Home · Register · Join Upload & Sell

Moderated by: Fred Miranda
Username  

  New fredmiranda.com Mobile Site
  New Feature: SMS Notification alert
  New Feature: Buy & Sell Watchlist
  

FM Forums | Photo Critique | Join Upload & Sell

  

Archive 2013 · Mr. Bill - Question about Proper Focusing

  
 
eeneryma
Offline
• • • • • •
Upload & Sell: On
p.1 #1 · p.1 #1 · Mr. Bill - Question about Proper Focusing


On my Sony NEX 6, I was experimenting with an old Minolta F1.8 prime lens which necessitates manual focus. I'm not sure what F stop the camera was at, probably near wide open. Even though I focused manually (using focus peaking) and thought the front of the character was in proper focus, it turns out the sharpest focus is behind the figure.
I'm most accustomed to using zoom lenses with auto focus. So my question is, when using manual focus lenses, does anyone have suggestions on how to insure that the Fstop is correctly set for proper depth of field and that focus will be spot on? In this case, should I have been focusing in front of the figure, instead of right on it? Your suggestions are much appreciated.



© eeneryma 2012

Mr. Bill




Aug 18, 2013 at 04:47 PM
AmbientMike
Offline
• • • • • •
Upload & Sell: Off
p.1 #2 · p.1 #2 · Mr. Bill - Question about Proper Focusing


Its pretty easy to miss focus with a 50mm lens at 1.8. Try to use live view if the NEX has it. Kind of need something like live view with alts. Great shot otherwise.


Aug 18, 2013 at 05:42 PM
RustyBug
Offline
• • • • • • •
Upload & Sell: On
p.1 #3 · p.1 #3 · Mr. Bill - Question about Proper Focusing


This is a question that would be great to ask in the Alt Forum, but here is a couple of thoughts. There are many, many folks there who are versed in differing techniques for focus/compose, and can explain better than I, but it I'm guessing it is the classic focus/recompose issue.

After you achieved focus on Mr. Bill, did you re-compose. If so, field curvature and/or the difference in distance from center to off-center can account for the placement of the plane of focus being different from the distance from where you originally focused. If you were "pointed down" toward Mr. Bill to set focus and then recomposed to a "level" shot, that would account for the difference in distance for the focal plane.

If you used your center focus point to check focus, you might have better results by changing your focus point to one that is in the same relative portion of the frame.

If you'll excuse the weak artwork ... this is what I think is happening if you are focusing and recomposing.







Aug 18, 2013 at 06:05 PM
eeneryma
Offline
• • • • • •
Upload & Sell: On
p.1 #4 · p.1 #4 · Mr. Bill - Question about Proper Focusing


Thanks Mike and Rusty. I appreciate your possible causes and corrections. I need to continue experimenting to solve this.


Aug 18, 2013 at 08:20 PM
AuntiPode
Offline
• • • • •
Upload & Sell: On
p.1 #5 · p.1 #5 · Mr. Bill - Question about Proper Focusing


FWIW, here's a couple of AAA cells, shot with a manual focus 50mm f1.5 lens (NOKTON) wide open at ISO 400 from a tripod with the subject at the minimum focusing distance of the lens (@ 0.9 meters). The second is a 100% crop of the cells. Shooting wide open at the closest focusing distance is not showing the lens at it's best. Both with focus assist magnification to judge the focus.












Aug 18, 2013 at 11:42 PM
eeneryma
Offline
• • • • • •
Upload & Sell: On
p.1 #6 · p.1 #6 · Mr. Bill - Question about Proper Focusing


Karen: If for instance, you're looking to shoot a portrait, and want to blur the background, what F stop do you choose to make sure you get the head in sharp focus, as well as to get the best results from your lens?


Aug 19, 2013 at 07:41 AM
dmacmillan
Offline
• • • • •
Upload & Sell: On
p.1 #7 · p.1 #7 · Mr. Bill - Question about Proper Focusing


eeneryma wrote:
Karen: If for instance, you're looking to shoot a portrait, and want to blur the background, what F stop do you choose to make sure you get the head in sharp focus, as well as to get the best results from your lens?

Lots of factors are involved.
How far away is the background. What focal length are you considering?

The rule of thumb is that most lenses perform best stopped down 2 stops from maximum aperture.

If I'm shooting 85mm on a full frame body and taking waist up. I can get away with f2.8 or even f1.8 (wide open for my 85mm). If I move in for head and shoulders or even tight face, I like f4.0. The nice thing is that the closer to the subject I am, the more the background will be out of focus for a particular aperture.

I sometimes shoot portraits at 180mm or even 200mm. f5.6 works well. I use DOF preview and check the background before settling in at a particular f-stop. I'll go higher, maybe to f8, if the background will allow.

I'm not sure Kent's theory works for this image. You show back focusing. If Kent's focus and recompose theory has an effect, then by his illustration you would have experienced front focusing.



Aug 19, 2013 at 09:08 AM
eeneryma
Offline
• • • • • •
Upload & Sell: On
p.1 #8 · p.1 #8 · Mr. Bill - Question about Proper Focusing


dmacmillan: thank you for your analysis and suggestions.


Aug 19, 2013 at 09:31 AM
RustyBug
Offline
• • • • • • •
Upload & Sell: On
p.1 #9 · p.1 #9 · Mr. Bill - Question about Proper Focusing


+1 @ much of Doug/Karen.


If the distance to the focal plane in the comp was 1' and the distance to Mr. Bill was 1'1" at the time of setting focus (angled downward), then the recompose would still have the (unchanged on lens) focus plane set at 1'1" (i.e. behind the intended focal plane), even though the desired plane is only 1' away.

I shoot manual focus alts for probably >95% of the time for my images. No issues if you don't recompose, but if you recompose your intended area of focus to a different area, the trigonometry and/or the COF of the lens can get you if you aren't watchful @ how you set your focus distance. Much like how a tilt-shift lens can be worked to generate a re-angled focal plane for more or less dof, this is essentiallly the same issue related to distance/angle change without involving the TS.

Red = intended plane
Purple = focused plane
Blue = recomposed plane

AC > AB
AC = AC2

DC = AB

If you lower you shooting position and maintain parallel orientation, then you'll be setting your lens to the same distance (i.e. same plane). If you tilt and focus, then recompose ... then your lens will be set to a longer distance that lies behind your intended plane of focus. If you maintain the composition from the downward perspective, no worries, but once you change your perspective @ recompose, you are relocating your focal plane.

At apertures with greater dof, this variance is less noticeable for a focus/recompose, but with a skinny dof, it is evident more readily. This is why heavy manual focus shooters will replace their focusing screen to a brighter screen so they can rely on the ground glass for focus, rather than the focus confirmation points. They can compose and set focus to areas not dependent upon aligning focus points, thus no need for the recompose. I would imagine Live View offers a similar advantage over focus confirmation points. (None of my cameras offer live view, so I can't confirm.)

Old school with no focus points, we composed, then focused ... not focus then re-compose. The recompose after setting focus changes things, and if you're on skinny-mini dof or critical alignment ... it can make a difference.







Aug 19, 2013 at 09:38 AM
dmacmillan
Offline
• • • • •
Upload & Sell: On
p.1 #10 · p.1 #10 · Mr. Bill - Question about Proper Focusing


RustyBug wrote:
Old school with no focus points, we composed, then focused ... not focus then re-compose.

Not sure what your experience was, but this may need to be explained.

It was camera specific for me:
Mamiya C330 - Rough focus, compose, fine focus
View Camera - Rough focus, compose (upside down and backwards, fine focus
35 Rangefinder - Focus, recompose
35mm SLR with microprism focus aid - Rough focus, compose, fine focus

I have thought about getting a Sony NEX for my Leica M lenses. I've decided that at least for a while, if I want to shoot with Leica lenses, I'll shoot with the M3 and scan. It's hard to get C-41 processed. I've decided that with care, so I don't contaminate my septic tank, I'll just buy a kit and process myself. I've got all the tanks, clips, thermometers, film washer, etc. stored away. I've been getting such good results with my Epson scanner, I might as well just go "old school".

I'm planning a test. I actually went out yesterday to shoot it, but the weather got in the way. I've got my 5D, a Mamiya C330 body loaded with Portra 400, a C33 body loaded with T-Max CN 400 (it's expired, but what the heck) and my Leica M3 loaded with Portra 400. I'm going to shoot the same scene with a normal lens on each and compare the results. It should be interesting. I won't have results for a while, I need to get the chemistry.



Aug 19, 2013 at 01:33 PM
RustyBug
Offline
• • • • • • •
Upload & Sell: On
p.1 #11 · p.1 #11 · Mr. Bill - Question about Proper Focusing


If you'll notice ... you always focused after your final composition for fine control.

The rangefinder ... remember good ol' parallax ... is a different approach from through the lens focusing and does not afford "critical focus" like this shot was trying to achieve. "F8 and be there" would allow for a tremendous amount of dof, such that the parallax difference was covered by either the dof or the negligible amount of parallax at longer camera-subject distances.. I had a Rangefinder with a 50/1.4 for my first 35mm. The parallax was part of the reason I went to SLR (along with more lens options). As long as you weren't trying to shoot from mfd distances, the parallax was largely negligible, but when you came in close, it would rear its head.

Also, as you mentioned before ... camera to subject distance plays an important role in dof (parallax also), it also plays an important role in how much difference there is in the two distances involved. From a farther camera to subject distance, the variance in angle is smaller, thus the difference in distance is smaller and may be less significant. Shooting from as short a distance as it was to Mr. Bill, the difference can matter.

I still shoot "rangefinder style" at set focus and aperture to "cover a range of distances" (hyper-focal being the extreme example) and can then freely compose into that zone/range of distances without too much concern for critical focus as dof (especially WA/UWA) can cover a lot of ground for applications that don't afford the time to focus after comp, i.e. pre-focused to a distance/range (hence rangefinder).

But, there is a difference between focusing to a range that will encompass your subject vs. achieving critical focus of your subject. Had you tried to shoot from this distance with a rangefinder and skinny dof for critical focus such as this ... that's a trick unless you've pre-tested the accuracy of your distance scale on the lens, or know how much compensation to make for the parallax.

Doug, it will be interesting to see the results of your test setup. You oughta share it with FM'ers over in the Alt Forum when you finish. They'll certainly be a group that can appreciate it.


BTW ... diggin' the shot.
Any chance we'll see him make an encore?



Aug 19, 2013 at 02:01 PM
AuntiPode
Offline
• • • • •
Upload & Sell: On
p.1 #12 · p.1 #12 · Mr. Bill - Question about Proper Focusing


eeneryma wrote:
Karen: If for instance, you're looking to shoot a portrait, and want to blur the background, what F stop do you choose to make sure you get the head in sharp focus, as well as to get the best results from your lens?


As Doug alluded, it's complicated if you try to look at it analytically. If the subject is directly facing the camera, less DOF is needed. If the subject's head is turned somewhat, more is needed because the plane of the face is at an angle to the image sensor plane. Apparent DOF also varies with distance, aperture and sensor size. For a given set-up example, an aperture of f4 might be right for a full-frame sensor camera, but an f2 might give a similar look for a micro 4/3 camera. Background distance, type of background, subject, type of pose (face, head and shoulders, waist-up, 3/4, full length), orientation of pose, and shooting distance (and by implication - focal length) are other factors. In the old film days, I'd do test shots for a given set-up. Now I make test shots as I go and chimp the magnified playbacks.



Aug 19, 2013 at 03:54 PM
dmacmillan
Offline
• • • • •
Upload & Sell: On
p.1 #13 · p.1 #13 · Mr. Bill - Question about Proper Focusing


AuntiPode wrote:
As Doug alluded, it's complicated if you try to look at it analytically. If the subject is directly facing the camera, less DOF is needed. If the subject's head is turned somewhat, more is needed because the plane of the face is at an angle to the image sensor plane.

This is a good point. We normally want both eyes in at least fairly good focus if we're doing a traditional portrait.

Now I'll editorialize.

What is the intent? What is the driving force?

If you're after getting a nice portrait of somebody, what you may gain in playing around with classic manual focus lenses will be lost by your attention being on the process of making the portrait instead of interacting with the subject. I prefer a more relaxed, informal portrait and that requires a good working relationship with the subject and a minimum amount of fiddling with gear. Modern DSLRs with good autofocus are a godsend compared to clunky manual focus MF cameras used in the old studio settings.

Also, unless you plan to do primarily macro photography, I'm not sure Mr. Bill is your best test candidate. I assume he's only 5 or so inches tall, even with the room around him I'm guessing you're closer to him than you would be to a human portrait subject. The closer you get, the more critical the focus becomes and the more noticeable even slight misfocus becomes. Test your equipment in the manner you plan to use it.



Aug 19, 2013 at 05:25 PM
RustyBug
Offline
• • • • • • •
Upload & Sell: On
p.1 #14 · p.1 #14 · Mr. Bill - Question about Proper Focusing


http://www.cambridgeincolour.com/tutorials/dof-calculator.htm

Something to play with to get a feel for DOF effects when you change variables @ camera-subjective distance vs. aperture vs. focal length vs. sensor size. Other charts and calculators exist as well of course.



Aug 19, 2013 at 06:27 PM
eeneryma
Offline
• • • • • •
Upload & Sell: On
p.1 #15 · p.1 #15 · Mr. Bill - Question about Proper Focusing


Thank you all for such great responses. A lot to think about and test. I have no choice but to retire Mr. Bill


Aug 19, 2013 at 06:35 PM
dmacmillan
Offline
• • • • •
Upload & Sell: On
p.1 #16 · p.1 #16 · Mr. Bill - Question about Proper Focusing


eeneryma wrote:
I have no choice but to retire Mr. Bill

Oh no!



Aug 19, 2013 at 06:57 PM





FM Forums | Photo Critique | Join Upload & Sell

    
 

You are not logged in. Login or Register

Username       Or Reset password



This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.