Has anyone here got the Sigma 30mm f/1.4 for his DSLR?

[Jeremy Z]

It looks like a beauty, but it seems like Sigma is really proud ($430) that no one else makes one yet...

Any technical reason it should cost double what a 50mm f/1.4 does?

 

[darin3200]

I've the 20mm f/1.8, which is similar to this, and it's a good lens.

Canon makes a 35mm f/1.4L lens that sells for around $1300.

I don't the principle behind it, but 50mm lenses seem to be cheaper and small, and of course more in demand. Lenses such as 85mm or 35mm are bigger at the same apertures. Just using canon as an example, their 35mm f/1.4 is $1300, a 50mm f/1.2 is about the same price although the 50mm is faster

 

[Jeremy Z]

I've the 20mm f/1.8, which is similar to this, and it's a good lens.

Canon makes a 35mm f/1.4L lens that sells for around $1300.

I don't the principle behind it, but 50mm lenses seem to be cheaper and small, and of course more in demand. Lenses such as 85mm or 35mm are bigger at the same apertures. Just using canon as an example, their 35mm f/1.4 is $1300, a 50mm f/1.2 is about the same price although the 50mm is faster

I think its that wide angles need fancier optical formulae to correct for barrel distortion, and telephotos need fancier optical formulae to correct for pincusion distortion.

But this 30 mm is equivalent to about 50mm in 35mm format, so it shouldn't have those problems.

 

[darin3200]

I think its that wide angles need fancier optical formulae to correct for barrel distortion, and telephotos need fancier optical formulae to correct for pincusion distortion.

But this 30 mm is equivalent to about 50mm in 35mm format, so it shouldn't have those problems.

You mean on digital? The sigma lenses also work on full-frame, so they need to address barrel distortion problems if you shoot with it on a film camera

 

[Big Mike]

I think he means 'in general'...not just on digital, when talking about the corrections that a lens has to make.

I have heard really good things about this Sigma lens and have considered it myself. I'm not 100% sure, but I think that it's made for APS-C cameras (all Nikon and Canon Rebels & 30D etc.)...and will not work for a full frame camera. To me, that is it's worst trait...even if you don't use full frame.

A Canon 35mm F1.4 or a 28mm F1.8 or any of those prime lenses...are made to be used on full frame (or 35mm film) which means that when used on an APS-C digital...that you are only using the middle of the lens...the sweet spot.

 

[Don Simon]

As I understand it, the Sigma lenses are designed for use on both full-frame and APS-C if they have the "DG" designation, and for APS-C only if "DC". I think the 30mm unlike most of Sigma's primes is a "DC" designed for APS-C sensors. Although obviously I stand corrected if anyone's used one successfully on 35mm film or a full-frame DSLR.

 

[Big Mike]

Sigma website

This large aperture standard lens was exclusively designed for digital SLR cameras featuring APS-C size image sensor

 

[Jeremy Z]

A Canon 35mm F1.4 or a 28mm F1.8 or any of those prime lenses...are made to be used on full frame (or 35mm film) which means that when used on an APS-C digital...that you are only using the middle of the lens...the sweet spot.

That is what it seems like, but I haven't read yet if that is how it works out in practice. I'm sure the photo magazines have gone over it and I just haven't been reading them lately.

 

[Big Mike]

I suppose it's hard to really compare...unless you use the same lens on an APS-C camera and then on a full frame digital. I've read a few reviews/tests that pretty much confirm that using only the centre of the lens is better.

Just look at most lens tests...they often mention that sharpness, CA & distortion etc. is worse at the edges and corners. If your camera/sensor crops off the bad parts...then you are left with the candy centre...well maybe that's a tootsie pop...but you get the point.

 

[darin3200]

So the 30mm f/1.4 can only be used on digital. Although it's bigger, the cheaper 28mm f/1.8 can also be used on full-frame cameras, so if you ever decided to upgrade it might be a good choice.

 

[Jeremy Z]

So the 30mm f/1.4 can only be used on digital. Although it's bigger, the cheaper 28mm f/1.8 can also be used on full-frame cameras, so if you ever decided to upgrade it might be a good choice.

That is a great point, darin. ...and since I'm considering a K1000 as a backup....

 

[nakedyak]

i debated about getting the sigma 30mm f1.4 for like a year. I just got the canon 35mm f2, and at about $215, its pretty great. Good sharpness at f2, and very good from about f2.5 on. Its a much easier focal length on the 20d than the 50mm f1.8 II is

 

[Jeremy Z]

I suppose it's hard to really compare...unless you use the same lens on an APS-C camera and then on a full frame digital. I've read a few reviews/tests that pretty much confirm that using only the centre of the lens is better.

Just look at most lens tests...they often mention that sharpness, CA & distortion etc. is worse at the edges and corners. If your camera/sensor crops off the bad parts...then you are left with the candy centre...well maybe that's a tootsie pop...but you get the point.

FYI:
http://www.popphoto.com/cameralenses/849/digital-lenses-the-f-stops-here.html

The 35mm optimized lenses don't work very well when shot wide open. If you have to stop them down, you might as well just buy the slow digital-only lens.

 

[Big Mike]

The 35mm optimized lenses don't work very well when shot wide open. If you have to stop them down, you might as well just buy the slow digital-only lens.

The better '35mm' lenses do look pretty good wide open...especially the high end lenses. My 'digital only' kit lens is much, much better when stopped down.

From what I've read...some lenses are just better than others when wide open...digital optimized or not. The big difference is that the newer lenses have more anti-reflective coatings, especially on the rear element...because the reflectivity of the sensor can cause a loss of contrast.

 

[fmw]

The 35mm optimized lenses don't work very well when shot wide open. If you have to stop them down, you might as well just buy the slow digital-only lens.

I started writing book here on the subject but stopped myself before I went too far. Look at these two test images.

Both are shot with a D50 aimed at the same piece of newspaper. The amount of blowup is different because the lenses are different in focal length. Both lenses are expensive, top-of-the-line Nikkor lenses. Both images are taken from the extreme lower right hand corner of the frame. The second one is a lot better, right? The reason is that it is a lens designed for a 35mm camera. While we are at the extreme corner of the camera frame, we are not at the extreme edge of the image circle.

Putting a lens for a 35mm camera on a digital not only decreases the angle of view, it also provides better corner to corner sharpness. If you need more explanation, let me know and I'll go back to writing the book.