Can Pentax make A Decent Lens? Ricoh have not fixed QC issues...

Started May 18, 2014 | Discussions
OP Trevor G Veteran Member • Posts: 6,559
Re: Can Pentax make A Decent Lens? Ricoh have not fixed QC issues...
1

RPulley wrote:

It seems that the Nikon cool-aid has strong optical filtering properties....

I'm an aussie so the kool-aid slur doesn't actually mean anything. 

I even asked my wife, who is american, and she could really explain it to me either.  But I know it's a slur, probably a bit like reminding folk that Ghandi used to drink his own urine, I guess.

If you are referring to the fact that the Nikon is soft on both sides then you are right, but I don't use it at f1.8.  It's better at f2.0

In fact, both the Pentax and Nikon 50mm lenses work quite well at f2.0 closeup in low lighting, which is where I use them.  However, since the Pentx is so obviously good on one side and bad on the other I would like to get my money's worth!

I hope that's ok!

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Trevor G
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OP Trevor G Veteran Member • Posts: 6,559
Re: Can Pentax make A Decent Lens? Ricoh have not fixed QC issues...
1

UtahManSir wrote:

I have found that most of my decentering questions resolve when I put the camera on a tripod, use MLU and I am very very careful about how I am setup.

I know that I can cause soft left sides when my shutter finger gets sloppy, drives me nuts.

You have described something other than decentring.

My cameras were on a tripod for the station shot, but only for framing purposes.

You really shouldn't need a tripod at 50mm and 1/4000s unless you have been drinking heavily.

Even then I doubt that you could move the camera quickly enough and still get it framed like that. 

BTW I don't drink alcohol.  Well, not full strength, not very often (it's 0.5% soft drink sold in supermarkets here) and not when I shoot.

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Trevor G
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DAVID MANZE Veteran Member • Posts: 4,631
Re: Can Pentax make A Decent Lens? Ricoh have not fixed QC issues...
1

Trevor G wrote:

RPulley wrote:

It seems that the Nikon cool-aid has strong optical filtering properties....

I'm an aussie so the kool-aid slur doesn't actually mean anything.

I even asked my wife, who is american, and she could really explain it to me either. But I know it's a slur, probably a bit like reminding folk that Ghandi used to drink his own urine, I guess.

If you are referring to the fact that the Nikon is soft on both sides then you are right, but I don't use it at f1.8. It's better at f2.0

In fact, both the Pentax and Nikon 50mm lenses work quite well at f2.0 closeup in low lighting, which is where I use them. However, since the Pentax is so obviously good on one side and bad on the other I would like to get my money's worth!

"I hope that's ok!"

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Trevor G
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It's certainly OK by me and that's how it should be,I've spend good money and a lot of time to get decent sharp lenses that are up to spec, returns, long waits, phone calls to service depts etc, finally I think I now have them, was it worth the aggravation? Absolutely and certainly! no doubt about it.

So good luck with your replacement lens!

BTW. The kool-aid slur flew straight over my head as well.

Dave's clichés

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justin23 Veteran Member • Posts: 4,347
Re: Can Pentax make A Decent Lens? Ricoh have not fixed QC issues...

Trevor G wrote:

BobORama wrote:

Trevor G wrote:

Perhaps I have no idea what you are getting at, in which case I apologise in advance. Post the full image so we can get some context.

Oops - here it is (I'm so used to posting this image in the past I tend to think everyone knows it):

If you want a real test, shoot a completely flat surface perfectly perpendicular to the normal. Or better, shoot a star field wide open. Focus the center of the image perfectly. You will see various aberations, but they should be equal in magnitude as you get farther from the center. Any decentering will be apparent.

Here's the other, easy to see shot which shows the skew to the DOF:

Open at max size and scroll from one side to the other while watching the DOF shift as you scroll - it's closer one side than the other, and also a different depth from side to side.

Also if 19 of your 20 lenses have this issue, perhaps the issue is with the camera body.

Both sold. It didn't matter - they all showed the same relative skew.

Do all of the lenes have a right - left focus shift? And with a top to bottom shift?

It's not the camera. Betcha.

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Trevor G
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In the train station shot, I'm struggling to see what is actually in focus. I just don't see it as a good representation myself.

In the mixer photo, I struggled, however i downloaded the photo, and drew some lines across the frame. Yes the right side is ever so slightly less sharp than the left however I really had to look for it. Its not that obvious in this photo. I'd also argue that potentially the right side with such a narrow DOF that the right side may not be the same distance from the camera as the left.

I think there is a combination of you knowing its there, so you'll see it a lot more than anyone else. I'm not convinced its that bad myself.

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Justin
--------------------------------------------------------
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Leandros S Senior Member • Posts: 1,970
Even in its smudginess, the Nikon is not symmetric either

Trevor G wrote:

rogerstpierre wrote:

Who see that your Nikon lens is equally decentred on the opposite side, except that as opposed to the Pentax lens, nothing is actually sharp!

That's not decentring, actually.

Many lenses are soft on the sides. It's when one side is in focus and the other out of focus that you have decentring or skew.

And you are right that the Nikon lens is not as sharp as the Pentax, but it's also not decentred.

You're not going to convince me that the Nikon is equally "sharp" on both sides. It's simply not true, and easy to see.

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No amount of perceived entitlement can replace actual expertise.

pseudobreccia
pseudobreccia Regular Member • Posts: 414
Re: Can Pentax make A Decent Lens? Ricoh have not fixed QC issues...

Yes...they can produce a good lens and they do!

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Steve A. Kleinheider

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OP Trevor G Veteran Member • Posts: 6,559
Re: Even in its smudginess, the Nikon is not symmetric either
1

Leandros S wrote:

You're not going to convince me that the Nikon is equally "sharp" on both sides. It's simply not true, and easy to see.

Then I guess the question is:

Would you buy that DA50 lens off me, then?

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Trevor G
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DAVID MANZE Veteran Member • Posts: 4,631
Re: Even in its smudginess, the Nikon is not symmetric either
3

Hi Trevor,

Before getting too involved in lens tests showing pictures on this site where it's difficult to see faults due to compression/posting/ different peoples screens etc, try using distant scenes where the focus will be effectively fixed on infinity, it will be shots like this which show decentering most obviously because you will always be at the center point relative to infinity so there's no skewed shots, distant trees etc show blur very well.

Rely on your "own" opinions and decide calmly,  there are a lot of defensive people here who don't want to hear any criticisms against Pentax and can conclude that you are searching for problems and the like. I put forward my experiences just to find myself labeled as someone who just looking for faults. Lastly if you decide to return the lens then do it, there are plenty of others out there which perform up their specs.

Good luck, your better placed to see your images than anyone else.

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DAVID MANZE Veteran Member • Posts: 4,631
Re: Even in its smudginess, the Nikon is not symmetric either
1

First person;   "My wife died yesterday."

Second person;  "Oh I'm so so sorry, had she been unwell?"

First person; "No but she was a hypochondriac".

Second person; I see, she was obviously a very good one!

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RPulley Senior Member • Posts: 1,134
Re: Can Pentax make A Decent Lens? Ricoh have not fixed QC issues...

Trevor G wrote:

RPulley wrote:

It seems that the Nikon cool-aid has strong optical filtering properties....

I'm an aussie so the kool-aid slur doesn't actually mean anything.

I even asked my wife, who is american, and she could really explain it to me either. But I know it's a slur, probably a bit like reminding folk that Ghandi used to drink his own urine, I guess.

If you are referring to the fact that the Nikon is soft on both sides then you are right, but I don't use it at f1.8. It's better at f2.0

In fact, both the Pentax and Nikon 50mm lenses work quite well at f2.0 closeup in low lighting, which is where I use them. However, since the Pentx is so obviously good on one side and bad on the other I would like to get my money's worth!

I hope that's ok!

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Cheers
Trevor G
Silkypix tutorials at: http://photo.computerwyse.com

It has little or nothing to do with being American, other than the product (Kool-aid, actually) is an American one.

It is also not a slur as much as a description of behavior and it has its origin in a historical event:

"Drink the Kool-Aid" comes from the 1978 tragedy at Jonestown, where, at the urging of their spiritual leader Jim Jones, over 900 people drank cyanide-laced Kool-Aid and died. Since that infamous event, the phrase drink the Kool-Aid eventually came to mean to follow someone (or some school of thought) blindly, without question.

Explain as much as you want, like a few others here have stated, you are not going to convince me that the Nikon 50 image isn't softer on the left that the right. If you wanted to make your point, you chose the wrong Nikon lens.

Ray

MightyMike Forum Pro • Posts: 37,051
Re: Can Pentax make A Decent Lens? Ricoh have not fixed QC issues...
1

Trevor G wrote:

MightyMike wrote:

emem wrote:

Trevor G wrote:

DAVID MANZE wrote:

In short 2/3 rds of the the lenses I've bought new or S/H were decentered and were returned.

Funny how some of us have all the baddies...

Some people are more discerning than others.

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Mike McEnaney. (emem)
www.veritasmea.com

Yes, and some people see problems where none exist, I'm not saying the OP is one of them but there sure are hypochondriacs out there that easily imagine problems which account for some of those who keep getting multitudes of bad lenses.

Do you think that sort of sharpness error is acceptable, even in a cheapskate new lens?

How can hypochondria make a good lens go bad?

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Trevor G
Silkypix tutorials at: http://photo.computerwyse.com

If 95% of your lenses are bad why haven't you sent the whole kit into Pentax for them to figure it out a long time ago before you kept buying lenses. I suggest you're testing technique is flawed and if there is such a massively widespread issue with your gear that maybe the camera is flawed and the lenses are fine. However we won't know for sure until either you do proper testing or send the whole kit into Pentax and have them figure it out. Maybe not the whole kit, just the worst offenders. I just figured it was common sense to get things fixed before acquiring more stuff that all has the same problem, maybe if you figured it out after the first couple lenses you wouldn't be all angry with Pentax now and you wouldn't have the problem anymore.

You see it on the forum all the time

Complainer "Wah Wah Wah my lens is bad and i hate company X for it"

Logical contributor "So send it into company X to get it fixed"

Complainer "Wah! i don't want to"

Logical contributor "Why not?"

Complainer "Wah! Because i won't have anything to complain about if i do that, and besides its easier to send it back to where i bought it from and have them resell it to the next person unfixed"

Its pretty much what happens in a nutshell

Then there is the hypochondria, How many times have i seen a new Pentax owner, a first time poster and their first post is "ok i just bought camera X and lens Y, what is the best way to test for problems?" Really? your first thought is look for problems not enjoy the gear until you discover a problem. These people are misled to believe that everything will have a problem and its the forum that is doing the misleading. Then there are the chronic testers, the ones that have a decent test procedure rarely find problems, the others with sloppy testing techniques continuously find problems which are ofter dismissed by most on the forums but regardless of detailed dismissal the original tester will always believe they've got a bad lens.

Another set of people sill sit there with a bad lens and fume for years with hatred and disgust. When they're finally ready to lash out about it because they're at their breaking point they write an angry rant about how company X failed them with so much hatred. After a few responses the forum finds out they knew they had the problem for years and now it will cost them a fortune to fix as they waited till it was off warranty to even consider fixing it.

There are all kinds of nuts on these forums, its a shame their illogical lack of common sense ruins the forum for the rest of us.

You asked me "Do you think that sort of sharpness error is acceptable, even in a cheapskate new lens?" I respond by asking you "If you just bought a new car and you found it didn't track straight on the road would you turn to a forum and complain or would you take it into the dealership and get it fixed at their cost?" What is the forum going to do other than tell you to get it fixed!

I now apologize to the rest of the forum, I know logic and common sense isn't always allowed on the forum, something i often forget.

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Mike from Canada
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MightyMike Forum Pro • Posts: 37,051
Re: Can Pentax make A Decent Lens? Ricoh have not fixed QC issues...

Maybe you should have looked at this review... clearly shows the decentering in their copy

http://slrgear.com/reviews/showproduct.php/product/1519/cat/45

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Mike from Canada
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OP Trevor G Veteran Member • Posts: 6,559
Re: Can Pentax make A Decent Lens? Ricoh have not fixed QC issues...
2

justin23 wrote:

In the train station shot, I'm struggling to see what is actually in focus. I just don't see it as a good representation myself.

Did you just look at the small image I just posted, or the two crops in the first post?

Here are the 2 100% criops from the full image shown in a previous post - surely you can see the difference, or did you not read the first post?

5052  Left view - very sharp for f1.8

5052 Right side view - very fuzzy, even for f1.8

These are 100% crops taken from their respective, as labelled, edges.

You can't see a difference?

In the mixer photo, I struggled, however i downloaded the photo, and drew some lines across the frame. Yes the right side is ever so slightly less sharp than the left however I really had to look for it. Its not that obvious in this photo.

Have another look at exactly what is oin focus.

On the right side look at the words LCR BLEND which are in focus, then the second AUX above that, still in focus.

Slide over to the left and AUX is OOF by the time you reach Input 14.  On the left side you cannot clearly read MAIN (which is at the same distance from the camera as LCR Blend) but the first word to really have clarity is MAIN.

Next check the lower (closer) limit of focus or DOF: the Input Channel number 6 is clear, as is the number 10 at the top of the fader slot.  However, as you move right the number 10 is lost by the time you reach Input Channel 10.

On the right hand side the closer point of real legiility is somewhere around MUTE  or PFL.

The focus point was on the brown knob above channel 13.

I'd also argue that potentially the right side with such a narrow DOF that the right side may not be the same distance from the camera as the left.

With respect, you don't know what you are talking about.

At the distance from the object, even at any distance, if you are not square on you would have convergence on 2 or 4 sides.

Check again at WHAT is in focus on each side.  Look at the numbers printed on the panel, not at the knobs.  At the very least you will learn how to check your own lenses.

I think there is a combination of you knowing its there, so you'll see it a lot more than anyone else. I'm not convinced its that bad myself.

And you actually looked at both left and right side edges of the station front?

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Trevor G
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OP Trevor G Veteran Member • Posts: 6,559
Re: Can Pentax make A Decent Lens? Ricoh have not fixed QC issues...
1

MightyMike wrote:

Maybe you should have looked at this review... clearly shows the decentering in their copy

http://slrgear.com/reviews/showproduct.php/product/1519/cat/45

Yes, but I would have still bought it because I don't want to gamble with the DA55mm at the moment.  That has had even worse decentring in DPRs experience, and also Photozone, I think.

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Trevor G
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OP Trevor G Veteran Member • Posts: 6,559
Re: Can Pentax make A Decent Lens? Ricoh have not fixed QC issues...
1

RPulley wrote:

the product (Kool-aid, actually) is an American one.

It is also not a slur as much as a description of behavior and it has its origin in a historical event:

"Drink the Kool-Aid" comes from the 1978 tragedy at Jonestown, where, at the urging of their spiritual leader Jim Jones, over 900 people drank cyanide-laced Kool-Aid and died. Since that infamous event, the phrase drink the Kool-Aid eventually came to mean to follow someone (or some school of thought) blindly, without question.

Jonestown was a peculiar sign of American madness and will always be very remote from Australia. It's a derogatory expression, isn't it.  You weren't trying to flatter or commend me by using it, were you?  But thanks for the historical backgound...

Explain as much as you want, like a few others here have stated, you are not going to convince me that the Nikon 50 image isn't softer on the left that the right. If you wanted to make your point, you chose the wrong Nikon lens.

<Yawn> The Pentax is very sharp on the left, though!

I suppose half a good lens is better than none.  I'll call them up tomorrow and see if they can supply the other half.

PS  Love the fact that you cannot see a problem with the Pentax lens!  Maybe you really are one-eyed?

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Trevor G
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OP Trevor G Veteran Member • Posts: 6,559
Re: Can Pentax make A Decent Lens? Ricoh have not fixed QC issues...
4

MightyMike wrote:

If 95% of your lenses are bad why haven't you sent the whole kit into Pentax for them to figure it out a long time ago before you kept buying lenses.

Mike - you aren't so Mighty if you don't read the original post in a thread you comment on.

It's all been explained already, but just in case you read this, I'll remind you (said at least twice in this thread already) for the third time:

I SOLD ALL MY PENTAX GEAR 4  YEARS AGO BECAUSE I WAS SO DISAPPOINTED WITH IT.  Each lens was accurately described with pictures posted but they still sold.

I now own three lenses.  I have just returned to pentax because I love old CCD cameras like the K200D (just purchased) and my original *istDS2.  I have no problem putting up with the flaws in the old FA28-70 f4.0 - they are well known and it's an old lens.

I shouldn't have to send back a brand new f1.8 prime lens.

But I will.

The other lens is an 18-55 kit lens, which is sharp in the centre but not so good on the sides.  That's not a problem.

I suggest you're  your testing technique is flawed and if there is such a massively widespread issue with your gear that maybe the camera is flawed and the lenses are fine.

This is a different K200D to the one I last had.

I only have one lens I am not happy with, the DA50 f1.8.

Very highly rated by DXOMark and, if I can get one with both sides performing like my sample is on the left, I will be ecstatic!

You don't need to do much to take a shot from this angle, straight on, do you?

I'm 110m away - that's too far for any camera misalignment to produce a soft right hand side.
 Isn't it?  Especially from straight on.

However we won't know for sure until either you do proper testing or send the whole kit into Pentax and have them figure it out. Maybe not the whole kit, just the worst offenders. I just figured it was common sense to get things fixed before acquiring more stuff that all has the same problem, maybe if you figured it out after the first couple lenses you wouldn't be all angry with Pentax now and you wouldn't have the problem anymore.

I'm not angry - just disappointed.

I wish they would get their act together.  Don't you?

If Sigma can do it, so can Pentax.

Why keep making excuses and encouraging them to keep serving up the same sloppy output?  I'm assuming this is your usual response?

You asked me "Do you think that sort of sharpness error is acceptable, even in a cheapskate new lens?" I respond by asking you "If you just bought a new car and you found it didn't track straight on the road would you turn to a forum and complain or would you take it into the dealership and get it fixed at their cost?" What is the forum going to do other than tell you to get it fixed!

I have contacted CRK today and sent some pics.  Fortunately I can return the lens if I feel it is not of merchantable quality, which it isn't.  I would like a good one, though - it looks like it certainly has the potential!

Maybe Pentax, one day, will do something about their very average lens QC.

Sigma had a very serious problem in that area but have, in the space of a couple of years, become  the supplier of the sharpest, best IQ lenses in the world.  That's what commitment to quality production and design can do.

I now apologize to the rest of the forum, I know logic and common sense isn't always allowed on the forum, something i often forget.

Perhaps you are right now leading the way in the very thing you deplore.

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Trevor G
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BobORama
BobORama Senior Member • Posts: 2,376
Re: Please use better experiment protocol
4

Trevor G wrote:

jf_tea wrote:

shallow DOF at f/1.8

subject distance at left vs. right is significantly different.

Not a very good guess, jf. I'm sorry I didn't post the full image as well so that you could see the layout.

Samples shown earlier cropped from each side of this image...

Please use better experiment protocol.

Hmmm...now that you can see what I did, do you still feel the same way?

Yes.   Thanks for posting this.   Look at the central lamp post, you have adjusted you camera so that the lamp post is perfectly aligned with the window behind it.   And the vertical center line of the photo is aligned with the lamp post.    The upper and lower roof line of the colonnade ( the alternating cream and burgandy roof ) is in perfect horizontal alignment down to a pixel level.   So we have our coordinate system.

But the building is actually skewed with the left side further back than the right.

You can see this very clearly looking at the angle of the seams in the slanted cream-burgandy roof.     IF the building were parallel with the focal plane of the camera, AND the center of the image were centered on the vertical axis of symmetry of the building, the slanted roof lines would be symmetric from right to left.   They are not.   And they suggests the left side is father back.   So my diagram explains your observation entirely.

Your lens is fine, its your expectations that are off center.

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miles green
miles green Veteran Member • Posts: 6,296
Re: Can Pentax make A Decent Lens? Ricoh have not fixed QC issues...

Shooting landscape/architecture wide open and grumbling about corner sharpness....... How does the lens perform in actual use?

Sure you might get a better copy, so you could try exchanging it.

Pentax makes plenty of excellent glass btw, but expect QC and wide open sharpness to be better on pricier models.

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Miles Green
Pentaxian with chronic LBA
Corfu, Greece

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jf_tea Senior Member • Posts: 1,016
Re: Please use better experiment protocol

Trevor G wrote:

jf_tea wrote:

shallow DOF at f/1.8

subject distance at left vs. right is significantly different.

Not a very good guess, jf. I'm sorry I didn't post the full image as well so that you could see the layout.

Samples shown earlier cropped from each side of this image...

Please use better experiment protocol.

Hmmm...now that you can see what I did, do you still feel the same way?

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Cheers
Trevor G
Silkypix tutorials at: http://photo.computerwyse.com

Thanks for posting the whole picture!

The subject is far enough that hot air turbulence can fuzz out minute details.

The building is behind an asphalt covered parking lot. Was warm or hot or cool ? Whatever is the answer, it's enough to fuzz out details at that distance. The turbulence would affect each picture taken a bit differently. (Quite interesting if that's one wants to get).

Unless you made a "control test" with a lens which you know is perfect (or near perfect), you cannot be sure what is the cause of massive visual aberrations at that distance, with a lot of heat absorbing and reflecting bodies between the camera and the whole width of the subject.

Actually, it would be good to read some serious professional documentation about how to test a lens at this point. Relying on the opinions of dozens of people in a forum for such a simple precise task has proven improductive. IMHO.

My enthusiasm for long lens is less since I have seen how distance affect pictures taken at different times of the day, in different season.

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OP Trevor G Veteran Member • Posts: 6,559
Re: Please use better experiment protocol
3

BobORama wrote:

Trevor G wrote:

jf_tea wrote:

shallow DOF at f/1.8

subject distance at left vs. right is significantly different.

Not a very good guess, jf. I'm sorry I didn't post the full image as well so that you could see the layout.

Samples shown earlier cropped from each side of this image...

Please use better experiment protocol.

Hmmm...now that you can see what I did, do you still feel the same way?

Yes.   Thanks for posting this.   Look at the central lamp post, you have adjusted you camera so that the lamp post is perfectly aligned with the window behind it.   And the vertical center line of the photo is aligned with the lamp post.    The upper and lower roof line of the colonnade ( the alternating cream and burgandy roof ) is in perfect horizontal alignment down to a pixel level.   So we have our coordinate system.

But the building is actually skewed with the left side further back than the right.

LOL.  By how much?  Remember we are 110m away from the front of the building.

Would you mind calculating the DOF at that distance, please?

And what does this say about the many hundreds of photos I have taken of this building which don't show OOF on one side, some of them with Pentax cameras and lenses?

You can see this very clearly looking at the angle of the seams in the slanted cream-burgandy roof.     IF the building were parallel with the focal plane of the camera, AND the center of the image were centered on the vertical axis of symmetry of the building, the slanted roof lines would be symmetric from right to left.   They are not.   And they suggests the left side is father back.   So my diagram explains your observation entirely.

Except that you are wrong, very wrong.

Fo the first time ever I used a DOF Calculator.  Here is what it says for an APS-C sensor with a 50mm lens at f1.8 :

Subject distance 110 m
Depth of field Near limit 42.8 m

Far limit Infinity

Total Infinite

In front of subject 67.2 m

Behind subject Infinite

Hyperfocal distance 70.2 m

Circle of confusion 0.02 mm

Your lens is fine, its your expectations that are off center.

I think you might belong to the Circle of Confusion. 

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Cheers
Trevor G
Silkypix tutorials at: http://photo.computerwyse.com

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