Any tips for focusing ultrafast lenses? (big image)

[sir pball]

I didn't want to weigh my bag down too much yesterday so I just stuck the 35/1.8 on my SLR and called it a day. Got some great shots, but looking at a few the plane of focus is off by just a hair. It doesn't actually ruin any of them, but I'd have liked to have it moved by just a few inches forwards or back. With my Nikkormat I just use the split-screen for a quick zero on the exact point, frame, shoot...it's one of the very few times I'd prefer manual over AF. I know I could just set the lens to MF and try to focus by eye, but my vision is a little iffy for that without an aid and I haven't as of yet gotten a KatzEye replacement screen with a prism. So how do you do it? Put the live AF dot exactly over where you want, focus, and AF-hold? Focus and slap the shutter to not refocus, or use Back Button Focus? Something else? Opening the lens isn't an option since I want the ultrashallow DOF...I just want it moved a bit.

Here's the pic that got me thinking about this. I quite like it regardless, but I'd have liked her eyes to be crisp instead of her hair. Yes, I realize that's literally an inch difference, such is the way at 1.8.

Full shot



100% crop

[NYC_SKP]

1. There's an app for that, or there should or could be.

.

There should be an application, a setting for DSLRs, that takes multiple shots milliseconds apart and progressively further or nearer focal lengths.

You needed a click/click/click/click/click set of images at different focal lengths and one of them would have captured in details the subjects eyes.

If you want everything in focus, well, then you need faster film or a more sensitive CCD, or longer exposure, or combinations of these. You know the drill.

[sir pball]

2. Nifty, it could work like the HDR setting.

Snap-snap-snap. At 6400 it would be trivial, that shot was 1/640 at 100.

Of course, I didn't want EVERYTHING in focus. I like that half-inch plane. I suppose it's time to invest in the screen, it's just a shame I grew up on 70s-era pure MF Nikon lenses so the focus ring on my 35 feels like the cheap plastic it is..

[NYC_SKP]

4. Yanno, I'm a dork geek about it, still have my old FE and FM bodies, lots of lenses, from the 80's.

Now I can scarcely find film, don't use them, should probably part with them.

[sir pball]

5. I'm spoiled as hell in NYC..

My Nikkormat wants film, of any stripe, B&H! Chemicals, too...I actually like the smell and feel of developer on my hands. Oh, you want Velvia instead? Vista Imaging will do it in a guaranteed three hours, usually about 90 minutes. I'm going to miss that much when I leave.

[NYC_SKP]

7. Thank goodness some things are still there!

I miss NYC, there were a handful of model train shops in midtown that had everything! We needed that for architectural models.

There were not digital cameras, and autofocus was brand new, and considered by many to be for lazy wooooususss (sp).

Find a kid today that knows what a contact sheet is, or negatives.

Negatives? Like shots you didn't like?

[sir pball]

11. TFMP always asks me why I rarely delete a shot..

"Because I keep them all, I couldn't delete film"
"Yes but you *can* delete digital so why not"
"It's a record of how terrible photography actually is...for every keeper, plan on 10 to 12 throwaways"
"So is that why you have four three-inch binders of film cluttering the shelf, and why it took you a year to scan that crate of your mom's old negatives...THAT ARE STILL IN THE CLOSET"
"SHUT UP"

[neeksgeek]

3. Suggestion... *careful* manual focus

I have many years of experience using very fast lenses wide open in low light, in particular 50mm f/1.4 or 85mm f/1.8 lenses for indoor sports at courtside, or photographing theater and musical performances. Focus can be quite a serious problem in these conditions. Long ago, I switched from a focusing screen with a focusing aid (such as Nikon's 'K' screen) to a plain matte screen (Nikon's 'B' screen). I actually did this because I found the blackout I experienced with the focusing aid to be annoying for macro work, but I grew to love the unobstructed view. This meant that I had to relearn how to focus using the image itself and not an optical aid. (This was good experience for large format work later on, using the view camera's ground glass!)

Anyway, what you do is this: using manual focus, turn the ring until what you want focused comes into focus, and then keep turning a little past that point, so that it blurs again. Then, turn the ring back in the other direction, just a little past the focus point, and then turn it back, again, to fine tune it. You're effectively zeroing in on the sharpest point, turning the ring less each time you switch directions. This is a manual equivalent to focus bracketing, but you only take the photo when you've gotten it as sharp as you can.

Obviously this is hard if your subject will not hold still.

There is one other problem with this: modern focusing screens are not optimized for faster lenses and thus don't give you the most precise focus wide open, since they don't accurately show the depth of field at the widest aperture settings. Here's a link to Zeiss that offers some suggestions. And here is a link on StackExchange discussing the problem.

The electronic focusing aid AF 35mm and DSLR cameras have is also useful, but ultimately since it uses the same sensor that the AF system does, it's no more reliable than that system. In my experience.

EDIT: As pointed out in the StackExchange discussion, you could also try using Live View to focus (if that feature is available on your camera), since this uses the sensor to display the focused image, it should be accurate.

My credentials: MA in Graphic Arts, BSc in Technical Photography, and over a decade of professional experience as a photographer's assistant, darkroom technician, photographer, and professor of photography.

[sir pball]

8. You're preaching to the choir, I was pure MF up until I was 26..

Started shooting a Nikkormat at six and didn't get a new SLR till my D70 - I do more or less what you say purely instinctually, it's just how I was raised - my Micro-Nikkor 55 is actually in my digital bag.

You nailed it with the design of the current screens on DSLRs though, on my 5100 her eyes did look in focus, quite crisp, so I took the shot. Problem is, in addition to the screen, I have a good bit of uncorrectable astigmatism (well, keratoconus, but that's irrelevant) in my right eye that makes "hunting" even harder; dialing in a diopter or two on the viewfinder helps, but on that tiny dark dull screen, an inch behind focus looks "sharp enough". Live view is usually my goto when I can, it is indeed flawless, but in this case at least it wasn't any kind of an option.

I'll probably just get a focusing screen, they're $150 with the "brightness" coating and I've heard they're worlds better than the stock crappy plastic no matter what. Or just AF-hold, the button is located well and my camera's AF system is actually spot on.

[neeksgeek]

10. Manual Focus All The Way!

I wish I still had my Micro-Nikkor! Sometimes I pull out my battered old F3HP and marvel at the view through that gigantic viewfinder...

[sir pball]

12. Oh god, I wish I could put the prism and screen from my Nikkormat onto my 5100

But then I'd have to hack up the camera my grandpa gave me when his cataracts got too bad, that he bought utterly state of the art in 1972, and spent thousands on lenses for...among others I also inherited a Nikkor-H 300mm tele and a PC-Nikkor. The second one...!!!!

[pscot]

6. You can get a replacement focus screen

http://www.katzeyeoptics.com/cat--Nikon-DSLRs--cat_nikon.html

That's the Nikon page but they seem to have them for all cameras. Probably most useful if you use manual focus lenses a lot.

[sir pball]

9. Thanks for RTFA ;)

I haven't as of yet gotten a KatzEye replacement screen with a prism

I kid, I kid...but I have always wanted one, since that's how I learned to focus on my Nikkormat, I've just never found the inclination to bother installing the damn thing..

[alfredo]

13. f8. Getting up close will take care of the Bokeh.

It really sucks when you miss the focus.

[sir pball]

14. I chose 1.8

I mean, the bokeh on the 35/1.8 isn't great but it fades out so fast it's a nonissue. I could have done the shot at f16 and 1/60 still at ISO100, it was bright. I think, without a screen, I'll go with "put the dot on her eye and AF-lock".

[alfredo]

15. When working with individuals I like using spot focus. On the street, I have "dots" everywhere.

I use 5.6 a lot when out and about, f8 when doing landscapes. 5.6 seems to be the sweet spot with the Sigma lenses I use.

I use manual focus for inanimate objects.

[ManiacJoe]

16. Untrashallow depths of field are tricky.

The best advice for this is purposely chosen focus points in single-point mode. Back-button or shutter-release will give the same results.

I am normally shooting back-button focus, af-continuous, 9-point. This allows me to shoot action and stills without changing the settings. However, if I am doing shooting shallower than f/2.8, I will change to single-point so that I know exactly where the camera is focusing.

In this photo, it would be easy to get one eye in focus while the other is not due to the slightly turned face. From the camera's perspective, the hairline makes for a good focus-target due to the contrast.

Another thing to note is that the actual focus points are often slightly bigger than the markers in the viewfinder, which can confuse things from the user's perspective.

[sir pball]

17. Unfortunately the focus points and framing didn't agree..

I guess a better question would have been "ultrafast lenses and street/quick shooting" - I didn't have time to focus-lock or back-button and recompose...I think the only real option would be manually focusing on the screen and hoping. Or stopping down, but that would defeat the whole point of the exercise.

[ManiacJoe]

18. Everything in photography is a compromise.

Ultrathin depths of field and quick focusing choices do not normally work together.

I would probably try an aperture of f/2.8 to hedge my bets on the focus while maintaining what would normally be called a DOF still to thin for people shots.

[Blues Heron]

19. I always grab the focus with the center point then reframe

I've gotten pretty fast at it, but I do miss manual focus with splitscreen on my old om1!

[rdking647]

20. one techinque to try.

i do this sometimes if im doing macro work with a really shallow depth of field.
using the live view lcd screen magnify the view by 3 or 4 times (or more) it and use that to focus

[groundloop]

21. You have to think about a lot of details with razor thin depth of field

When you're dealing with such a thin depth of field you really can't focus and recompose, if you do you've more than likely moved the plane of focus away from your intended focus point.

Also, the slightest movement on either your part or the subject's part will move your subject out of the plane of focus.