I found a Sigma 500mm 1:4.5 prime lens in the Pentax mount at a reputable used online camera dealer. This lens was discontinued five or more years ago for the Pentax cameras, but still supported today for Nikon and Cannon.

I mounted the lens to a 2x teleconverter giving me 1000mm focal length (500mm isn't always enough for shooting birds) and an f stop of 9 or 10 as a doubler/teleconverter cuts the light to the camera sensor in at least half.

I took a test shot from 20 feet of some yucca blossoms (ideally I would use a shorter lens at a much closer distance). I also took a shot of a Red Tail Hawk nest on a power girder that is about 1/4 mile from my back deck and had an image that would be acceptable for documentation photography as I could identify that the birds were hawks, and had enough detail to make out the specie... this photo would be a piss poor art photo.

Here is the result of the yucca blossoms:

I have a rudimentary understanding of the technical aspects of what you posted and zero understanding of how they actually apply to photographs, so hope you don’t mind my enjoying your picture for what it is. It’s a beautiful photograph.

quote:

Originally posted by trapper189:
I have a rudimentary understanding of the technical aspects of what you posted and zero understanding of how they actually apply to photographs, so hope you don’t mind my enjoying your picture for what it is. It’s a beautiful photograph.

Thank you.

I like the photo too. Very painterly.

I have a Pentax screw mount f/5.6, 400mm lens with aperture preset. It’s a dinosaur, but a fine piece of sculpture.

I always liked the Sigma apochromatic lenses. Excellent stuff.

Painterly describes it and it's a great composition too.

Not a photographer at all. Wow, maybe my eyes are just messed up, but it looks to me like on the left side of the photo the forward bits are super clear and the rear bits are slightly out of focus. Seems like a ton of optical power.

Painterly indeed, I’d guess it would take a crazy good painter to show depth of field like that.

Very Impressed!

quote:

Originally posted by Pipe Smoker:
I like the photo too. Very painterly.

I have a Pentax screw mount f/5.6, 400mm lens with aperture preset. It’s a dinosaur, but a fine piece of sculpture.

I have an adapter so I can use my M-42 Pentax screw mount lenses on the digital bodies.

quote:

Originally posted by slosig:
Not a photographer at all. Wow, maybe my eyes are just messed up, but it looks to me like on the left side of the photo the forward bits are super clear and the rear bits are slightly out of focus. Seems like a ton of optical power.

Painterly indeed, I’d guess it would take a crazy good painter to show depth of field like that.

Very Impressed!

oh the optical power is way overkill for this photo. I could have put a much shorter lens on and taken this same shot by getting closer as this is in my backyard.

I needed to see if the lens/teleconverter combination would work as sometimes adding a teleconverter with some lenses makes the image really soft and almost out of focus.

Getting the background out of focus is done by using the lens aperture open as wide as it will go to let in the maximum light... using a 2x teleconverter cuts the light entering the camera by 50%, but also increases the magnification of the lens. You get some and lose some when using a teleconverter.