question still remains. The 70mm is good for macro's and portrait, but how about on infinity? Say I want take a picture of a building across a river. Would this lens help me out?
07-03-2011, 05:05 AM   #4
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QuoteOriginally posted by vinni Quote
The 70mm is good for macro's and portrait, but how about on infinity?
The Sigma 70/2.8 EX has a floating focus system. This means that it will -- unlike older macro design -- also perform at infinity. Its three way focus limiter is also very useful in these circumstances.

07-03-2011, 08:03 AM   #5
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QuoteOriginally posted by vinni Quote
Thanks for your reply! I took a closer look to your previous posts about this lens. Can't see any reason to NOT buy it. This would be my first purchase of a new lens. Until now I've only used M or A lenses on my K-5.

One question still remains. The 70mm is good for macro's and portrait, but how about on infinity? Say I want take a picture of a building across a river. Would this lens help me out?

Most lens test are performed at distance that informs infinity focus more than it does macro focus. The sigma 70 shines in such tests, bettering even the DA 70/2.4, which is a great lens. In my experience, great macro lenses are also great at infinity, though there may be exceptions.
07-03-2011, 09:53 AM   #6
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QuoteOriginally posted by civiletti Quote
Most lens test are performed at distance that informs infinity focus more than it does macro focus. The sigma 70 shines in such tests, bettering even the DA 70/2.4, which is a great lens. In my experience, great macro lenses are also great at infinity, though there may be exceptions.
The DA 70/2.4 would indeed be my alternative. What makes you say that the sigma 70 is the better of the two? Do you have any sample images?

Pentax-DA 70mm F2.4 Limited Reviews - DA Series Primes - Pentax Lens Reviews & Comprehensive Database
07-03-2011, 11:21 AM   #7
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QuoteOriginally posted by vinni Quote
What makes you say that the sigma 70 is the better of the two? Do you have any sample images?
is this enough?



there were some that say that the DA70 and Sigma 70 are equally good. I however disagree on those statements. although I admit the DA70 is a great lens, I don't see it to be as technically optically as good as the macro. I had seen images from both lenses and I see that the macro is a step up to the DA70 overall. unless size and AF speed matters to you, the DA70 would be a perfect fit. but if you want to do macro, better IQ and could live with slow AF, the Sigma 70, it is.
07-03-2011, 02:02 PM   #8
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QuoteOriginally posted by Pentaxor Quote
s this enough?
Thumbs up for that one! Could you also post a non-macro photo with focus on infinity? By the way, what kind of freaky plant is that?

07-03-2011, 04:47 PM   #9
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QuoteOriginally posted by vinni Quote
The DA 70/2.4 would indeed be my alternative. What makes you say that the sigma 70 is the better of the two? Do you have any sample images?

Pentax-DA 70mm F2.4 Limited Reviews - DA Series Primes - Pentax Lens Reviews & Comprehensive Database

I went back to the Photozone test data and checked my conclusion by calculating relative camera MTF factors. After doing this a few different ways, I found that the DA70 actually has a slight edge in MTF, but it is VERY slight. The DA70, Sigma 70, and Tamron 90 are all so close, that it would be very difficult to see a difference in resolution or contrast in field images. I would go for the DA70 if size and build quality are more important to you than macro performance. The Pentax lens is more expensive, of course.
07-03-2011, 05:53 PM   #10
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More analysis of MTF results:

The previous statements refer to optimum aperture results, which are at f5.6 for the Sigma 70, DA70, and Tamron 90. The Sigma, however, stays closes to that IQ from f2.8-8. The DA70 IQ is down noticeably at wider and smaller apertures, and the Tamron 90 is down sustantially at f2.8. So, if you are likely to do much shooting away from f5.6, you should find the Sigma sharper than the DA, but still not by much.

Of course, the DA70 has f2.4.
07-03-2011, 07:16 PM   #11
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QuoteOriginally posted by vinni Quote
Thumbs up for that one! Could you also post a non-macro photo with focus on infinity? By the way, what kind of freaky plant is that?
not really at infinity but mid-range. although the IQ is just about the same, of course you have to shoot at lower apertures to increase the DOF if you are going to shoot something at infinity. this was shot with a JPG format. it is much better than this if you shoot RAW but anyways, you can see the lens is still great even with JPG only. I lost mostly of my old files when my backup drive got smoked. and I haven't used it that much yet again recently. as far as the plant is concerned, I forgot the read all about it, but it's a beautiful plant once the flowers starts popping out.

here is a sample of a jpeg shot at midrange.
07-03-2011, 08:45 PM   #12
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QuoteOriginally posted by civiletti Quote
I went back to the Photozone test data and checked my conclusion by calculating relative camera MTF factors. After doing this a few different ways, I found that the DA70 actually has a slight edge in MTF, but it is VERY slight.\
Note that the two lenses have been measured on two different cameras. The MTF results are therefore not comparable. Even if you normalised them according to sensor resolution, they wouldn't be comparable because of different AA filter strength, different sharpening by Klaus, etc.

One sign that the Sigma 70/2.8 EX is the better lens optically is that its centre sharpness peaks at f/4. That's an indication of excellent performance (low abberrations). The Pentax DA 70mm peaks at f/5.6 which is very good, but not as good.

QuoteOriginally posted by civiletti Quote
The Pentax lens is more expensive, of course.
If that's true, that's a bit of a joke.

The Sigma contains a lot more glass, more expensive glass (3 SLD elements) and has a focus limiter.

You'd be paying more for less, if you went for the Pentax (which can be exactly what people want, if "less" refers to the size).
07-03-2011, 08:51 PM   #13
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QuoteOriginally posted by Pentaxor Quote
not really at infinity but mid-range.
Are you certain that's a shot from the Sigma (EXIF data is missing)? You would have had to be quite a bit away from the subject.

It looks too soft, AFAIC. Also, I've never seen such an amount of CA with my copy.
07-03-2011, 10:00 PM   #14
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QuoteOriginally posted by Class A Quote
Are you certain that's a shot from the Sigma (EXIF data is missing)? You would have had to be quite a bit away from the subject.

It looks too soft, AFAIC. Also, I've never seen such an amount of CA with my copy.
it is the Sigma 70. sorry about the white background as it makes it difficult to see the image FOV, but if you are able to see it is very wide. as I mentioned, this was shot under JPG and soften a little bit more during pp because the skin blemishes are showing a lot. what you are seeing is not actually CA, I accidentally messed up the color channel when I was trying to warm up the color tone, since the Sigma 70 seems to render on the colder side. the original image and the final image (corrected) doesn't have what you see as RED CA, but unfortunately I lost those copies as well. this is the 2nd prototype image btw.

I did however manage to view the exif using LR.

the EXIF shows SIGMA 70 shot at f2.8 and ISO 400. shutter speed is at 1/30.

anyway, if you want, I could add some black borderline to see where the FOV is.

Last edited by Pentaxor; 07-03-2011 at 10:05 PM.
07-03-2011, 10:15 PM   #15
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QuoteOriginally posted by Pentaxor Quote
...this was shot under JPG and soften a little bit more during pp...
That explains it. Even wide open (at f/2.8) the Sigma is sharper than this.

QuoteOriginally posted by Pentaxor Quote
...what you are seeing is not actually CA, I accidentally messed up the color channel
That explains the colour fringe.

Thanks.

P.S.: No need to add a border. I can see the image dimensions just fine.
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