Reduced aperture through viewfinder

Discussion in 'Nikon' started by ron_togger, Nov 29, 2012.

  1. Hi guys - can anyone enlighten me...
    Yesterday I tried to manually focus an 85/1.4D on a D5100 and despite sharpness in the viewfinder, the results (also shot at 1.4) were way out of focus. I had to compensate the distance manually to get a sharp result - but then it was out of focus in the viewfinder.
    Could it be that the viewfinder does not actually show exactly what the sensor is seeing or is the camera somehow reducing the viewing aperture of the lens?
    Cheers
    Ron
     
  2. Basically your focusing screen can't show you f/1.4 DoF...
    Have a read of this thread: http://www.photo.net/casual-conversations-forum/00awQJ
     
  3. OK, just tried mine. Occasionally get the same as you....say 5 in 20 times. I think this demonstrates the difficulty of MF with a poor VF and a very fast lens.
    Pop camera on a tripod and find a nice target. Use zoomed LV to ensure sharpest focus and then tern off LV ...how is the Viewfinder view? Is the little green Dot illuminated?
    If the VF is fuzzy, whilst LV is sharp, it could be out of calibration or maybe badly adjusted for your personal eyesight.
    Could it be that the viewfinder does not actually show exactly what the sensor is seeing​
    Undeniably TRUE, the image bounces off 1 big mirror and a bunch of surfaces in the pentaprism/pentamirror before you see it..... for it to accurately show the true focus the image, the optical path needs to be very precise in length and calibrated as such. However, the LV LCD screen shows the actual image the sensor sees.
     
  4. The best feature of modern bodies for MF is LIVE VIEW. Once you get used to it, it can't be beat!
     
  5. +1 Elliot. It's one of the great advances for pretty much all fields, short of action photography, where MF is rarely used these-days anyway.
    There's still the LV 'oddity' that the aperture actually closes down somewhat if you're not shooting wide open before you take the shot. It makes the in-focus or not-in-focus 'pop' less obvious..... but i guess it stops the sensor getting too excited (and noisy)
     
  6. Hmm interesting. I tried it again as per Mike's suggestion. Curiously, the green dot does light up indicating focus in the viewfinder, (but results are still out of focus). I guess the rangefinder feature is not reading directly off the sensor...However the LV technique worked flawlessly - extremely useful feature if a little power-hungry.
     
  7. Pentamirror viewfinders have
    notoriously fuzzy views and it is really
    hard to tell when a fast lens is in optimal
    focus with them. The precision of
    assembly is also not as good as with
    glass prism viewfinders
    (d80/90/7000/200/300/300s/FX). The
    latter are easier to view and crisp. You
    can adjust the calibration of the screen
    using a hex screw at the lower right
    corner seen from the bayonet side of the
    body in the D700; probably a similar
    adjustment exists for your camera.
    Better quality focusing screens are
    made by e.g. Katz Eye Optics.
     
  8. It doesn't matter whether it's pentaprism or pentamirror. Optical viewfinders of today are incapable of showing sub-f/2.8 depth of field. For critical focus work, live view is better.
     
  9. Is the information at the bottom of the viewfinder blurry too? If so, your diopter needs adjustment
     
  10. On the consumer DX cameras the green dot isn't very precise - it has a lot of slack in both directions. I've never been able to get sharp focus with it with big apertures. Live view is the way to do it.
     
  11. How do you manual focus with live view?
     
  12. Engage live view, and use the live view magnification to nail focus, and/or use something like a hoodman loupe. It's the same as manual focusing with the viewfinder, except you do it off of the rear LCD. There are tons of Youtube videos illustrating this. Here's one from Zeiss, jump to 3 minutes in:
    http://www.youtube.com/watch?v=T5JTww9jdPI
    And here's a video of using a Sony DSLR, but it's the same idea:
    http://www.youtube.com/watch?v=Uzr2Y8ZiES8
     
  13. If you only skimmed the first page, read Ariel's post there again. I shot with MF lenses on a digital body for years before I owned a camera with live view(or they even had one), and I always found that I needed to stop down to f/4 in order to be sure that 'in focus' in the viewfinder was 'in focus' in the image. After Ariel's response, it all makes perfect sense now. I always thought my vision was really bad; it turns out that my vision is only sort of bad, and the viewfinders are to blame for the rest :)
     
  14. Engage live view, and use the live view magnification to nail focus, and/or use something like a hoodman loupe.
    Ariel, live view focusing is fine if you have the camera on a tripod and the subject is completely stationary. The 85/1.4 the OP is talking about is a portrait lens and typically it used wide open to create a certain kind of unsharp background and sharp eye effect, or photographing e.g stage events in dark night clubs . In these real-world scenarios (you do make real world photos?) live view is worthless when the depth of field is around 1cm, or it could be less. The subject moves slightly even in the most formal portrait sessions, and the photographer has to compensate to keep the framing the way they want it constantly moving the camera. In this scenario there is no practical possibility of using the blinking, out of date, noisy live view image for focusing. What's more in many Nikon DSLRs live view is associated with delays both before and after the exposure, making it impossible to take shots in rapid succession to get the expression and focus just right. So suggesting live view shooting with extremely shallow depth of field on a moving subject necessarily moving photographer scenario is a really bad idea. Of course, if the OP uses the 85/1.4 to photograph statues made of rock with a camera mounted on tripod, then live will will work. I somehow doubt this is the case, however.
    It doesn't matter whether it's pentaprism or pentamirror.
    It absolutely matters a great deal. I use both types of cameras almost every day, and with the D3100 which I use for photogrammetry at work, I can't even get the focus right when using an aperture of f/8 using the optical viewfinder. With the D700 (+Katz Eye screen) by contrast, there is no such problem with any of my lenses even shooting at the widest apertures.
    Optical viewfinders of today are incapable of showing sub-f/2.8 depth of field.
    This is not at all the case. The viewfinder has nothing to do with it it, the problem is in the focusing screen. It is possible to replace the Nikon screen with a screen of your choice and solve the depth of field issue. The problem is that when you do that, and get e.g. a Katz Eye screen for a pentamirror camera, you'll be able to focus but the horribly imprecise construction of such viewfinders comes into plain light: e.g. on my D70, the left side of the focusing screen caused backfocus and right side frontfocus (or the other way around, it's been so many years I can't remember). This problem conveniently disappeared when I got the D200 and D700, for which precise manual focusing using optical viewfinder is not a problem with the appropriate screen and screen position is calibrated. It is of course easier on the D700 because of the size of the viewfinder and other reasons.
    For critical focus work, live view is better.

    Live view image is worthless in a number of practical screnarios. It's good for landscape and macro focusing if the plants don't move (if they do, it's hopeless), also architecture. For photography of living people? Does not work especially when it's dark and the aperture large. So please let's focus on advice that helps the OP solve their real-world problem and stick to facts that you know from experience.
     
  15. There's still the LV 'oddity' that the aperture actually closes down somewhat if you're not shooting wide open beforeyou take the shot.
    It's not an "oddity" but a feature. Some lenses shift focus as you stop down so in order to use live view to get optimal focus with these lenses is to activate the live view with the lens stopped down to shooting aperture. If this were not done, and the lens was always wide open during the LV focusing operation, the optimal focus could not be achieved in any way controllable by the photographer. Now the user has the choice to adjust the aperture for the purpose of focusing and then stop down the lens separately, if they prefer a brighter, less noisy, and shallower DOF image for focusing (but by doing this they risk the effects of the focus shift), or use the default LV image stopped down to shooting aperture and avoid the issue of focus shift.
     
  16. Ilkka, I guess that means every shot ever taken before LV (with an Auto aperture lens on an SLR) suffered focus shift issues on stopping down?
    On my D3200 or D5100, LV doesn't stop-down lower than f8 (ish) even if the taking aperture is lower. I haven't tried my D300.
    How accurately does the 85mm 1.4D MF on the D7000? Is it a case of not expecting a 'cheap' camera to MF well with a fast 'expensive' lens?
     
  17. Ilkka, it's just a choice of picking your poison. Either you shoot using the viewfinder, and can take quick photos, but can't get accurate manual focus below f/2.8, or you shoot using live view, and have accurate focus, but with shutter lag. In either case, it's just understanding the limitations of the camera, and working around them. As a teacher once told me, "Blessed are the flexible, for they shall never be bent out of shape." I shot auto racing one day with a compact digicam; it just took understanding that it wasn't going to track focus, and expecting shutter lag, so pre-focusing on the turn where the car was going to be and anticipating how long it would take the camera to fire a photo were necessary to get a good photo. It DOESN'T matter whether it's a pentamirror or pentaprism. Take any DSLR, from a D3200 to a D4, off of a store shelf today, and its viewfinder is incapable of showing sub-2.8 depth of field. Sorry man, those're the facts. But even the best DSLR viewfinder, in my opinion, doesn't compare to the rather large LCD on the back of modern cameras for discerning focus, with the shortcoming being that you lose the stable to-your-eye grip. But, hey, you can't have everything in life. Your opinion of live view seems to be based on some archaic 1940's-era technology. Go to a store and play with a modern camera. Again, a little foresight with photography can go a long way.
    Look at that second video I posted. The guy was able to focus handheld just fine. I have the same experience with my Panasonic G2, and so do the THOUSANDS of users that have taken to adapting manual focus lenses on their mirrorless cameras (micro 4/3, NEX, etc). To get a depth of field of 1 cm, you'd have to be focused less than 1.5 meters away. But even then, if I can manually focus a 90mm f/2.5 macro lens with my Panasonic G2, which has a crop factor of 2, handheld using the LCD instead of the viewfinder down to 1:2, then someone with an 85mm f/1.4 and a D5100 shouldn't have an issue handholding. Heck, it's easier than using my D200's hallowed pentaprism viewfinder to do the same. Sometimes in life, you gotta do what you gotta do to get the photo the way you want. Plus, what's wrong with using a tripod? The OP never said that he was shooting horse racing, so I don't know why you came in here with the personal attacks, when I simply stated facts. A modern viewfinder can't "see" faster than f/2.8 or so. No matter how much you feel you valiantly need to defend some way of shooting, there's no getting around that fact. Feel free to google search to your heart's content to verify this.
     

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