Search results for 'back focus' - page 1626
what is your tip when using manual focus under f2.0?
... so line up the orange marks and you have hyperfocal set anyway ;) Bret Hyperfocal distances were set in the 1930's for large format cameras.... just not good enough for digitals especially on a screen. I've been trying to sort out 24mm and 28mm lenses recently. They seem to have a massive ...
Posted by Algernon on 19/08/2011 - 09:37
what is your tip when using manual focus under f2.0?
Hyperfocal distances were set in the 1930's for large format cameras.... just not good enough for digitals especially on a screen. That's not really true because don't forget that depth of field tables were issued for 35mm format lenses, assuming a different circle of confusion than large format len...
Posted by johnriley on 19/08/2011 - 09:43
what is your tip when using manual focus under f2.0?
It doesn't work with 24/28mm lenses anyway.... possibly due to field curvature. Mattmatic did post a link to an article on the Phase One site showing how to correctly set up WA lenses on digital.
Posted by Algernon on 19/08/2011 - 09:51
what is your tip when using manual focus under f2.0?
What doesn't work Algi? Field curvature will only be a problem in the near field, or at wide apertures, so not really changing the usefullness of that red-coded f8 setting on the pentax manual focus WA lenses.
Posted by johnriley on 19/08/2011 - 10:03
what is your tip when using manual focus under f2.0?
What doesn't work Algi? Field curvature will only be a problem in the near field, or at wide apertures, so not really changing the usefullness of that red-coded f8 setting on the pentax manual focus WA lenses. You can get an idea what I'm talking about from this post. Look at the "1:1 (100%) RHS o...
Posted by Algernon on 19/08/2011 - 10:42
what is your tip when using manual focus under f2.0?
I will take the 28 out at the weekend and do some landscapes to check this; f8 or so, focussed at 2.xm for hyperfocal, focussed at infinity and then again at f11. Let's see what happens (this will be with the K5). Bret
Posted by bretti_kivi on 19/08/2011 - 10:47
what is your tip when using manual focus under f2.0?
What doesn't work Algi? Field curvature will only be a problem in the near field, or at wide apertures, so not really changing the usefullness of that red-coded f8 setting on the pentax manual focus WA lenses. You can get an idea what I'm talking about from this post. Look at the "1:1 (100%) RHS o...
Posted by johnriley on 19/08/2011 - 11:19
what is your tip when using manual focus under f2.0?
I can't get anything approaching sharp at the edge of a Pentax 28mm A f/2.8 :oops: I've found the lens test I noticed it on. It was a Kiron 28-105mm Zoom I'll post a screen grab later. I did try it with a Sigma 24mm f/2.8 and found that best set to the middle of the infinity symbol. I'm gla...
Posted by Algernon on 19/08/2011 - 11:40
what is your tip when using manual focus under f2.0?
Something is muchly amiss here. There's no reason why a wide angle lens should not be sharp at the edges. Maybe stopped down for optimum results, but it should be sharp. Do you have a problem with current wide angle designs?
Posted by johnriley on 19/08/2011 - 11:45
what is your tip when using manual focus under f2.0?
Something is muchly amiss here. There's no reason why a wide angle lens should not be sharp at the edges. Maybe stopped down for optimum results, but it should be sharp. Funny you should say that John, check this out on my new DA15mm. :oops: It vastly improves on stopping down to f8 (althoug...
Posted by Pentaxophile on 19/08/2011 - 23:08
what is your tip when using manual focus under f2.0?
Something is muchly amiss here. There's no reason why a wide angle lens should not be sharp at the edges. Maybe stopped down for optimum results, but it should be sharp. Funny you should say that John, check this out on my new DA15mm. :oops: It vastly improves on stopping down to f8 (althoug...
Posted by Smeggypants on 19/08/2011 - 23:10
what is your tip when using manual focus under f2.0?
Maybe a tad soft, but not unacceptably so for max aperture IMO (I haven't done any sharpening to the shot at all). 100% (Sorry! Totally hijacking this thread :oops::oops:)
Posted by Pentaxophile on 19/08/2011 - 23:16
what is your tip when using manual focus under f2.0?
It's very difficult to judge properly on a small image, but if you want a proper answer you can e-mail me a full sized picture to have a look at. Just PM me and we'll take it from there.
Posted by johnriley on 19/08/2011 - 23:44
what is your tip when using manual focus under f2.0?
This shows what seems to be a massive curvature of field and what nonsense DOF calcs are: Lens: Kiron 28-105mm Camera K-5 200ISO All at f/8 1/200th sec. All shots are straight Jpgs off the camera with no PP and all were captured by pressing the PrtSc button with the screen set to 800 x 600...
Posted by Algernon on 20/08/2011 - 10:14
what is your tip when using manual focus under f2.0?
You say an example where DOF "doesn't work" but DOF always works. It is what it is, an unavoidable result of optical laws. I would seriously look at your lenses if you can't make a landscape sharp front to back with a wide angle lens.
Posted by johnriley on 20/08/2011 - 16:40
what is your tip when using manual focus under f2.0?
A useful trick is to set up hyperfocal distance (or any other DOF requirement) for an aperture, say f8, but actually use f11 instead. This results in a more conservative estimate of the DOF available and allows for better qquality enlargements. That's a great little tip - thanks !
Posted by Frogfish on 20/08/2011 - 16:46
what is your tip when using manual focus under f2.0?
For anyone interested in properly focusing wide angle lenses here's the link again that MattMatic posted some time back. It quite clearly shows that DOF calcs aren't reliable (possibly because the assumption that the lenses are perfect and give the same resolution at every aperture) In this case the...
Posted by Algernon on 21/08/2011 - 10:35
what is your tip when using manual focus under f2.0?
I can see that there is a clear misunderstanding here about what the first article is saying, which is not new in any respect. DOF increases with using smaller apertures, but it is also true that the resolution of a lens falls off either side of an optimum aperture, usually about two stops down f...
Posted by johnriley on 21/08/2011 - 10:56
what is your tip when using manual focus under f2.0?
The more pedantic we are, the less true anything becomes. I'm going to shamelessly steal that for a sig.
Posted by Steep on 21/08/2011 - 11:54
what is your tip when using manual focus under f2.0?
As I have said before, the example here of the 15mm f4 shows why I flogged mine (at a profit :D). At open aperture it's not very sharp. At f8 it matches the kit lens, albeit with less distortion. One of the characteristics of this lens is that if you focus it on, say, a brick wall, the edges will...
Posted by lemmy on 22/08/2011 - 00:14
