Telephoto Compression and “Super Sun” / Potato Masher Effect in LF?

**Kerosene Hat** · 19-Oct-2023, 22:15

Originally Posted by Corran

If you are going up to Stone Mountain to shoot the sun behind Atlanta let me know! I've always wanted to do that. Sadly October/November is usually my busiest time at work so hasn't happened.

I've been wanting to shoot it with my Pentax 67, 500mm, and 1.4x or 2x TC. I think on LF you'll need something crazy huge as Lachlan mentioned. Perhaps the 720mm on 6x12 would be something interesting.

@Bryan, I'm looking at Friday or Saturday afternoon - let's go together, if possible! M: 404.747.0097. It's a once-in-6-months thing, and I figure might as well try in LF after doing it in digital APS-C long ago.

**Kerosene Hat** · 19-Oct-2023, 22:34

Originally Posted by reddesert

Something is wrong with this (simulated 35mm overlaid on 4x5) image. The image of the sun is improperly scaled for focal length. You can tell because the image of the sun should be 10x linearly smaller in the "200mm" image than in the "2000mm" image, but it looks only about 3x smaller.

The sun's disk is about half a degree diameter or 1/110 radian. That means the diameter on film will be about 1/110 of the focal length. So for a 2000mm lens, you get about an 18mm diameter disk on film. The simulated 2000mm image shows the sun nearly filling the 24mm dimension - about 21mm image diameter. So that is maybe 10% exaggerated. For the 200mm image, the sun will be only about 1.8mm diameter on film, but the image shown is about 8-9mm diameter, so simulated 4 - 5 times too large.

As people say, perspective is a property of your viewpoint - "telephoto compression" comes from standing far away and excluding a lot of the foreground/sideground. For which you need to either use a long focal length lens, or crop a lot.

Fair. I whave a 450MM Nikkor and/or 19" Artar that can go on a 5x7 Wisner (formerly Steve Simmons', mojo = interesting, desert dust = moderate), with a 4x5" reducing back. No need to print full frame, just a challenge to do this shot w/ LF vs. APS-C and baby format. Plus, an excuse to hike a mile straight up a granite rock, as @Corran knows...