Fast Wides vs "slow" wides and night photography

[Pfsor]

Are you here to contribute meaningful discussion and discourse or just sell books?

Sorry I told you about the book. On the other hand, you don't need to buy it. Borrowing it in a library would do too. Sorry again about it. I won't do it anymore, I promise.

[Pfsor]

One more try for those who want to learn about pinpoint star exposure -

http://www.kodak.com/global/en/consu...50/p150a.shtml

[Pfsor]

One more try for those who did not learn from the first try -
https://books.google.ch/books?id=IIP...20time&f=false

[neil poulsen]

I have a couple of questions . . .

6 all of them are optimized for f22 and are diffraction limited at f22. For star tracks that is probably a moot point. But are you only going to shoot star tracks? . . .

My understanding is that, once one closes the aperture of an f22 diffraction limited lens beyond f22, sharpness decreases in the plane of focus. In other words, f22 is the point at which decreasing the aperture further no longer improves sharpness in this plane. (Is this correct?)

To a second question, what would be involved in designing a lens that had better than f22 diffraction limited performance? What would be the trade-off?

2 because of the larger circle the fall off starts further out from the center so it is less then the slower lens over the same film area. . .

To what degree is fall off caused by the off-axis angle becoming greater as the image gets closer to the edge of the film, versus the construction of the lens?

[Pfsor]

One more try for those who like a "rather verbose" variant on the same theme.
http://petapixel.com/2014/01/29/pick...y-photography/

[FredrickSummers]

Now when you're comfortably seated in your - my experience is more than the optical science theory - seat go and do yourself a favour. Read the book Wide-field astrophotography by Robert Reeves published by Willmann Bell publisher and learn about the roll of physical and numerical aperture of lenses (yes, even LF lenses, the guy went through it all) in star trails photography, the background night light etc.
But! I warn you - this astrophotographer he too uses the optical science laws you deny. As a starter for this brain washing experience take a look at his www. robertreeves.com website - you can read some chapter of the given book there.

One thing I would discourage you to do though - asking him for his LF lens photographs to prove the optical science laws he talks about. I think it would be too revelatory and he could lose interest in further communication with you.

Easy with the hostility there. Thanks for the suggestion of the book, I will check it out on my next book run. I don't care enough to break it down into the science, stars can make some very cool landscape photos, that's the extent I care about right now. I didn't start the thread to become a debate of aperture vs "real aperture". Thank you for your contribution thus far, but the hostility is not needed.

Also thanks for the links, I'll check them out when I get more 5 minutes free


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[FredrickSummers]

Yes, the faster lenses also use center filters for best evenness of illumination across the frame. But, as I mentioned, Nikon never made center filters. You could go to a sharper and faster 90 by going to the Rodenstock Grandagon-N 6.8. Granted, it's only a half stop faster. But it will outperform the one that you are considering without being much, if any, larger and heavier.

Bob, I always value your opinion, and thank you again. I assume by sharper and faster you mean as compared to the Nikon 90 f8? What makes the rodenstock sharper? I thought all the large format lenses were more or less the same for sharpness, etc? I'm not doubting you, just asking.


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[FredrickSummers]

How about 75s, I assume they would prefer very similar, but 24mm is the popular astrophotograpy focal length and also one I really like/liked. If I'm going to change to a different wide may as well consider those. They are all pretty fast too!


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[Pfsor]

From one who learned the laws of optics and does some astrophotography with his LF equipment - http://www.cloudynights.com/documents/large.pdf

[Drew Wiley]

Fun stuff. If I had the money and time for this, I've got a friend who is a noted astrophysicist. The only problem is, those kinds of people have a very very different definition of "large format" and "tripods" than we do.