JPL

I have been using mirrorless cameras, Nikon 1 J2 and Sony A7r, quite a lot for more than a year now. I have bought some adapters to use older glass on both those cameras and find it give me much better results in general than I actually expected before I started doing this. I was kind of thinking that I was actually wasting my money when I started doing this, I would never get a good shot with old glass and an adapter er even with a new lens and cheap adapter to use it on a camera with different mount. But cheap adapters are cheap so I thought, what the hell, the fun is worth it!

But what have I learned?
I have learned that some of what is considered bad glass, or not as sharp as later models etc, etc. is just as good and sharp, but it is the the autofocus system that makes it bad. Some of this glass gives much better results when you take it out of the original "system" and put it on a different system like the Sony A7r where you can focus manually with precision. I have experienced this again and again lately with older autofocus lenses that I own. I have read reviews about those lenses and everyone agrees they are bad glass and not sharp enough for today's standard or even not up to the standard at the day of release, still it is easy to get tack sharp shots with them when I change the camera behind the lens and focus manually.

And when I get deeper into this experience and try to figure out what is the actual problem I have noticed that it is more likely the lens mechanism that is designed to focus the lens that is bad than the glass or the autofocus system in the camera. This is based on how I have to focus the lenses to get sharp pictures. It is not always just about focus manually, but about how you turn the focus ring to get the focus. Some focusing mechanism is just designed and built in a way that it will never be possible to acquire sharp focus constantly due to this. It is not possible to correct this by fine tuning focus in camera because it is just a slack in the focusing mechanism.

Has anyone experienced the same or do you think what I am saying here is just bs :wink:

joer Loc: Colorado/Illinois

Interesting.

Not surprising that older focusing mechanisms are less accurate than ones developed recently or manual focus done properly.

Other considerations may be that you are using a focusing aid such as focus peaking (not familiar with A7r) and or the sensor characteristics cause the image to improve.

If you look at the sharpness values of any lens comparing a high pixel count camera to a lower one the higher one is always sharper.

CO

Older lenses have the screw type autofocus. That relies on a focusing motor in the camera body. At the camera's lens mount there's what looks like the tip of a small screwdriver that engages with a slot on the lens mount. There would be more slack in the mechanism as compared to the newer ring type focusing motors that are built into the lens. Nikon calls their's the Silent Wave motor and Canon calls theirs the Ultra Sonic motor.

CHOLLY Loc: THE FLORIDA PANHANDLE!

Joer hits on a good point about modern sensors... but I can tell you that my excellent glass becomes exceptional on my mirrorless camera.

The Sony Zeiss 24-70mm f/2.8 is stunning on my APS-C Sony A77II. But put it on my A7RII and it literally takes your breath away... ESPECIALLY when manually focusing using focus peaking.

So yes... I think there is something to what JPL is saying. And I agree with Joer too.

dpullum Loc: Tampa Florida

JPL, the title of you post, Bad glass or bad auto-focus system?? is incomplete.
Bad glass or bad subject or bad auto-focus system??

Many cameras depend on contrast. One morning the sky was fantastic! I tried to focus one the gossamer low clouds and the camera (Canon SX-50) went crazy. I had to focus on solid things like the field across the way, hold focus and then shoot the clouds. Photo attached. EXIF info:

Camera Model: Canon PowerShot SX50 HS
Lens: 4.3-215.0 mm
Image Date: 2015-12-16 08:19:56 +0000
Focal Length: 4.3mm
Aperture: ƒ/4.0
Exposure Time: 0.025 s (1/40)
ISO equiv: 100
Metering Mode: Matrix
White Balance: Auto
Color Space: sRGB
Software: Adobe Photoshop Elements 13.0 (Windows)
Copywrite: DPullum

FOCUS PROBLIMATIC GOSSAMER LOW CLOUDS

(Download)

zigipha Loc: north nj

Can someone explain why the camera would focus better or worse depending on the lens (aside from mechanical focusing mechanism on the lens having some play, as was mentioned above)?

If the camera tweaks a signal to move focus until the camera's focusing algorithm says stop..why does the lens matter?

Its not like the lens splits the light into a focusing stream and a image capture stream..single light stream goes into the body and the camera does the rest

comments?

camerapapi Loc: Miami, Fl.

I cannot make any comments on using adapters to fit old lenses to the M43 system because I have no experience with them but I can surely tell you that most AF errors are made by the operator of the camera.
Manual focus can give you fine precision but it is inconvenient except for the static subject when there is plenty of time to focus.
I do not have the eyesight I had 20 years ago and for someone like me AF is a godsend. As I said, I have no experience using adapters and AF.

jro1010

Thank you for the contribution. This is something I had never considered and that definitely worth trying. I had always relied on the camera autofocus system and never thought that what I though was defraction, or camera movement to justify some blurriness could be an old autofocus issue. So, once again thanks for bringing it up and I'll go back and check this. Peace, jro

dpullum Loc: Tampa Florida

Perhaps this will help
http://www.ct-digiphoto.com/how-phase-detection-autofocus-works/
short quote:
"Autofocus is a standard feature in all contemporary cameras, and aging phase-detection technology is still considered to be the most reliable method of autofocus control, even though the technology is complex and prone to errors.

In this post based upon a c’t Digital Photography Magazine article by Robert Altmann, we zoom in on autofocus technology to better understand what’s happening when we press the shutter button half way."

blackest Loc: Ireland

There is always the hyperfocal distance to fall back on.

JPL

Thanks all for your comments. The main reason for this post is an old Sigma lens i got for very little some years ago. It is a 135-400 f4.5-5.6 D APO for Nikon. This lens has low ratings in all reviews and is generally considered bad glass. And so it was at first in my case also. I tried to use it for awhile, then put it aside because I never got really sharp photos with it no matter what. Then I got my Nikon 1 J2 and adapter to use Nikon F mount lenses on it. And then I decided to try the Sigma again for fun. But I was using cheap adapter so it was only possible to focus manually. And I was surprised to see that I started to get sharp photos. So back it went on my Nikon cameras for further testing and there I managed also to get sharp photos in live view when focusing manually. And when I bought me a Sony A7r it became easy for the first time to get sharp photos with this lens. Of course it is not a good lens in comparison to newer lenses, but it is actually not bad either when I switched to use it by focusing manually. Today I consider this a decent glass with useless autofocus mechansim. Further research on this indicates that it is some of the mechanism in the focusing part of the lens that is too poorly designed and built to keep up with the camera autofocus system. There is play in the focus ring and it must be used very carefully to get sharp focus. I have tested more lenses that I own and this Sigma is not the only lens where sharpness can be improved by focusing manually.

And when I think of it, all this makes sense. At some point in time Sigma lenses were considered nice lenses, then they got worse and even later they are good again. I tend to believe that Sigma was not going backwards in terms of manufacturing the lens glass itself, but that they had problem developing good mechanism for lenses to focus them accurately. And it would be very strange if no lens manufacturer had failed in this at some point in time. But I have never seen anything about this on the internet, there all the discussion is about the glass getting good, worse, better etc without any logic thinking about lens construction and the mechanism involved. After all a lens is not only pieces of glass, but much more complicated technical structure of glass, metal, rubber, plastic and electronics.

imagemeister Loc: mid east Florida

ALL your assumptions are correct !

GENorkus Loc: Washington Twp, Michigan

Older lenses, in a simple sence, "splattered" the light on the film. This can be done because film was basically flat.

Modern lenses try to get the light going on the sensor in as straight a line as possible.

This is because of the small amount of depth a sensor needs to have. Looking at it in a simple way, think of a honey comb. Even though they have brought the sensor towards the front, there still is a touch of "wall" that blocks each sensor.

When the light travels "less straight" a very small part of it bleeds into the next sensor "honey comb". (Purple fringing and the likes.)

I think I said that right?

sirlensalot Loc: Arizona

Love the Sony "focus peaking". Almost too easy!

MW

I have a little experience using some old lenses (cold war era Russian an East German) mounted on a Fuji X-E2 using an M42(screw mount) >> Fuji X adapter. I tend to use them wide or nearly wide open and close to the subject. With a little practice and "focus peaking" accurate focus is not difficult. As you may guess from the above, I'm deliberately using them in a way that results in some softness.

However, when these are stopped down and the composition needs sharpness only in the center you would be hard pressed to see any difference from modern lenses. AF even in the latest lenses often doesn't work too well close up. I find focus peaking when the subject is very close but not necessarily at macro distance gets more reliable results.

I also have an an older Nikon AF-D 105mm micro. I always found focusing hand held at very close distances was very difficult on a D7100. Adapted to the Fuji and using focus peaking its actually a bit easier.