rgibbons

rgibbons

Lives in United States Los Altos, CA, United States
Works as a Design, Build & Repair things
Joined on Jun 21, 2005

Comments

Total: 24, showing: 1 – 20
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Thank you Phottix, The thing I've missed most with my Pentax system is using multiple flashes with TTL. I've had to use manual settings for 3 or more flashes. This looks promising.

Link | Posted on Mar 1, 2018 at 04:42 UTC as 5th comment | 1 reply
On article Why you should own a 135mm F2 lens (387 comments in total)
In reply to:

darlot: "The only downside with that lens is that it is manual focus, which might not be suitable for photographing sports or children."

How many Olympics and generations of kids were photographed by manual focus lenses before Autofocus was invented. LOL

Manual focus is part of the enjoyment of the hobby, I get to pick what is in focus, and how much of my depth of field is used for objects in front of or behind. With a large aperture, it is easy and fast to manually focus, because you know very quickly when you are out of focus. An dark view finder with an F5.6 zoom is hard to focus, a fast lens is much much easier.

In answer to riding a horse to work, I ride a bicycle, but would ride a horse if the city roads supported it. I very much enjoy riding a horse at my house in the country side.

Russell G.

Link | Posted on Jan 3, 2018 at 05:02 UTC

I enjoyed this, till he flew the drone close over the nesting birds at night. I hope they found their way back to their nests safely. Always sad to see people disturbing animals in nature at night.

Russ G.

Link | Posted on Aug 29, 2016 at 05:21 UTC as 13th comment | 1 reply
On article Pentax K-1 Pixel Shift Resolution: Updated Field Test (209 comments in total)

Thank you for the good article, it was informative and enjoyable. I appreciate the effort you took to redo the output in SilkyPix. Your interactive pictures, allowing me to zoom into different regions of the photo, comparing the processing options, was very helpful to allow me to see for my self how dynamic range in shadows, and motion blur are improved. I also appreciate the effort you took to hike up that long trail on a rainy day, since your subject matter was beautiful, and made reading the article even more enjoyable.

Russ G.

Link | Posted on Jun 3, 2016 at 17:55 UTC as 89th comment | 1 reply

Thank you Richard for the nice article, I enjoyed reading it, and appreciate the efforts you go through in these camera tests.

Russ G.

Link | Posted on May 10, 2016 at 05:35 UTC as 38th comment
On article 4K video: What you need to know (285 comments in total)
In reply to:

mxx: A question about white screen backgrounds: Doesn't it consume more power than a black background? Especially when screens keep on getting bigger?

Richard, you mean that when my laptop and smart phone dims the screen to extend battery life, it is negligible, and I could just use the bright setting and not notice any difference in battery life?

Link | Posted on Nov 19, 2015 at 19:09 UTC
On article 4K video: What you need to know (285 comments in total)

I like the black background better, it is easier on my eyes.

Link | Posted on Nov 19, 2015 at 18:40 UTC as 40th comment
In reply to:

The Name is Bond: This is the fault of those prats who published unflattering pics of Beyonce.

The terms are reasonable, get over it.

Huh?

"Sure, they're reasonable... I wonder why I just needed to repeat myself...Goodluck with telling yourselves whatever it is that you want reality to be."

Link | Posted on Jul 15, 2015 at 20:27 UTC
On article Canon warns about dangers of counterfeit camera gear (154 comments in total)
In reply to:

Everythingis1: Sooooo, what exactly are the dangers again?

It would be VERY difficult to get electrocuted by the low amperage 250V on a flash, from the tiny contact points that are close together, and would have a hard time passing current through your heart.

Capacitors of Top brand flashes will explode if they aren't used for years (using them keeps the oxide separator refreshed), They make noise, smoke and smell when they blow, but don't explode in your eyes since they are encased in the plastic housing.

Batteries won't fry your camera, (mostly they leak, and don't have a long life).

It seems like people are trying to scare the consumer with things that are lower risk than they really are.

Russ G. (MSEE electronic design engineer, that has repaired and rebuilt many flashes and battery packs).

Link | Posted on Jul 4, 2015 at 18:27 UTC
In reply to:

mpgxsvcd: I agree with everything you said for short exposure photography but what about long exposure photography like astrophotography(Several minutes or more)? There longer exposures increases the electrical read noise and decreases the shot noise because the signal is more consistent over the longer period of time.

It would be interesting to find the shutter duration at which shot noise is surpassed by electrical read noise in particular cameras.

In addition stacking light exposures along with dark frames can reduce the shot and read noise by using some form of averaging with multiple frames. Since the noise is random the difference between each frame is the “unwanted signal”.

1) I don't see why Rishi thinks astro photography is too small a nitch to address with more information. There is an astro photography forum on DPR; and they are a good target audience for this information. I am more concerned about noise when doing astro photography with my DSLR, than the few times it has bothered me in normal low light pictures (I carry 2 flashes in my camera bag, and several light modifiers.)

2) Long exposure thermal noise isn't as troublesome as shot noise for me. I can subtract "dark" exposures from the "light" exposures to compensate for thermal noise on hot summer nights, much easier than I can stack additional "light" exposures to compensate for shot noise.

Link | Posted on May 1, 2015 at 21:56 UTC
In reply to:

rgames1: Interesting but I'm skeptical that the variation in number of photons can cause anywhere near the amount of noise produced by the camera electronics.

The argument is made by comparing to tubes collecting raindrops. However, nowhere in the article does it say how many photons are captured in the shadow pixels, so the comparison is never backed up with any data. Making the argument requires that that number be established then compared to the variation in number of photons.

So, how many photons are captured by each pixel in the shadows? Further, what is the variation in that number? My strong suspicion is that the variation in number of photons in any part of the image is still extremely small compared to the number captured but that information is nowhere to be found. That information is implied by the analogy but never quantified.

The answer to those questions will show whether or not the analogy is valid.

rgames

Dpreviewmember wrote: "since there is no light...pixels are pure electronic noise"

The electronic read noise from the A/D conversion and amplifiers should be somewhat constant, across exposure times. If you find noise goes up 10 times, from the 1/2 second exposures in your gallery, compared a 5 second exposure, than much of the noise is probably linear thermal noise generated from heat in the pixels. I didn't see mention of what temperature you ran the noise test at. If the camera was in an enclosed space with the LCD screen on, it could warm up the sensor.

When I take astronomy pictures with my DSLR (new Pentax K3), I use an external power supply to reduce heat from the battery, and use external monitor to reduce heat from the LCD. I set the camera body outside in the cool night air an hour before taking pictures to help it cool down from the indoor temperatures during the winter.

Link | Posted on Apr 28, 2015 at 00:27 UTC
In reply to:

rgames1: Interesting but I'm skeptical that the variation in number of photons can cause anywhere near the amount of noise produced by the camera electronics.

The argument is made by comparing to tubes collecting raindrops. However, nowhere in the article does it say how many photons are captured in the shadow pixels, so the comparison is never backed up with any data. Making the argument requires that that number be established then compared to the variation in number of photons.

So, how many photons are captured by each pixel in the shadows? Further, what is the variation in that number? My strong suspicion is that the variation in number of photons in any part of the image is still extremely small compared to the number captured but that information is nowhere to be found. That information is implied by the analogy but never quantified.

The answer to those questions will show whether or not the analogy is valid.

rgames

rgames1 wrote: " That information is implied by the analogy but never quantified."

When I take astronomy pictures of dim nebula, the darker points have tens of photons per pixel. The nebula I want to see have hundreds of photons per pixel, and the brightest stars have tens of thousands of photons per pixel. Pixels themselves max out after holding several tens of thousands of pixels (well-capacity). I need to take exposures for hours, with a large aperature telescope to expose the dimmer nebula (stacking pictures taken over several nights).

In the cool winter, the sensor noise is negligible. On a warm summer evening the sensor noise becomes very noticeable (increases exponentially with temperature), and I need to take "dark" exposures to subtract the sensor noise from the real signal in the "light" exposure.

Link | Posted on Apr 27, 2015 at 22:14 UTC
In reply to:

rgibbons: Is the flat lens efficient at passing light? My camera lens with coatings can pass over 95% of the light. Do the flat lens antennae block some light, and are less efficient?.

Thank your Prossi for the link to the published results and graphs. It looks like it only passes narrow bands (won't pass yellow, cyan, magenta, violet), and would require longer exposures.

Link | Posted on Mar 11, 2015 at 01:39 UTC

Is the flat lens efficient at passing light? My camera lens with coatings can pass over 95% of the light. Do the flat lens antennae block some light, and are less efficient?.

Link | Posted on Mar 10, 2015 at 23:29 UTC as 49th comment | 8 replies
On article Making 'Art': We go inside Sigma's lens factory (196 comments in total)

I love these factory tours on your website. Please keep doing these.
It gives me a much better appreciation for the tools we use.

Link | Posted on Mar 9, 2015 at 03:10 UTC as 93rd comment
On article Consumer DSLR Camera Roundup (2014) (124 comments in total)
In reply to:

Marty4650: A really interesting "update"...

1. Canon SL1 - 17 months old
2. Canon T5i - 17 months old
3. Nikon D3300 - 7 months old
4. Nikon D5300 - 10 months old
5. Pentax K-50 - 14 months old
5. Sony SLT-A58 - 18 months old

It's like a trip to a museum to see the dinosaurs.

I think you wanted to say invertebrate, (no back bone), like worms and insects.

Link | Posted on Nov 27, 2014 at 04:02 UTC
On article Tamrac brand and assets acquired by Gura Gear (30 comments in total)
In reply to:

jrg: Used Tamrac camera straps for years. Loved'em.

Still love them, they are built to last a long long time.

Link | Posted on Jun 25, 2014 at 19:11 UTC
On article Review: Ona Lima camera strap (148 comments in total)
In reply to:

LeeS: As long as the neck pad is fixed to the strap, the dual buckle design is necessary to keep the pad centered. That seems like an "obvious gain" to me.

I think the dual buckle refers to having dual buckles on both sides (for a total of 4 on the strap). Having just one buckle on each side would be sufficient for centering the pad.

Link | Posted on Mar 25, 2014 at 18:27 UTC

Thank you, I used many of your ideas, and purchased your recommended items.
One correction however, the inverse square law is only valid for point light sources, in a black room. If you are very close to a large light source (an inch for example), there is no noticeable drop off if you double the distance. A few feet away the drop off is roughly proportional to 1/r, and very far away it is 1/(r squared).

the article said:
"If you use a diffuser closer than 1 diagonal/diameter the light will be extremely soft but the ratio between the light and shadow intensities on the sides of the face closest and furthest from the light will be very large since the light is falling off rapidly (see the inverse square law for light intensity)."

Link | Posted on Apr 16, 2013 at 05:06 UTC as 13th comment
On article Canon launches EOS 60Da DSLR for astrophotography (224 comments in total)
In reply to:

Edmond Leung: An expensive and ineffective way to discover the sky.

Seems like I don't know much about astronomy as I thought I did, I never knew there were nebula in our solar system to be celebrated, as Cannon is quoted as saying in this article. I've only seen Hydrogen Alpha line photographs of nebula outside of our solar system.

“This new camera enables an accurate depiction of a part of our solar system which is hard to achieve with conventional cameras but should be enjoyed and celebrated.”

Link | Posted on Apr 3, 2012 at 16:45 UTC
Total: 24, showing: 1 – 20
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