Focal Length problem with EF 70-300mm f/4-5.6 IS II USM - shows up as 267mm

[MickKazik]

Hi everyone, I just received my new EF 70-300mm f/4-5.6 IS II USM and I'm battling a big issue.

On its long end (supposedly 300mm), the zoom ring rotates all the way but lens indicate 267mm in the photo data (Canon 200D). Since it has got an APS-C sensor, the display on the lens should indicate 480mm. In reality the marker on the lens is lined up at 300mm but on the built in lens display if falls a quarter of an inch short.

On my ancient 1D mk II n the indicator on the display should point to 390mm but falls short again. 

In both cases only the shorter focal length of 70mm is lined up properly and also shows as 70mm in photo info.

Both in-camera info and Lightroom EXIF data indicate incorrect values. Basicaly, the longer you extend, the bigger the discrepancy. Example:

70mm = 70mm

100mm = 94mm

135mm = 126mm

200mm = 176mm

300mm = 267mm

Do you think I can do anything with it or did I get a faulty piece?

Thanks in advance!

[MickKazik]

'ebiggs1' could you clarify what gave you an impression I may have assumed 480mm marking would give me 480mm? Or are you just saying it for the sake of it? 

Also, have you actually read the posts above carefully? Have you noticed the focus breathing issue was quickly dispelled? Yes, the lens sould report correctly in both Lightroom and internally as userd already demonstrated. 

Thanks for suggestions but let's stick to facts. That way, going forward others with similar problem may benefit from it. 

Cheers!

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@ebiggs1 wrote:

1) BTW, you do understand the 480 'number' that is indicated in the window is not and does not confirm you have a 480mm lens?

2) I also don't know if this lens reports accurately to Lightroom about FL when focus breathing is involved. Sometimes lenses will  lie to the camera and LR will read that.  

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[MickKazik]

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@Waddizzle wrote:

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@MickKazik wrote:

I brought it up with regards to your previous statement Waddizzle:

"It would be wise to completely ignore what results you see with this lens mount adapter when used with an APS-C body".

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???  So, why bring it up again.  It is not even an adapter for a Canon camera. ???  My advice was to ignore it.  ???

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Maybe I should explain why I made a reference to your point about the adapter (again...).

You probably recognised by now you made a mistake with regards to an APS-C adapter on a Canon SL2. Canon SL2 doe's not require an adapter, it accepts both EF and EF-S lenses. 

Canon 1D mk II n accepts EF lenses.

Fuji Adapter only confirmed the flaw, the issue persisted in the same manner so I really beg to differ - you do not ignore something that gives you an accurate confirmation of the defect. 

I appreciate you trying to help out anyway. Regards!

[ebiggs1]

"...what gave you an impression I may have assumed 480mm marking would give me 480mm?"

The "impression" was if you expected LR to report the exact FL you may be disappointed. The 70-300mm zoom lens may not be capable of 300mm even on a perfectly working lens. LR may still report that it is at 300mm although it is impossible for the lens to reach 300mm.

Like, I think Mr. wadizzle, said these are just numbers printed on the lens. They are not meant to be an accurate representation of the true FL. This was meant simply as a clarification point. Nothing more! I know it is frustrating but everyone here is just trying to help. And, it looks like the consensus, now, is your lens is faulty and needs to be returned.

[wq9nsc]

Mick,

Glad to hear that you are returning it.  It does sound like it was probably a defective return and sometimes retail distributors just put a returned item back into distribution even though they shouldn't.  I buy a fair amount through Amazon and twice I have received "new" items that clearly weren't but at least the return process was very easy.

I haven't done extensive testing but in a quick test with my Canon EF 70-200 f2.8 and EF 24-70 f2.8 lenses, both indicate the correct focal length at both zoom extremes regardless of focus distance from minimum focus distance to infinity.  I suspect that the zoom mechanism feeds the commanded focal length data which may not be exact for the actual focus length but the numbers will be invariant with respect to focus distance. 

In reality, the true focal length (you could measure in terms of what is actually in frame at a specified focal length) will vary somewhat due to tolerances and "focus breathing" but the data reported should be the same as it is with these two lenses I tested.  I use mostly prime glass and these are the only two zoom lenses I own but I suspect that other Canon zooms (including non L types) will report data the same way based upon a mechanical control rather than an optical result.

Rodger

[Waddizzle]

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@MickKazik wrote:

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@Waddizzle wrote:

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@MickKazik wrote:

I brought it up with regards to your previous statement Waddizzle:

"It would be wise to completely ignore what results you see with this lens mount adapter when used with an APS-C body".

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???  So, why bring it up again.  It is not even an adapter for a Canon camera. ???  My advice was to ignore it.  ???

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Maybe I should explain why I made a reference to your point about the adapter (again...).

You probably recognised by now you made a mistake with regards to an APS-C adapter on a Canon SL2. Canon SL2 doe's not require an adapter, it accepts both EF and EF-S lenses. 

Canon 1D mk II n accepts EF lenses.

Fuji Adapter only confirmed the flaw, the issue persisted in the same manner so I really beg to differ - you do not ignore something that gives you an accurate confirmation of the defect. 

I appreciate you trying to help out anyway. Regards!

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Make no mistake. I did not make a mistake.  I immediately dismissed it.  

The only mistake is your continuing to beat this dead horse.  How poorly that Fuji adapter performs is totally irrelevant.  It is not Canon gear.  If the adapter does not work well with some Canon gear, so what.  It does not mean the Canon gear is bad.  I really do not know or care what it might mean.

The only real test that matters is testing Canon gear with Canon gear.  As for your focal length display issue, I think that it is probably a non-issue.  What might be your issue is discussed beginning around the #:30 mark in this video by Tony Northrup.

https://youtu.be/bfhudi0d-go 

[jrhoffman75]

Does anyone here, besides Mick and myself, actually own the lens?

The lens reports 70-300 on my 1D X and 112 to 480 (stating 35mm equivalent) on my wife’s Rebel T6s crop sensor.

Lens appears to be defective.

[ebiggs1]

"... a quick test with my Canon EF 70-200 f2.8 and EF 24-70 f2.8 lenses, both indicate the correct focal length at both zoom extremes regardless of focus distance from minimum focus distance to infinity."

And how are you determining that they are reporting true?  My very loved Sigma 150-600mm f/5-6.3 DG OS HSM Sports Lens reports to LR that it is at 600mm. Yet DXO measured the actual FL of that lens to be 577mm. 600mm isn't possible. My, no longer with me, expensive, Nikkor 300mm f4 reported to LR it was 300mm. But again DXO measured the actual FL of the lens to be 303mm. So, it is not just a zoom lens phenomenon.

LR simply reads the EXIF data supplied by the lens to the camera. All I am trying to say here is LR or any EXIF reader is not an accurate way to now the true FL. It can be and it might not be.

[ebiggs1]

"Lens appears to be defective."

Agree, it needs to go back, today!

[ebiggs1]

"... in this video by Tony Northrup"

I would take anything he said with a grain of salt. He's wrong about as much as he is ever right. But to each his own, I guess.

[wq9nsc]

Ernie,

I think you missed part of my response.  I was stating what the lens REPORTS in terms of EXIF data for the two lenses I checked and noted later that the true focal length is likely slightly different.  The OP started this thread based upon the EXIF data not matching where the lens control ring was set.

I suspect very few lenses, including L series primes, would consistently measure within 1mm of stated focal length because even a very slight difference in mount or sensor placement will impact TRUE focal length.  But the electronics should report the stated focal length even though that isn't the perfectly accurate focal length.

A lens that doesn't report the stated focal length range to the camera has an issue.

Rodger