Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
02-09-2012, 08:56 AM   #61
Loyal Site Supporter
Loyal Site Supporter
monochrome's Avatar

Join Date: Mar 2008
Location: Working From Home
Photos: Gallery | Albums
Posts: 26,276
Can't find the link, but (counterintuitively) when California wanted to prohibit black paint on cars (to save on airconditioning increase in fuel consumption) the required study discovered that there is no appreciable difference in heat absorbtion under sunlight between light colored and dark colored cars. The proposal died in committee.

02-09-2012, 09:12 AM   #62
Veteran Member
eddie1960's Avatar

Join Date: Aug 2010
Location: Toronto
Photos: Gallery | Albums
Posts: 13,666
QuoteOriginally posted by m8o Quote
... so is that what one calls "embracing their weaknesses"? ... i.e. if you have terrible subject focus isolation, go completely the other way.
You can make a pinhole lens with a body cap (you just need to get the right size hole) so it better be cheap. it falls in line with the toy lens line. it really is becoming a digital holga they need to get it into the Lomo stores for sale I think
02-09-2012, 09:19 AM   #63
Loyal Site Supporter
Loyal Site Supporter
boriscleto's Avatar

Join Date: Dec 2009
Location: North Syracuse, NY
Photos: Gallery
Posts: 16,464
QuoteOriginally posted by ogl Quote
DA40XS is in roadmap
That's because it was announced on the day the roadmap was released.
02-09-2012, 09:20 AM   #64
Site Supporter
Site Supporter
Rorschach's Avatar

Join Date: Nov 2007
Location: Kuusamo, Finland
Photos: Gallery
Posts: 652
QuoteOriginally posted by monochrome Quote
Can't find the link, but (counterintuitively) when California wanted to prohibit black paint on cars (to save on airconditioning increase in fuel consumption) the required study discovered that there is no appreciable difference in heat absorbtion under sunlight between light colored and dark colored cars. The proposal died in committee.
I find that a bit hard to believe actually. It is basic physics after all. This one is about roofs, not cars, but the idea is the same:
http://docserver.nrca.net/pdfs/technical/457.pdf
If I decipher that correctly, color matters when insulation is poor...e.g. in cars.

Now as to what that required study found out and how, and why the committee decided to do nothing, I have no idea.

02-09-2012, 09:38 AM   #65
Veteran Member
bobmaxja's Avatar

Join Date: Mar 2010
Location: Laval, Quebec Canada
Posts: 2,171
Color is a big marketing strategy in big lenses. When you do birding or sport in group, you know exactly what brand of lenses peoples use. This is a big $$$$ business
02-09-2012, 09:45 AM   #66
Veteran Member
Frogfish's Avatar

Join Date: Dec 2009
Location: Shanghai
Posts: 4,490
QuoteOriginally posted by bobmaxja Quote
Color is a big marketing strategy in big lenses. When you do birding or sport in group, you know exactly what brand of lenses peoples use. This is a big $$$$ business
Camo webbing has a brand following ?
02-09-2012, 10:01 AM   #67
Loyal Site Supporter
Loyal Site Supporter
monochrome's Avatar

Join Date: Mar 2008
Location: Working From Home
Photos: Gallery | Albums
Posts: 26,276
QuoteOriginally posted by Boucicaut Quote
I find that a bit hard to believe actually. It is basic physics after all. This one is about roofs, not cars, but the idea is the same:
http://docserver.nrca.net/pdfs/technical/457.pdf
If I decipher that correctly, color matters when insulation is poor...e.g. in cars.

Now as to what that required study found out and how, and why the committee decided to do nothing, I have no idea.
Cars are a closed environment witha lot of glass, so the internal temperature rises to 170+ degrees almost immediately when in full sun, regardless of the paint color. Apparently the largest controllable variable is whether the car has tinted windows

02-09-2012, 11:06 AM   #68
Pentaxian




Join Date: Apr 2007
Location: Romania
Posts: 15,132
QuoteOriginally posted by bobmaxja Quote
Color is a big marketing strategy in big lenses. When you do birding or sport in group, you know exactly what brand of lenses peoples use. This is a big $$$$ business
So Pentax should make theirs pink
02-09-2012, 03:20 PM   #69
Site Supporter
Site Supporter
Douglas_of_Sweden's Avatar

Join Date: Apr 2008
Location: Stockholm
Photos: Gallery
Posts: 3,374
QuoteOriginally posted by boriscleto Quote
I would hope that it is based on the 1.4, but with 6 blades instead of 8. It would make no sense to base it on the 1.7 and then make it a 1.8.
I would think so to, but as both designs have their followers and comprehensive tests doesn't agree on which is the best lens, I didn't want to restrict myself for just one possibility.
02-09-2012, 03:24 PM   #70
Site Supporter
Site Supporter
Douglas_of_Sweden's Avatar

Join Date: Apr 2008
Location: Stockholm
Photos: Gallery
Posts: 3,374
QuoteOriginally posted by Frogfish Quote
For sure they would be hotter ! However I'm also sure Nikon/Sigma considered that a black finish may negatively affect the optical qualities of their lenses. If they still went with black then obviously there is no visibile image degradation.
Can we agree on that it would be a bad idea to paint one side of the lens black and one white? In which case the lens would probably curve itself in strong sunshine...

BTW, regarding Nikon and Canon long lenses. Aren't in-lens-image-stabilized lenses by definition always misaligned a bit as soon as the image stabilization is active? When some lens elements move to correct for motion and vibrations, they deviate ever so little from the ideal lens diagram, which may very well be a larger effect than any temperature changes. Maybe this is what Nikon and Sigma realized.
02-09-2012, 03:26 PM   #71
Pentaxian
Jean Poitiers's Avatar

Join Date: Apr 2011
Location: Lost in translation ...
Photos: Gallery | Albums
Posts: 18,076
Ditto ...

QuoteOriginally posted by Docrwm Quote
Glad to hear that they have already been added to the database. I am looking forward to seeing how the 50/1.8 handles, if it is anything like the 35/2.4 it will be a real bargain.
On est d'accord ... à 100% !!!

May look "cheap" to some, but doesn't shoot like it, IMHO ...

A+, J
02-09-2012, 04:19 PM   #72
Veteran Member
Smeggypants's Avatar

Join Date: Sep 2010
Posts: 1,536
QuoteOriginally posted by TOUGEFC Quote
Away with f/2.

Do it proper with f/1.4 or dont bother at all
Agreed!

I also wish the new DA50 was a 1.2. I'd also like a 30/1.2
02-09-2012, 04:32 PM   #73
Veteran Member




Join Date: Feb 2011
Posts: 4,873
30/1.2? That would need about 86mm front filter or so, correct?
02-09-2012, 04:49 PM   #74
Veteran Member




Join Date: Aug 2007
Location: Madison, Wis., USA
Posts: 1,506
QuoteOriginally posted by monochrome Quote
Cars are a closed environment witha lot of glass, so the internal temperature rises to 170+ degrees almost immediately when in full sun, regardless of the paint color. Apparently the largest controllable variable is whether the car has tinted windows
I agree - you can quickly feel how hot the exterior paint of a black auto is. On the other hand, most of us don't ride on the outside of the auto .....

In another and (perhaps) more serious vein, a building's roof is rather static. A moving auto, OTOH, is shedding heat by conduction as the "moving" air carries the heat away as well as by radiation.

If California were really worried and had a legislature with a slightly smaller proportion of the victims of modern education, they'd figure out that the real improvement would come from banning black tarmac streets and car parks, replacing them with white concrete. I'm filing a patent tomorrow from my shell company in Tyler, Texas. (That last sentence really does make sense if you've been following the legal/IT news this week.)
02-09-2012, 06:30 PM   #75
Veteran Member
Smeggypants's Avatar

Join Date: Sep 2010
Posts: 1,536
QuoteOriginally posted by ElJamoquio Quote
30/1.2? That would need about 86mm front filter or so, correct?
fine by me
Reply

Bookmarks
  • Submit Thread to Facebook Facebook
  • Submit Thread to Twitter Twitter
  • Submit Thread to Digg Digg
Tags - Make this thread easier to find by adding keywords to it!
da, images, lens, lenses, pentax news, pentax rumors
Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
Sample images taken with C-mount lenses Laurentiu Cristofor Pentax Q 11 06-07-2013 10:20 AM
Images of the New Upcoming Lenses and Adapters! userage Pentax News and Rumors 3 02-08-2012 01:05 PM
What method do u use of keeping track of images taken with different lenses? altopiet Pentax DSLR Discussion 19 08-02-2011 10:32 PM
K5 and lenses are here, first impression and images! Woohoo! Armanius Pentax K-5 & K-5 II 8 03-26-2011 01:26 PM
My K20D takes terrible images with my 645 lenses, why? drougge Pentax DSLR Discussion 23 06-01-2010 10:19 AM



All times are GMT -7. The time now is 08:56 AM. | See also: NikonForums.com, CanonForums.com part of our network of photo forums!
  • Red (Default)
  • Green
  • Gray
  • Dark
  • Dark Yellow
  • Dark Blue
  • Old Red
  • Old Green
  • Old Gray
  • Dial-Up Style
Hello! It's great to see you back on the forum! Have you considered joining the community?
register
Creating a FREE ACCOUNT takes under a minute, removes ads, and lets you post! [Dismiss]
Top