Are lens reviews reliable?

[dem]

A similar discussion from 4 years ago
Human Body Framing - DoF Cheat Sheet

[xpatUSA]

What Manfred said is true for the same subject and only when dof is shallow (when focusing distance is much shorter than hyperfocal as in macro, portraits, wildlife). Same framing means same magnification.

Yes, I understand that, Dem, thank you.

Hopefully Manfred will confirm my second question: "by 'the subject' did you mean the same subject situated at the same distance?"

Wasn't obvious to me but then I'm almost 80 ...

[Manfred M]

Yes, I understand that, Dem, thank you.

Hopefully Manfred will confirm my second question: "by 'the subject' did you mean the same subject situated at the same distance?"

Wasn't obvious to me but then I'm almost 80 ...

No the subject must be the same size in the frame, so with a wide angle lens I will have to be very close to the subject whereas with a long telephoto lens I have to be some distance away. If I am shooting a head and shoulders shot the size of the subject in both instances need to fill the same amount of space in the frame.

[dem]

Hopefully Manfred will confirm my second question: "by 'the subject' did you mean the same subject situated at the same distance?"

The same subject, but the camera-subject distance does not have to be fixed. Because we have the condition of "constant framing", the focal length and the camera-subject distance are free to vary as long as they produce the same magnification.

[Manfred M]

Same framing means same magnification.

Which is what I was trying to suggest is the same sizing in the framing. I find the term "magnification" confuses many people when I try to explain this to them.

[dem]

Which is what I was trying to suggest is the same sizing in the framing. I find the term "magnification" confuses many people when I try to explain this to them.

True. It is just Ted has magnification in his spreadsheet as "mag. factor", so it is easy to monitor if the number is the same or not between two shots.

[xpatUSA]

The same subject, but the camera-subject distance does not have to be fixed. Because we have the condition of "constant framing", the focal length and the camera-subject distance are free to vary as long as they produce the same magnification.

Thanks Manfred and Dem, now it is clear and my calculator agrees - as long as the focus distance stays reasonably less than the hyperfocal distance.

[William W]

Thanks Manfred and Dem, now it is clear and my calculator agrees - as long as the focus distance stays reasonably less than the hyperfocal distance.

. . . and does not get into 'Close Up' or 'Macro'.

Which is why the Axiom of DoF is so very useful for all Portraiture.

WW

[xpatUSA]

Originally Posted by xpatUSA Thanks Manfred and Dem, now it is clear and my calculator agrees - as long as the focus distance stays reasonably less than the hyperfocal distance.

. . . and does not get into 'Close Up' or 'Macro'.


Which is why the Axiom of DoF is so very useful for all Portraiture.

Quite so. Fortunately my calculator was designed for macro/close-up work and can account for inaccuracies caused thereby when using conventional calculators. Case in point: a 35mm lens at 2:1 magnification ** has an effective focal length of 105mm (gasp) and a whopping DOF of 0.2mm ...

** some might insist on "1:2" but what I mean is that the image is double the size of the subject.

[george013]

The same subject, but the camera-subject distance does not have to be fixed. Because we have the condition of "constant framing", the focal length and the camera-subject distance are free to vary as long as they produce the same magnification.

The ratio focal length and subject distance won't change when I read the table well. And it only counts for the 2-dimensinal subject plane.
Far away from lens reviews anyway

George

[Tord]

As I wrote in the thread A DSLR superzoom camera, my decision of buying the lens Nikkor 18-300mm f/3.5-6.3 was influenced by the reviews published by DXOMARK, Photographyblog and Ken Rockwell.
These reviews indicated to me that the Nikkor 18-300mm f/3.5-6.3 was sharper than the Nikkor 18-300mm f/3.5-5.6.
I discovered recently other reviews with the same opinion, but I found another review that told me otherwise: PCMag.
I can not compare the two lenses, so I decided to compare the reviews on the lens I have (mainly the analyses on the resolution of the image). I noticed that recomended apertures and opinions varied from review to review.

Hi,

After having been around cameras since the 60's I must say my review-reading has essentially boiled down to three steps:

1. See if IR have tested the lens, and check their blur diagram (if that not OK, I abort at once).

2. See if Optical Limits (used to be photozone.de), and see if they have tested the lens, and look at their diagrams (if not OK, abort!).

3. Go to Lenstip and do the same, abort if not OK.

4. If OK, I read IR's reviews, read everything I can find at Lenstip, LensRentals, and Optical Linmits.

5. If I'm still is interested, I might even read Ken!

DxO and other technical sites are OK for cameras, but handling is much more important than facts, as cameras are supposed to be scrapped after five years, to be replaced by other updated cameras.

I use Nikon and Sigma, and have one Samyang (their 14/2.8).

Mostly shoot birds, so I have two long Sigma zooms, and a couple of shorter (70-300) Nikons.

Plus macros, and primes.

[george013]

As I wrote in the thread A DSLR superzoom camera, my decision of buying the lens Nikkor 18-300mm f/3.5-6.3 was influenced by the reviews published by DXOMARK, Photographyblog and Ken Rockwell.
These reviews indicated to me that the Nikkor 18-300mm f/3.5-6.3 was sharper than the Nikkor 18-300mm f/3.5-5.6.
I discovered recently other reviews with the same opinion, but I found another review that told me otherwise: PCMag.
I can not compare the two lenses, so I decided to compare the reviews on the lens I have (mainly the analyses on the resolution of the image). I noticed that recomended apertures and opinions varied from review to review.

Hi,

After having been around cameras since the 60's I must say my review-reading has essentially boiled down to three steps:

1. See if IR have tested the lens, and check their blur diagram (if that not OK, I abort at once).

2. See if Optical Limits (used to be photozone.de), and see if they have tested the lens, and look at their diagrams (if not OK, abort!).

3. Go to Lenstip and do the same, abort if not OK.

4. If OK, I read IR's reviews, read everything I can find at Lenstip, LensRentals, and Optical Linmits.

5. If I'm still is interested, I might even read Ken!

DxO and other technical sites are OK for cameras, but handling is much more important than facts, as cameras are supposed to be scrapped after five years, to be replaced by other updated cameras.

I use Nikon and Sigma, and have one Samyang (their 14/2.8).

Mostly shoot birds, so I have two long Sigma zooms, and a couple of shorter (70-300) Nikons.

Plus macros, and primes.

On for the road.
Reading the sharpness by example I pay a lot of attention to the differences in the middle and the borders. If that's to big it's a minus for me. Unless you use a ff lens on a crop camera.

George

[Panama Hat & Camera]

Hi,

After having been around cameras since the 60's I must say my review-reading has essentially boiled down to three steps:

1. See if IR have tested the lens, and check their blur diagram (if that not OK, I abort at once).

2. See if Optical Limits (used to be photozone.de), and see if they have tested the lens, and look at their diagrams (if not OK, abort!).

3. Go to Lenstip and do the same, abort if not OK.

4. If OK, I read IR's reviews, read everything I can find at Lenstip, LensRentals, and Optical Linmits.

5. If I'm still is interested, I might even read Ken!

DxO and other technical sites are OK for cameras, but handling is much more important than facts, as cameras are supposed to be scrapped after five years, to be replaced by other updated cameras.

I use Nikon and Sigma, and have one Samyang (their 14/2.8).

Mostly shoot birds, so I have two long Sigma zooms, and a couple of shorter (70-300) Nikons.

Plus macros, and primes.

Tord, thank you for your advices, but what is IR (IR reviews)?
Cheers,
Antonio.

[Tord]

Antonio,

IR is Imagining Resource: https://www.imaging-resource.com/

Have a great day, all!

[Antonio Correia]

As I wrote in the thread...
I would appreciate the comments, corrections and help (about English Language and technical aspects).
Cheers, Antonio.

Antonio... I am astonished of how much you have worked on this !
Cheers !
See you !

[Panama Hat & Camera]

Antonio, thank you for your comments.
This thread really gave me some work to write it, but I learned a lot by writting the thread and reading the comments.
I really enjoyed the topics of these three links:
https://www.lensrentals.com/blog/201...h-translation/
https://wordpress.lensrentals.com/bl...s-test-either/
https://theonlinephotographer.typepa...are-wrong.html

Now, I'm spending much more time testing my Nikon 18-300mm f/3.5-6.3 lens in differents situations, but don't worry: "I won't post the test of my lens here".

Cheers,
Antonio.

[Antonio Correia]

..."I won't post the test of my lens here". Cheers, Antonio.

How lucky we are !

[Panama Hat & Camera]

Yes!

[bralk]

http://lenstip.com - Very objective mostly numbers based tests. But only 1 sample tested.

https://www.reidreviews.com - Very thorough and professionally executed practical tests. But only 1 sample tested. (subscription site)

[royent]

Doesn't life get complicated ?