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Forum: Pentax SLR Lens Discussion 01-17-2019, 12:46 AM  
Interesting unknown K-mount 200mm F2.8 lens: Goi-mc-telegoir
Posted By kds315
Replies: 9
Views: 1,095
Here now a few images shot in my famous park, also at f2.8 on GH4













Forum: Pentax SLR Lens Discussion 01-15-2019, 07:40 AM  
Interesting unknown K-mount 200mm F2.8 lens: Goi-mc-telegoir
Posted By kds315
Replies: 9
Views: 1,095
Weather got better, so I grabbed the Telegoir 2.8/200mm and took it to my friend's flower shop.
All shot at f2.8









Forum: Pentax SLR Lens Discussion 01-14-2019, 12:42 AM  
Interesting unknown K-mount 200mm F2.8 lens: Goi-mc-telegoir
Posted By kds315
Replies: 9
Views: 1,095
Well, yes, but I'm not here that often... ;-)

It is a great lens and a wonderful, unexpected find and so far I'm very happy with this lens..

Now I just need better weather!!!

The album I will be putting more into is here: GOI MC Telegoir f2.8 200mm | Flickr

Unfortunately there are only four (4) such GOI prototype lenses currentgly known to exist,
but my friend's lens is 10 numbers from mine, so there were a few more made...

This lens was the prototype of the later made OBERON 2.8/200mm, which uses the same
optic design but unfortunately a very badly made housing, plastics and wobbly focusing, quite a
nightmare lens from what I heard. Also optically far from that prototype. A friend has one and
he just calls it "crap".
Forum: Pentax Price Watch 05-17-2014, 05:17 AM  
Quartz Takumar 85/3.5
Posted By kds315
Replies: 14
Views: 5,417
Just in case, a shot with the quartz Takumar 3.5/85mm

UV image (300-4400nm) using Baader-U-filter
Forum: Post Your Photos! 05-20-2014, 12:43 AM  
Nature Ultraviolet and animal vision photography
Posted By kds315
Replies: 4
Views: 729
Well, here comes my first try showing some of my work regarding reflected ultraviolet (UV) photography as well as simulated (tetrachromatic/trichromatic) butterfly and bee vision.

Humans see blue, green and red, whereas butterflies can see UV, blue, green and red and bees see UV, blue and green only. So I developed a method to make that visible by mapping their color space into ours we can see.

This is a Apache beggarticks - Bidens ferulifolia flower as an example.

Human Vision (400-750nm):


Reflected Ultraviolet (300-400nm):


Simulated Butterfly Vision (300-700nm):


Simulated Bee Vision (300-600nm):


Quadriptych to compare:


It gets quite obvious that this Bidens flower has a prominent UV pattern, completely invisible to us humans.
Its petal tips are UV bright around 365nm, its center is quite UV dark, thus serving as a landing guide (nectar guide)
for bees which gets nicely visible also in the simulated vision images.

I won't go into the details of how to achieve this here, as it is shown in detail on my Blog (last link in my signature)
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