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11-06-2008, 11:11 AM   #1
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Sigma MINI-WIDE II 28mm f/2.8 owners - help please!

Today I received my copy of this lens. The first thing I do, when receive an old MF lens is to check the aperture stops and blades functionality.

This lens is very strange. If you set the lens to f/2.8 and then stop it down, you really don't notice any aperture blades movement till f/4.5... When I open the aperture from f/4.5 to f/4, I can see the blades disappear, but not showing again, when I move it back from f/4 to f/4.5.

It seems not normal to me. This means that f/2.8, f/3.5 and f/4 are the same aperture stops for this lens?!

I checked the exposure with my K100D and found out, that the exposure really isn't consistent.

Did anybody else notice this "feature"?

11-06-2008, 11:53 AM   #2
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I have a 24mm f2.8 version here in Spain with me now and the 28mm version back in the UK but they are the same build from what I can see.

If I put my 24mm version to f2.8 and then stop it down using the aperture ring you can see the blades closing from f2.8 all the way through.
I will be selling my 28mm version when I go back in a couple of weeks if you decide to return that one :-)
11-06-2008, 01:19 PM   #3
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Pentagor:I have the 28mm version (i absolutely love it, it may be my sharpest lens) and have had no such problems with it.

Mike: There's a 24mm? that would be sweet
11-06-2008, 01:34 PM   #4
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Thanks blotzphoto. And yes, there is a 24mm, it is also on its way to me....

11-06-2008, 04:28 PM   #5
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28mm: Mini-Wide

24mm: Super-Wide

And both were available in the original verion, and then a newer "II" version.

For some reason I have both the Mini- and Super-Wide II lenses...must be that thing they call BLA or something...
11-06-2008, 06:47 PM   #6
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QuoteOriginally posted by pentagor Quote
Today I received my copy of this lens. The first thing I do, when receive an old MF lens is to check the aperture stops and blades functionality.

This lens is very strange. If you set the lens to f/2.8 and then stop it down, you really don't notice any aperture blades movement till f/4.5... When I open the aperture from f/4.5 to f/4, I can see the blades disappear, but not showing again, when I move it back from f/4 to f/4.5.

It seems not normal to me. This means that f/2.8, f/3.5 and f/4 are the same aperture stops for this lens?!

I checked the exposure with my K100D and found out, that the exposure really isn't consistent.

Did anybody else notice this "feature"?
Had 2 copies of this lens. I have never experienced what you described. The aperture blades should retract and open up normally. Could be oil on the aperture blades that could account for the sluggish aperture.
01-09-2010, 07:35 PM   #7
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Ugh! I just bought one of these and it has a Ricoh pin! I'm really looking forward to trying it, but I'm afraid to put it on! It's a PKA mount but there's a spring loaded Ricoh pin.... anyone know if it will get stuck???

Seller listed it as a PKA mount, which is correct, but since there were no photos of the mount, I didn't know about the pin until I got it just now....

I'd prefer to use it as is rather than try to remove the pin, but not if it's going to get stuck on my K-x... The pin is spring loaded, but I imagine they're all that way?? If it's easy, I will remove the pin I guess... Bummer!

Please advise!
01-09-2010, 08:37 PM   #8
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QuoteOriginally posted by Optical Illusion Quote
Ugh! I just bought one of these and it has a Ricoh pin! I'm really looking forward to trying it, but I'm afraid to put it on! It's a PKA mount but there's a spring loaded Ricoh pin.... anyone know if it will get stuck???

Seller listed it as a PKA mount, which is correct, but since there were no photos of the mount, I didn't know about the pin until I got it just now....

I'd prefer to use it as is rather than try to remove the pin, but not if it's going to get stuck on my K-x... The pin is spring loaded, but I imagine they're all that way?? If it's easy, I will remove the pin I guess... Bummer!

Please advise!
The lens will invariably get stuck on your camera. Don't bother mounting it. Take a small screwdriver, unscrew the screws on the metal mount, pull off the mount, take out the pin, and screw the mount back on. It's a very painless procedure and completely fixes the problem you will run into.

Here's an informative guide:
theatre of noise: Ricoh Lenses On Pentax Cameras -- The Ricoh Pin Fix

01-09-2010, 08:51 PM   #9
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QuoteOriginally posted by Optical Illusion Quote
Ugh! I just bought one of these and it has a Ricoh pin! I'm really looking forward to trying it, but I'm afraid to put it on! It's a PKA mount but there's a spring loaded Ricoh pin.... anyone know if it will get stuck???

Seller listed it as a PKA mount, which is correct, but since there were no photos of the mount, I didn't know about the pin until I got it just now....

I'd prefer to use it as is rather than try to remove the pin, but not if it's going to get stuck on my K-x... The pin is spring loaded, but I imagine they're all that way?? If it's easy, I will remove the pin I guess... Bummer!

Please advise!
If it has the Ricoh pin, then it's most likely not a PKA lens, but a Ricoh "P" lens, which is a K mount variant with electrical contacts similar to Pentax's "A" lenses, but in a different location that are meant to provide automatic control of aperture with some of Ricoh's K mount cameras with a "P" setting on the shutter speed dial (like the XR-P, for example). The differences between a PKA and Ricoh P lens is pretty subtle, but the Ricoh pin is a common giveaway. Another is the "A" setting actually being marked "P" or "P[A]". Unfortunately, if it is actually a P lens, the contacts won't line up with your Pentax camera and the "A" setting won't work.

I was unaware that Sigma (or Quantaray, which also sold a version of these lenses) marketed either the 24mm Super-Wide or 28mm Mini-Wide in a Ricoh mount. I've only seen genuine "A" lenses or those with no contacts whatsoever. Can you post pictures of the mount so we can see?

Consider performing minor surgery to the mount by unscrewing it and removing the offending pin just to make sure that it doesn't get stuck on your camera. It's a simple procedure by all accounts that I've seen in Ricoh and Sears lenses.

Last edited by indytax; 01-11-2010 at 10:29 AM.
01-09-2010, 08:59 PM   #10
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Thanks for your help guys. Here is a link to a seller on this forum who sold the exact lens I have now (I didn't buy his).

https://www.pentaxforums.com/forums/sold-items/66204-sale-[sold]-sigma-28mm-f...acro-lens.html

The mount is shown clearly in his listing - but there is no mention of it being a problem. I have the exact same lens. There is an "A" position, and the contacts appear proper for Pentax use.

I used a magnifying glass to get a close up look at the pin. It is rounded, ball shaped, and spring loaded. From what I can tell reading around the net - this type is less of a problem, or not at all...

I still have not put it on the body, since I was waiting to hear from you guys! I would rather not remove the pin if it is really no problem... I have feeler gages in case it gets stuck, but right now I don't have the right screwdriver to remove the mount and get at the pin...

I've PM'd a couple sellers who sold the lens, asking their experience, so we'll see.

Last edited by Optical Illusion; 01-09-2010 at 09:36 PM. Reason: fixed link
01-09-2010, 09:28 PM   #11
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I have three Sigma KA lenses with a Ricoh pin. I used my 24mm f2.8 Superwide II for a couple of years before I noticed the pin, and haven't bothered it. I also have a 50mm f2.8 macro with the same pin, still there. Both these lenses resemble the archived marketplace ad you tried to link to (brackets probably messed that up). They have the newer style focus grip with diagonal slashes. My third lens is a 16mm f2.8 fisheye with the older style grip, rectangular blocks and the Sigma name. When I mounted that lens once, I felt some drag, so I removed the pin (thinner than the other lenses) just in case. Here's my 24mm, Ricoh pin at the top:

01-09-2010, 09:46 PM   #12
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Thanks Dave - I think I fixed that link, but it just shows what you've pictured here. It seems like there is no problem with this style, so I am tempted to put it on and try it... I really wanted to check out the close focusing! However, there's no rush and if I can get the right tool tomorrow, maybe I'll try to take out the pin.

Mine pretty much looks exactly like what you show... and I don't really see anyone reporting these Sigmas getting stuck...

Thanks again for your help.
01-10-2010, 06:26 AM   #13
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Many Years Ago.

I had a Sigma over 25 years ago, I think it was the 28mm f2.8. I noticed there virtually no change in aperaure at the widest aperture even though it was moved to the next stop. From then on it worked properly. I also noted it showed significant vignetting at the widest aperature. This would not show on a 2/3 APS sensor, due to the affected image not being projected onto the sensor. Put me off Sigma for many years. However they have got their act together and now my main body of lens are Sigma.

17-70 f2.8 fabulous, 70-200 f2.8 mk2 again fabulous
01-10-2010, 03:12 PM   #14
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I've decided to wait until I can remove the pin. Should only be a few more days at the most until I can get the right tool. Thanks for your responses!
01-10-2010, 03:26 PM - 1 Like   #15
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I have had a couple of the 28mm's now and the 24mm.
All I did was get a pen and push the pin in hard.

It stayed in and never had a problem.
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