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-   -   sigma 20mm f1.8 EX DG problems (

DorkUnderwater Nov 2, 2006 4:44 PM

i just came back from B and H and their used department had a deal for the sigma 20mm at around 300 with tax, i have no fixed lens on maxxum and with 1.8 it sounded very attractive. however, the focus disc is wobbly, but worst of all the camera wont recognize the lens, at all!

the lens also has the 8 chip design which means it should work, it also doesnt work with my maxxum 5 film slr (but it has low battery so not sure). i really got excited about this lens, but at least B and H has a 14 day return policy.

i dont know if its worth it to send it for rechipping which may cost extra......

JimC Nov 3, 2006 11:37 AM

It depends on what you need it for. That Sigma is a bit more than twice as bright as the Minolta 28mm f/2

JimC Nov 3, 2006 12:27 PM

Test Post at 1:27PM Eastern

JimC Nov 3, 2006 10:43 PM

If your film camera won't recognize it either, it sounds more serious than just a firmware issue (it's probably got a defective component, unless the contacts are just dirty and not making a good enough connection).

Sigma could probably fix it. It's your call if it's worth the hassle or not.

DorkUnderwater Nov 3, 2006 11:28 PM

contacts are fine, thanks for the tip, i'll return it now.

the minolta 20mm f2.8 looks to be a finer replacement, and has 72mm filter thread akin to my 2 tokina lenses.

JimC Nov 5, 2006 8:10 AM

We had some forum problems which should now solved after we upgraded the WowBB Software earlier this weekend. So, you may not have seen my previous posts, right before the forums were taken down after we noticed the problems (since they're in the wrong order within this thread).

Anyway, the Sigma would be twice as bright. So, I'd personally go that route instead. It looks like B&H has another one in right now, according to the listings in their used department. So, you may want to see if they'll just swap out the one you got for it (giving it a try in the store if you're planning on another visit anyway).

I skipped the wider primes, starting out with my Minolta 28mm f/2 as my widest prime, since my Tamron 20-40mm f/2.7-3.5 covers the 20 and 24mm focal lengths, and it's sharper compared to both the Minolta 20mm f/2.8 and 24mm f/2.8 primes, even at f/2.8 (according to the MTF tests at

I wouldn't mind having something a stop brighter than my Tamron 20-40mm (like that Sigma 20mm f/1.8 ). But, I don't have a need for the Minolta 20mm or 24mm f/2.8 primes (since I've got that end covered with a bright wide zoom that should be sharper compared to these Minolta primes).

DorkUnderwater Nov 5, 2006 7:09 PM

yeah i dont have an ultra wide covering zoom, my widest going to 28 is very nice and is also my walkabout lens (28-70 f2.8 tokina), but when i'm docked somewhere and wantt a great photo viewing the port of call i'm at, i need something realllly wide, or in cramped quarters (for instance indoors photo shoots on the ship).
I'm surprised the minolta 20mm f2.8 isnt as sharp as its competition (though i am assuming it still is very good, heck it is almost half a grand i think from Sony).

If I can get BnH to replace the one they have in the used department now I definitely will keep it, 1.8 is really nice, and i'm thinking it will be good for city night shots (bulb exposure). I will go first thing Monday morning. Thanks for the suggestion :)

JimC Nov 5, 2006 7:41 PM

The Minolta 20mm f/2.8 probably is as sharp as it's competition.

The Tamron 20-40mm f/2.7-3.5 just tests much better than most wide zooms. So, according to the MTF Charts, it's actually slightly sharper than the Minolta 20mm f/2.8 (although they're very close). This Tamron also tests sharper than the Minolta 24mm f/2.8

I don't own a Minolta 20mm f/2.8, and MTF Charts never tell the entire story. It may be a pretty decent lens and may do a better job compared to my Tamron. There are more qualities to a lens compared to what an MTF chart is going to tell you.

I just didn't feel like I needed one, since my Tamron seems to do a pretty good job for when I need a wider lens.

So, if I were going to buy a wider prime, I'd get one that offers an advantage in an area like brightness over my Tamron. I often find that f/2.8 is not quite as bright as I need. For that matter, my 28mm f/2 is sometimes not as bright as I need. lol

You can find the MTF Charts for them at

Minolta 20mm f/2.8
Photodo test result: 3,5
Effective focal length: 20
Weighted MTF for 20 mm: f2,8 0,70, f4 0,75, f8 0,79
Average Weighted MTF: 0,77 Grade: 3,5
Weighted MTF 10 lp/mm: 0,88
Weighted MTF 20 lp/mm: 0,72
Weighted MTF 40 lp/mm: 0,44
Distortion: -3,95%

Tamron 20-40mm f/2.7-3.5
Photodo test result: 3,7
Effective focal length: 20 - 39 mm
Weighted MTF for 20 mm: f2,7 0,71, f4 0,77, f8 0,79
Weighted MTF for 28 mm: f2,8 0,70, f4 0,76, f8 0,81
Weighted MTF for 40 mm: f3,5 0,71, f8 0,82
Average Weighted MTF: 0,78 Grade: 3,7
Weighted MTF 10 lp/mm: 0,88
Weighted MTF 20 lp/mm: 0,73
Weighted MTF 40 lp/mm: 0,50
Distortion: -3,7% - 3,2%

DorkUnderwater Nov 6, 2006 2:02 PM

hmm well i was able to return the sigma 20mm, and try on the other sigma 20mm they had, which was a better version (it didnt have the EX tag, but somethin else).

however this too didnt work, i got my camera almost a year ago, i think it should work!

i then tried some lenses at the booth, the KM 17-35mm is nice, maybe it was the good lighting conditions but it was impeccably superfast at focusing, much faster than my tokina! (the downside of older models) i'll have to research quality though as i barely trust anything that isnt metal. f2.8-4 is much better than the 4.5-5.6 on the sony ultra wide.

now maybe theres an older minolta 17-35mm with a 72mm thread, that would be sweet :G.

JimC Nov 6, 2006 2:15 PM

Sigma lenses do tend to have more issues than other brands.

Looking through some of the user reviews for it at, I see one user report that Sigma was able to rechip one of them to work (apparently, the first batch of lenses were made before they ironed out the compatibility issues).

See the second review in the list from the top (June 16, 2006):

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