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MACRO LENS - Page 2

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Posted: Tue Apr 17th, 2012 19:44

11^th Post

Doug

Joined:	Sun Apr 8th, 2012
Location:	Adelaide, Australia
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Before you decide to jump either way have a read of the article at the following link

Lens Variation:LINK

Roger Cicala
Lensrentals.com Wrote:

... I don't say conclusion, because this little post isn't intended to conclude anything. It simply serves as an illustration showing visually what we all (or at least most of us) already know:
Put different copies of the same lens on a single camera and each will vary a bit in resolution.
Put different copies of the same camera on a single lens and each will vary a bit in resolution.
Truly bad lenses aren't a little softer, they are way softer.
Autofocus isn't as accurate as live view focus, at least when the camera has not been autofocus microadjusted to the lens.
All of this needs to be put in perspective, however. If you go back to the first two charts, you'll notice the bad copies are far different than the shotgun pattern shown by all the good copies. And when we looked at those two bad copies, we had to look fairly carefully (looking at 50% jpgs on the monitor) to see they were bad.
The variation among â€œgood copiesâ€ could probably be detected by some pixel peeping. For example if you examined the images shot by the best and worst Canon 100 f2.8 IS L lenses you could probably see a bit of difference if you looked at the images side-by-side (the images I took on my test camera). But if I handed you the two lenses and you put them on your camera, they'd behave slightly differently and the results would be different.
So for those of you who spend your time worried about getting â€œthe sharpest possible lensâ€, unfortunately sharpness is rather a fuzzy concept.
Roger Cicala
Lensrentals.com
October, 2011

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Posted: Wed Apr 18th, 2012 00:36

12^th Post

Ed Hutchinson

Joined:	Wed Apr 4th, 2012
Location:	Washington USA
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I like that, sharpness is a fuzzy concept!
a subject to contemplate along with several other unfathomable ones LOL

I am seriously drifting towards a nikon 60mm 2.8 but one never knows where one might end up when drifting, it is one of the things I do well.

be well

Ed

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Posted: Wed Apr 18th, 2012 01:40

13^th Post

Robert

Joined:	Sun Apr 1st, 2012
Location:	South Lakeland, UK
Posts:	4066
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For anybody with even a slight interest in close up photography this is wonderful reading.

Michael Erlewine is an expert on the art of making close up images with very little fuzz, or bokeh as it is more properly known, by using the technique known as Focus Stacking. Michael Erlewine's writing style is individual, and may not please everybody but the content is wonderful and well worth the effort to download and read.

A list of Michael Erlewine's publications can be found and downloaded in PDF form for free at:

http://www.macrostop.com

Just hit the 'Download' button for each PDF you want to view. Set aside time to read!

Michael is highly respected and these PDF's are a wonderful resource. The macro bit is a pity because by his own admission Michael's main interest is in close up photography, not macro.

Macro photography properly means creating images where the image on the film or sensor in our case, is greater than 1:1. That is the image on the sensor is larger than the subject. Macro is a word which is heavily misused to mean close up photography, made worse by some lens makers using the term to describe lenses which can take close up images. Very few lenses are true macro lenses which enable greater than 1:1 without further attachments like a bellows or extension tubes. This is particularly irksome with zoom lenses which while they can be very handy to get close up to the subject, they don't generally respond well to being put on extension tubes!

http://en.wikipedia.org/wiki/Macrophotography

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Posted: Wed Apr 18th, 2012 02:40

14^th Post

Joined:	Sun Apr 1st, 2012
Location:	Carthew, Cornwall, United Kingdom
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Doug wrote:
Before you decide to jump either way have a read of the article at the following link

Lens Variation:LINK

Roger Cicala
Lensrentals.com Wrote:

... I don't say conclusion, because this little post isn't intended to conclude anything. It simply serves as an illustration showing visually what we all (or at least most of us) already know:
Put different copies of the same lens on a single camera and each will vary a bit in resolution.
Put different copies of the same camera on a single lens and each will vary a bit in resolution.
Truly bad lenses aren't a little softer, they are way softer.
Autofocus isn't as accurate as live view focus, at least when the camera has not been autofocus microadjusted to the lens.
All of this needs to be put in perspective, however. If you go back to the first two charts, you'll notice the bad copies are far different than the shotgun pattern shown by all the good copies. And when we looked at those two bad copies, we had to look fairly carefully (looking at 50% jpgs on the monitor) to see they were bad.
The variation among â€œgood copiesâ€ could probably be detected by some pixel peeping. For example if you examined the images shot by the best and worst Canon 100 f2.8 IS L lenses you could probably see a bit of difference if you looked at the images side-by-side (the images I took on my test camera). But if I handed you the two lenses and you put them on your camera, they'd behave slightly differently and the results would be different.
So for those of you who spend your time worried about getting â€œthe sharpest possible lensâ€, unfortunately sharpness is rather a fuzzy concept.
Roger Cicala
Lensrentals.com
October, 2011

I think this is excellent comment.

We need to remember that while lenses are manufactured in a factory process the products are not identical but similar.

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Posted: Wed Apr 18th, 2012 05:20

15^th Post

whiteiris

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jk wrote: Doug wrote:
Before you decide to jump either way have a read of the article at the following link

Lens Variation:LINK

Roger Cicala
Lensrentals.com Wrote:

... I don't say conclusion, because this little post isn't intended to conclude anything. It simply serves as an illustration showing visually what we all (or at least most of us) already know:
Put different copies of the same lens on a single camera and each will vary a bit in resolution.
Put different copies of the same camera on a single lens and each will vary a bit in resolution.
Truly bad lenses aren't a little softer, they are way softer.
Autofocus isn't as accurate as live view focus, at least when the camera has not been autofocus microadjusted to the lens.
All of this needs to be put in perspective, however. If you go back to the first two charts, you'll notice the bad copies are far different than the shotgun pattern shown by all the good copies. And when we looked at those two bad copies, we had to look fairly carefully (looking at 50% jpgs on the monitor) to see they were bad.
The variation among â€œgood copiesâ€ could probably be detected by some pixel peeping. For example if you examined the images shot by the best and worst Canon 100 f2.8 IS L lenses you could probably see a bit of difference if you looked at the images side-by-side (the images I took on my test camera). But if I handed you the two lenses and you put them on your camera, they'd behave slightly differently and the results would be different.
So for those of you who spend your time worried about getting â€œthe sharpest possible lensâ€, unfortunately sharpness is rather a fuzzy concept.
Roger Cicala
Lensrentals.com
October, 2011

I think this is excellent comment.

We need to remember that while lenses are manufactured in a factory process the products are not identical but similar.
There is a tolerance range of 'acceptability' that Nikon publish on all their lenses.

I recall taking my 50mm 1.4 into ACS and asking them to 'check the sharpness'. When told it was OK and I pressed them further, they offered to swop my lens for theirs...the one they use for calibration ....as mine was sharper!

I declined the offer.

Posted: Wed Apr 18th, 2012 07:38

16^th Post

Squarerigger

Joined:	Wed Apr 4th, 2012
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This may be a dumb question Eric, but how did ACS check the sharpness of the lens? What type of testing did they use if you were privy to such information.

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Posted: Wed Apr 18th, 2012 12:20

17^th Post

whiteiris

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Squarerigger wrote:
This may be a dumb question Eric, but how did ACS check the sharpness of the lens? What type of testing did they use if you were privy to such information.

Not absolutely sure as I know they use manual and digital methods.

But I would have thought using standard Modulation Transfer function charts.

Interestingly, I need to ask them about Chromatic aberration. I am convinced one of my lenses is worse than when I bought it.. with more colour fringing. I haven't knocked it so I don't know if CA can drift??

Posted: Wed Apr 18th, 2012 12:38

18^th Post

Squarerigger

Joined:	Wed Apr 4th, 2012
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whiteiris wrote:
Squarerigger wrote:
This may be a dumb question Eric, but how did ACS check the sharpness of the lens? What type of testing did they use if you were privy to such information.

Not absolutely sure as I know they use manual and digital methods.

But I would have thought using standard Modulation Transfer function charts.

Interestingly, I need to ask them about Chromatic aberration. I am convinced one of my lenses is worse than when I bought it.. with more colour fringing. I haven't knocked it so I don't know if CA can drift??

Thanks Whiteiris, aka Eric, I took the term modulation transfer function and went looking on the internet for some education. I found several sites which were helpful with one in particular http://www.normankoren.com/Tutorials/MTF.html.webloc.

Always learning.

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Posted: Wed Apr 18th, 2012 12:45

19^th Post

Robert

Joined:	Sun Apr 1st, 2012
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Slightly interestingly there is a way to check image sharpness in Photoshop.

If you look at a histogram of a clean sharp test card black and white image the histogram should show a sharply defined absolutely perfectly vertical edge to the difference between the black and the white portions of the image.

If the lines on an image of a test card are blurred then that blur will be a graduated grey.

If there is any graduated grey in an image it will show up on the histogram.

There is also a numerical display which gives a definitive reading. I just forget how that is done, will try to remember to check it out. It's on a tiny icon on the Histo panel I think.

By selecting portions of the image at say corners, edge and centre, the differences can be assessed.

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Posted: Wed Apr 18th, 2012 13:41

20^th Post

Ed Hutchinson

Joined:	Wed Apr 4th, 2012
Location:	Washington USA
Posts:	214
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Iam back

I am sorry i did not mention that both my cameras are dx bodies. another find is the 90mm 2.8 tamron looks interesting, as i dont go tramping through the bush and boonies anymore and i take very good care of my equipment.

thanks

Ed

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