Lenses

On a digital SLR, mine anyway, there is a 1.5 'crop' factor. In essence, my
16-45mm lens has a bottom end of 24mm. Fair enough. I knew that going in.

I hadn't realized how handy it might be to have a shorter lens, an actual 15 or
16mm.

Now, the only available lenses appear to be 8mm or 15mm fisheyes.

I've never worked with fisheyes, in large part because there was no need, but
also because I find the effect ugly.

If I use an 8mm fisheye with the 1.5 FOV crop, will I still get that gawdawful
barrel distortion? Seems likely to me, but I don't really know. The 15mm is no
gain from the 16mm base of my Pentax zoom.


Charlie Self
"America does not go abroad in search of monsters to destroy. She is the
well-wisher to freedom and independence of all. She is the champion and
vindicator only of her own." John Quincy Adams

On 28 Sep 2004 20:21:47 GMT, otforme (Charlie Self)
wrote:

On a digital SLR, mine anyway, there is a 1.5 'crop' factor. In essence, my
16-45mm lens has a bottom end of 24mm. Fair enough. I knew that going in.

I hadn't realized how handy it might be to have a shorter lens, an actual 15 or
16mm.

Now, the only available lenses appear to be 8mm or 15mm fisheyes.

I've never worked with fisheyes, in large part because there was no need, but
also because I find the effect ugly.

If I use an 8mm fisheye with the 1.5 FOV crop, will I still get that gawdawful
barrel distortion? Seems likely to me, but I don't really know. The 15mm is no
gain from the 16mm base of my Pentax zoom.

You will still get the effect

GT40 wrote in
:

If I use an 8mm fisheye with the 1.5 FOV crop, will I still get that
gawdawful barrel distortion? Seems likely to me, but I don't really
know. The 15mm is no gain from the 16mm base of my Pentax zoom.

You will still get the effect

But just the central part of it where is not so noticeable. Get any photo
taken in a full frame camera with that lens, the promotional one could
serve. Then crop the central part making the crop 1.5 times smaller and
that would be exactly what you will get.

Charlie Self wrote:
On a digital SLR, mine anyway, there is a 1.5 'crop' factor. In essence, my
16-45mm lens has a bottom end of 24mm. Fair enough. I knew that going in.

I hadn't realized how handy it might be to have a shorter lens, an actual 15 or
16mm.

Now, the only available lenses appear to be 8mm or 15mm fisheyes.

I've never worked with fisheyes, in large part because there was no need, but
also because I find the effect ugly.

If I use an 8mm fisheye with the 1.5 FOV crop, will I still get that gawdawful
barrel distortion? Seems likely to me, but I don't really know. The 15mm is no
gain from the 16mm base of my Pentax zoom.


Actually the 15mm will be noticably wider than a 16 mm zoom lens. Some
discussion of that he

http://forums.dpreview.com/forums/re...essage=5908443

I use a 15mm fisheye at times. Sometimes I want the fishey effect. If
not, I use PTLens (free) to defish the shots. Works quite well.

Phil

Charlie Self wrote:
On a digital SLR, mine anyway, there is a 1.5 'crop' factor. In essence, my
16-45mm lens has a bottom end of 24mm. Fair enough. I knew that going in.

I hadn't realized how handy it might be to have a shorter lens, an actual 15 or
16mm.

Now, the only available lenses appear to be 8mm or 15mm fisheyes.

I've never worked with fisheyes, in large part because there was no need, but
also because I find the effect ugly.

If I use an 8mm fisheye with the 1.5 FOV crop, will I still get that gawdawful
barrel distortion? Seems likely to me, but I don't really know. The 15mm is no
gain from the 16mm base of my Pentax zoom.


Actually the 15mm will be noticably wider than a 16 mm zoom lens. Some
discussion of that he

http://forums.dpreview.com/forums/re...essage=5908443

I use a 15mm fisheye at times. Sometimes I want the fishey effect. If
not, I use PTLens (free) to defish the shots. Works quite well.

Phil

"Antonio Martos" wrote in message
...
GT40 wrote in
:

If I use an 8mm fisheye with the 1.5 FOV crop, will I still get that
gawdawful barrel distortion? Seems likely to me, but I don't really
know. The 15mm is no gain from the 16mm base of my Pentax zoom.

You will still get the effect

But just the central part of it where is not so noticeable. Get any photo
taken in a full frame camera with that lens, the promotional one could
serve. Then crop the central part making the crop 1.5 times smaller and
that would be exactly what you will get.

Make an 8x12" print, and take a paper cutter and cut out a 5x7.5" from the
center. This is what the FOV is with a 1.5 camera

Phil Wheeler responds:

Charlie Self wrote:
On a digital SLR, mine anyway, there is a 1.5 'crop' factor. In essence, my
16-45mm lens has a bottom end of 24mm. Fair enough. I knew that going in.

I hadn't realized how handy it might be to have a shorter lens, an actual
15 or
16mm.

Now, the only available lenses appear to be 8mm or 15mm fisheyes.

I've never worked with fisheyes, in large part because there was no need,
but
also because I find the effect ugly.

If I use an 8mm fisheye with the 1.5 FOV crop, will I still get that
gawdawful
barrel distortion? Seems likely to me, but I don't really know. The 15mm is
no
gain from the 16mm base of my Pentax zoom.


Actually the 15mm will be noticably wider than a 16 mm zoom lens. Some
discussion of that he

http://forums.dpreview.com/forums/re...essage=5908443

I use a 15mm fisheye at times. Sometimes I want the fishey effect. If
not, I use PTLens (free) to defish the shots. Works quite well.


I'm getting an undistorted 24mm view with the basic 16-45mm lens. If the 15mm
fisheye would give me a close approximation to 19 or 20mm, it would be worth
thinking about, but I'd really need to see the results in the kind of shooting
I'd be doing--the Sigma 15mm for the Pentax is about $450, a lot of money to
spend for something you're not sure of...at least it is for me. Now, the 8mm
will obviously give 12mm results, but that's a round fisheye, or so it's
listed, as compared to the 15mm diagonal fisheye. And it's also $590, even more
of a wallet lightener. The effect might be interesting, but I'm not sure I've
got 600 bucks worth of use for it.


Charlie Self
"America does not go abroad in search of monsters to destroy. She is the
well-wisher to freedom and independence of all. She is the champion and
vindicator only of her own." John Quincy Adams

Charlie,

Let me jump in here and point you to an article in Oct issue of PCPhoto,
page 26 by Rick Sammon, "Transforming a Photograph". In the article he
discusses how to use the Perspective control in PS.

Find a used lens or borrow one and see how it works out.

Bob S.


"Charlie Self" wrote in message
...
On a digital SLR, mine anyway, there is a 1.5 'crop' factor. In essence,
my
16-45mm lens has a bottom end of 24mm. Fair enough. I knew that going in.

I hadn't realized how handy it might be to have a shorter lens, an actual
15 or
16mm.

Now, the only available lenses appear to be 8mm or 15mm fisheyes.

I've never worked with fisheyes, in large part because there was no need,
but
also because I find the effect ugly.

If I use an 8mm fisheye with the 1.5 FOV crop, will I still get that
gawdawful
barrel distortion? Seems likely to me, but I don't really know. The 15mm
is no
gain from the 16mm base of my Pentax zoom.


Charlie Self
"America does not go abroad in search of monsters to destroy. She is the
well-wisher to freedom and independence of all. She is the champion and
vindicator only of her own." John Quincy Adams

Charlie Self wrote:


I'm getting an undistorted 24mm view with the basic 16-45mm lens. If the 15mm
fisheye would give me a close approximation to 19 or 20mm, it would be worth
thinking about, but I'd really need to see the results in the kind of shooting
I'd be doing--the Sigma 15mm for the Pentax is about $450, a lot of money to
spend for something you're not sure of...at least it is for me. Now, the 8mm
will obviously give 12mm results, but that's a round fisheye, or so it's
listed, as compared to the 15mm diagonal fisheye. And it's also $590, even more
of a wallet lightener. The effect might be interesting, but I'm not sure I've
got 600 bucks worth of use for it.


Yes -- fisheyes are a bit of an occasional lens, unless you need to
shoot wide a lot.

Phil

Bob S responds:

et me jump in here and point you to an article in Oct issue of PCPhoto,
page 26 by Rick Sammon, "Transforming a Photograph". In the article he
discusses how to use the Perspective control in PS.

Find a used lens or borrow one and see how it works out.

I probably have the issue. If not, the library does.

But finding a Pentax AF fish-eye may be more than this area can handle. Small
towns are not great sources of offbrand camera gear for loan. Well, Bedford is
small, 6600 people, and I don't even live in town, but 10 miles out.

I wonder if Ritz in Roanoke carries Pentax gear? If they have something I can
plug in and shoot a few frames in the store...

Ah, hell. I probably won't have the money until the Christmas bills are paid,
so why worry.

Thanks for the idea, though.

Charlie Self
"America does not go abroad in search of monsters to destroy. She is the
well-wisher to freedom and independence of all. She is the champion and
vindicator only of her own." John Quincy Adams