Saturday, February 21, 2015

Depth of field

Depth of field control is one of the most important ways that DSLR and other large sensor cameras are better than point and shoots or camera phones.  Depth of field is affected by the distance from the subject, the size of the sensor (or film) the aperture of the lens and the focal length.  Smaller sensors have more depth of field.

These pictures were all taken under the same conditions except aperture--Pentax Kx with 50mm prime lens at various F stops.   The buds were near the minimum focus distance--if the subject is farther away the background will not be as blurred at a given aperture.

 f1.8.  Normal DSLR zoom lenses do not have an aperture this wide/fast.   Virtually no background details visible.   (click any picture to embiggen)


f3.5.  The widest aperture available on most short zoom lenses, (although many change to 5.6 at 50mm)  Beginning to make out the buds farther back.

An example of distance affecting depth of field, this is also same camera and lens at f:3.5--but since it is focused farther away the background is much clearer. 


f:7--Buds are almost there, beginning to see the bushes farther back. 



f:13  seeing individual branches on the bushes in back


f:22, the minimum aperture most cameras have.  Buds farther back now show some details.

It is unfortunate that modern cameras don't have a good method of showing depth of field.   In the 70's, a manual focus version of the 1.8 50mm used here would have been the standard kit lens.  Zoom lenses are quite a bit slower, and therefore dimmer--the kit zooms for my camera are typical, letting in 1/4 to 1/8 the light compared to the 50mm.  To counter that the viewfinders have been modified to brighter ones that makes everything appear to be more in focus than it will be on the final picture.

Wednesday, February 04, 2015

Time Warner Cable bait and switch?

I want to see about upgrading my Internet speed.  I log on to my account, see this:


...which brings me to this:

$10 per month sounds reasonable, so I go on.


A few minutes later, I get this in email:
...of course, "we are experiencing higher than usual call volume...". Eventually after 2 different people I find that the reason they need additional information is to see if I'm OK with $20 more per month instead of $10.  "We have to take Turbo off to add Extreme, that's $10, but then we have to add it back on, then... "I found you a better package"  "But it's still $20 more, right?"  "Yes"

I'm logged on to my account, the system sees what my services are and how much my bill is...but can't figure out that I can't actually get that rate.  Riiiight.    I'm sure their lawyers have insured that they aren't quite technically legally engaging in bait and switch...but I've got a different opinion.

Wednesday, June 11, 2014

Update on sous-vide

When I ordered my sous-vide circulator, I thought I'd probably use it occasionally, but I was worried I wouldn't use it often enough to justify the cost.  Since then, I don't think I've cooked normal meat any other way.  (Normal meaning minimally processed, not including things like bacon, ham or hot dogs)

One of the huge advantages is repeatability--Either Wife or I can cook medium rare beef reliably every time.  We switched from 135 to 134 degrees F--that small tweak made an improvement, but that amount of difference wouldn't be repeatable with traditional methods.  It turns out that 133 is too rare.  Another advantage is that you can get the tenderizing effect of a long cook time while keeping medium rare--London Broil is a cheap cut, but is tender and tastes fantastic sous vide for 6 hours or so.   I like it better than Sirloin--more flavor and as tender.

We often cook in bulk, running a beer cooler full of meat that needs to cook at the same temperature, then cooling in an ice water bath, and freezing most of it still vacuum sealed.   This means that for a later meal instead of a 4 hour (or 36 hour) cook, we just put it in the sous-vide bath long enough to warm back up, usually about an hour.   I've started marking the cook temperature on the package so whoever is cooking knows how hot to reheat.   I still have to look up temperatures other than beef.  I'm keeping a notebook of times and temperatures.

Even hamburgers benefit--did a batch of burgers at 140 for 2 hours.  Next batch will be at 138, but the burgers were very good--not as good as the best charcoal grilled, but well above average for indoor burgers.  I'm guessing that over a blazing hot charcoal fire for a minute or two would make them excellent.    Burgers from loose ground beef need to get a large dimple in the center, otherwise you wind up with meatballs. Pre-formed frozen patties don't go spherical, but they weren't improved over fried, tasted too processed, possibly cooked too long.  (I may try making my own frozen patties to see if they go spherical)

And while sous vide takes a little more planning, the time the cook has to spend watching, stirring, flipping, etc is a lot less.  Fill the pot, set the circulator, drop the bags in and come back for dinner, a minute or two searing.  No defrosting necessary for most foods.  Cleanup is easier too, no baked on goo.

Using a torch for searing is easier than a pan, and for some foods can be more even.  I started with a hardware store propane torch, but I got the wrong model--its nozzle was mostly upright, and tipping the torch enough to reach the food made the flame sputter out.  Others have reported nozzles at right angles to the tank work well.  I bought an Iwatani butane culinary torch, that works very well, and I've wound up using it for other foods, like crisping leftover pizza or toasting cheese.

When I bought cans of butane fuel, Amazon's "people who bought this also bought" list lead me to butane hash oil equipment.  Apparently some people soak marijuana  in liquid butane, throw the marijuana out, then cook the butane away and smoke what's left...if nothing catches fire.

Having hours between "barely long enough" and "cooked too long" is great--get everything else ready, the meat won't overcook or sit out getting cold if your timing is off on side dishes.  One downside is that meat needs to be served immediately after searing, since even with a sear the outer 'well done' extra hot layer isn't thick enough to keep the rest warm very long.   I got some cast aluminum platters at a restaurant supply place, that helps.

Not everything has been completely successful.  I've tried smoking meat to start, and sous vide to finish--texture is great, but the smoke flavor changes in a way I don't like. Apparently some of the smoke migrates through the bag, there's a smoky smell in the water.   Chicken can be overcooked, it turns mushy and grainy.  Chicken also has different ideal temperatures for light and dark meat, a minor inconvenience.  Medium rare chuck roast cooked for 24 hours is tender...but the combination of strong beefy "pot roast" flavor is odd with the medium rare texture.  




Friday, December 06, 2013

Motorcycle turn signal beeper

I finally got around to installing a turn signal beeper on Wife's motorcycle.  Rather than a simple beeper that's on whenever the signal is on. I did one that's on only when the signal is on...and the brakes are off.   With brakes on, the buzzer shuts up.   Much easier than I expected.   The trick is to ground the buzzer through the positive wire of the brake light.   When the brakes are off, there is a path to ground through the bulb--you don't get full voltage, but plenty to run the buzzer whenever the turn signal is on.  When the brakes are on, you get 12 volts on both sides of the buzzer...so no sound.

An additional benefit is that a blown out brake light bulb will keep the buzzer from working,  and a bad brake light switch (a problem Wife's Savage had when we got it) means that the buzzer will be on even with the brakes applied.

Sunday, December 01, 2013

Sous Vide cooking

Sous Vide is a method of cooking food in a vacuum sealed plastic bag (Sous Vide means "under vacuum" in french, although vacuum is a minor part of the process) in a precisely controlled hot water bath, generally for a longer than normal time but at a lower than normal temperature--usually at the final temperature of the food.  It was invented in the late 60's.  I first heard about it in a restaurant trade magazine in the late 80's.  Until recently the equipment needed would cost several thousand dollars, but prices have come down drastically.    Last year I ran across a couple of articles on sous vide machines at the high end of consumer prices.  A few months ago saw an article on a Kickstarter project for Sansaire, Sous Vide for $200.  That sparked my interest, and I almost pre-ordered before doing more research.

With Sous Vide, doneness (as in medium rare or well-done) can be controlled separately from cooking time.  Long cooking times still makes the meat more tender, but at a temperature low enough that the meat does not cook past the level of doneness you select.  Also the entire portion is the same level of doneness, rather than a well-done exterior gradually changing to a rare interior.  You can safely cook many foods to a much lower temperature than otherwise--In most cases, internal temperature of 130F for an hour is sufficient.  (Don't rely on me for exact times and temperatures, do your own research)

To cook this medium rare London Broil, I set the temperature to 135 degrees F.  I sealed the meat in a Foodsaver bag and put the bagged meat in the bath for several hours.  Just before serving heat a frying pan or griddle to high heat with a little oil, then dry the meat and sear for 30 seconds or so per side--just enough to brown the outside layer, not long enough to further cook the inside.  Serve immediately.  An added bonus is that the meat doesn't lose its juices on your plate--this means my wife can eat medium rare meat without being turned off by the bloody juices.   According to many sources the most expensive cuts of beef are prized for tenderness, despite having less flavor than cheaper cuts.

For Country-Style pork ribs, 145 for 32 hours resulted in a moist rib that could be cut even across the grain with a fork.

You can put meat in directly from the freezer, and it thaws quickly, passing through the spoilage "danger zone" for a fraction of the recommended maximum time.  If the meal is delayed, the meat can stay in the hot bath until serving time without burning or over-cooking.

There are some oddities--You apparently can't use raw garlic with most meat, because the garlic needs a much higher temperature to cook.  It is difficult to cook vegetables and meat in the same bath, since vegetables require much hotter temperatures.  Without a sear, meat appears as if boiled or poached.  Meat needs to be served immediately after removing from the bath and searing, since there isn't a layer of overheated meat to keep it warm.   For most foods that require long cook times, you can pre-cook, then refrigerate or freeze in the bag and re-heat in the bath just long enough to heat through.

Currently home Sous-Vide setups can be divided into 3 broad categories--All in one, Circulator, and controllers.

All in One units (Sous Vide Supreme) are generally the most expensive and include the container for the water--but generally rely only on convection to circulate the water.  They are also quite large.





Controllers (Dorkfood) are the least expensive, but require your own appliance-a rice cooker, manual crock pot or coffee urn for example.  These also rely on convection.   If you already have an appropriate appliance, these take the least storage space.








Circulators generally clamp to a container you provide, which can be a large pot, bucket, plastic bin or cooler.    They are generally less expensive and take up less storage space. Most of the latest generation of moderate cost Sous Vide machines are circulators--Anova, Polyscience, Sansaire, Nomiku, and SideKIC. Most of these are very similar in design--they are fairly tall an narrow, clamp to your container with the heater and impeller submerged.

The PolyScience circulators are made by a lab equipment company, and appear to be well made and versatile--but they are at least twice as expensive as the Anova or Sansaire.

Nomiku is a kickstarter project, and appears to be a well made unit at around $300.


The SideKIC uses the same principles, with a different implementation.  It is the cheapest by a relatively small amount, but also the most limited in design. Based on reviews its heater is weak--it maintains temperature well, but takes a long time to raise the temperature. It has a  narrow range of acceptable water levels, is often out of stock and has reliability problems.

Sansaire and Anova are both around $200, and both have received positive reviews.  The deciding factors for me were that the Anova has been quietly selling for the last year, it's reviews are based on production units.  Like the PolyScience, it is made by a (competing)
 established US lab circulator company.   Meanwhile the Sansaire is being contract manufactured in China for a start-up company and has yet to ship retail (reviews have all been on pre-production samples).  With Anova dropping their price to $200 (plus $20 shipping) to match the Sansaire, the decision was easy, and I bought the Anova.  So far I've used it in a large stock pot covered in aluminum foil.  I just bought a cooler, cut a hole in the lid for the circulator  and I've got chicken breasts in it right now.  Update-Chicken breasts cooked at 147 degrees for 4 hours were slightly more tender than I'd prefer.  Next time I'll probably try 150 for 2 hours.