ProfHankD

ProfHankD

Lives in United States Lexington, United States
Works as a Professor
Has a website at http://aggregate.org/hankd/
Joined on Mar 27, 2008
About me:

Plan: to change the way people think about and use cameras by taking advantage of cameras as computing systems; engineering camera systems to provide new abilities and improved quality.

Comments

Total: 400, showing: 1 – 20
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On LensRentals tests Lomography's Petzval lens article (25 comments in total)
In reply to:

Paul P K: It was previously tested at Ephotozine too

http://www.ephotozine.com/article/lomography-x-zenit-85mm-f-2-2-petzval-art-lens-review-24105

Their conclusion:
'Even though the performance is quite respectable, this lens will still divide people as to whether it's a genuinely exceptional product, or a bit of a gimmick, especially given the high price tag. It's certainly not for everyone, but those who love the effect will probably cherish this lens, providing they picked up a good copy.'

and given all the reactions on this message and the earlier review they were right

Very interesting: huge sample variation and apparently better results from the better (later serial number one) than LensRentals got.

Direct link | Posted on Jul 11, 2014 at 11:29 UTC
On LensRentals tests Lomography's Petzval lens article (25 comments in total)

Confirms my concern with this lens: Petzval lenses actually get good sharpness in the center viewing large-format plates/film/contacts 1:1. Basically, the "Petzval look" of sharp centers doesn't really scale to smaller formats.

Direct link | Posted on Jul 11, 2014 at 04:22 UTC as 8th comment
On What is equivalence and why should I care? article (1533 comments in total)
In reply to:

ProfHankD: Different aspect ratios don't really have straightforward crop factors, although using the diagonal is common. It gets even more confusing when one, for example, quotes a 2X crop factor for micro4/3 and then shoots 16:9 video on it... because the crop factor jumps up a bit more than it does from a 3:2 aspect. There are also perversions like Canon's slightly-small-APS-C (1.6X vs. 1.5X crop).

The problem with these notions of "equivalence" in general is that the equivalence only holds for one attribute at a time. For example, DoF equivalences don't imply equivalent exposure times or field of view. For that matter, DoF really is a function of allowable circle of confusion, which is a function of system resolution (combined effect of pixel count, CFA interpolation, etc.), NOT format or sensor size. In sum, there's really no substitute for actually understanding what each measure means.

Not "nothing to do with... format," but I stand by my claim that it has much more to do with total pixel count and pixel pitch (more precisely, sensor resolution attributes). Without specifying resolution, format size tells you nothing about viable magnifications.

Direct link | Posted on Jul 10, 2014 at 13:10 UTC
On Quick Review: That Steady Thing article (58 comments in total)

As a Whovian, I certainly can understand why adding a Dalek-like pair of arms to a wibbily wobbly monopod makes sense to a British guy. I don't think it will exterminate many light tripods.... ;-)

Direct link | Posted on Jul 10, 2014 at 12:11 UTC as 30th comment | 2 replies
On What is equivalence and why should I care? article (1533 comments in total)
In reply to:

ProfHankD: Different aspect ratios don't really have straightforward crop factors, although using the diagonal is common. It gets even more confusing when one, for example, quotes a 2X crop factor for micro4/3 and then shoots 16:9 video on it... because the crop factor jumps up a bit more than it does from a 3:2 aspect. There are also perversions like Canon's slightly-small-APS-C (1.6X vs. 1.5X crop).

The problem with these notions of "equivalence" in general is that the equivalence only holds for one attribute at a time. For example, DoF equivalences don't imply equivalent exposure times or field of view. For that matter, DoF really is a function of allowable circle of confusion, which is a function of system resolution (combined effect of pixel count, CFA interpolation, etc.), NOT format or sensor size. In sum, there's really no substitute for actually understanding what each measure means.

A good question. Wikipedia talks about CoC being defined by visual acuity... which gets into assuming a print size and viewing distance, but then produces DoF values folks can agree on. However, the sad truth is that there never has been general agreement on numerical DoF values. Even with film cameras, different manufacturers assumed significantly different CoCs.

Now, cameras using higher resolution sensors are expected to enable producing larger prints that can still withstand close viewing. There isn't a "standard formula" mapping system resolution into expected viewing circumstances, CoC, and hence DoF -- but physical sensor dimensions clearly do not determine print size nor viewing distance. I make the same size prints from my 24MP NEX-7 (APS-C) that I do from my 24MP A7 (FF). My 10MP A100 (APS-C) produces smaller prints covering a smaller view angle from the same viewing distance, but arguably identical DoF to my A7, which has the same pixel pitch....

Complex, eh? ;-)

Direct link | Posted on Jul 10, 2014 at 11:44 UTC
On What is equivalence and why should I care? article (1533 comments in total)

Different aspect ratios don't really have straightforward crop factors, although using the diagonal is common. It gets even more confusing when one, for example, quotes a 2X crop factor for micro4/3 and then shoots 16:9 video on it... because the crop factor jumps up a bit more than it does from a 3:2 aspect. There are also perversions like Canon's slightly-small-APS-C (1.6X vs. 1.5X crop).

The problem with these notions of "equivalence" in general is that the equivalence only holds for one attribute at a time. For example, DoF equivalences don't imply equivalent exposure times or field of view. For that matter, DoF really is a function of allowable circle of confusion, which is a function of system resolution (combined effect of pixel count, CFA interpolation, etc.), NOT format or sensor size. In sum, there's really no substitute for actually understanding what each measure means.

Direct link | Posted on Jul 7, 2014 at 12:13 UTC as 290th comment | 5 replies
On Beyond the ordinary: Tim Dodd's Everyday Astronaut article (91 comments in total)

Very nice... but a lot more props than my wife would let me buy. ;-)

Direct link | Posted on Jul 6, 2014 at 12:29 UTC as 14th comment
On A look at the Lomography Petzval 85mm F2.2 lens article (148 comments in total)

One of the problems with this is that Petzval lenses were generally used with large film formats that were not enlarged for viewing, so apparent sharpness was fairly good despite mediocre lppmm resolution. I'm not really seeing the same look here, although I do believe the lens replicates a Petzval formula fairly well. Put another way, not all lens aberrations scale with format, and there are other lenses that make FF images that arguably look more like old large-format Petzval images than these do (I'm thinking of some old USSR lenses).

One could also argue that the lens should be used on a tripod with an ND filter to give the longish exposures also associated with Petzvals (e.g., for sharp portraits with motion-blurred tree leaves in the background).

Anyway, it's interesting and looks very distinctive.

Also, if you're gonna use a manual lens, install a real focus screen or use a camera with peeking live view.

Direct link | Posted on Jul 3, 2014 at 15:19 UTC as 20th comment | 1 reply
On Getting off the ground: Cheap drones for photography article (137 comments in total)
In reply to:

racin06: I’m an experienced RC airplane and helicopter pilot/enthusiast. I want to clarify the legalities of performing aerial photography with multi-rotor RC helicopters (MRRCH)…I hate the term “drone.” There is no license required to fly a MRRCH as a hobby or for not-for-profit. Currently, it is only illegal if you are flying MRH commercially and/or for pay. Now, even though you may be conducting aerial photography as a hobby or for not-for-profit, there are still rules that must be followed to fly RC aircraft in a safe manner. I strongly encourage visiting the Academy of Model Aeronautics (http://www.modelaircraft.org), which is the sanctioning body for the RC aircraft hobby. These RC aircraft are not toys and command respect and proper training to learn to fly. Anyway, below is a rent video of my flying my electric-powered 87” Sbach 300 RC airplane. This is a fantastic hobby!

http://www.youtube.com/watch?v=yeDB6q4t6vg

They are all UAVs (unmanned aerial vehicles) and I've often heard "quad copters" as the generic term for this particular type of UAVs. There are many types, including balloons, and some even go into the upper atmosphere (with appropriate craft and permissions). We have a lot of this sort of thing going on here at the University of Kentucky, including a lot of space systems work, like CubeSat: http://ssl.engineering.uky.edu/

PS: There's actually been a very active community doing photography from kites for many years: look-up KAP (kite aerial photography).

Direct link | Posted on Jul 3, 2014 at 14:31 UTC
On Getting off the ground: Cheap drones for photography article (137 comments in total)

I've had an AR for a year+ now. The video is really pretty good, and there are postprocessing techniques that can piece-together a higher-res view from a video sequence of a fixed scene. However, I fully agree that even it is not all that easy to fly, especially outdoors if there is any wind.... You also have to be a bit careful about getting out of 802.11 range.

Direct link | Posted on Jul 3, 2014 at 12:38 UTC as 51st comment
On Glass Mosaic in the Mosaic challenge (4 comments in total)

You mean stunning mosaic. The shot is rather mundane, although that's what this challenge seems to have drawn and also how people voted. ;-)

I think this challenge proves that it's hard to create a NEW work of art by photographing a work of art....

Direct link | Posted on Jun 29, 2014 at 14:27 UTC as 2nd comment
On Olympus debuts 'Anywhere Classroom' video series article (43 comments in total)
In reply to:

ProfHankD: It's an ad... no real photographic insights. :-(

I had no problem with him showing off the features of Olympus cameras... I just expected some real insights or advice. However, now that you mention it, I generally prefer a wider-than-4:3 aspect ratio for landscapes... but maybe I'm just too used to my Sonys...?

Direct link | Posted on Jun 27, 2014 at 09:02 UTC
On Olympus debuts 'Anywhere Classroom' video series article (43 comments in total)

It's an ad... no real photographic insights. :-(

Direct link | Posted on Jun 26, 2014 at 20:22 UTC as 16th comment | 5 replies
In reply to:

vkphoto: Hello,
Thank you dpreview for featuring the project and thank you all for kind comments. I acquired ICA long time ago but used it only few times with original glass plates, and then it was collecting dust sitting as a decoration on the bookshelf.
Few comments/answers
1.I did the project purely for fun and yet after almost two years, still using the camera.
2.I chose Sony NEX because of its compact body, excellent focus peaking and tilting LCD. I think it was a good choice because now I can attach A7 using the same adapter.
3.I did little post processing in ACR, Tessar is surprisingly sharp and works well for the close-up photography
4.Old ICA’s front/rear standard has some movements for tilt, shift, rise, fall and swing.
All the best and have fun!

Well, here are a few from my Instructables on using a 4x5 with a NEX in the back....

A 127mm Ektar: http://cdn.instructables.com/FX7/CRVE/H742SZED/FX7CRVEH742SZED.LARGE.jpg

A 150mm Rodenstock 4x5 enlarger lens: http://cdn.instructables.com/FZ3/TWJ7/H82UNFC9/FZ3TWJ7H82UNFC9.LARGE.jpg

Something a bit more extreme; a 19" Red Dot Artar: http://cdn.instructables.com/FUC/8F51/H7431TQB/FUC8F51H7431TQB.LARGE.jpg

That last one covers an 18" image circle, but still pulls at least 50lppmm pretty easily. My worst large-format lens came on a circa 1901 Golf Montauk, about a 152mm f/9; it barely clears 30lppmm at f/32 or so.

Direct link | Posted on Jun 25, 2014 at 21:01 UTC
In reply to:

vkphoto: Hello,
Thank you dpreview for featuring the project and thank you all for kind comments. I acquired ICA long time ago but used it only few times with original glass plates, and then it was collecting dust sitting as a decoration on the bookshelf.
Few comments/answers
1.I did the project purely for fun and yet after almost two years, still using the camera.
2.I chose Sony NEX because of its compact body, excellent focus peaking and tilting LCD. I think it was a good choice because now I can attach A7 using the same adapter.
3.I did little post processing in ACR, Tessar is surprisingly sharp and works well for the close-up photography
4.Old ICA’s front/rear standard has some movements for tilt, shift, rise, fall and swing.
All the best and have fun!

Actually, the "sharpness" is NOT very surprising if the lens is in good condition. People tend to think lenses with larger coverage resolve fewer lines per mm, but that's not the case... although microcontrast is often a bit low.

For example, http://www.hevanet.com/cperez/testing.html contains measurements of lots of large-format (4x5) lenses, and they average around 50 lppmm -- which is a tad better than 35mm SLR lenses average! It mostly has to do with moderate focal lengths and speeds being easy to handle with simple designs....

Direct link | Posted on Jun 25, 2014 at 19:27 UTC

No pun intended, but this is old news. ;-)

Multiple such projects have been discussed before in DPReview forums, and the DIY forum really doesn't provide any better mechanism for giving details of such projects or browsing them -- a well-indexed DIY user article mechanism would make more sense than a DIY forum. DIY instructions are either omitted or posted at other sites -- as I've been doing for years, mostly in the Sony NEX forum. For example, here are two 2012 Instructables, both introduced in the NEX forum, explaining how I made a mount for my NEX-5 to be used as a digital back on an old 4x5 ( http://www.instructables.com/id/Large-Format-Adapter-For-Your-Mirrorless-Camera/ ) and how to make custom lensboards including one that can take SLR lenses ( http://www.instructables.com/id/Custom-Lensboards-For-A-Large-Format-Camera/ ).

Direct link | Posted on Jun 25, 2014 at 13:04 UTC as 42nd comment | 1 reply

Several comments:

1. Bad that the default scene area is lit very differently in the shots (somebody turned on/off some lights)....

2. The 5DIII does ok, but keeps underexposing more at higher ISOs. Shadow regions are pure noise in the 5DIII images by 102K. Still, pretty comparable to the A7R at higher ISOs, with the A7S modestly better.

3. The Sony JPEGs are better than the Canon -- less noise and better detail. Not sure when Canon fell behind on this, but there they are.

I really don't care much about this. Photon shot noise, granularity of the light itself, ensures IQ will be lousy at these ISOs even with 100% quantum efficiency. There just are not enough photons to get a reliable sampling of the scene. Put another way, the biggest IQ improvement at these ISOs will come from sophisticated computational methods for reconstructing credible image content replacing "dumb" raw processing. Higher resolution with computational processing should favor the A7R....

Direct link | Posted on Jun 22, 2014 at 18:47 UTC as 86th comment
In reply to:

BarnET: "Developed using the company’s unparalleled optical expertise, the EF-M 55-200mm f/4.5-6.3 IS STM features Canon’s powerful optical Image Stabilizer and STM technology to deliver outstanding levels of detail when shooting stills and movies."

What does an AF motor and stabilisation system have to do with optical expertise and outstanding level of details.

Mechanics are something different then optics. Would someone be kind enough to explain this to the canon marketing idiot before he writes a stupid press release again!

Canon's expertise that allows them to copy a Sony lens a mere two years later. ;-) Wow, I'm impressed.

Direct link | Posted on Jun 18, 2014 at 07:53 UTC
In reply to:

Dave Luttmann: Equivalent to 39mp....same nonsense from Sigma with inflated rez numbers.

The Foveon sensors have luminance info at every pixel, so it starts with a superior monochrome image (although a B&W test chart essentially gives luminance for a Bayer filter at every pixel too -- resolution is color dependent). However, the differencing process used by Foveon to recover the colors is a little dicey, so colors can be weak, noisy, and somewhat wrong.

Still not clear which tech, if either one (actually, I suspect neither), wins overall in the longer term....

Direct link | Posted on Jun 15, 2014 at 08:31 UTC
On Panasonic Lumix DMC-FZ1000 First Impressions Review preview (1235 comments in total)
In reply to:

ProfHankD: Quite good IQ against other 1" sensors. When you compare to an APS-C body, this isn't as good at 100 as the A6000 is at 1600... and the A6000 isn't bigger nor more expensive (actually, the FF A7 is smaller than the FZ1000). The FZ1000 lens is fast and long, as the smaller sensor permits....

In sum, it's a very good camera, looks more than equal to the Sony RX10, but I'm not a compact user looking for a DSLR-size-and-shape camera without the IQ benefits. Is that really a big market?

This is a superzoom... good ones have been around forever. For example, my old Sony F828 (which I still sometimes use for NIR). I'm just less impressed now that Sony and others are fitting bigger, better, sensors into mirrorless cameras that can compete on size, price, and ease of use. Heck, even some tiny compacts now have zoom ranges we would have considered superzooms a few years ago. I just see this market shrinking....

Direct link | Posted on Jun 14, 2014 at 12:34 UTC
Total: 400, showing: 1 – 20
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