Go Back   Steve's Digicams Forums >

LinkBack Thread Tools Search this Thread
Old Apr 30, 2011, 11:25 PM   #1
Senior Member
Bynx's Avatar
Join Date: Jun 2007
Location: East of Toronto
Posts: 8,800
Default Manual vs Auto Focusing

I was experimenting today and noticed that manual focusing was not as good as auto focus. I have a Sigma 28-300mmD lens on a Nikon D7000 body. Manually focusing so the image was razor sharp in the viewfinder produced an image that was really not in focus at all. Then I switched to Auto Focus and the image was much improved. Shouldnt I get what I see in the viewfinder, as far as sharpness due to focus? I was shooting a bird and paid particular attention to the details of the feathers. Auto focus was way better than manual focus. Does anyone know how this can be fixed? I prefer to go manual most of the time.
Bynx is offline   Reply With Quote
Sponsored Links
Old May 1, 2011, 5:17 AM   #2
JimC's Avatar
Join Date: Jun 2003
Location: Savannah, GA (USA)
Posts: 22,378

It's may be your your diopter adjustment.

BUT, without a split prism focusing screen it's very difficult to tell what's in focus using an optical viewfinder with a modern dSLR

I've read that it's virtually impossible for the human eye to distinguish correct focus with as hallower depth of fields without a split prism focusing screen (with accompanying math showing apertures you can expect to be able to focus at, and why the eye can't see well enough to focus with shallower depth of fields).

IOW, the optics are going to limit what the eye is capable of focusing accurately; in the same way you can look at a smaller image on a camera's LCD and think it's sharp (until you view it on a larger display and find out that it's really blurry from being out of focus or from subject movement/camera shake).
JimC is offline   Reply With Quote
Old May 1, 2011, 10:01 AM   #3
Senior Member
tizeye's Avatar
Join Date: Mar 2010
Location: Orlando, FL
Posts: 382

I have that problem with the viewfiner all fuzzy...then realize I don't have my glasses on. Amazingle, the photos turned out in focus when I didn't have my glasses on.

Diopter adjustment could be an issue, and I use to lament the lack of a split prism focusing screen, then somebody told about the lights. They substitute for the split prism. On the D90, the "in-focus indicator" is the first item on the lower bar in the viewfinder, but only lights up when in focus.
tizeye is offline   Reply With Quote
Old May 1, 2011, 10:57 AM   #4
Senior Member
TCav's Avatar
Join Date: Sep 2005
Location: Washington, DC, Metro Area, Maryland
Posts: 13,826

Certainly, the diopter adjustment on the eyepiece can increase the accuracy of your efforts at manual focus, but autofocus is usually more accurate than manual focus.
  • The lens is the thing.
  • 'Full Frame' is the new 'Medium Format'.
  • "One good test is worth a thousand expert opinions." - Tex Johnston, Boeing 707 test pilot.
TCav is offline   Reply With Quote
Old May 2, 2011, 4:09 AM   #5
Senior Member
kazuya's Avatar
Join Date: Sep 2008
Posts: 1,009

i read somewhere that when using manual focus most cameras will still light up or beep to let you know when its in focus.
so i thought well i might as well just let the camera do the lot then and turned autofocus on
kazuya is offline   Reply With Quote
Old May 2, 2011, 7:44 AM   #6
Senior Member
Bynx's Avatar
Join Date: Jun 2007
Location: East of Toronto
Posts: 8,800

Thanks for your comments guys. I think I will be playing with the diopter now. Id really prefer to use manual focus if I have a choice.
Bynx is offline   Reply With Quote

Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

All times are GMT -5. The time now is 5:37 PM.