Zoom and focus or rely on peaking?

[Peter Rush]

Hi all - I've just done a little test to see how accurate the focus peaking is vs the old 'zoom in, focus and then zoom out' traditional method. Now unless I'm mistaken the kit lens on the EA50 is not parfocal so really zooming in to focus, in theory, is not the best idea because as you pull out you could loose focus.

However with the lens at 18mm and relying purely on the EA50 peaking (using expanded focus to help), what looks in focus is actually not when you zoom in to check it. In fact it can be way out! It seems the traditional method trumps it every time for me. Any thoughts?

[Theo Dilworth]

yeah, i only shoot manual focus (most of the stuff i do is action & motorsports, so the autofocus won't keep up) -- i've found that the peaking combined with the digi zoom to check focus works pretty well as long as you're not shooting wide open. then again, i rarely shoot with the stock lens either. the peaking definitely seems to work differently depending on the lighting conditions, so sometimes the smallest amount works great, but other times have to bump it to medium.

[Chris Harding]

Hi Pete

I have never found the peaking to give me an incorrect focus position or be fooled! My peaking is set to medium and yellow and is pretty accurate I have found. I doubt whether the stock zoom is parfocal either. At weddings my only worry is that the AF might decide to change a fixed focus so I let AF give me a ball park focus and then switch to manual ... I have found that peaking is pretty accurate. The issue is probably more DOF related? at 18mm on the stock lens at F3.5 if you are at a venue and 20' away from subjects you are in focus from 8' to infinity so it's hard to be out of focus at full wide! Even at 10' away you still are in focus from 6' to 27' so you might get a tiny bit of fuzzy at the back of a room but again it's hard to be out of focus.

I find that my 17-50 Tamron is a LOT sharper than the Sony lens so maybe the stock lens is simply a bit soft at 18mm ???

Chris

[Steven Digges]

Hi Pete,

Your test does not make any sense because it is flawed. The kit lens is not parfocal. So therefor, the moment you press the zoom control you are changing the focus you had set when wide. But, I am not sure I understand your procedure correctly when you say your comparing that to peaking?

On broadcast quality parfocal lenses I rarely find my wide focus to be as sharp as it looks like it is, after I zoom in. A high contrast, B&W CRT studio monitor also helps with focusing those cameras. They are very easy to work with.

I have found the EA50 peaking to be very accurate. Never once have I found a shot in post that was soft when I counted on peaking. But, it took some time to "trust" it that much. To me, that is the test that counts. Are you finding soft images after you used peaking?

Chris, Are you switching back and forth from AF to manual with the hard switch? It is faster and easier to leave that switch in manual and use the AF button to pull a quick AF.

Steve

[Marlon Martins]

i started to use a sigma 18-35 f1.8 on EA50, and peaking/expand appears to be great (move the expand point to center-top, where the face are most likely to be)

not 100% sure, but my test so far shows the this lens in particular do not change focus on zooming, but i need more precise tests to be sure.

i may start to soot full weddings with this lens alone...

[Dave Allen]

How do you like your Sigma f1.8? in low light? How's the bokeh?

[Chris Harding]

Hey Steve

At weddings because thing can happen in a heartbeat I leave the cameras in full auto all the time so if I have to gran 'n shoot I have a better chance of getting the shot than if it was in manual and by the time I have it sorted the action is over. Yep I know that I can use the AF button and with peaking in manual it's seldom necessary. Hence the use of the hard switch when I know I have plenty of time to adjust everything ...habit I guess?? However, yes I do use the AF button if I have to reframe during the wedding ceremony and then see if the shot is in focus still with peaking. I have yet to find any soft shots at 18mm so peaking must be quite accurate.

Dave? there is another post here by Marlon on the Sigma. At F1.8 and such a useful range for wedding receptions it's definitely on my "to buy" list!! Sounds like he is very happy with it ...Remember it only has a tiny zoom range (around 2X only) so even if it's not parfocal your DOF won't change that much but if it is indeed parfocal that's an extra bonus .. My Tokina 11-16 also appears to be the same but at such wide angles you would be in focus anyway. The Tokina 17-50 F2.8 zoom is a LOT sharper than the stock lens for some reason at 17mm ..I even notice that my stills on my Nikons are much sharper on one still camera than on the other with a 17-55mm Nikon lens!!

Chris

[Peter Rush]

Originally Posted by Steven Digges

Hi Pete,

Your test does not make any sense because it is flawed. The kit lens is not parfocal. So therefor, the moment you press the zoom control you are changing the focus you had set when wide. But, I am not sure I understand your procedure correctly when you say your comparing that to peaking?


Steve

Hi - I suppose what I'm saying is I find it more accurate to zoom in, manually focus using peaking as an aid, and then zoom out to reframe and shoot - vs - leave it wide and use expanded focus and peaking - I get a sharper shot using the first method. If you are wide and use expanded focus/peaking it can be hard to be accurate IMO.

[Jody Arnott]

I just got back from shooting a 5 day sports event and I really got to put the EA50 to the test. I used manual focus all week, using peaking and expanded focus to assist me. Not once did that method fail me, I didn't have any soft shots.

If I understand correctly, zooming in to focus with the stock lens won't work, because the act of zooming out again changes the focus.

I use the white peaking on my EA50 and leave it on most of the time in run-and-gun situations. It really is awesome and makes for easy focusing on the go.

On a side note, a cyclone came to visit in the middle of the event yesterday. I got the EA50 a little wet at one point before I could get the rain cover over it. It's spending tonight in the cupboard with the hot water cylinder just in case.

[James Manford]

I have peaking set on high and yellow and don't shoot any other way ... it's the best way to shoot manual.

FYi ... the VG10 has Focus Peaking as well. Sony released an update.

[Chris Harding]

I tried all the colours and prefer yellow..probably cos white would be useless on a bride's white dress and we all know that the bride HAS to be in focus.

I tried high on yellow but sheesh, the whole image ends up yellow and it peaks on so many objects..try it on high when your subject is in front of a shrub! Every darn leaf is a yellow shape. I decided that medium was the best level to use and certainly outlines all the subjects I need it too. Funnily if you focus on a timber finished lectern/podium it won't peak??? Well not in medium level anyway but it easily picks up the gooseneck mic on the top!! Once the speaker comes to the lectern it works as normal again ... wonder why it doesn't like lecterns???

Chris

[Steven Digges]

Hi Peter,

I hate to use the word wrong, because this is an each to their own thing, but technically you ARE asking for trouble. Focus is an exact process, either your in or your out. By pulling a focus, and then zooming on a non parfocal lens, it is going to change. Sometimes a little, sometimes a lot, and maybe sometimes not at all. The bottom line is you are taking a huge risk on knocking it out of focus. What are you doing if you use your method and after recomposing you have no peaking? Are you still trusting it? I don't think you should. You are employing a technique that should be reserved for parfocal lenses that are in an entirely different league than your EA50 kit lens. It is going to bite you sooner or later.

Steve

[Marlon Martins]

Originally Posted by Dave Allen

How do you like your Sigma f1.8? in low light? How's the bokeh?

well, i don't like fixed focal length for video, too limiting. a 18-35 is 2x zoom, also limiting, but is the "most used focal length" in my videos/photos, so it's the best lens to my eyes for video on this cam. a 2.8 zoom lens with speedbooster may be almost equivalent, but this lens is very cheap, no need to buy extra adapters, and zoom and focus rings are very very smooth (and not too "loose", so you won't move accidentally on holding the lens") which makes great for video (can zoom during recording with no bumps). also, the sharpness at 1.8 is amazing. if the focus is not changed with zoom (to be fully tested) it's a plus.

didn't test bokeh yet, the venues i shoot are normally very dark, not much ambient light from the decorated ambient. also, for bokeh wide lens aren't the best, unless you are very close to the subject

photo sample of the bokeh blur at f1.8/35mm/close to the subject (Canon 50D):
http://i.imgur.com/wX2EwW2.jpg

[Chris Quevedo]

Originally Posted by Peter Rush

Hi all - I've just done a little test to see how accurate the focus peaking is vs the old 'zoom in, focus and then zoom out' traditional method. Now unless I'm mistaken the kit lens on the EA50 is not parfocal so really zooming in to focus, in theory, is not the best idea because as you pull out you could loose focus.

However with the lens at 18mm and relying purely on the EA50 peaking (using expanded focus to help), what looks in focus is actually not when you zoom in to check it. In fact it can be way out! It seems the traditional method trumps it every time for me. Any thoughts?

well since it's not parafocal, the punching in and punching out is deceiving you too. I have that same 18-200mm lens. on these cameras you are supposed to use the digital zoom, not the zoom on the lens itself, for checking focus.

the focus peaking is working, and the moment you zoom in with the focus ring the focus shifts anyways. digital zooming doesn't shift

[Chris Harding]

Hi Pete

Actually you are 50% correct. Take this scenario. You are 20' away from the subject and we will take the widest aperture of F3.5 ... Zoom to 100mm and focus and your DOF is only 1.29' ...very critical!! Now zoom right out to 18mm and it looks perfectly in focus simply because although the focus ring is physically set at 20' when zoomed, when you go wide to 18mm your have a HUGE DOF from 9' right to infinity so yes it will stay in focus because it's in the DOF range whether the lens is parfocal or not. Technically you need to refocus due to the lens BUT due to the huge DOF at 18mm you don't have to!! You will find that focus peaking will show it in focus too!!

Do the same story but start at full zoom 200mm and then drop back to halfway 100mm and then the DOF being critical will result in a fuzzy image. In bright sunshine at F16 you are in focus all the way regardless of how accurately the focus ring is set.

The habit came from the older 1/3rd or 1/4 chip CCD cameras that, due the small sensor had huge DOF ranges so even with non parfocal lenses they still appeared to be parfocal.

Chris