Erik Magnuson

Erik Magnuson

Lives in United States Cape Canaveral, FL, United States
Has a website at http://www.pbase.com/maderik
Joined on Dec 29, 2000
About me:

This is what I'd like to appear on my public 'posters (sic)
profile.'

Comments

Total: 218, showing: 21 – 40
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On What is equivalence and why should I care? article (1716 comments in total)
In reply to:

Happy Jones: In the article is shows an APS sensor does not use the full aperture of a FF lens. Since f-stop is focal length divided by lens diameter and has no relationship to sensor size, this is confusing. Couldn't an APS lens be made with a much smaller diameter since much of it is not being used and still have the same light gathering? Are we saying an APS F1.8 lens projects more light on to an APS sensor since f-stop does not change with sensor size? An APS lens will vignette on a FF sensor because it concentrates light more to the center than a FF lens.
Say for a 50mm lens couldn't a lens direct all the light of a 28mm opening towards an APS size sensor rather than spreading it out over a FF size sensor? We would see vignetting on the FF sensor with the lens because the light is more focused. To me then this F/1.8 lens would put the same amount of light on the APS sensor (but more concentrated to a smaller area) as a FF lens would on a FF sensor.

*This* article compares lenses designed for each format (Canon 85mm F1.2, Fujifilm 56mm F1.2, Panasonic 42.5mm F1.2 OIS, Nikon 1 32mm F1.2). Depending on the design goals an APS-C lens can be made smaller (i.e. Canon 22mm f/2 EF-M).

If you change the cone of light optically as you suggest, it's called a focal-reducer (one such product is called "SpeedBooster".) But it actually changes the optical properties such that the combination is no longer "50mm" focal length or the same f-stop ('cause the "f" has changed). Just like adding a 2x teleconverter to a 200mm lens make it 400mm optically.

Direct link | Posted on Jul 7, 2014 at 18:34 UTC
On What is equivalence and why should I care? article (1716 comments in total)
In reply to:

Lab D: Nice in theory, but not so much in real life. Sensors of difference sizes simply do not perform the same. Even sensors of the same size can be engineered to perform very different at the same ISOs (A7 vs, A7s).
It is for this reason, as photoguy622 points out, that often if you match DoF, the smaller sensor will have higher IQ. For example, not many larger sensors can match the E-M1's DR at most ISOs. DR translates in to less shadow noise and cameras such as the 800E simply are not 2 stops better at most ISOs even after normalizing resolution.

Sensor performance is a snapshot in time - step back a generation or two and FF *was* two stops better. If someone made a FF sensor with the E-M1's pixel architecture (or equiv) would the two-stops hold?

Direct link | Posted on Jul 7, 2014 at 18:22 UTC
On What is equivalence and why should I care? article (1716 comments in total)
In reply to:

joeletx: Thank you for clarifying numerous on going debates for a long time. This confirms my understanding the ISO-FL-FStop-EV relationship; that a FT lens 50mm F/2 at ISO-1000 will have the same image exposure (EV) as a FF lens 100mm F/2 at ISO-1000.

Applying the same thing, a FT lens 300mm F/2.8 at ISO-1000 will have the same image exposure (EV) as a FF lens 600mm F/2.8 at ISO-1000.

A FF lens with 600mm F/2.8 is a huge deal financially and physically comparing to a FT lens with same equivalent for wildlife shooting.

I'm not saying one or the other always has the advantage (you also have to consider price, AF performance, weight, etc.) but as the article implies, you have to account for ISO vs. noise *as well as* f/stop. An EM-1+Oly 300mm f/2.8 vs. a Nikon DF +Tamron 150-600mm would give roughly *equivalent* noise performance (and the Nikon+Tamron combo is lighter and 1/2 the price!).

Direct link | Posted on Jul 7, 2014 at 18:11 UTC
On What is equivalence and why should I care? article (1716 comments in total)
In reply to:

RFC1925: I would summarise the article regarding the difference between MFT and FF like this:

If you want:
1) Shallow DOF = FF is better
2) Deep DOF = MFT and FF are tied (FF can compensate with better ISO performance)
3) Portability = MFT is better

All the above have exceptions of course since there are such a great variety of cameras and lenses in both formats.

@BeaverTerror: I did not say anything about the usefulness of shooting smaller than f/22 on FF -- just that it's an area where direct equivalence is usually missing from lenses. (For some reason quite a number of MFT lenses stop down to f/22!)

Direct link | Posted on Jul 7, 2014 at 17:42 UTC
On What is equivalence and why should I care? article (1716 comments in total)
In reply to:

mostlyboringphotog: I'm really lost at the value of this article. To whom these things are improtant should know what these numbers mean. To most camera useres, they zoom until they get the frame they want and keep the cam in the auto (intelligent auto, in some cases) and most of the time they get what they are happy with and when not they take another photo or blame the camera. They will not be blaiming, ah, I forgot the equivalence.

But Jogger uses an "app" called "a fast lens on a large sensor camera". I typically just say "a specialized portrait setup" if they are not camera-savvy.

Direct link | Posted on Jul 7, 2014 at 17:37 UTC
On What is equivalence and why should I care? article (1716 comments in total)
In reply to:

joeletx: Thank you for clarifying numerous on going debates for a long time. This confirms my understanding the ISO-FL-FStop-EV relationship; that a FT lens 50mm F/2 at ISO-1000 will have the same image exposure (EV) as a FF lens 100mm F/2 at ISO-1000.

Applying the same thing, a FT lens 300mm F/2.8 at ISO-1000 will have the same image exposure (EV) as a FF lens 600mm F/2.8 at ISO-1000.

A FF lens with 600mm F/2.8 is a huge deal financially and physically comparing to a FT lens with same equivalent for wildlife shooting.

Noise, exactly. So you don't want the *same numeric ISO* but a *noise equivalent ISO* if you are comparing two different systems. DxO uses one of these for their low-light-score: EM1: ISO 757, Nikon DF: 3279 (+2.1 stops), 5D3: 2293 (+1.6 stops)

Direct link | Posted on Jul 7, 2014 at 17:31 UTC
On What is equivalence and why should I care? article (1716 comments in total)
In reply to:

mgrum: The bottom line that everyone always misses when the whole equivalence thing comes up is this:

*** It all depends on what lenses are actually available ***

A 24mm f/1.4 full frame lens is equivalent to a 12mm f/0.7 lens for micro four thirds. But no-one makes one so there is no equivalent to the 24mm in the real world. Likewise Hasselblad's claims of medium format offering shallower depth of field due to the larger sensor is nonsense, as the required lenses simply don't exist.

Sometimes people *do* want to take "equivalent" photos. It's one reason why people ask about camera/lens settings. ("How did you get that image?" "Oh, I used a 135mm f/2 lens at f/2 on FF.")

Direct link | Posted on Jul 7, 2014 at 16:59 UTC
On What is equivalence and why should I care? article (1716 comments in total)
In reply to:

RFC1925: I would summarise the article regarding the difference between MFT and FF like this:

If you want:
1) Shallow DOF = FF is better
2) Deep DOF = MFT and FF are tied (FF can compensate with better ISO performance)
3) Portability = MFT is better

All the above have exceptions of course since there are such a great variety of cameras and lenses in both formats.

FF cannot *always* compensate mainly because most FF lenses don't go past f/22. The question is *for the same size print*, how does f/11 on MFT compare to f/22 on FF in terms of sharpness. And the answer is "about the same."

Direct link | Posted on Jul 7, 2014 at 16:46 UTC
On What is equivalence and why should I care? article (1716 comments in total)
In reply to:

joeletx: Thank you for clarifying numerous on going debates for a long time. This confirms my understanding the ISO-FL-FStop-EV relationship; that a FT lens 50mm F/2 at ISO-1000 will have the same image exposure (EV) as a FF lens 100mm F/2 at ISO-1000.

Applying the same thing, a FT lens 300mm F/2.8 at ISO-1000 will have the same image exposure (EV) as a FF lens 600mm F/2.8 at ISO-1000.

A FF lens with 600mm F/2.8 is a huge deal financially and physically comparing to a FT lens with same equivalent for wildlife shooting.

Why ISO-1000? Why not shoot a 600mm f/5.6 at ISO-4000 on FF? (The Tamron 150-600mm is only 1/3 stop off and much cheaper than the Olympus 300mm f/2.8 even if you add the cost of a 5D3 body.)

Direct link | Posted on Jul 7, 2014 at 16:15 UTC
On Light Field Cameras - Focusing on the Future article (133 comments in total)
In reply to:

CraigArnold: 5Mp is enough for many applications. 8x12 prints, online images, photobooks. Keep in mind that slight misfocus decreases effective resolution in so many amateur shots anyway...

Also there seems to be a lot of potential to develop these as a higher resolution camera with a smaller focus range for stills photography.

Yeah I want one for sure.

Megapixels are a size, not a resolution. The article states "[e]dges are soft, colors are desaturated, and there’s a general graininess to the shots". Other articles on light-field technology suggest the effective resolution varies with distance. It will be interesting when someone produces side-by-side images vs. other 5MP outputs to see what the real practical resolution ends up at (including misfocus although camera shake is often worse.)

Direct link | Posted on May 15, 2014 at 18:13 UTC
On Found film: Keep a lookout for photographic treasures article (12 comments in total)
In reply to:

Paul Janders: Someday in the year 2414 a person will enter an antique store. They will purchase a box of old memory cards from various cameras of the early 2000s.

When the images are processed they will all be found to contain nothing but thousands of pictures of brick walls and out-of-focus Christmas lights. Occasionally, a photo of a cat will be seen.

After years of study no historian will be able to explain the significance or purpose of the photos.

@backayonder, SmartMedia USB card readers are not uncommon - quite a lot of older 6-in-1 type readers handle SM and work with modern computers. It's a bit harder for old cameras with only built-in storage, but I've been able to get Linux drivers for all of the ones I've tried.

Direct link | Posted on May 9, 2014 at 14:09 UTC
On Found film: Keep a lookout for photographic treasures article (12 comments in total)

Someone who's been doing this for a while now:

http://westfordcomp.com/updated/found.htm

Direct link | Posted on May 8, 2014 at 15:41 UTC as 7th comment
In reply to:

bobbarber: Disclaimer: I'm a hypocrite, because I've bought converters for compact cameras before.

Comment: If you're buying converter lenses for your compact or fixed-lens camera, isn't that telling you that you need/should have bought an interchangeable lens camera in the first place?

Check the size/cost of the EOS-M+22mm f/2.

Direct link | Posted on May 2, 2014 at 15:24 UTC
On MIT algorithm predicts photo popularity article (97 comments in total)
In reply to:

AbrasiveReducer: It was very generous of her to compensate all the photographers whose photos were used in this study. Some people think that images online are just there for the taking.

Flickr has a large number of photos with permissive licenses - the photos actually are there for the legal taking for many non-commercial purposes.

Direct link | Posted on Apr 29, 2014 at 17:35 UTC
On Am I missing something here? article (636 comments in total)
In reply to:

joeyv: from another perspective: The V3 is not the best "all-around" camera out there but it already is the best photographic tool for OUTDOOR sports shooting, by far. At a fraction of the size and cost of the D4s or 1d5. Don't be surprised if you find this being used for professional outdoor sporting events or the olympics.
Nikon needs to improve the 1 series' low light IQ, produce more f/1.0-1.2 lenses and make it fully compatible with Nikons' dslr flash system. But clearly, this format has some serious potential. Specially, if it is used in conjunction with dslrs.
This camera wasn't made for "soccer moms". It's made for professional sports photographers.

I *will* be surprised if they use it for anything but a few special cases. Ever shoot from field level in a stadium? The background of all those people or rows seats is horribly distracting; you really want relatively shallow DOF for subject isolation. Even for the Olympics, look at the photos carefully to see what's needed. If the remote operation support is good enough, perhaps as a remote control camera if battery life is not an issue.

Direct link | Posted on Mar 13, 2014 at 19:09 UTC
In reply to:

instamatic: To answer Nikon why their mirrorless is not selling in the US: Nikon 1 has a small sensor, while the US consumer expects at least a DX sensor. Why? Probably because many hobbyists are vainly hoping to one day have some success at shooting weddings, or whatever - which for most people never materializes, but still the illusion is there. Regardless of where the hobbyist is on their photography journey, it is universally known that wedding/portrait photography requires a large sensor for shallow and popular depth of field with fast lenses. And where are the fast lenses for mirrorless? Thirdly why in the world the lesser Nikon 1 cameras have flash sync only at 1/60 sec? Why aren't DSLR speedlights compatible?

Nikon's compact cameras are also not up to par. Where is a compact with a 'standard' zoom lens and aperture somewhere between f/1.4 and f/2.5 or similar. Why aren't all Nikon's compact cameras allowing saving RAW files. Where is built in WI-FI?

Where is the D400?

No company's mirrorless are selling well in the US, so Nikon is hardly alone. The lower-end Nikon 1 cameras do not have a physical shutter and the electronic shutter is limited for sync speed.

Direct link | Posted on Feb 17, 2014 at 19:28 UTC
On Sony Alpha 7R Review preview (795 comments in total)
In reply to:

TN Args: Canon 6D with Canon 70-200 f4 L IS is no bigger or heavier than an A7 with Sony equivalent lens.

So, compact shmompact.

The A7R+70-200 is about 200g (13%) lighter and ~10mm or so shorter.

Direct link | Posted on Feb 13, 2014 at 22:31 UTC
On Sony Alpha 7R Review preview (795 comments in total)
In reply to:

fabio riccardi: I have a question about lenses for full frame mirrorless cameras.
I notice that pretty much all the Sony lenses for these cameras have relatively small maximum aperture. The 55mm normal lens is 1.8, vs the 1.4 we are accustomed to for normal full frames. Similarly for the rest of the line. I guess that bright lenses also mean heavier, larger, lenses, which don't quite make sense on smaller camera bodies.
This kind of defeats the purpose of a full frame sensor, where you can benefit from the shallow depth of field it allows.
On APS sized sensors, brighter lenses can still be fairly compact. Fuji, Panasonic, and Olympus lenses are all much brighter than the new FF mirrorless Sony.
Brighter lenses on APS sensors deliver equivalent DOF and look than the dimmer lenses on FF. At the end what is gained with the full frame is lost with the smaller maximum practical aperture.
What do you guys think?
- Fabio

To be fair, the Zeiss is also T-1.8 while the other brands 1.4's are often darker than spec at T-1.6 or T-1.7. The real difference is much less than the f-numbers imply.

Direct link | Posted on Feb 13, 2014 at 20:47 UTC
On CP+ 2014: Hands-on with Sigma DP2 Quattro article (256 comments in total)
In reply to:

Jon Ragnarsson: I wonder if the is the same lens design as the Sigma 30mm f2.8 lens for NEX. Still no good photos of people holding this thing...

Different lens from the 30mm DN ART: 8 elements in 6 groups vs. 7 elements in 5 groups. Similar design for the back groups but different front groups (larger, more complex on dp lens).

Direct link | Posted on Feb 13, 2014 at 19:18 UTC
In reply to:

Brigcam: PENTAX Film Duplicator-

Anyone else make this?

Depends on how much it automates film handling. "Slide duplicator" attachments have been around since the 60's.

Direct link | Posted on Feb 5, 2014 at 23:56 UTC
Total: 218, showing: 21 – 40
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