Rectilinear vs fisheye wide angle question - Page 2

danielchtong · 09-01-2008, 02:09 PM

Originally Posted by PentaxPoke

Even if I did get the 200 or 300, I think that I wouldn't notice the difference in the tele shots I usually take. They are usually more limited in sharpness by motion of the subject than the lens.

Ok you are not a tele person. Camera or subject motion do have major effect. But there is major merit of either DA200/300 over that of a consumer zoom at the tele end.

This is from a manual focus A300mm

Originally Posted by PentaxPoke

I find that the 14 is not as wide as I want to go relative to the 17 on my Tamron. I mainly bought the fixed 14 for the high-altitude balloon flights as an upgrade to the 18-55 II kit I used last time.

The theoretical FoV of a FE 16mm is on paper the same as a rectilinear 16mm. But my FE 16mm looks definitely wider than its rectilinear counterpart. I did not research into this subject and I am sure about it though. If you want to go wider or wilder, go with FE

You may compare the rect WA 16mm (J Scott sample at 14mm)above with the same 16mm FE 16mm in here

Daniel

danielchtong · 09-01-2008, 02:12 PM

Originally Posted by J.Scott

I have a DA 10-17mm and really do like the images it produces. However, be prepared for a lot of PF (purple fringing) under the 'right' conditions. Below is an example. In fact, it should be described as torture testing the poor lens! I produced the image on a very bright winter afternoon by deliberately including some sun flare. The crop is a 500% blow up of a small area on the image. Under less strenuous conditions it performs admirably. (In this case I just wanted to bend lamp posts in the sun - it's lots of fun. But just thought it fair to warn you that PF will happen with this lens.

Hey J,
It is physically unavoidable to have PF in WA shots. Your example is an exagerated one facing direct sunlight. Even for normal FL like 50mm it is problematic

Daniel

danielchtong · 09-01-2008, 02:52 PM

Originally Posted by troyz

Makes sense to me -- if you need better results than defishing can provide you can always go back to the DA14.

Even with Zen 16mm, defished image/lines are almost in straight lines. All I need to do is to set the FoV to around 70 degree under PSP version 8

Daniel

PentaxPoke · 09-01-2008, 03:07 PM

Daniel, my understanding is that the last picture was taken with the FE, and then converted to RL with a FOV of 70 deg? I like that shot. Do you still happen to have the unconverted version?

*troyz* · 09-01-2008, 09:02 PM

Originally Posted by danielchtong

The theoretical FoV of a FE 16mm is on paper the same as a rectilinear 16mm. But my FE 16mm looks definitely wider than its rectilinear counterpart. I did not research into this subject and I am sure about it though.

Here are two useful discussions of the differences between fisheye and rectilinear lenses (trigonometry included)

Field of View - Rectilinear and Fisheye Lenses

Fisheye Projection - PanoTools.org Wiki

Field of view for a 16mm fisheye is greater than field of view for a 16mm rectilinear (magnification at the center is the same).

PentaxPoke · 09-01-2008, 10:21 PM

Thanks for all the advice here. I have decided to go with the Pentax 10-17 fisheye. Your comments and pictures were very helpful. I guess I have learned that wide angle 2D projections are a somewhat subjective subject.

I am looking forward to using this lens. It seems to me that one really has to "think" when framing any type of wide-angle shot.

*Russell-Evans* · 09-02-2008, 02:51 AM

Originally Posted by PentaxPoke

Thanks for all the advice here. I have decided to go with the Pentax 10-17 fisheye. Your comments and pictures were very helpful. I guess I have learned that wide angle 2D projections are a somewhat subjective subject.

I am very susceptible to motion sickness. Even a couple of minutes with a fisheye lens is enough to produce a headache and general feeling of unease for me. It probably isn't an issue for most people, but it is worth enough thought before making a purchase just check to it off as not an issue.

Thank you
Russell

PentaxPoke · 09-03-2008, 11:14 PM

Just got my 10-17 Fisheye today! I really like this lens. It is really not as "fishy" as I thought, and I enjoy how wide I can get with this lens. When I take a very wide angle shot and then use a conversion to rectilinear, it confirms my personal preference that very wide angle shots look better to me with fisheye distortion than rectilinear stretching.

Thanks for the advice all. The lens is also very nice and compact and feels very well made. The metal lens cap feels great and very "old school"

RioRico · 09-03-2008, 11:45 PM

My original kit when I bought my K20D were the DA 10-17, DA 18-250, and FA 50/1.4 or indoors and night. It's been, what, four months now? and I'm still happy with those. But not happy enough to keep from buying more lenses... So a Vemar 12mm sits on my desk waiting for the right mount, and a Zenitar 16mm should arrive Real Soon Now, and a Lentar 21mm has a prominent place in my bag, and I'm desperately trying to squeeze my budget to get a Pelang 8mm. Now I need to go somewhere to use these, somewhere that isn't crowded with pine trees. I HATE PINE TREES -- TOO MANY VERTICAL LINES FOR FISHEYEING!! Maybe I should go crawl around a quarry.