[jmc]

Which is better in terms of IQ ?
Is the 55mm focusing significantly slower ?

[jmc]

I can't believe no one has an opinion on this ...

[pentaxman]

The Pentax did not get a glowing review - they claim it has problems with PF even in the center at wide apertures:

Pentax DA* 55mm f/1.4 SDM Lens Review

This review raved about the Sigma 50 F1.4 image quality:

Sigma 50mm F1.4 EX DG HSM Lens Review: 6. Conclusion & samples: Digital Photography Review

I personally would go with the Sigma based on these two reviews. It is not cheap, though.

[KjetilH]

SLRgear.com says the DA*55 is the best of the 50 1.4 lenses they've tested.

Pentax's comparable lens is the 55mm ƒ/1.4. At around $700 it's the most expensive lens in its category, but offers the best results of them all. It's decently sharp wide open at ƒ/1.4, and by ƒ/2.8, it's about as sharp as we can record. CA performance is good wide open, slightly worse as the lens is stopped down. Corner shading and distortion are both slightly better than the Sigma. Did we mention it costs $700?

To compare results of the Sigma 50 and the Pentax 55, I would check SLRgear for both of them.

[GLXLR]

I would probably get the 55mm just b/c it is WP. The IQ doesn't look bad either. Where I am though, the 55mm is slightly more expensive ($100-200) more than the Sigma.

Klaus from photozone said that they could test in July 3 Pentax lenses including the DA*55. My personal belief is that it will score highest from all Pentax lenses in sharpness.

Radu

[cwood]

The only bad thing that can be attributed to the Pentax 55mm is slow AF. Several Sigma lenses have had issues with quality control. I'd go for the Pentax no question.

[brecklundin]

Which is better in terms of IQ ?
Is the 55mm focusing significantly slower ?

Here are some tests of both lenses from a site, which in my experience is very accurate on the lenses they actually test. In this case they tested both lenses pretty close together:

Sigma Lens: Primes - Sigma 50mm f/1.4 EX DG HSM (Tested) - SLRgear.com!

Pentax Lens: Primes - Pentax 55mm f/1.4 SDM SMC DA* (Tested) - SLRgear.com!

In general I ignore the actual user reviews (upon which the ratings system is based) in favor of the actual test results. The tests seem to run true to how a given lens will perform in real life.

Not having used either I have no opinion. Seems though the trade off is much better CA vs. weather sealing. And maybe a bit better sharpness for the Sigma. I seem to recall the Sigma 1.4 is prone, at times, to needing recalibration when new...but it's usually only a week or so trip to Sigma in the US. You do not even need to contact them first, just send it in and they will check it, clean it and make any adjustments needed.

As for focus issues, yup, Sigma can have front/back focus issues in a number of the lenses. From my reading Pentax's newer lenses are no better or worse. In fact even Canon/Nikon probably have just as many lenses with the same issues.

The warranties are similar with 4yrs for the Sigma and 3yrs for the Pentax.

[asdf]

The Pentax did not get a glowing review - they claim it has problems with PF even in the center at wide apertures:

Pentax DA* 55mm f/1.4 SDM Lens Review

You gotta be f***ing kidding me. That site is run by retards.

https://www.pentaxforums.com/forums/pentax-slr-lens-discussion/55729-doing-wr...eview-com.html

[GLXLR]

They can't possibly be that retarded. If you really don't like their testing methods, just skip down to the conclusion ehh?

[deejjjaaaa]

Not having used either I have no opinion. Seems though the trade off is much better CA vs. weather sealing. And maybe a bit better sharpness for the Sigma.

Sigma is an officially full frame lens.

Sigma has a ring type USM motor.

Pentax has 5mm more under the tube, probably better for portraiture.

Pentax has better glass coating.

Sigma uses a lot more expensive filters 77mm vs 58mm.

Sigma has a faster turnover in their service center if you will send your lens there for a service.

Pentax has a hood optimized for APS-C FOV, Sigma has not as it is a FF lens.

etc

[brecklundin]

yeah, I left out the FF issue....probably since other than using it for film I doubt you will need a FF mount for a while in a Pentax mount, but, since there are a lot of folks here shooting film I need to remember it matters a lot!! d'oh!! Pentax rookie error!!

As for the coatings how is the SMC better? Asking because I am really not up on the topic not to pic nits...genuine question. Being a recovering Canoholic I need the help...hehehehe....I can say I have never noticed any difference in a Sigma that had only been upgraded to the DG coating they use. So, as a rule I bought whichever version was cheaper and not too old. Did that with my 100-300 and was very happy with the thing. Still I have to think the SMC coating is one of the reasons I like the colors in shots taken with SMC coated lenses. Of course I usually just figure it's placebo for me and it's not the end all when I am picking a lens.

[tenpointnine]

I've no way of directly comparing the two lenses, as I only have the Sigma, which I'm thoroughly enjoying.


larger size

larger size

[Class A]

Several Sigma lenses have had issues with quality control.

Dpreview went through three copies of the DA* 55/1.4 and couldn't get one that didn't have a tilt in the focus plane.

I'd like to be a fan of the DA* 55/1.4 (it was designed by Jun Hirakawa, the designer of the FA 77/1.8) but I think its bokeh is too distracting most of the time.

[bdery]

Both will serve you well, and that's the truth of it.

The Pentax is smaller, weatherproof, and uses smaller filters. Supposed to be amazing.

The Sigma is FF, supposed to focus a tad faster, and supposed to be amazing too

Pentax coatings ARE different than Sigma's. They are recognized as better for flare controland the colours are a bit more realistic. sigma lenses, in my experience, produce a slightly (slightly!) yellower cast. Not bad, just different.

If money was no issue, I'd go with the Pentax in a heartbeat. If money was an issue, I'd think about it. WR in itself is a strong selling point.