AP7

AP7

Lives in Canada Canada
Joined on Feb 24, 2007

Comments

Total: 79, showing: 21 – 40
« First‹ Previous1234Next ›Last »
In reply to:

AP7: The definition and interpretation of terms: Acutance in Field Map (Acutance Map) and Profiles (Acutance Profiles) are not clear in dxomark website.

Both show % acutance as a function of field position for different focal lengths and apertures. While first shows in color code, the latter shows in % value from 50% to 90%.

Acutance is defined as follows:

http://www.dxomark.com/index.php/About/Glossary/A-B-C-D

My concern is how do we interpret the curves? For example, the acutance values in % at 35mm and f/5.6 are 68.6%, 67.6%, 65% and 61.4% at the center, 1/3 field, 2/3 field and corner respectively. The measurements are done on Canon 7D with 18 MP sensor (5184 pixel x 3456 pixel) and Canon EF 35mm f/2 lens.

Then, what does 68.6% mean? Does it mean that P-Mpix is 68.6% of 18MP at centre for that focal length and aperture combo? or perceptible horizontal resolution is 68.6% of 5184 pixels or what? The interpretation should be made clear with enough examples.

@DxO Labs: Do you know the answer of the above question? If yes, could you explain?

Direct link | Posted on Dec 18, 2012 at 20:54 UTC

The definition and interpretation of terms: Acutance in Field Map (Acutance Map) and Profiles (Acutance Profiles) are not clear in dxomark website.

Both show % acutance as a function of field position for different focal lengths and apertures. While first shows in color code, the latter shows in % value from 50% to 90%.

Acutance is defined as follows:

http://www.dxomark.com/index.php/About/Glossary/A-B-C-D

My concern is how do we interpret the curves? For example, the acutance values in % at 35mm and f/5.6 are 68.6%, 67.6%, 65% and 61.4% at the center, 1/3 field, 2/3 field and corner respectively. The measurements are done on Canon 7D with 18 MP sensor (5184 pixel x 3456 pixel) and Canon EF 35mm f/2 lens.

Then, what does 68.6% mean? Does it mean that P-Mpix is 68.6% of 18MP at centre for that focal length and aperture combo? or perceptible horizontal resolution is 68.6% of 5184 pixels or what? The interpretation should be made clear with enough examples.

Direct link | Posted on Dec 18, 2012 at 17:57 UTC as 23rd comment | 2 replies
In reply to:

AP7: More interpretations of the test data is better than the less. I believe that this M-Pix score is not going to replace other test score, such as, standard MTF, etc.

So, I don't see anything wrong. DPReview can certainly use this.

It'll be certainly useful.

@micksh6: You are not completely right.

I just checked dxomark website and checked few tested lenses. They only replaced Lens Metric Scores for Sharpness. Previously, they had average resolution lp/mm, now they have P-Mpix. Both are single valued (So, no problem of accepting P-Mpix instead of lp/mm).

However, all the detailed measurements for Sharpness (Global Map, Field Map, Profiles), Transmission, Distortion, Vignetting and Chromatic aberration are still there. Nothing is changed in that section.

So, I am not worried at all for the change. Its kind of renaming. I welcome the change.

Direct link | Posted on Dec 17, 2012 at 21:16 UTC
In reply to:

AP7: More interpretations of the test data is better than the less. I believe that this M-Pix score is not going to replace other test score, such as, standard MTF, etc.

So, I don't see anything wrong. DPReview can certainly use this.

It'll be certainly useful.

Then, it is an extremely bad idea.

Direct link | Posted on Dec 17, 2012 at 19:57 UTC

More interpretations of the test data is better than the less. I believe that this M-Pix score is not going to replace other test score, such as, standard MTF, etc.

So, I don't see anything wrong. DPReview can certainly use this.

It'll be certainly useful.

Direct link | Posted on Dec 17, 2012 at 18:30 UTC as 75th comment | 3 replies
On Nikon marks production of 75 millionth Nikkor lens article (81 comments in total)
In reply to:

jim stirling: @Henry M. Hertz

You might want to check the accuracy of your claim or maybe not . Or provide an genuine link to the data

Well, newer lenses have latest optical formula, state-of-art coating technology optimized for digital DLR camera and latest fast focusing motor. It does not make sense counting obsolete lenses that is no longer in production due to no use with current DSLR. IMO, Canon is in right track!

Direct link | Posted on Dec 17, 2012 at 18:25 UTC
On Nikon marks production of 75 millionth Nikkor lens article (81 comments in total)
In reply to:

jim stirling: @Henry M. Hertz

You might want to check the accuracy of your claim or maybe not . Or provide an genuine link to the data

Some correction:

"In 53 years, Nikon produced 75 million interchangeable lenses (Nikkor F-mount FX/DX and Nikon 1 CX-mount lenses) (1959-2012)"

Direct link | Posted on Dec 17, 2012 at 16:37 UTC
On Nikon marks production of 75 millionth Nikkor lens article (81 comments in total)
In reply to:

jim stirling: @Henry M. Hertz

You might want to check the accuracy of your claim or maybe not . Or provide an genuine link to the data

Looks like some peoples are not happy with Henry M. Hertz because of mentioning some true facts. Why not use google then?

This what I got from google search:

http://www.usa.canon.com/cusa/about_canon?pageKeyCode=pressreldetail&docId=0901e024806188ec

EF Lens Introduced: March 1987
60 million mark: January 2011
70 million mark: October 2011
80 million mark: August 2012

In 25 years, Canon produced 80 million EF lenses (1987-2012)

In 53 years, Nikon produced 75 million F-mount lenses (1959-2012)

Nikkor Lens Introduced: 1959
Nikkor 65 million mark: October 2011
Nikkor 75 million mark: December 2012

http://www.popphoto.com/gear/2011/10/nikon-celebrates-65-million-nikkor-lenses

Cheers !

Direct link | Posted on Dec 17, 2012 at 16:05 UTC
In reply to:

Lelitsch: I have one question about the tests: Why do all the lenses tested so far seem to have much worse sharpness on a D7000 compared to the 7D? The glass is basically the same as well as the sensor resolution.

Also, one request: Would it be possible to match the intermediate tested focal lengths? The 18-250 has 80mm and 135mm while the 18-270 has 100mm and 200mm.

I also have similar question. When I compare, I found that the test data for 35mm is missing from Sigma 18-200mm II lens.

I think it is better to fix the focal lengths (15/17/18mm, 24/28mm, 35mm, 50mm, 70/80/85mm, 105/135mm, 200mm, 250/270/300mm) and f-stops in all test.

Direct link | Posted on Dec 4, 2012 at 02:13 UTC
In reply to:

AbrasiveReducer: Surprising performance; sharp at wide angle (the hard part) and inferior to a Sigma lens at the other end. But I guess the whole point is convenience.

The optical performance of Sigma is getting very close to what you overall get from two kit lenses combo. The only issue is the price, which will get down over time.

Other than convenience, Sigma is better built, its front element does not rotate, has faster AF motor and distance scale, etc.

Direct link | Posted on Dec 4, 2012 at 01:06 UTC
In reply to:

Retzius: 99% of the people who buy this lens won't read a review about it, or even check to see if one exists. Instead, how about we review the types of lenses that enthusiasts use, you know, the people who actually read lens reviews.

Probably, his own research results. BTW, where it is published, any URL, etc?

Direct link | Posted on Dec 4, 2012 at 00:38 UTC
In reply to:

Retzius: Let me guess... its sharp stopped down to f8, soft wide open, especially at the long end, and is only recommended if you need an all-in-one convenience lens.

Am i right?

You are wrong. It is not soft wide open in all the focal lengths and also it is not sharp in f/8 in all the focal lengths.

That's why we need review and lens data!

Direct link | Posted on Dec 3, 2012 at 22:01 UTC

Thanks for the review. Since test data are ready, please publish following lens review soon:

1. Canon EF-S 18-135mm STM
2. Sigma 18-200mm II DC OS HSM

Also, waiting for:

1. Canon 40mm STM
2. A group review of 18-105mm/125mm/135mm (Sony/Pentax/Canon/Nikon/Sigma)
3. A group review of 18-55mm
4. A group review of 55-200/250/300mm
5. A group review of 50mm f/1.8
6. A group review of 35mm f/1.8

Also, why dxomark does not show lens data for Sigma 18-250mm Macro? How does the resolution scale differ from that of dxomark limiting resolution profile (dxomark: 0-100, dpreview: 0-1875)?

Direct link | Posted on Dec 3, 2012 at 21:52 UTC as 25th comment | 1 reply
In reply to:

Clint Dunn: Great review. Too bad it's of a lens that I would not look at twice let alone buy. Slow superzooms = compromises, nothing to learn here, end of review.

How about the new Fuji line of lenses, or the new Zeiss 15mm 2.8 ZE, or any of a number of other far more interesting lenses.

Similarly, the quality of a lens is proportional to its price.

Expensive lens = Better Lens, very simple.

Therefore, no need to review expensive lens!

Inexpensive lens needs to review because we need to know within some price bracket which lens gives more.

Direct link | Posted on Nov 21, 2012 at 16:22 UTC
In reply to:

AP7: It is better to have 18-55mm and 55-250mm lenses than this expensive superzoom ($300 for two vs $550 for one). Two lenses combo is cheaper and optically better than Sigma.

Comparison with Canon 18-200mm is missing (only IS performance is compared, no comparison on Sharpness, etc.).

Thanks Andy for your excellent work. Please review lenses from all the categories: budget and luxury/professional, prime and zoom, etc. Please not concentrate only on the expensive lenses as many people suggested. There are lots of non-professional folks here.

Direct link | Posted on Nov 21, 2012 at 13:58 UTC

It is better to have 18-55mm and 55-250mm lenses than this expensive superzoom ($300 for two vs $550 for one). Two lenses combo is cheaper and optically better than Sigma.

Comparison with Canon 18-200mm is missing (only IS performance is compared, no comparison on Sharpness, etc.).

Direct link | Posted on Nov 20, 2012 at 20:30 UTC as 29th comment | 2 replies

Nikon, Sony, Pentax ... all have affordable, newer built 35mm f/1.8, 50mm f/1.8, etc prime lenses for non-professional folks.

Canon should also update their enthusiastic prime lenses and offer at affordable price point. All the new lenses that Canon updated recently are way more expensive. Seems they forgot their enthusiastic market.

Also, really surprised, being one of the major camera manufacturer, Canon took so long to realize the importance of center-pinch cap design. Why Canon cannot take initiative/lead and be innovative? So far, what I see is, Canon is always forced to update their product by other manufacturer. What a shame for Canon !

Direct link | Posted on Nov 6, 2012 at 14:56 UTC as 31st comment | 3 replies
On Just Posted: Hands-on Canon EOS 6D preview article (590 comments in total)
In reply to:

George Veltchev: OK ...lets say that the D600 has the upper hand in regards to some specifications, despite the amateurish build in flash and the cheap plastic body. The 6D has to be superior in the Image quality comparison however. As a proud owner of the old Canon 5D MarkII, I personally do not care so much about the type of auto-focusing since I have always use the central focusing point. And lets do not forget the fact that Canon's EF lens lineup is very ...very and I mean very strong indeed, a fact which many people are willing to forget. After all a great lens is a better investment than a camera body which in few months or a year time will be replaced with another.

@T3: At least, after 16hours of deep sleep, you found "certain types of photography" that benefits from off-center AF point. Can you name some? Did you try any of those yet?

Direct link | Posted on Sep 19, 2012 at 19:09 UTC
On Just Posted: Hands-on Canon EOS 6D preview article (590 comments in total)
In reply to:

montygm: Hi Steve,
I know the built in flashes that come with SLR"s are not the greatest and their range is very limited but as I mentioned sometimes it comes down to convenience and less baggage to carry. Nikon were quite clever to incorporate this with their FF D800 where as Canon decided against it on their 5D range. This will appeal to a greater range of users that aren't uniquely based exclusively in the "Pro user" category only. Mostly I prefer not having to use flash if I can help it, as it can be very harsh and has unpleasant cold colour to it.But there have been a few moments that "pop up' has come in very handy though. When shooting outside on a bright day to lighten up shadows in eyes sockets for one.
But putting that aside I feel Nikon are listening more to what their customers want than what Canon is lately. They have made a quality camera in the D600 without being afraid like Canon are of losing the high end sales of the 5D MK III. You will see Nikon leading by a miles with this.

@T3: LOOOOOOOOOOOOOOL, You at last wake up after 16hours of deep sleep. Stop your stupid comparison. Many top quality Leica, Zeiss, etc. lenses are manual focus only, then why Canon produce AF lens. Better learn how to use off-center focus point to improve your photography. Still you have time to do. Nobody is asking for gazillion focus point.

Try to understand photography is pretty subjective. For example, many people know how to use flash, many people don't. Those who can't always say flash produce unnatural looking photos.

Direct link | Posted on Sep 19, 2012 at 19:07 UTC
On Just Posted: Hands-on Canon EOS 6D preview article (590 comments in total)
In reply to:

montygm: I was hoping to upgrade my 500D soon and go full frame. Have been waiting for the announcement of this new camera for ages but now having read about it I will be holding off. If the Canon 5D MK III had a pop up flash and was less bulky I would have bought it. All the extra gizmos with GPS is all marketing hype aimed at people who are more interested in tech gadgets as opposed to a quality camera that takes good photos. Get yourself a GPS unit instead.

@T3: "More powerful", did you ever read the Specification of 90EX, don't establish yourself funny.

Direct link | Posted on Sep 19, 2012 at 01:54 UTC
Total: 79, showing: 21 – 40
« First‹ Previous1234Next ›Last »