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04-03-2011, 09:27 PM   #31
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Corrected -2 microfocus adj.

Then when I changed to -2, almost all shots were accurately AF-ed (imgs - center AF point used)

(crop)




You can easily read the barcode!! (crop)


This was where it was really difficult for the Siggy to decide on the AF. Dont know if it was sigma or the K7 itself. I had focused on the Ver!zon flag.



Last edited by icypepsi; 04-03-2011 at 09:51 PM.
04-03-2011, 10:29 PM   #32
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QuoteOriginally posted by icypepsi Quote
Here, it had a -8 microfocus adj. and it seemed just perfect
Looks OK but there is a slight chance that the camera might have picked up some of the grey print. Did you verify that it couldn't obtain focus when you point it below or above the focus bar?

My AF adjustment hints contain links to alternative focus charts. However, the main thing that your real world focusing works and you seem to have achieved that.
04-04-2011, 08:04 AM   #33
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QuoteOriginally posted by Class A Quote
Looks OK but there is a slight chance that the camera might have picked up some of the grey print. Did you verify that it couldn't obtain focus when you point it below or above the focus bar?

My AF adjustment hints contain links to alternative focus charts. However, the main thing that your real world focusing works and you seem to have achieved that.
Yes, that's the first thing I checked. It's a 10% gray bg and, at least, my K7 sensors are not able to "see" it. I have read your adjustment hints' article. Very nice and exhaustive. Thanks. I like your preferred chart there, but I thought that I would not be able to use it at a larger subject distance (say greater than 2 mts), as I wanted something that did not have the side scales very close to the center focus line. The sensor might have a choice to select other "visible" lines since they will be closer to the sensor region of the image, at that subject distance. Yes... I started testing at different subject distances too since the time I got to know about the focus shift problem in super-fast lenses.

Another story why I prefer the 10% gray chart: If we have a chart with numbers only to the sides, in the event of a horizontal (horizon) alignment error (and the built in K7 is off by a few degrees sometimes), the numbers to the side of such a chart could be misleading. This is because we are at an angle to the plane of where the paper is lying and now we are also at an angle that is not 90degrees to it, but slightly misaligned. So the paper itself will appear tilted, rendering the scale on one side slightly above or below the other. But, the 10% gray scale, being right at the line being focussed, will not lie.

Last edited by icypepsi; 04-04-2011 at 10:30 AM.
04-04-2011, 10:20 AM   #34
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QuoteOriginally posted by robgo2 Quote
I have no experience with the Sigma 85/1.4, but I did try the Sigma 50/1.4 on my K-7, and I noted very inconsistent focusing. It was almost as though the lens was focusing randomly around the true focus point and only occasionally hitting it. This matters when you are using an ultrafast lens with a paper thin DOF. If you cannot trust such a lens, why own it?

I agree that you might exchange it for another copy, but do not be surprised if it exhibits the same behavior. FWIW, the Pentax 77/1.8 Limited costs less and is regarded as one of the most beautiful rendering lenses from any manufacturer. It never misbehaves, at least on my K-7. It does not have SDM, but I should think you could live without it.

Rob
Thanks Rob. With stuff I've seen, I think Sigma does have some QC issues. I'm sure all manufacturers have bad units off the facility, but it looks like maybe Sigma has a little more. On the other hand, if I'm correct, then of the copies I've seen, I think Sigma took care of focusing problem in the 85mm F1.4 very well, as far as focus shift is concerned. AFAIK, Sigma is the second one to take care of this problem, after Leica. And then again, given the affordability of Sigma, it's day vs night.

I've seen some fantastic images from FA 77/1.8 and FA 85/1.4. But the Sigma 85/1.4 images I've seen are mind blowing too. For me, I needed HSM because I already own a screwdrive lens and I know it's limitations. And when it comes to LV, the difference is enormous. Not that I live by LV, but just giving it a mention. Besides the sound of the screwdrive motor, the speed is what I looked for, because, given comparable IQ, I felt I needed to go for a "newer" technology. No doubt screwdrive is accurate too. But, especially when it comes to F1.4, I think the speed really matters when you want to take candid shots where the DOF is so thin and you are in AF-C, trying to follow your subject. This will be difficult even if you have SDM/HSM. But certainly better than screwdrive. K7's motor is fast, but not comparable to SDM/HSM. Having said all this, again, it's my personal choice. Hell, people even manually focus at F1.4! I'm sure it's like the joy you get out of metering manually!


Last edited by icypepsi; 04-04-2011 at 10:34 AM.
04-04-2011, 10:24 AM   #35
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QuoteOriginally posted by Pentaxor Quote
as far as the 50/1.4 being just slightly sharper at wide open, I believe it has much to do with the 85 being made consistently sharp (balanced sharpness) all over the frame from wide open. from the multiple comparative 85mm lens test results, the Sigma 85 is sharper in the borders and corners in comparison with other 85mm lenses.
Thanks. Yes, this could very well be a reason. There is a clear improvement with Sigma 85/1.4. But if factors that make sharpness were kept the same, then maybe even just doing it for 85mm instead of 50mm made the sharpness difference. I know enough just to be able to make a good guess.

Last edited by icypepsi; 04-04-2011 at 10:36 AM.
04-04-2011, 11:44 AM   #36
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QuoteOriginally posted by icypepsi Quote
Thanks Rob. With stuff I've seen, I think Sigma does have some QC issues. I'm sure all manufacturers have bad units off the facility, but it looks like maybe Sigma has a little more. On the other hand, if I'm correct, then of the copies I've seen, I think Sigma took care of focusing problem in the 85mm F1.4 very well, as far as focus shift is concerned. AFAIK, Sigma is the second one to take care of this problem, after Leica. And then again, given the affordability of Sigma, it's day vs night.

I've seen some fantastic images from FA 77/1.8 and FA 85/1.4. But the Sigma 85/1.4 images I've seen are mind blowing too. For me, I needed HSM because I already own a screwdrive lens and I know it's limitations. And when it comes to LV, the difference is enormous. Not that I live by LV, but just giving it a mention. Besides the sound of the screwdrive motor, the speed is what I looked for, because, given comparable IQ, I felt I needed to go for a "newer" technology. No doubt screwdrive is accurate too. But, especially when it comes to F1.4, I think the speed really matters when you want to take candid shots where the DOF is so thin and you are in AF-C, trying to follow your subject. This will be difficult even if you have SDM/HSM. But certainly better than screwdrive. K7's motor is fast, but not comparable to SDM/HSM. Having said all this, again, it's my personal choice. Hell, people even manually focus at F1.4! I'm sure it's like the joy you get out of metering manually!
I'm glad that you got a copy that is working for you. Good luck with it. FWIW, I did not find that the Sigma 50/1.4 HSM was faster than my FA 31 Limited on my K-7. Quieter, but not faster and definitely not as accurate.

It certainly seems as though Sigma has stepped up its game in terms of optical quality. Until recently, they were known for decent, but not superb optics. Some of their newer lenses are turning heads amongst serious shooters.

Rob

Last edited by robgo2; 04-05-2011 at 03:29 AM.
04-04-2011, 01:23 PM   #37
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QuoteOriginally posted by robgo2 Quote
I glad that you got a copy that is working for you. Good luck with it. FWIW, I did not find that the Sigma 50/1.4 HSM was faster than my FA 31 Limited on my K-7. Quieter, but not faster and definitely not as accurate.

It certainly seems as though Sigma has stepped up its game in terms of optical quality. Until recently, they were known for decent, but not superb optics. Some of their newer lenses are turning heads amongst serious shooters.

Rob
I think I understand what you mean by not faster than your FA 31. I felt the same thing at times when i tried out the Tamron 70-200 2.8. It has a screwdrive mechanism too. But was fast. I thought it was faster than the Sigma 70-200 2.8 non-OS. Like I said, the K7's motor is way faster than the previous models. I'm thinking the K5 is still better
04-12-2011, 02:42 PM   #38
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Now, a problem with my copy 2. Coating problem?

I didn't want to visit this thread again for problems... but, it seems they are not yet over. Out of love for the second copy of Sigma 85mm F1.4, I was ogling at it's rear element, at how beautifully the F1.4 blades open up. Just then, I noticed a "speck" on the rear element. "Big deal", I thought and fished out my cleaning kit. First the lens pen, that cleans off most of the dust. The "speck" remained. I thought it must be some oil smudge from my fingers. Used the cleaning solution, didn't go. Instinct told me it is on the other side of the glass element. Ok, I thought... no problem. It's probably going to get displaced sometime.

But, wait a minute. I opened the aperture, looked through into the lens at a light source. Sure, there was plenty of dust. For one, I was amazed at the amount of dust it had between the elements. And it's a new lens. But I know it is not weather proofed. So, that's kind of fine.. I know it won't ruin my images. What struck me is that that "speck" I had seen earlier was not a dust particle, like all the other dust between the elements. It shined bright and it even changed some color as I varied my viewing angle. I was alarmed. For hours I kept wondering what it could be. An oil smudge from one of the employees while assembling? Not likely. I'm sure Sigma will not have such a bad QC. If not, it has to be some deformation in the glass itself. Again, it did not seem likely. That is too much damage for a glass element that is constructed with so much precision.. unless someone knocked it against something. I gave it a few days to see how the "speck" will "behave" in terms of its location. But it did not budge. Then it struck me that it could even be a bad coating on the surface. This is what I concluded. Can I live with it? I don't want to after paying a grand.

I tried photographing it. but given the size of the rear element and the high reflections when you look at the glasses, it is so damn difficult. It was hard enough explaining it to the rep while exchanging. But the nice guy trusted me. I'll post the image in 2 hrs.

So I just wanted to post this as an info note and see if folks have come across such a thing. I don't know what to conclude. I don't want to tarnish the reputation of an optically excellent lens producing company like Sigma. At the same time, my experience is a fact. I'm all praise for the lens, otherwise. But, it is definitely painful going to the reps each time at B&H (he said he better not see me again, probably jokingly And I hope that's what will happen). It may even seem to them like I'm making up stories each time and renting their brand new equipment for $0.

I made sure that the copy 3 is not the copy 1 I returned. Now, how the copy 3 will turn out to be, is another story. Gotta do the whole process again. Keep your fingers crossed!


Last edited by icypepsi; 04-12-2011 at 02:53 PM.
04-12-2011, 03:53 PM   #39
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if you cant live with it, I can offer you $500.
04-12-2011, 05:21 PM   #40
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I hope you get a good copy. Sigma has some excellent optic formulars, but their QC is almost none exist. I am personally 1 for 7 on sigma lenses... 1 for 2 on tamron, 2 for 3 on Tokina...
and sadly 2 for 4 on Pentax so far.
04-12-2011, 09:21 PM   #41
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pics of the speck

QuoteOriginally posted by Pentaxor Quote
if you cant live with it, I can offer you $500.
There you go, that's how much the "speck" hurts me!

QuoteOriginally posted by MaK5 Quote
I hope you get a good copy. Sigma has some excellent optic formulars, but their QC is almost none exist. I am personally 1 for 7 on sigma lenses... 1 for 2 on tamron, 2 for 3 on Tokina...
and sadly 2 for 4 on Pentax so far.
Sad. I understand your pain. But I also think of it this way. With Pentax you have the option of making a FF/BF lens focus perfectly! With most Canon/Nikon, you'd have had to try a lot more lenses before you get a "matching" one. I'm not biased with brands, but looking at the "others" struggle, I'm happy(ier) about my choice

Now only if I settle with this copy, I can start worrying about a flash next. Wish me luck!

Here's the "speck" I'm talking about. Sorry, but it is extremely difficult to capture something that's not contrasty, minute, yet millimeters away from other contrasty things, indoors (on a K7 ), non-fast non-macro lens. Would have been better with a macro lens.



not much detail (crop)


long exposure with ISO100


(crop)

Last edited by icypepsi; 04-12-2011 at 09:27 PM.
04-12-2011, 09:46 PM   #42
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Oh, I forgot to add that I saw a similar speck through the front element in the same copy 2. I even wondered if it was some kind of an image/reflection of the one on the rear element. It was just too much of a headache to determine what it was. That's one of the reasons I exchanged it.
04-12-2011, 10:08 PM   #43
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QuoteOriginally posted by icypepsi Quote
There you go, that's how much the "speck" hurts me!
not really. actually, that is how much I can afford to spend right now. anything twice my offer would hurt my budget. although I'm capable of buying one right now, I just can't afford it at the same time. you know what I mean.
04-12-2011, 11:42 PM   #44
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QuoteOriginally posted by Pentaxor Quote
not really. actually, that is how much I can afford to spend right now. anything twice my offer would hurt my budget. although I'm capable of buying one right now, I just can't afford it at the same time. you know what I mean.
I do and I've gone through it. I just caught onto what you said and used it to express myself
04-13-2011, 12:18 AM   #45
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QuoteOriginally posted by icypepsi Quote
Oh, I forgot to add that I saw a similar speck through the front element in the same copy 2. I even wondered if it was some kind of an image/reflection of the one on the rear element. It was just too much of a headache to determine what it was. That's one of the reasons I exchanged it.
I have a habit of buying lenses with optical defects, fungus included. The fun part is that I almost never saw any image degradation. About the only time I got bad results was with a lens that had a completely crystallized back group.

Based on your photos I could understand why you exchanged it (because it's a new lens) but I would gladly buy one with such a "defect" at a discount price.
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