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Forum: Post Your Photos! 07-19-2016, 08:00 AM  
Nature Cooperative Dolphin
Posted By Kerrowdown
Replies: 12
Views: 708
This one said to the old Kerrowdown... " you want to play, catch me if you can?". :D

You can tell by his smile, he's out to play with me. ;)
Forum: Post Your Photos! 07-21-2016, 09:09 PM  
Nature Square-tailed Kite
Posted By Rebootoz
Replies: 6
Views: 1,256
Circling around above my backyard:
Forum: Post Your Photos! 07-21-2016, 06:47 PM  
Abstract Hummingbird from egg to flight in 20 Photos
Posted By rkappleby
Replies: 16
Views: 1,897
Continued....the last four photos were taken the day before the chicks left the nest. It was a really amazing process to watch.
Forum: Pentax News and Rumors 07-16-2016, 06:27 PM  
D-FA 100-300mm f/4
Posted By asahi man
Replies: 103
Views: 15,422
Pentax 4.0 / 100-300 is not only a sleeping patent.
Best regards
Forum: Lens Clubs 07-15-2016, 10:03 PM  
300mm plus Lens Club: discuss your long lenses
Posted By cleaverx
Replies: 36,050
Views: 3,672,955
Here are some shots with my old manual lens SMC 500mm f/4.5

IMGP9739 by Mako_Elite, on Flickr


Some more pics with my SMC A 400mm f/5.6

IMGP2230 by Mako_Elite, on Flickr

IMGP2231 by Mako_Elite, on Flickr
Forum: General Photography 05-29-2016, 04:38 PM  
Old Photo's found
Posted By Mistlefoot
Replies: 10
Views: 1,217
Forum: Lens Clubs 05-11-2016, 02:14 AM  
The 15mm Limited controls my mind - club
Posted By rayallen
Replies: 11,787
Views: 2,099,877
Boats at Mosman Bay, Sydney.

_IMG6344_Mosman_Bay by Ray Allen, on Flickr
Forum: Mini-Challenges, Games, and Photo Stories 05-10-2016, 12:42 PM  
Thematic Wildlife
Replies: 11,012
Views: 595,882
Arctic tern IF.
Forum: Lens Clubs 04-17-2016, 02:47 PM  
300mm plus Lens Club: discuss your long lenses
Posted By dane.dawg
Replies: 36,050
Views: 3,672,955
Tried some Swallow flight shots today.
Forum: Post Your Photos! 04-07-2016, 10:15 AM  
Nature Backyard Birds April 4th to the 7th
Posted By boriscleto
Replies: 5
Views: 835
A Cardinal in the front yard...
_IMG7427.jpg by Ben McGann, on Flickr

Female House Sparrow
_IMG7431.jpg by Ben McGann, on Flickr

Song Sparrow
_IMG7439.jpg by Ben McGann, on Flickr

White-throated Sparrow
_IMG7454.jpg by Ben McGann, on Flickr

Fox Sparrow
_IMG7543.jpg by Ben McGann, on Flickr

Another House Sparrow
_IMG7568.jpg by Ben McGann, on Flickr

Female Northern Flicker
_IMG7594.jpg by Ben McGann, on Flickr
Forum: Pentax Medium Format 03-31-2016, 11:38 AM  
Post your medium format photos!
Posted By ffking
Replies: 16,533
Views: 2,703,220
sounds quite... er... specific - do you have a particular temptation in mind?
Forum: Post Your Photos! 02-17-2016, 09:26 AM  
Travel Birds and Landscapes from Puerto Rico
Posted By slowpez
Replies: 5
Views: 730
Looks like you had a wonderful vacation.
Forum: Post Your Photos! 02-17-2016, 05:26 PM  
Travel Birds and Landscapes from Puerto Rico
Posted By micromacro
Replies: 5
Views: 730
I wonder if we have met there in December :D
Looking at your pictures, I really regret for not taking my DA*300 there...
Forum: Post Your Photos! 02-17-2016, 04:59 PM  
Travel Birds and Landscapes from Puerto Rico
Posted By Tonytee
Replies: 5
Views: 730
Wonderful photography. Yes, PR is a tropical paradise that is often overlooked as a great place to relax and try some locally made Rum.

Great series, thanks for sharing.

Forum: General Photography 06-02-2015, 03:22 AM  
Why are fast lenses sharper?
Posted By PJ1
Replies: 43
Views: 3,687
How about sharp starting at f4? S-M-C/Super Macro-Takumar 50mm F4 It will probably out resolve a lot of lenses at f4 but it still gets sharper as it is stopped down.

A good macro is designed to be sharp across the frame but nearly all lenses (even macros) will be sharper in the centre than at the edges. After all, it is mostly subjects towards the centre of the frame that we want to capture. Without getting too much into optics, if a lens is sharper at the centre, it will get sharper as it is stopped down because we are using more of the "better" part of the lens (That is putting it a bit crudely but one of the factors to consider is that a lens has a curved surface and it is projecting onto a flat surface. Sony are developing a curved sensor which will supposedly to address that. But how finicky do we need to get?). If we stop down further - usually past f11 but it depends on sensor size - diffraction effects start to degrade the perceived sharpness of the lens. That is why some lenses may be described as "diffraction limited". It means that the decline in sharpness past a certain point is due to diffraction and not the optical qualities of the lens. If you look at graphs of lens tests you will see that almost all lenses get sharper as the are stopped down and then start to decline after f8 or f11 (some even sooner). Diffraction is there at wider apertures too but it is not so noticeable.

The dpreview site allows different lenses to be compared - with caution, because there are only a couple of Pentax lenses there and other comparisons must be made on the same sensor to be meaningful. It is here: Lens review data: Digital Photography Review

The Zeiss Otus 55/f1.4 is about the sharpest lens around at the moment. It is at the bottom of the list. It is very sharp at f1.4, peaks at f2.8 and then starts to decline (while still being very sharp). It has 12 elements in 10 groups. They must have gone to all that trouble for a reason. It is undoubtedly a good lens, but costs about $5000. The SMC Pentax-DA* 55mm F1.4 SDM can be had for about one eighth of that price. It has nine elements in eight groups - less glass, less weight, but also a reputation for being very sharp, and getting sharper as it is stopped down. It is not so much a question of why manufacturers don't make all lenses as sharp as possible. They all work to a price and even an ordinary kit lens these days is produced to fine tolerances and can deliver a great image in the right hands.

If you want to get right into the optics side though, I propose this: If we had an optically perfect lens projecting onto a matched, curved sensor, It would exhibit maximum sharpness at maximum aperture because diffraction would be at the minimum. The moment we began to stop down, sharpness would decrease as diffraction increased. In our imperfect world, it doesn't quite work that way, but the Zeiss Otus optics are pushing towards that limit.

That should open a can of worms! :),
Forum: Post Your Photos! 06-08-2015, 05:26 PM  
Misc Culling geese
Posted By audiobomber
Replies: 13
Views: 1,027
The world needs room, for more humans. Eight billion are not enough. There's no room for wild creatures. :eek:
Forum: Post Your Photos! 05-04-2015, 09:22 PM  
Abstract BIFs, Turkey, Hummingbird, ETC
Posted By Stavri
Replies: 7
Views: 748
I'd like to know that chick's name..:cool:

(great set, my compliments)
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