[uday029]

I did my first ever outdoor photoshoot on past weekend for my friends maternity photos (I am no portrait photographer). I planned to exclusively use A 50mm 1.4 (with K-3) as that was the fastest lens I had. We went out during sunset, clicked some nice photos. Since I was using manual lens, I tried hard to make sure that the subjects were in focus. I even switched on the focus confirmation. I made sure that the red dot in the center of my viewfinder lit up and heard the beep.

I downloaded the photos today to find 90% of the photos were out of focus. Most others that were in focus had a soft glow to them (as if I was using a soft lens). Is there anything wrong with the lens? Is there something else I should do for proper focusing?

[jatrax]

The green hex focus confirmation is not particularly accurate with a lens that fast. It was designed for slower AF lenses say f/4 and slower. It can be used as a guide but don't rely on it. The DOF at f/1.4 will be measured in millimeters so if you used it wide open you might have the eye or nose in perfect focus and nothing else. The AF confirmation will confirm OK with anything within a range that roughly compares to a lens at f/4 or f/5.6. At f/1.4 the DOF is only a part of that range.
The red square indicates which AF zone is being used, not necessarily that anything is in focus.

I would try focusing at a focus target and practice. Manual focusing is a skill that requires work to get good at. Also, modern focusing screens are designed for AF lenses not manual ones so it is not nearly as easy to use manual focus on a modern camera. But it can be done, it just takes practice.

Also, make sure the diopter setting is correct for your eye. That is not that important for AF but is critical for manual focus since it changes the appearance of the focusing screen.

[fb_penpho]

As Jatrax said these are difficult lens to use. What I am writing you may well have done already but here goes. I use these 'awkward' lens to what I call calibrate the camera. I put the camera on tripod and look down on my dining table that has a steel measuring rule laid out. Then looking down at a bout 30deg I pick a easily found marking on the ruler 4-5 ft away. I then use live view to nail the focus point. Then using a pencil mark where the lens metal where the focus point is. I then use the dioptre to nail the focus again. Next comes the AF adjustment, making sure that I turn the focus from both directions. I adjust the AF point until the viewfinder either is the same as my pencil mark, or on equal sides of it depending upon what focus direction It is coming from. Then change to a slower lens and make sure that your settings make sense.

[RKKS08]

As my first ready to send posting was nearly identical to what jatrax said, I stopped sending it.
Instead, I there is another (additional) suggestion.

Nearly all 1.4/50 lenses produce very visible softness fully open.
I think Zeiss (and probably the Leica Summilux-R) lenses of the eighties or newer being the only exception (and you pay for that).

There was a thread showing the slight softness of Pentax 1.4/50 lenses at 1.4 can be drastically reduced by using a step down ring (49mm-46mm). It reduces light coming to the front lens just outside the angle of view, and with a slim one vignetting should not become visibly increased, nor the T-stop visibly changed.

I myself have NOT tried it, but other members have.
Sorry to him if I am wrong, but I think it was stevebrod who found out about this a couple of years ago.

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Last edited by RKKS08; 07-10-2015 at 10:07 AM. Reason: Typing

[aleonx3]

First, it is a lot more demanding than you would think when you use manual focus with wide-open aperture. It could be many things including focus accuracy (according to you, may be but not the camera in the actual situation). With a good eye, you can use better focusing screen and proper adjustment of the viewfinder diopter to help you nail the focus. But if you like me, not the sharpest eye by any means, have to rely on the camera (PDAF) to come up with the accuracy (at least to some degree). Most of the problems I have seen is the front focussing issue (the exact focus distance in hitting the 'air') which can be easily detected when there is nothing in the picture in focus even thought your shutter speed is fast enough (1/500 or higher). In that case, you will need to stop down the lens, thus providing more DOF so you can hit the focus target. Another important step is to turn focus ring "from far-to-near" instead of "from near-to-far"....that way you can catch at least the tail end of the DOF...... as I said, not easy but doable. Have fun....

[kh1234567890]

I downloaded the photos today to find 90% of the photos were out of focus. Most others that were in focus had a soft glow to them (as if I was using a soft lens). Is there anything wrong with the lens? Is there something else I should do for proper focusing?

Like this (M50 f1.4 wide open) ?




I think that it is caused by too much stray light bouncing round the sensor box. It didn't used to be as bad on film. The cure is to avoid certain scenes when shooting at f1.4 or to stop the lens down just a touch. Or use a reducing ring on the front of the lens - search the forum for "49-28mm".

[fredralphfred]

Also, aren't people's faces "bumpier" than the DOF of 50mm at f/1.4 will allow? I thought you had to stop down to f/2 or f/2.8 if you wanted, say, everything from the nose to the earlobe in focus. I could be wrong.

[Dipsoid]

1.4 is very had to focus, The depth of field is so narrow, one eye will be in focus and the other will be out of focus. My 1.4-A has a very soft glow in contrasty light at 1.4-2. Spherical aberrations? Sometimes it's pretty, sometimes it's obnoxious. I would stop it down to at least 2.8-4, that should afford you a big enough depth of field with beautiful bokeh. Even 2.0 is not enough sometimes, only the eyes will be in focus depending on your working distance.

[ScooterMaxi Jim]

I'm not a fan of the glowing look at all on the m50/1.4 - and will never shoot it at wide open (but f/2 is fine). I don't get the intrigue with the f/1.2 either - as it glows past f/2!

You can focus the 50/1.4 on the K-3 without focus problems in the harshest of conditions. Use LV with FP and magnify to 4x. Very easy to shoot a sunset or just about anything else, frankly.

I agree with Fred. If you are shooting a 50 for portraits (I think 70-85 is far preferable, though), you need at least f/2.4 to get the proper amount of facial sharpness. Generally, super soft noses and ears are rather distracting and unpleasant.

[K David]

Have you tried to adjust your diopter?

[uday029]

Thank you all. This was my first ever portrait shoot and I learnt some good lessons. Thank you for all your suggestions. I got some practicing to do. Can any one tell me where I can get the "49-28mm" step down ring/hood? Cant seem to find it on amazon or B&H.

Have you tried to adjust your diopter?

I did not adjust the diopter. Frankly because when I use auto focus lenses to obtain focus, the image on view finder looks pretty sharp so I assumed that diopter was dialed correctly.

[fredralphfred]

. . . I did not adjust the diopter. Frankly because when I use auto focus lenses to obtain focus, the image on view finder looks pretty sharp so I assumed that diopter was dialed correctly.

This is because your beautiful Pentax camera comes with a user-replaceable crappy focusing screen for which Pentax makes no replacement.

If you're going to rely on the viewfinder, make a quick trip to Focusing Screen. Or save some money and frustration (no guarantee it's going to be aligned correctly, in which case you'll need to order shims & test it) and shoot Live View magnified.

[K David]

I assumed that diopter was dialed correctly.

Well, as one of my old bosses used to say to me, you know what happens when you assume?

So, your diopter probably needs to be adjusted. Mine has on every Pentax DSLR I've used, which is about seven DSLR bodies now. It's not a knock against Pentax, but the diopter slides get bumped during transit, when carried, and so forth. So they need to be verified from time to time. Also, primes are significantly faster. So if you have a zoom that tops out at, let's say, f/4, then your diopter may be set just fine. But for f/2 or f/1.4, it could be way off at the same setting.

I asked Adam if I could write a comprehensive guide on how to do a diopter adjustment for the home page, so if that gets approved it will help a lot. In the interim, you'll need to mount your camera on a tripod. place it with a fine object nearby. I like to tape a sharpened pencil about a few inches further than the lens' minimum focusing distance. I'll tape it in place with masking tape to make sure it's stationary. Then I'll focus on the pencil's point in the viewfinder and take a photo. I'll compare if the pencil's point is in focus on the image. If so, I'm done. If not, then I'll adjust diopter settings (you'll need to refocus after each adjustment) until what I focus on in the viewfinder is what the sensor has in focus.

---------- Post added 07-11-15 at 11:18 PM ----------

This is because your beautiful Pentax camera comes with a user-replaceable crappy focusing screen for which Pentax makes no replacement.

Doesn't Pentax make the ones they sell?

Viewfinder Accessories | Attachments, Lenses & Eyecups | Pentax

[Dlanor Sekao]

My thoughts....check and clean the rear of your lens......and use LV with some magnification.
I had a similar problem and later found a nice big finger print on the rear glass......took care of that real quick.
I know this probably sounds so stupid simple , but sometimes the obvious is overlooked.

[fredralphfred]

[about focusing screens]Doesn't Pentax make the ones they sell?

Viewfinder Accessories | Attachments, Lenses & Eyecups | Pentax

Considering that the ones they sell fit only discontinued cameras, sure. (K-7 & K-5). Nowhere on their web site do they tell you if those screens fit cameras they currently manufacture.

Also, they have NO FOCUSING AIDS, so are just as worthless as the original screen for focusing fast MF lenses (why? why? why?)

Why advertise a "user-replaceable focusing screen" when you don't make any (that fit it)?