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07-04-2013, 09:07 AM   #121
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I've found lenses at garage sales and flea markets that I paid very little for. There is a big difference in what I will avoid at garage sales and what I will actually buy from a shop or online. Buying a box of camera gear for $10 that was left at a campground and never claimed will usually turn up something of value. One that came to mind was a pair of JC Penney lenses, a 135/2.8 and a 28/2.8. Wide open, they are dreadful and while usable stopped down, I have other lenses that size that are much better. But inside that camera bag was a genuine Pentax M42-K mount adapter and some Hoya CPL filters in various sizes so I still came out ahead I think. The least useful item in my dog pen is an Opteka 500/8 mirror lens. I have had a few decent shots from it so it isn't a total waste but I still feel guilty about spending 40 bucks on it.

07-04-2013, 11:28 AM   #122
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QuoteOriginally posted by stevebrot Quote
Whatever...I guess I am old school. If it looks cheaply made and feels cheaply made, chances are it is cheaply made.


Steve
Heartily agree
07-04-2013, 11:42 AM - 1 Like   #123
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QuoteOriginally posted by Digitalis Quote
The sigma 30mm f/1.4 EX DG springs to mind.
OP, don't listen to him. That's my favorite lens of all time. Best $300 I've ever spent. I've used it more than any other lens since I bought it.

There are valid reasons for disliking it (vignetting, poor corner performance, bokeh not to everyone's taste), but the vigorous debate over how terrible/awesome Sigma's 30mm and 35mm lenses are just goes to show you that everybody's priorities are in different places.
07-04-2013, 05:26 PM   #124
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QuoteOriginally posted by Digitalis Quote
The sigma 30mm f/1.4 EX DG springs to mind.
Only to the minds of people who don't get this lens.

Anyone not knowing what brilliant images this lens can produce should have a look at the Sigma 30/1.4 EX image thread.

07-04-2013, 05:49 PM   #125
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QuoteOriginally posted by scratchpaddy Quote
OP, don't listen to him.
QuoteOriginally posted by Class A Quote
Only to the minds of people who don't get this lens.
LOL I knew this would get as rise out of you two..

I know the sigma 30mm f/1.4 is capable of producing good images - but it isn't sharp* across the frame, which is in my opinion a serious flaw in a general purpose "Normal" 45mm equiv. lens. Nearly every 50mm lens I own performs superbly across the frame at f/4~f/5.6, the sigma 30mm f/1.4 isn't critically sharp in the corners even at f/11.

*
Yes sharpness is a bit overrated - but with the 180 50mm lenses I own the average lens resolving power across the frame at f/5.6 for the entire collection is somewhere around the 74 Lp/mm mark - an average rating like that cannot simply be an accident.

Last edited by Digitalis; 07-05-2013 at 02:24 AM.
07-05-2013, 10:13 AM   #126
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QuoteOriginally posted by wombat2go Quote
Incidentally I have a SMC Pentax -M 1:2.8 24mm which had heavy use before i got it. It has some cosmetic wear, White spots are visible on one of the inner elements in front group, and it shows in the images as loss of sharpness and contrast. The diaphragm is sluggish, not snappy, so it does not stop down below about f/8 and the filter thread is slightly distorted.
Is it worth trying to get this one repaired?
If you mean a K24/2.8, it may be worth asking Eric to take a look.
Mine got sluggish after use in an extremely hot environment,
but Eric got it back to top form.

The only issue with yours might be the white spots,
if they're separation of the join between the 3rd and 4th elements.
07-05-2013, 10:50 AM - 1 Like   #127
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QuoteOriginally posted by Digitalis Quote
The sigma 30mm f/1.4 EX DG springs to mind. There are also certain Pentax FA 28-80mm cheap zoom lenses lenses that should be avoided.
Sigma 30mm is one the best lens I owned, loved it more than my FA35 and arguably even better than FA31.

QuoteOriginally posted by Digitalis Quote
I know the sigma 30mm f/1.4 is capable of producing good images - but it isn't sharp* across the frame, ....
Sigma 30mm is amazingly sharp, even sharper than most Pentax 50mm in center. Corners are slightly weak but not noticeable in real life. In fact that creates 3D effect in portraits.

Last edited by yusuf; 07-05-2013 at 10:59 AM.
07-05-2013, 08:58 PM   #128
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QuoteOriginally posted by Digitalis Quote
I know the sigma 30mm f/1.4 is capable of producing good images - but it isn't sharp* across the frame, which is in my opinion a serious flaw in a general purpose "Normal" 45mm equiv. lens.
And who says the Sigma 30/1.4 EX is meant to be a general purpose lens?

Do you honestly believe that Sigma would not have been able to achieve across the frame sharpness if they wanted to? They could have copied numerous designs that achieve just that but don't come near the rendering the Sigma 30/1.4 EX can deliver. A flat field isn't everything. I'm glad that there are manufacturers that refrain from building boring glass that performs well on test benches but in order to do so compromises on bokeh, focus to OOF transition, etc.

N.B., your 50mm lenses are much easier to design on K-mount and, again, I'm convinced Sigma had other plans for the 30/1.4 than to aim for across the field sharpness.

07-05-2013, 10:27 PM   #129
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QuoteOriginally posted by Class A Quote
Do you honestly believe that Sigma would not have been able to achieve across the frame sharpness if they wanted to?
I'm sure they could have, and if they wanted to they could have accomplished it without compromising the optical characteristics of the lens itself - however, they chose not to. Probably because of the cost involved, after all the lens was designed as a "normal" lens for a cheap high volume format : APS-C which as it happens to be a near perfect "normal" lens on sigma's flagship camera the SD1. It is as simple as that, that is why many people are willing to fork out for the FA31 limited because pentax didn't make that compromise.

QuoteOriginally posted by yusuf Quote
Sigma 30mm is amazingly sharp, even sharper than most Pentax 50mm in center. Corners are slightly weak but not noticeable in real life. In fact that creates 3D effect in portraits.
This completely ignores the fact that the Sigma 30mm f/1.4 has higher distortion* than the FA31 - for portraiture, the best lenses that are designed for this purpose have practically zero distortion. Sure, you can correct this in post processing but the coma and astigmatism which are affected by this trait cannot.

*1.7% vs 0.8% - for reference 1% distortion will be visible to the trained eye.
07-05-2013, 10:50 PM   #130
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It seems that all of our lenses have their pros and cons. I am a big fan of the FA31, and despite some of the well discussed cons of the Sigma 30, I could never say that it is one to avoid, just based on some of the great photos I've seen people (our fellow member TOUGEFC aka Simon Thomas especially comes to mind) produce with it.
07-05-2013, 11:58 PM   #131
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QuoteOriginally posted by Digitalis Quote
This completely ignores the fact that the Sigma 30mm f/1.4 has higher distortion* than the FA31 - for portraiture, the best lenses that are designed for this purpose have practically zero distortion. Sure, you can correct this in post processing but the coma and astigmatism which are affected by this trait cannot.
Actually I bought Sigma for portraits & shooting at f1.4 and it never disappoints (some of my portraits on FB page, link in my signature). It can seriously create magic. May be you are right clinically but I seriously stopped doing that kind of pixel peeping as I started enjoying photography as an art. And I exclusively shoot portrait and street so a bit of distortion and corner doesn't matter for me, may be my eyes are not trained for seeing those faults.

I owned FA35 and it's an excellent lens but the images ir produces are too flat without any special characteristic. FA31 wasn't too different (I posted comparison in one of my previous post). Sigma 30mm has magic this, might be those faults made it achieve that.
07-06-2013, 12:38 AM   #132
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QuoteOriginally posted by todd Quote
... despite some of the well discussed cons of the Sigma 30, I could never say that it is one to avoid, just based on some of the great photos I've seen people (our fellow member TOUGEFC aka Simon Thomas especially comes to mind) produce with it.
Didn't you notice the unsharp corners and the terrible distortion?
07-06-2013, 01:45 AM   #133
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QuoteOriginally posted by yusuf Quote
Sigma 30mm has magic this, might be those faults made it achieve that.
Which is why I suppose the Helios crowd has so much fun, But I prefer clinically accurate results - My eyes are drawn to optical faults in lenses, it was something I have been taught to do when assessing image quality. In many ways it is a bit of a curse because many of the lenses I work with commercially are incredibly expensive. But my clients do notice the quality of my images and appreciate the extra effort I go through so that makes it worth it IMO. People who don't earn money with their photographs sometimes measure IQ by different standards than people who do.

Bear in mind I use the Pentax FA43mm f/1.9 Special on my Leica M9, whilst not being the sharpest lens in the corners at wide apertures, it sharpens to the point of rivaling the performance of the superb Leica Summilux-M 50mm f/1.4 ASPH. Which is widely regarded as being one of the best 50mm lenses ever made.

Last edited by Digitalis; 07-06-2013 at 01:56 AM.
07-06-2013, 06:14 AM   #134
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Pentax 80-320 - probably the worst I ever owned (apart from a 180mm Telegor which went back decades ago) = soft at the long end and gradually got so sloppy in the barrel that I dare not off-load it on anyone else:-(
John
07-06-2013, 08:43 AM   #135
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QuoteOriginally posted by Digitalis Quote
Which is why I suppose the Helios crowd has so much fun
Exactly. To my untrained-non-professional eye, I really enjoy what some people can do with Helios.. Check out a few of the images of this photographer for example. I wouldn't mind having me some heliosinations.

QuoteOriginally posted by Digitalis Quote
My eyes are drawn to optical faults in lenses
I wouldn't mind having your problem. I am not a pro and not very experienced, but I can say that for years I always thought (because this is my favorite cropped focal length range) that I'd end up getting the Sigma 30 at some point... I assumed the FA31 would never be possible or justifiable for me, and I always liked what I saw from the Sigma. Then this year I was fortunate to come into just enough dough to be able to get the 31 if I wanted. I almost had the money in time when I could have got the Sigma during that $289 deal that was going on this year and then that would have been a no-brainer for me, but I just missed that window and then the price shot back up over $400. That made it hard to want to buy the Sigma in my situation, in part because I had to make the buy fast or lose the money to other bills.. Despite all that I spent a lot of time trying to convince myself to just get the Sigma and be practical. The more I looked at the matter though I realized that if low light shooting and subject isolation stuff was all or mostly what I wanted to do, then I could have been content with the Sigma. Aside from the special rendering that made me really drool for the 31, it was the across the frame issues of the Sigma (the triangular highlights, BD.. and (as you've stated well - the sharpness across) that helped me realize the 31 was the way to go for me, in order to get as much of an all purpose prime lens in this range as possible. There was also the FF factor in my equation, but all that said, as an amateur, if I had only had enough dough for the Sigma, I would have got it and had been happy with it too and made the most of it that I could, just as I am trying to do with the 31.
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