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02-19-2012, 09:41 PM   #31
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Earlier, I suggested some primes. Primes are good. Primes are basic. I was raised with primes. I'd been shooting awhile before zooms and AF and digital were invented. I'd been shooting 40 years before I even had a zoom or AF. I'll repeat a gross (but true) oversimplification: AF zooms are great for TAKING pictures, MF primes are great for MAKING pictures. And primes make me move around more -- they're good exercise.

When I travel, the DA18-250 is on the camera. After I've been someplace a day or so and have scoped-out the possibilities, I grab the DA10-17 and Tamron 10-24 and some selected prime(s) and concentrate on specifics. But with the DA18-250 I can grab street shots, then capture out-of-reach details, etc. And the next day I'll be back with the Vivitar 24/2 or 28/2 or 90/2.8 macro; or the Nikkor 35/2 or 85/2; or the K50/1.2 and Macro-Tak 50/4 and Super-Tak 55/1.8 and maybe other Fifties with different characteristics. Can't have too many primes, eh?

02-20-2012, 03:40 AM   #32
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These lens reviews tell me a lot about available 18-250 mm lenses. In the sharpness category, which is the deciding factor for me, the Pentax is top dog. I also like the idea of a Pentax lens on a Pentax camera and the lens is a bit cheaper than the others. Must try to get one and try it out.
02-20-2012, 03:16 PM   #33
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The Sigma only has three reviews. Had one Sigma "reviewer" chosen a "9" as well, the average would be "9". The tests Abbazz pointed to are much more informative.

QuoteOriginally posted by Abbazz Quote
I agree that technical reviews are to take with a pinch of salt, but SLRGEAR.COM has tested both lenses:
Thanks for the pointer to these tests. The Tamron clearly comes out as the winner in terms of sharpness.

QuoteOriginally posted by RioRico Quote
I'll repeat a gross (but true) oversimplification: AF zooms are great for TAKING pictures, MF primes are great for MAKING pictures.
Maybe that applies to beginners.

For someone who knows what they want, a prime is limiting in the sense that it ties perspective to AOV. This limitation can help beginners to understand the importance of perspective, i.e., distance to subject, but for a photographer familiar with perspective a zoom is a much more flexible tool.

Can primes be useful to teach beginners photographic seeing? Yes.

Is the use of a prime the difference between taking a picture vs making an image? No.
02-20-2012, 03:25 PM   #34
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The best place I know for lens tests are photozone. I wont buy any lens until i see test results on here.
All Tests / Reviews

02-20-2012, 04:43 PM   #35
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QuoteOriginally posted by Class A Quote
The Sigma only has three reviews. Had one Sigma "reviewer" chosen a "9" as well, the average would be "9". The tests Abbazz pointed to are much more informative.
I did not say that the user reviews were definitive. I said that of the reviews I had seen, the DA and Tamron rated higher than the Sigma. I'm very glad Abbazz linked to real tests. I haven't bothered deeply investigating the Sigma myself because Sigma's known QC issues drive me to look elsewhere.

QuoteQuote:
Is the use of a prime the difference between taking a picture vs making an image? No.
And I also said that it's a gross oversimplification. Once *can* work carefully with AF zooms, and sloppily with MF primes. But I think *most* toggrs take more care with the picture-making process when using MF primes, in part because we need to be 1) more active when framing shots, and 2) more cognizant of focus and aperture issues. AF zooms allow (but don't mandate) sloppiness, moreso than MF primes. YMMV.
02-20-2012, 06:30 PM   #36
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QuoteOriginally posted by RioRico Quote
I haven't bothered deeply investigating the Sigma myself because Sigma's known QC issues drive me to look elsewhere.
I believe that today's Sigma lenses are no worse in terms of QC than lenses from any other manufacturer.

Name just one lens in the current Sigma line up that has a reputation that is as bad as the two Pentax flagship DA* zooms, the 50-135 and 16-50. The latter is not only notorious for its SDM motor to die, but also for serious decentering issues.

I would not hesitate a single moment to buy a used Sigma lens with an HSM motor. In contrast, I'd buy a DA* 50-135 or 16-50 essentially as an MF lens only. SDM reliability is just too low with these models.

QuoteOriginally posted by RioRico Quote
And I also said that it's a gross oversimplification.
You also said it was a "true" one, though.
I don't think it is true, even as an oversimplification.

QuoteOriginally posted by RioRico Quote
AF zooms allow (but don't mandate) sloppiness, moreso than MF primes. YMMV.
I know that this is a commonly held opinion, but I don't believe it.

Will a manual lens slow most photographers down and thus help them with their composition, etc.? Yes.

Does a zoom lure a photographer into slopiness more so than a prime -- provided that the photographer knows about the importance of perspective? I don't think so. Only beginners who have not yet internalised the importance of perspective should have a problem with zooms.

Finally, one should take note of the serious disadvantage of primes that they couple perspective and AOV (framing). If I have the choice between one prime that would either yield the wrong perspective or the wrong framing, I'll take the zoom. The latter will allow me to make the desired image, whereas the former would force me to take a picture.
02-21-2012, 08:29 PM   #37
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OK, you win, I'm wrong, you're right, I'm too tired to argue this further. All those retailers who said that Sigma lenses are returned at higher rates wre lying, as were the pros who bitched to me about Sigma's quality problems. Everyone who says they take more care shooting MF primes than AF zooms are lying too. Everything I thought I knew is false. Ciao.
02-23-2012, 12:01 AM   #38
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QuoteOriginally posted by RioRico Quote
All those retailers who said that Sigma lenses are returned at higher rates wre lying,
A retailer who doesn't speak the truth. That's certainly unthinkable.

I have personally witnessed retails pouring pure BS over customers just to push a product with higher margins.

Granted, some retailers may genuinely belief in their recommendations. Sometimes, however, these beliefs are misguided. Just like we tend to belief that we somehow manage to always chose the one out of several queues that takes the longest to be processed. Its human nature to see patterns even if they are not there.

Fifteen years ago, Sigma probably deserved its bad rep. But that's not a good reason to perpetuate the lame "Sigma = bad" prejudice.

If you had written "Sigma's QC is bad, but at least its better than Pentax's" I may have not taken issue with your statement. Seriously, where is the Sigma equivalent of the "DIY SDM repair" thread or the numerous "SDM petition" threads?

A forum member tried five DA* 55/1.4 lenses before he finally gave up. He couldn't get a good sample. Dpreview went through three copies and even the third had decentering issues.

Maybe the Pentax Ltd lenses are beyond reproach? Unfortunately, in particular the FA 31mm seems to come with quite some tolerance in the built and one hears of Ltds disassembling themselves because the three screws holding the front part haven't been correctly installed.

Is Pentax QC rubbish overall? I'll leave the answer to you, but I don't see where Sigma is worse. On the contrary.

QuoteOriginally posted by RioRico Quote
... as were the pros who bitched to me about Sigma's quality problems.
I understand that top pros typically rent their equipment and care little about brands. Maybe you haven't heard pros bitching about Pentax because they don't use it?

I heard benjikan bitch about Pentax when his DA* 16-50 SDM motor crapped out during a paid shoot. It was MF from then on.

QuoteOriginally posted by RioRico Quote
Everyone who says they take more care shooting MF primes than AF zooms are lying too.
I didn't claim anything like it.

02-24-2012, 03:33 PM   #39
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Gentlemen, since my initial posting on this thread, I've received a tremendous amount of advice on finding a sharper lens to replace my Tamron 28-300mm f/3.5-6.3 mm zoom. I want a lens that will complement my Pentax 12-24 mm which is tack sharp. After digesting your information I planned to get a Pentax 18-250 mm lens which can still be bought used. By chance I reviewed the performance of third-party lenses for Pentax, given in this forum, and discovered the Vivitar 28-90 mm f/2.8-3.5 lens which has a 10 rating for sharpness (my main criterion for purchase). After reviewing my photographic habits I think that about 80% of my shots fall in this zoom range. The average price for this lens is said to be $65, which is nothing. Can anybody recommend this lens for use with my Kx? I believe it has lots of plastic in it, but I don't beat my equipment to death like some of you advanced amateurs and pros. What say ye?
02-29-2012, 08:34 AM   #40
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QuoteOriginally posted by P. Soo Quote
Gentlemen,
A few ladies are here too. And some indeterminates. And some who may not even be human. On the internet, nobody can hear you slither. Unless you post a video.

QuoteQuote:
By chance I reviewed the performance of third-party lenses for Pentax, given in this forum, and discovered the Vivitar 28-90 mm f/2.8-3.5 lens which has a 10 rating for sharpness (my main criterion for purchase). After reviewing my photographic habits I think that about 80% of my shots fall in this zoom range. The average price for this lens is said to be $65, which is nothing. Can anybody recommend this lens for use with my Kx? I believe it has lots of plastic in it, but I don't beat my equipment to death like some of you advanced amateurs and pros. What say ye?
I can't comment on this specific lens. I *can* say that:

1) Much of the 'plastic' in modern lenses is polycarbonate aka Lexan, extremely tough stuff. When dropped, such plastic bends and rebounds, while metal dents.

2) That Viv is manual-focus, right? I have a few MF zooms that, except for a very few very special cases, don't see a lot of use on my K20D because of SR issues.

I use SR constantly except with my MF zooms. In bright light that's no problem. In less-than-dazzling light, I have various options:

* Switch SR off and maybe use a tripod.
* Re-enter the SR focal length when zoomed.
* Calculate a best-possible focal length for the SR'bot.

To calculate the optimal FL, use this formula: FL= (2*M1*M2)/(M1+M2) where M1 and M2 are the minimum and maximum focal lengths in the zoom's range. For a 28-90mm that's 42.7mm, so I'd enter either 40mm or 45mm to the SR'bot.

But if SR-aided sharpness is important, this isn't really satisfactory. So when shooting a MF zoom in good light and I want sharp images, I either use a tripod, or re-enter the FL, or shoot with the 1/FL*5+ shutter-speed rule. So at 28mm, shoot at least 1/160 second, and at 90mm, at least 1/500 second. That's if sharpness is desired. Otherwise, whatever.
02-29-2012, 12:49 PM   #41
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Hi Rio, thanks for your reply. I apologize for using the word "gentlemen" but I guessed that the people who gave me advice on my initial question were men. I may have been wrong so I will be more careful in future. I saw a couple of good reviews on the Vivitar 28-210F/4.2-210 mm, Series 1 lens. Based on this, I just purchased it used from B&H for $80. The exterior is polycarbonate except for the mount which is metal. It is very well constructed and even with the lens fully zoomed there is no play in the barrels. It looked brand new. It is also auto focussing and seems to be fully compatible with my Kx. I took a few quick shots in my backyard and I think that it is at least as sharp as my Tamron 28-300 mm lens. I intend to keep it since it will be a good backup for the Tamron, or vice versa. How can I go wrong for $80?
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