Originally posted by alamo5000 Here are some further questions...and comments...
The Pentax DA15mm on a crop camera has a FOV of 77* horizontal
The 20mm on a FF has a FOV of 84* horizontal
The Irix 15mm on a FF has a FOV of 100* horizontal
The Irix 11mm on a FF will have roughly 115* horizontal (estimate/rough guess)
The Irix 15mm is 23* wider than the DA15mm! That's 30% wider than the DA15mm!! That's crazy!
At this point I am leaning towards something in the FF 15mm range or the 20mm range but that yet to be released 11mm could be just insane. Right now 20mm is winning for a few reasons.
I have rarely shot ultra wide before but I am getting the urge to try it again. Before I owned the DA15mm and the Tamron 10-24.
The Irix 15mm on paper is about as wide (roughly) as the 10-24mm was at 10mm. IIRC at that mark the Tamron had quite a bit of distortion.
Given I don't have a lot of experience with the Ultra Wide does anyone have any opinions to offer up?
So far the reason why the FA 20mm is winning is because of size and auto focus. I could throw that in my bag and not even know it's there. The Samyang version though is nearly twice the weight. All that said both are STILL wider than the DA15mm.
Honestly I feel like I would probably use the 20mm focal length more. Plus it would not be a huge burden to carry (I travel a lot) and it's fast enough. I have one manual focus lens and yes I like it but I am not completely sold on manual focus yet. Yes I don't mind it but no it hasn't grown on me all the way yet.
I am not totally sold yet on the "so wide I can't stand it" wide... I mean yes I would give it a go but I don't recall ever quite falling in love with the 10mm end of the Tamron or really knowing what to do with it.
I am trying to think the through the process here and so far all roads lead to the FA20mm so far. That being said I really am interested in hearing how people shoot with the reeeeally wide lenses.
Your concern is not misplaced.
Like clackers, I have the Sigma 12-24 which I bought 9 years ago for the K-10D, also used on the K-5, and really really enjoyed on APS-C. Now, on the K-1, 12 mm is insanely wide which makes it very special but also limits it's use. As clackers said, it does create drama -- my wife just about divorced me when she saw herself in the corner of one of the 12 mm photos! UWA really stretches people and circles at the edges and corners.
I'm sure you'd use the 20 mm more. Yet even if a crazy-wide lens gets less use, the results can be more powerful. A focal length like 11 to 14 mm on FF is a very cool for architecture (cathedrals, ceilings, facades) and landscapes (zenith shots of tree canopies, sweeping mountain vistas, long-views across flower-strewn meadows). And the extreme distortion can be useful for abstracts and crazy compositions. I still keep the Sigma 12-24 in my bag.
Overall, I'd definitely get the 20 mm for everyday WA but do think about something wider because UWA can be a real photographic challenge that can be really rewarding. Also, you can always crop a UWA image down to WA but unless you like the labor of panoramas, it's much harder to create a UWA image with just a WA lens.
Enjoy!