Focus for Infinity?
Apr 30, 2016 10:19:51 #
you are not dumb. and you are right.you do set the distance scale to infinity.you may not be able to accomplish this with auto focus because the dslr camera may not focus to infinity but with manual focus you can and there is an icon in each dslr camera to do that and you do that by adjusting the focus ring.focusing to infinity works well for night photography.but for day time photography especially for landscape photography you are better of resorting to hyperfocal distance or by focus stacking,joseph
Apr 30, 2016 10:25:05 #
zigipha
Loc: north nj
can someone comment - why is focusing "pretty far" and then letting depth of field cover infinity not good enough?
Apr 30, 2016 10:35:45 #
zigipha wrote:
can someone comment - why is focusing "pretty far" and then letting depth of field cover infinity not good enough?
Pushing the focus adjustment to its maximum is going beyond infinity, which is noticeably not the optimum setting. You don't have to be a sharpness freak to want the benefits of optimum focus, especially with subjects like stars which are focus-critical.
Having said that, I'm very fond of using a small aperture and then getting the focus point in roughly the right ball park to get the DOF covering what I want it to cover most (for landscapes mostly).
In the case of stars, you want the aperture to be as wide as possible to avoid using a high ISO or too long a shutter speed (about 30 sec is considered the maximum if you want to avoid pronounced star trails. 20 sec or less is regarded as being more desirable).
Apr 30, 2016 10:39:52 #
jradose wrote:
I want to thank all of you who took the time to respond, and give me answers and information I could use and understand. I will certainly experiment with the information, especially the idea of focusing on a star.
It's a shame you have to premise your honest question, so as to keep the nasty remarks away.
Apr 30, 2016 10:48:52 #
there is no need to use words like "sharpeness Freak".a civilized conversation or a remark will go a long way,joseph
Apr 30, 2016 10:57:13 #
joseph premanandan wrote:
there is no need to use words like "sharpeness Freak".a civilized conversation or a remark will go a long way,joseph
I am familiar with several members in this forum that are self-confessed sharpness freaks (that's exactly the expression they'd use). The term wasn't used in a derogatory or insulting way.
Apr 30, 2016 11:07:45 #
zigipha
Loc: north nj
I agree....i would not take "xxx freak" as derogatory.
buy "xxx nazi"...might be pushing it :)
buy "xxx nazi"...might be pushing it :)
Apr 30, 2016 11:08:47 #
zigipha
Loc: north nj
R.G. wrote:
Pushing the focus adjustment to its maximum is going beyond infinity, which is noticeably not the optimum setting. You don't have to be a sharpness freak to want the benefits of optimum focus, especially with subjects like stars which are focus-critical.
I wasnt thinking of beyond infinity..but like far off trees or buildings.
the moon would be pretty good too :) focus on that and I bet the stars snap into place as well.
Apr 30, 2016 13:34:01 #
JimH123 wrote:
Absolutely correct. And I use the focus magnifier also and very critically focus for infinity. If looking at stars, they will have their smallest diameter and will be the brightest when at perfect focus. And the perfect focus point is a very elusive point. If off even the tiniest bit, the stars become fat and dim.
I too couldn't agree more. Jim H knows of what he speaks.
Craig
Apr 30, 2016 13:40:50 #
zigipha wrote:
I wasnt thinking of beyond infinity..but like far off trees or buildings..... focus on that and I bet the stars snap into place as well.
That would be my assumption as well. I can't speak from experience as far as stars are concerned, but in other contexts, if the angle of view is wide* and if the focus point is far off, the DOF is fine for stuff beyond the focus point, even when you're using a wide aperture.
Perhaps somebody who has explored these possibilities with stars can comment. I suspect that the big no-no is to go beyond the infinity focus point, and providing you're avoiding that it should be OK to focus on far off stuff and have the really far off stuff come out sharp thanks to the DOF. In that context I'd expect auto focus (followed by focus lock) to be fine (as a previous poster has stated).
* For anybody that's interested in star photography, the ideal lens is one with a very wide angle of view and a very wide maximum aperture.
Apr 30, 2016 13:48:20 #
jradose wrote:
Okay...I know the "experts" will get sho... (show quote)
Not a stupid question!
A common one asked in introductory course on photography.
Without going into detail, there is a great difference between focusing AT infinity and focusing TO INCLUDE infinity.
Two terms to Google when you've just sat down with a mug of coffee are:
"Depth of field"
and
"hyperfocality"
For each of those terms find an article that approaches it at a reasonable level for your level of understanding, relax, and learn.
Best regards,
Dave
Apr 30, 2016 17:53:47 #
Wanderer2
Loc: Colorado Rocky Mountains
Pinenuts wrote:
It possibly is not as accurate, but I just auto-focus on a distant object (mountains about twenty miles distant in my case) and then switch to manual focus. DOF gets larger with distance. I seem to get good results.
I do a lot of the same shooting - mountains many miles away. I was wondering if putting a focus point on the mountains and using back button focus would result in more accurate focusing than simply using autofocus? I would think not but I don't understand BBF very well. I have some difficulty with MF because of poor eyesight. Thanks.
Apr 30, 2016 19:07:35 #
For anyone pondering this issue and has not been to this site, take a stroll through. In essence it does all of the math for you so you can focus at the hyperfocal distance of your rig and have the greatest amount of the scene in focus.
http://www.dofmaster.com/dofjs.html
http://www.dofmaster.com/dofjs.html
May 1, 2016 01:07:16 #
quagmire
Loc: Greenwood,South Carolina
Once read that focusing on infinity was good for shooting thru glass with no glare,but have not tried it. Might be a good project for someone.
May 1, 2016 07:59:34 #
JD750 wrote:
Yes adjust the focus dial until it achieves sharp focus on a distant object. It might be off the INF mark a tad bit. That is not unusual. You can put a mark there for future reference.
If you are using a zoom lens, infinity focus may not occur at the same focus ring position for all the different focal length settings.
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