[CarlJF]

You can solve any impact this has on the field of view by taking one step forward or back. Or cropping. Or not thinking about it, framing your image the way you see it in the viewfinder and enjoy the gorgeous results.

Exactly this. Unless your doing lab tests, or looking specifically for it, focus breathing doesn't pose any practical problem for photography.

Focus breathing is something to be expected for most lenses, from all manufacturers. Some are better, some are worst, but if you're looking for it you will find it. In this regard, the 60-250 isn't the exception but fit quite well with the rule.

Some people suggested the Tamron or Sigma 70-200, but they also show a significant amount of focus breathing, as well as the new DFA 70-200... It's probably better just to learn to live with it and not loose sleep over this...

[Andrea K]

The new DFA 70-200 doesn't seem IF.

I did some shots at infinity and the focal length is more comparable with FA 80-320. Image quality at infinity in the 250mm zone isn't comparable at all.... the DA* really outperformes the FA.

[CarlJF]

The new DFA 70-200 doesn't seem IF.

It doesn't matter, it still has focus breathing. Focus breathing isn't specific to IF lenses, or zoom or telephoto... For example, one the best is the Canon 70-200 2.8, with almost no focus breathing, although it's a telephoto zoom with IF...

Focus breathing is something that has to be expected, although there are some exceptions. Somewhat in the same way that you expect, for most leneses, the corners to be not as sharp as the center, although some exceptional lenses will do better than others... But you will not begin to worry if one your lens isn't as good in the corners as in the center.

[normhead]

Focus breathing is really only an issue with folks who are used to lenses that extend their front element to achieve focus. The problem with those lenses is its very tough to maintain resolution as the barrel extends, and if you look at the test charts for that type of lens, they get very soft in the long end, where as the DA*60-250 is right up there with the DA*300 and DA*200 primes in the long end. Sure you don't get the same magnification close to the lens, but every thing you get is sharp, as opposed to cranking my old 70-300 out to the long end and realizing I had to reduce the image size to have the images look sharp. The focus breathing lenses have the advantage. You may not get the magnification you want, but everything you get is going to be sharp as framed. You get better resolution measured in lw/ph with the sharp lens even though the images is smaller. In my experience no 70-300 type lens is going to match a 60-250 image, no matter how much ovesample you get.

My Sigma 70-300 images look less sharp than my DA*60-250 images at web size. No amount of image reduction will help them measure up to a DA*60-250 image in sharpness. The 70-300 type lens I own is good until about 180mm. So, it's quite normal to be disappointed with the focus breathing, but, the real story is they've just done what they had to do to make the lens excellent throughout it's entire range. I can put a TC on my 60-250 @250mm with great results. My non-focus breathing F 70-210 with a TC is a disaster waiting to happen. The 55-300 is the only lens of it's type that is strong enough in the long end to be worth carrying IMHO. ( and even it isn't going to measure up to a 60-250 with a TC.)

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Last edited by normhead; 05-24-2017 at 10:39 AM.

[mikesbike]

If you find "focus breathing" or closer focus FL shortening to be a problem with your work, then it is a problem. That is one of the reasons I'm holding on to my very good HD DA 55-300mm WR compared with the new, slower, PLM model. Now, that said, the DA* 60-250mm, even with that problem, may be able to focus closer than your FA 80-320mm, so maybe you can still get a similar closeup image.... but you have to get much closer to get it! And that is the catch.

[bscott]

Is focus breathing a new issue with digital zooms or has this been a problem for a long time with our old film zooms?

[clackers]

Is focus breathing a new issue with digital zooms or has this been a problem for a long time with our old film zooms?

Nothing to do with analogue vs digital, Bscott!

[mikesbike]

Is focus breathing a new issue with digital zooms or has this been a problem for a long time with our old film zooms?

It goes way back. As clackers indicates. One example was the Pentax (by Tamron) FA 28-200mm, an AF lens for 35mm film bodies, which broke new ground in how close it could focus at longer focal lengths back around 1997. Unheard of closeness back then at 200mm. The only caveat being the FL shortening phenomenon now known as "focus breathing".

[Andrea K]

From another thread, very useful:

Il you look at the EXIF with a software like ExifTool by Phil Harvey you can see the SRFocalLength information which is transmitted by the lens to the body, to know what focal length should be used for share reduction.
With the 60-250 at 250mm, depending on the distance, this SRFocalLength can take the following values: 244, 236, 228, 220, 212, 204, 196, 180, 172, 164, 148.
By the way, with the 60-250 at 200mm, this value spans between 204 (at infinity) and 140 (at closest focus distance).

[shardulm]

All those who are defending:
Focus breathing exists and its heavy with DA* 60-250. The DA*50-135 on the other hand which is Internal Zoom and Internal Focus does not need that breathing space. Several times I feel that I could just use DA*50-135 over DA*60-250 for its superior handling and do away in the crop. It is that bad. Although I respect the physics of these lenses.. some IF lenses (well plenty of them) do not exhibit this. And here is a list of them
DA*16-50 (Only IF)
DA*50-135 (IZ and IF)
DA*55 (IF)
DA*200 (IF)
Possibly DA*300/f4 as well I don't own it but it should be I am assuming.

The lenses that focus breathe heavily
DA*60-250
D-FA*70-200 (Btw Canon equivalent does not have FB at all, the Tamron variant does not either, the Nikon variant does Breath equally albeit their older 70-200 variant does not)

The issue is the specification does not meet the real world results and that is where the frustration is. Why is it hard for the manufacturers to keep the spec true (or conservative) to its field behavior? That DA*60-250 is more like 60-200 (unless used at infinity) or potentially less as someone pointed out earlier although its a brilliant lens. If "IF" or "IZ" is to blame then why isn't the DA*50-135 is exhibiting this? GIven this I also feel that this DA*50-135 is the most superior lens they every made for its size and handling (hate to have SDM wake problems though). I am saying that having dealt with K-5ii+50-135 and K-1+D-FA70-200 for the same given FOV.

In conclusion it is a legit issue which is not evident in the focal length spec. of the lens and people rarely every get down to comparing the magnification.
On the other hand .. I am now looking at FOV and Mag. spec of the lenses to know what it actually is instead of relying on the FL spec.

[CarlJF]

All those who are defending:
The issue is the specification does not meet the real world results and that is where the frustration is. Why is it hard for the manufacturers to keep the spec true (or conservative) to its field behavior? That DA*60-250 is more like 60-200 (unless used at infinity) or potentially less as someone pointed out earlier although its a brilliant lens. If "IF" or "IZ" is to blame then why isn't the DA*50-135 is exhibiting this? GIven this I also feel that this DA*50-135 is the most superior lens they every made for its size and handling (hate to have SDM wake problems though). I am saying that having dealt with K-5ii+50-135 and K-1+D-FA70-200 for the same given FOV.

All these lenses meet their specifications since the standard measure for FL always was, and still is, given for infinite focus. If close focus performance is what you look for in a lens, the magnification factor is a much more useful and significant specification than FL, focus breathing or not...

In conclusion it is a legit issue which is not evident in the focal length spec. of the lens and people rarely every get down to comparing the magnification.

But it's also not the manufacturer's problem if people don't look at the relevant specification when they compare or choose their lenses... Manufacturers always give this information, and its also not rocket science to understand. For K-mount lenses, this information is even quite easy to find by looking at the PF lens database. If we look at the 80-320 of the OP, the mag factor is 0.28, which is very good. The 60-250 has 0.15. Thus, it's quite obvious when looking at this spec that the 60-250 will not give the same close focus magnification as the 80-320. Which is exactly what the OP observed and what is expected based on the specifications, no matter if the lens is focus breathing or not. When you look at the right specification, the difference is quite evident.

[shardulm]

All these lenses meet their specifications since the standard measure for FL always was, and still is, given for infinite focus. If close focus performance is what you look for in a lens, the magnification factor is a much more useful and significant specification than FL, focus breathing or not...



But it's also not the manufacturer's problem if people don't look at the relevant specification when they compare or choose their lenses... Manufacturers always give this information, and its also not rocket science to understand. For K-mount lenses, this information is even quite easy to find by looking at the PF lens database. If we look at the 80-320 of the OP, the mag factor is 0.28, which is very good. The 60-250 has 0.15. Thus, it's quite obvious when looking at this spec that the 60-250 will not give the same close focus magnification as the 80-320. Which is exactly what the OP observed and what is expected based on the specifications, no matter if the lens is focus breathing or not. When you look at the right specification, the difference is quite evident.

Agree.. like I said.. I am now looking at FOV and Mag. spec of the lenses to know what it actually is instead of relying on just the FL spec.

[Andrea K]

...When you look at the right specification, the difference is quite evident.

Could be quite evident if the magnification is different between two lenses with same focal length. For example, I thought that the difference between 0,15 and 0,29 was due only to the different focal length between 250 and 320.

[normhead]

If you look, the magnification spec of the DA*200 is .20, 1/3 more magnification than the 60-250, which is why part of the reason I ended up with a DA*200 for shooting from my blind. More magnification, faster aperture, what's not to like?

Meanwhile my F 70-210 with it's extending front element magnifies .25 times, another 20% better than the DA*200, and 60% better than the 60-250. With more modern lenses the 16-85 with a front element that really gets cranked out there has a magnification factor of .26 and the 18-135 has a magnification factor of .24.

The previously mention 50-135 has a magnification factor of .17. Slightly better than the 60-250 but no where near the barrel extending lenses.

Just another of the reasons for taking the K-3 and 18-135 as a walk around. There's no need to carry a macro lens.



You can do pseudo macro with many lenses that extend their barrels.
htop://s1132.photobucket.com/user/Norm_Head/slideshow/Pentax_forum/Sample_by_lens_name/DA_18-135-small_flowers?sort=3

Sadly my 28-105 doesn't do well, as it is mainly used on a K-1. Magnification isn't as dramatic on a sensor with bigger pixels, or more surface area.

[geoffw]

I don't think my 70-300 would have cropped as this did from the 60-250. I reckon this is the beauty of this lens and my technique isn't the worlds greatest