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Forum: Pentax DSLR Discussion 03-31-2011, 10:11 AM

Should I return my Sigma 50mm 1.4 HSM ?
Posted By icypepsi

Replies: 47
Views: 12,943

Sorry, I got a bit emotional with the decision. SDM shouldn't be so much of a problem for me, as long as it focuses it right, given the problems that there are at F1.4. Mostly, I don't like the slow AF, that gets to be noisy too. Sometimes the slow AF and noise can be quite embarrassing. It's difficult for candid shots when people are usually talking/walking/expressing, etc. Take for instance following a F1.4 focus plane wafer over the eye of a toddler. I don't think even SDM can do it. But, it will cover other situations that screwdrive will not. I feel that screwdrive is better for smaller apertures where the DOF is ok to accommodate for small erratic subject movements.

Besides, I don't know if the missing coating on FA77 will affect DSLRS. And I'm not a pro with experience to tell the difference. So, it's more of not taking a chance there. And then, if you are spending almost the same amount of money, why not go for a better technology, given the comparable IQ?

Forum: Pentax DSLR Discussion 03-30-2011, 07:13 AM

Should I return my Sigma 50mm 1.4 HSM ?
Posted By icypepsi

Replies: 47
Views: 12,943

I hope that's not the case with me. Coz, the previous time, this problem was shown by the DA 55 also. Besides, the DA 55, Sigma too has some fantastic optics. I would surely have gone for the FA 77, if it were SDM.

Forum: Pentax DSLR Discussion 03-29-2011, 10:55 AM

Should I return my Sigma 50mm 1.4 HSM ?
Posted By icypepsi

Replies: 47
Views: 12,943

For those wondering what the hell this guy did eventually, I returned the Sigma 50mm F1.4 HSM and went on the vacation without it :( But after I got back, I waited and purchased the Sigma 85mm F1.4 a week ago and see similar problems, but much less pronounced and much more acceptable. Actually, I have another issue with the 85 in that I must be having a bad copy. I discussed it in this thread. Please take a look, you may have an answer!

Forum: Pentax DSLR Discussion 11-24-2010, 10:54 PM

Should I return my Sigma 50mm 1.4 HSM ?
Posted By icypepsi

Replies: 47
Views: 12,943

I don't know if you read my experience about the K7 not saving the microfocus adj. even when it says "Saved". I had the same problem, until I discovered it wasn't. Same thing, I used to feel it magically settles for some one value. But the weekly drifting... stranger still!! Maybe some more testing should tell what it is.

Forum: Pentax DSLR Discussion 11-24-2010, 10:50 PM

Should I return my Sigma 50mm 1.4 HSM ?
Posted By icypepsi

Replies: 47
Views: 12,943

I think it will be far less "noticable" with lenses F2.8 and narrower. But I'd be very comfortable with a F2.8 lens, as my experience with the 3 lenses virtually disappeared with and after F2.8

Forum: Pentax DSLR Discussion 11-24-2010, 10:48 PM

Should I return my Sigma 50mm 1.4 HSM ?
Posted By icypepsi

Replies: 47
Views: 12,943

Sorry, I've been a bit busy. Well, the issue is definitely there. But not just with Sigma. I think it is "noticable" with lenses wider than F2.8. Congratulations. So, how's your K5 + Sigma turning out?

As for me, I would settle with that problem, coz there's no cure as of today. Like an online article pointed out, getting used to the lens' behavior, manually! I hate it, but I really really love the way a prime's picture's look. That "raw" brightness and sharpness.

For myself, I also discovered that 50mm was a bit short for my style of shooting. So I'm actually waiting for the Sigma 85mm F1.4 HSM. They seem to have solve this "focus plane shift" problem; of some online posts I read. They are on sale right now, but I just don't have the time to buy one and test... So, for me it's going to be this new year. Money's intact for it!
I'm also considering the FA 77mm F1.8. Seems more sharper, with screw-drive AF.

Forum: Pentax DSLR Discussion 11-20-2010, 09:53 PM

Should I return my Sigma 50mm 1.4 HSM ?
Posted By icypepsi

Replies: 47
Views: 12,943

Here's one more thing I was rocking my head side to side on. We know that viewfinders show the image at the widest open aperture of the lens. But, I read that APS-C DSLRs can only show a preview in the viewfinder at the widest open aperture of F2.8. I can easily make this out with my K7. First, when I set the lens to F1.4 and use the "optical DOF preview" trigger on K7 and nothing happens. Technically, the lens is already at F1.4 and the K7 is not widening the aperture blades inside to bring the preview aperture of F1.4. Makes sense, so far that's normal. But you'd think that it's showing you a preview of F1.4. However, if I were to stop down to F2.0 (or anything else right up till F2.8), internally, the K7 has widened the lens to F1.4 for the viewfinder image. But, as I pull the optical preview trigger it makes a noise where the blades are brought back to F2.0 (or whatever your aperture is) to show the DOF preview, but the viewfinder was just the same. Intact. No decrease in brightness. You'd think it was at F1.4 and now it got to F2.0 with that sound and the viewfinder would go darker. It does it all, but the viewfinder does not get darker. Only when I stop down below F2.8, say F4, pull the optical DOF preview trigger, can I actually make out the difference in viewfinder brightness. This means, that wider than F2.8, and the viewfinder is not capable of seeing brighter, in this case at F1.4, showing the AF sensors the exact DOF.

Given this viewfinder limitation, assuming you are trying to focus at F1.4, and the depth of field that is a lot wider at F2.8, how in the world will the AF sensors make out what is happening? Obviously there will always be a +/- error on a focus fix that could be as wide as the depth of field at F2.8 (of course, depending on all the DOF parameters of that situation). Can someone please confirm this?

I don't know about FF, can someone also fill this gap please?

Forum: Pentax DSLR Discussion 11-19-2010, 12:29 AM

Should I return my Sigma 50mm 1.4 HSM ?
Posted By icypepsi

Replies: 47
Views: 12,943

[I did go to B&H and they were very helpful in getting me a replacement. But you can always make out that face of the gentleman who is doing it for you. He'll have an expression of helplessness!]

I discovered two very mysterious facts. Read on.

Mysterious fact 1. The gentleman was kind enough to let me try another Sigma in exchange, before I decide to take it home. By now I was an expert at seeing this flaw in the lens and I quickly tested and found that at 1.4 there is some BF, this time. I quickly set the microfocus to an appropriate value (must've been +3 or something, which is pretty acceptable) using an obj that was around approx 2-3ft away. And guess what, stopping down to F2.0, F2.8, F4, the lens (remember it is now at +3) started to FF progressively. I could not help but think of what what Laurentiu Cristofor had pointed out here https://www.pentaxforums.com/forums/showthread.php?p=1270746. Then, I shifted focusing to an object that was approx 6ft away. To my horror the plane of sharp focus had shifted again (same aperture and microfocus adj. value)!! So the microfocus adj. has to be done fresh for the changed subject distance!!!!

So, this lens is behaving exactly like my previous copy. Coming to think of it:
Copy 1:
sharp focus for F2.8 at -7 microfocus adj.
sharp focus for F1.4 beyond -10 (out of K7's reach)

Copy 2:
sharp focus for F2.8 at (approx.) -4
sharp focus for F1.4 at +3

Only, copy 2 was well within the reach of my individual K7 body. At this point, I began thinking that this is a general problem with all Sigma 50 1.4 HSMs and I did not take the exchange, further thinking that it may be something to do with my individual K7 too. But then again, why will the body be at fault to shift focus planes for different subject distances? Maybe not. So, I went straight up and tried a DA* 55mm F1.4. This thing was tiny compared to the Siggy! Pretty soon, as the expert that I am, I set my K7 to +X microfocus adj. value for sharp focus at F1.4. To my total surprise, this lens behaved exactly the same way as the Sigma 50mm F1.4!!! How shocking is that!!! Can I blame all 3 lenses? Not even a school kid will. But then, how could the K7 be at fault if the subject distance changes. It just seems unrelated. This is puzzling. Could some learned souls please solve this misery for me. Or, is it after all correct what Laurentiu Cristofor pointed us to? Quite possible (good I didn't shrug it off yesterday, or I'd be embarrassed today!!)

Now, I was so pissed that I even tried a DA* 50-135 F2.8. Quite surprisingly, set to a -4 microfocus adj, it appeared to be very consistent at anything I pointed it to. But let us not forget that my Copy 1 of Sigma too was fine beyond F2.8. Probably because there's not much to worry about given the heft of the DOF with 2.8 upwards.
[Btw, the 50-135 was an astronomically amazing lens!!! It was so damn sharp throughout it's zoom range that I felt like I was trying out just another prime!! I almost settled for it, when I told myself that I really wanted those 2 (or less) extra stops in indoor shooting. The difference I found between the Siggy HSM and the Pentax DA*s' SDM was that the HSM didn't give up easily in low light situations where SDM would give up too quickly, and the HSM does not seem to care about very minute focus adjustments when the subject changes position, but the SDM seems to have an intelligence to lock on to the changed position.. in other words tracks the subject beautifully! Maybe that is why the HSM's change in focal plane was noticeably more than that of the SDMs. I even like the perspective that I get out of shooting at, maybe 75mm. I really really liked this lens, but for not being able to go below F2.8. May I say it was way better than the Tamron 70-200 2.8 also in terms of sharpness and AF accuracy? And I also dread the scary SDM failure info. But frankly, there have been a lot of them out there buying it without a problem.]

Mysterious fact 2. Here's another horror that I discovered about the K7 (at least mine). It is running v1.10. If you remember I was mentioning in my OP that no matter how much microfocus adjustment I applied, it did not seem to matter, asif the cam had decided beforehand what to do. For some reason today, I swiched OFF and back ON everytime that I changed the microfocus adj. And OMG, the change is reflected even if there is a 1 notch change!!!! Now, that is the exact reason why in the outdoor testing of my Copy 1 of Sigma, no matter what I did, the FF was unshakable.

Here's what I did:
1. No microfocus adjustment change is registered by K7 when you get to the menu and change it, hit the "OK" button and immediately start shooting (I have a habit of half-pressing the shutter-focus button to spring the K7 system back into action for shooting). That is, without getting back using the "Menu" button. But, after hitting "OK", the damn thing confirms with a "SAVED" on the display. I believed it all these days!! What a waste of time!
2. microfocus adj. change is properly registered by K7 if you switch it OFF and back ON after the change. I don't know if it even does that if you "gracefully" come out of all the menu options to the status screen by hitting the "MENU" button repeatedly after it said "SAVED".

I swear, this is a real let down of all that precious night-time I spent without sleeping. I guess I'll start out another thread just to check if people have noticed this of if it's a v1.10 bug, or if it's just my cam. I strongly think it must be a bug.

So now, I came back with only the K7 body and no lens :( I am not sure if I must get a Sigma 50 1.4 or a Pentax DA* 55mm F1.4 and live with it, coz it could be that this is what lenses are meant to do below F2.8, or go for something else, like the Pentax DA* 50-135 F2.8. Please advise what is happening in this optical world. I'd really appreciate it. Hoping to have a lens to take with me on my vacation next week.

Forum: Pentax DSLR Discussion 11-18-2010, 10:38 AM

Should I return my Sigma 50mm 1.4 HSM ?
Posted By icypepsi

Replies: 47
Views: 12,943

Nope, LV and MF cut it just fine. At least for all my trials so far. On some instances MF did not hit it, but I attribute it to me not doing it well on the small K7 viewfinder.

Thanks, Georg. Looking forward. I have read about even the K7 not being able to contrast AF, on dpreview. But I can confirm that my K7 (firmware v 1.10) fantastically determins the correct focus. Too bad, I hardly use it :) But, with what I just found out, my Sigma copy could be out of the close-to-latest-batch (and looks like the last of the lot that have the velvet finish, posted above), maybe Sigma fixed it!?

Forum: Pentax DSLR Discussion 11-18-2010, 10:06 AM

Should I return my Sigma 50mm 1.4 HSM ?
Posted By icypepsi

Replies: 47
Views: 12,943

so with all the mending, it is still something like my copy. I can feel your pain. In 2009 when I bought the K7, I looked at the 50D and was very particular about having the microfocus adj. I'm happy I chose one that has it too. But with the images I've seen, especially at F2.8 (posted by me above)/F4, don't you think it is pretty sharp? Well, maybe just a veenie bit less, compared to all of the pics I've ever seen online. Besides, online review graphs seem to tell that these tend to loose sharpness when stopped down more than F8/f11. I could not ask for anything more than this.. given my level of expectation (that I would maximum blow up the thing in to a 30" to 40" poster). Now if I were assigned to make a hoarding out of it.. maybe not :)

But out of curiocity, can you please post the pics of the canon lens (100% crop too). I want to see how sharp it can get.

Forum: Pentax DSLR Discussion 11-18-2010, 10:00 AM

Should I return my Sigma 50mm 1.4 HSM ?
Posted By icypepsi

Replies: 47
Views: 12,943

Interesting (and scary, for the money we all spend on it!), but I think there is more to this. Like including the subject distance into consideration. He did, but needs elaboration and more study. So the article says my glass (tumbler) is half empty, instead of what I thought half full. Ok same thing. Even if I think that wide open is what my lens is built for and stopping down back focuses, getting the wideopen focus correct also needed clearly more then -10 microfocus. With that, again, my lens is out of the normal behavior. I was close to considering to try focusing a little behind, probably for the rest of my days with the lens. But humanly it was almost impossible for me, with the DOF being so thin :) If possible, could take time, but I don't want to buy that because again I would have to know exactly how much behind, which again varies on the subject distance. Now that compounds things. Would need tremendous practice. But with people out there that say it should not be the way my Sigma is behaving, I will certainly try to get a new copy.

Forum: Pentax DSLR Discussion 11-17-2010, 11:03 PM

Should I return my Sigma 50mm 1.4 HSM ?
Posted By icypepsi

Replies: 47
Views: 12,943

Quite right. Gonna do that tomorrow, will pay the additional tax and check the lens at the store itself. Not that I can guarantee myself coz it will be low light and not ideal at the store. But at least I can get some idea. Besides, I need it for a vacation I'm leaving for on 24th. No point in waiting for the shipping to arrive.

I've read articles that talk about the tolerances to which these are manufactured and that it is quite difficult to get things perfect. I'd be ok if it were a fixed back/front focus throughout all apertures. But a BF/FF that shifts with subject distance and apertures.. hard to handle. Think of having a dial on the cam for adjusting it!! Insane!!!

Btw, what firmware is your K7? I believe the banding was fixed with the latest firmware.

Forum: Pentax DSLR Discussion 11-17-2010, 10:53 PM

Should I return my Sigma 50mm 1.4 HSM ?
Posted By icypepsi

Replies: 47
Views: 12,943

1) The bokeh can get jittery at times. if you do want it, then it does, but not too much
2, 3) Mostly the bokeh is smooth and even
4) Wall at F2.8 and -8 microfocus adj. Sharpest it can get.
5) 100%

All are with amazing color straight out of the cam (K7 on vibrant option). The CA is very less in my copy. Only 1 or 2 pics did I notice significant CA out of a lot that I tested.

Forum: Pentax DSLR Discussion 11-17-2010, 10:45 PM

Should I return my Sigma 50mm 1.4 HSM ?
Posted By icypepsi

Replies: 47
Views: 12,943

1, 2, 3) All the test charts are at F1.4. Clearly front focused. Some significant
4) As sharp as F1.4 can get, 100% crop, indoors.
5) 100% crop. Outdoor, even F2.8 gives front focus. Had focused on the center of the flower, but leaves towards me are in focus.

Forum: Pentax DSLR Discussion 11-17-2010, 07:11 PM

Should I return my Sigma 50mm 1.4 HSM ?
Posted By icypepsi

Replies: 47
Views: 12,943

Well mine is a 11018xxx having a velvety finish. I noticed my box was old, too. Mine must have been the last of the velvet lot :)

Forum: Pentax DSLR Discussion 11-17-2010, 01:16 PM

Should I return my Sigma 50mm 1.4 HSM ?
Posted By icypepsi

Replies: 47
Views: 12,943

You're right there about the "not happy" thing.

Btw, I looked at (or looked through!) the DA* 55 and found it about just as sharp. Very good lens. What I thought:
I was worried about the dreaded SDM failure that very many have reported. Even heard someone writing to Pentax for paid SDM replacement (on a dead SDM lens) with no response coming. Others say the SDM is going fine for them so far. So, my ideas about it are mixed, of course not liking to take that risk.

Reviews say the DA* 55 is not very accurate on AF. But I know that a Sigma 50 could have it's own flavour there :-| I have even read about the Sigma 70 200 having that curved plane of focus.

Alhough the Sigma 50's bokeh is smooth (something that's generally desired.. by me too), I sometimes do like the "jittery" bokeh of the DA* 55 not achievable on the Sigma.

I know both can go Full Frame (I was waiting on a FF from Pentax, but with the K5 so good on low light, I have to re-think)

So I might go the DA* 55 route if things don't turn fine with the Siggy.
That's reassuring, Raylon. Thanks.
I can see what you mean, Rory :)

I'll exchange it tomorrow and let you ppl know what happens.
Thanks everybody.

Forum: Pentax DSLR Discussion 11-17-2010, 10:35 AM

Should I return my Sigma 50mm 1.4 HSM ?
Posted By icypepsi

Replies: 47
Views: 12,943

Very true. But I just have this thought in one corner that all Sigma 50s are this way (out of so many people facing this problem with this lens) and if so, there's no point exchanging and getting another one guaranteed to have it again.

So, what I also want to know is if anybody has a Sigma 50 1.4 HSM that is "just fine". As in, indoors, outdoors, long focus, short focus, stopped down, wide open.. even if it turned out "just fine" only after a microfocus adjustment.

Forum: Pentax DSLR Discussion 11-17-2010, 10:15 AM

Should I return my Sigma 50mm 1.4 HSM ?
Posted By icypepsi

Replies: 47
Views: 12,943

Dear Pentaxians,
I bought this Sigma 50 1.4 and still have a week to go for the 15 day return window given by BnH. It is intended to be a second wife of my K7.

First, the good: [skip this if you already know abt the Siggy. I'm saying it all because I feel like boasting about the lens!]. I love that the damn thing is so sharp, I could cut myself if I'm not careful!! Just like everybody else, I'd say the build quality is very welcome, and a pleasure to hold and MF. HSM is buttery. A tad heavy, but reassuring heft. The color rendition is different, but I'd say it looks very saturated (like having a bit of a polarizing filter permanently attached!), and IMO very professional looking and a little warm. (Now, in a challenging lighting situation, this could be a little more of a problem.. but, anyways).

Now, the not so good: I have a gripe about it's AF accuracy. I've read at a lot of places about this lens doing a front focus when the aperture is opened up. Well, I have a copy that does it :( I know everybody will pounce at me in saying that that should not be a problem coz I have the k7 with the AF microfocus adjustment. But, my second problem is that this FF is different for different subject distances. Here's what I can summarize based on some real life and otherwise (tripod - IR remote - mirror up - non stabilized - test chart) testing.

Indoor, K7 set to 0 microfocus adjustment:
subject at greater than 6ft:
F2.8 and smaller, AF seems to be very accurate. Sharpness... don't you dare ask!

F2.0 and larger, AF is more and more front as aperture widens.

subject at lesser than 3ft:
F2.8 and smaller, AF mostly is accurate (I'd give the benefit of doubt to low light)

F2.0 and larger, the FF is sometimes too much and at times even back.

Indoor, K7 set to -7 microfocus adjustment:
subject at greater than 6ft:
F2.8 and smaller, again, AF seems to be very accurate (surprisingly the -7 has not done anything in this department. I really wonder how! But it's good!!)

F2.0 and larger, -7 adj. seems to be a sweet spot and there is hardly any FF as aperture widens.

subject at lesser than 3ft:
F2.8 and smaller, again, AF is quite accurate. But does BF at times.

F2.0 and larger, AF does FF as aperture widens, but a lot lesser than what it does without microfocus adj. It would wobble b/n FF and BF. I'd say it is quite acceptable, unless you are aiming at the center of a flower and sometimes it goes out of focus and the petals are sharp :(

Surprisingly, the results for (2) holds good even if the microfocus adj. is -10, with the close subject giving a BF sometimes.

Having found the sweetspot at -7 microfocus adj, now I headed outside with my Sigmatic Pentaxian torpedo... (someone rightly coined the verb for photography as "shooting" :) )

Outdoor, K7 set to -7 microfocus adjustment:
subject at greater than 6ft:
F2.8 and smaller, as expected, AF seems to be quite accurate

F2.0 and larger, AF seems to be softest at F1.4 (of course), but on underexposing, you can make out traces of sharpness. On the whole, I'd say ok with F2.0, and F1.8, but not very happy with F1.6 & F1.4.

subject at lesser than 3ft (And here's the big bummer...):
F2.8 and smaller, AF does FF.

F2.0 and larger, AF does significant FF. If I were to focus on the center of a flower, there's no way even the petals are sharp. What's sharp is only a couple of leaves in front. Shutter speed being pretty fast (like 100 or more) and mind you, I'm a pretty steady cam holder.

In fact, no matter what I do for 4.ii.a & b, my cam just does not focus on what I want. I even tried -10 microfocus adj. Still the same. Hell, I even tried 0 microfocus adj., and no damn difference. (Call me an idiot, but just being curious, I even tried +3, or something like that, of microfocus adj. and no difference what so ever!). It almost seems to me like the newly wedded couple (K7 + 50 Sigma) have a mind of their own and make up their mind before I even make the microfocus adj!!!!!

Having said all this, no matter what I do, what the subject distance is, (with microfocus adjustment between -7 and -10), or what the aperture is, if I aim it at flesh tones (faces), I always get a sharp face! The problem is clearly visible only in my test chart testing.

[If you've read through all this to here... man you've got patience!]
So my questions to you Sigma 50 1.4 HSM owners and to other experienced photographers are:
Q1. (And this is the $500 question!): Is my lens faulty? Do I need to return it and try another "piece"?
Q2. Less significant and much as I don't mind (but for the curious person that I am) how come my K7 is behaving this way, giving almost the same results with huge microfocus adjustments???

Could the kind hearted Pentax Forums' knowledgeable souls please congregate.

Thanks in advance. Happy shooting..

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