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12-30-2009, 11:53 PM   #1
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DA* 55/1.4 vs. Sigma EX 50/1.4 Question Re: Selective Focusing

So I'm currently debating between these two fine primes. I've done some extensive research, and I'm leaning towards the Sigma, but I'm concerned that the selective focus features of my sweet new K-7 won't function as well with a third party lens.

Does anybody have any experience or insight on this?

12-31-2009, 12:09 AM   #2
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QuoteOriginally posted by porterHause Quote
So I'm currently debating between these two fine primes. I've done some extensive research, and I'm leaning towards the Sigma, but I'm concerned that the selective focus features of my sweet new K-7 won't function as well with a third party lens.

Does anybody have any experience or insight on this?
The only thing that will not work is in-body auto-correction for barrel distortion and lateral chromatic aberrations...but in the case of these two lenses, barrel distortion is negligible. Sigma 50 f/1.4 is a bit of a beast size-wise, but it's exceptionally sharp wide open and the HSM motor is pretty fast...and it's probably easier to find it at a good price somewhere. EDIT: The Pentax has weather sealing, (possibly) better peak performance and is smaller.

Last edited by asdf; 12-31-2009 at 12:48 AM.
12-31-2009, 01:00 AM   #3
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hmm...and bokeh CA seems to be the major issue wide open with both lenses. Things to think about.

Thanks for the info!
12-31-2009, 03:22 AM   #4
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The Sigma is as large as the Pentax FA 85/1.4!
It seems to be very good from the reviews.
I suspect that the HSM is faster than Pentax SDM.

If you buy the Sigma tell us about your impressions!

Compare:
Sigma 50 mm f/1.4 EX DG HSM review - Summary - Lenstip.com

"The situation is rather rare Ė I have a problem with the cons in the conclusions because I donít know what to add."

12-31-2009, 07:47 AM   #5
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QuoteOriginally posted by asdf Quote
The only thing that will not work is in-body auto-correction for barrel distortion and lateral chromatic aberrations...but in the case of these two lenses, barrel distortion is negligible.
Doesn't in-body auto-correction apply only if one shoots JPEG?

It is really interesting to compare Sigma 50/1.4 with Pentax 50/1.2 size-wise...
12-31-2009, 11:40 AM   #6
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If it was me I'd get the Sigma, for 2 reasons.
Pentax still seems to be having problems with their SDM.
Sigma's warrenty on EX lenses is 5 years in the USA (10 years in Canada) compared to the 1 year you get from Pentax.
12-31-2009, 03:34 PM   #7
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The corrections (barrel distortion and lateral CA) are only available in JPEG format, along with other fun features of the K-7. Knowing this, my main concern was whether the selective focusing features worked with third party lenses. They do indeed. So, image quality between the two being about equal...coupled with the DA*'s SDM motor issues, harsher bokeh wide open, and a price tag $200 more than the Sigma, are making my decision much easier.

I can deal with the size and lack of weatherproofing. I want big and beautiful bokeh...will just have to watch out in high contrast situations for the bokeh CA...and spend a bit more time post production if and when it's encountered.

Thanks for the input! Happy to have found this forum.
12-31-2009, 07:18 PM   #8
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porterHause,

If you can live with manual lenses the Pentax K-mount 55mm f1.8, or the SMC screwmount versions have some of the nicest bokeh I've ever seen.
The best part about them, is they can be had for next to nothing, I got my K-mount version practicably given to me.

Here's a sample image, taken with mine.

It was mounted on my Sigma, but still offers stunning results while on a Pentax.

The bokeh rivals my 200mm f2.8 Zeiss, in some cases.

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