MTF discrepancy between Lens Rental and Photo Zone (FE 85 1.8)

[c1o4o0l]

Hi, Photo Zone and Lens Rental are my two trusted sources when it comes to lens resolution review. But from time to time, I am baffled to see quite some discrepancy between them. Wanted to make a post here to see if anyone had the same doubts or have answers to this.

 

Eg.1 photo zone shows very minor difference in resolution between the batis 85 and Sony 85 1.8, while LensRental shows the MTF chart between the two lens has quite a perceivable difference.

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Eg.2 photo zone shows quite a bit resolution difference between the Zony 55 1.8 and Sony 85 1.8. While LensRental shows the MTF charts are very comparable between the two.

 

The first discrepancy might be explained in that the main difference in LensRental MTF chart is in the high frequency lines, and the CMOS pixel density was not fine enough to pick up the difference.  (50lp/mm is equivalent to 1200 line pairs across the sensor height of 24mm, while A7R2 has around 5000pixel across CMOS height, so about 4 pixels per line pair, 2 pixels per line) However the second discrepancy really baffles me. Maybe it’s because of different focus distance? (LensRental does test at infinite distance, while photo zone does it at a finite if not close distance)

Anyone has any thoughts on this?

 

reference:

http://www.photozone.de/Reviews/overview#sony_aps

https://www.lensrentals.com/blog/2017/06/sharpness-tests-of-the-sony-fe-85mm-f1-8-g/

https://www.lensrentals.com/blog/2016/06/the-sony-fe-lenses-mtf-and-variance-summary/

 

[Username]

This simply does not matter. Forget about it.

[krishary]

This simply does not matter. Forget about it.

It matters to him and that should be enough for you not to dismiss his question like that

 

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[Username]

It matters to him and that should be enough for you not to dismiss his question like that

 

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I did NOT dismiss his question. I ANSWERED it, something you did NOT do. 

  

IOW your reply is, charitably speaking, ironic .... CHARITABLY spoken, cuz

you're a noob.  

[Guest Jaf-Photo]

As far as I know, Photozone tests one copy of a lens while LensRentals tests several copies. So, sample variance could be a factor for Photozone but not for LensRentals.

[krishary]

I did NOT dismiss his question. I ANSWERED it, something you did NOT do.

 

IOW your reply is, charitably speaking, ironic .... CHARITABLY spoken, cuz

you're a noob.

Take it easy man. So emotional, so frustrated...

 

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[Username]

Take it easy man. So emotional, so frustrated...

 

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ROTFLMFAO

[tinplater]

ROTFLMFAO

No, telling someone to read the Fing manual or to "forget about it" is only answering the question in the broadest sense.  It does not increase anyone's knowledge of the queried subject.  I too have wondered how reproducible and consistent lens testing can be.  It is worthy of discussion, not simple dismissal. 

[Username]

There's a discrepency. It is meaningless. 

Broad or narrow, thaz the situation, and 

the best advice is to forget about it.  

   

You're funny too !   

    

Jaf offered a plausible idea of how such 

discrepancies occur. Even assuming it's

the reason for the discrepancy, having a 

reason changes nothing. Only thing to 

do about meaningless data is ignore it. 

Thaz excellent, experienced advice.  

   

The OP asks:   

Anyone has any thoughts on this?   

   

Jaf and I have offered our thoughts. You 

and krish have yet to do so, but perhaps 

in time you might .... there's still room on 

the page to actually address the OP. 

[tinplater]

User has spoken!  We are all enriched

[ddown]

Normal Variance in Samples is a natural occurrence