[aslyfox]

the EXIF data read - Resolution 1350 x 900 pixels
Focal Length 100.0mm (35mm equivalent: 154mm)
Exposure Time 1/320s (0.0031)
Aperture F/1.4
ISO Equivalent 640
White Balance Auto
Metering Mode Center weight
Focus Range Distant
JPEG Quality 85
Lens ID Smc PENTAX-D FA 100mm F2.8 Macro

???

Alphabet Race (a very quick game) - PentaxForums.com

Alphabet Race (a very quick game) - PentaxForums.com

lens was set at physically set at F 2.8

and when using AV

EXIF Information

Resolution 1350 x 900 pixels
Focal Length 100.0mm (35mm equivalent: 154mm)
Exposure Time 1/25s (0.040)
Aperture F/2.8
ISO Equivalent 200
White Balance Auto
Metering Mode Pattern
Exposure Aperture priority (semi-auto)
Focus Range Close
JPEG Quality 85
Lens ID Smc PENTAX-D FA 100mm F2.8 Macro

https://www.pentaxforums.com/forums/210-pentax-k-3-iii/423608-post-your-k3-i...ml#post5423538

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Last edited by aslyfox; 10-24-2021 at 11:17 AM.

[tabz]

Camera can recognize and write to the EXIF the aperture value if the aperture ring is in A position. Otherwise you can set the EXIF's registered value manually in the camera menu (K3-lll only).

[aslyfox]

Camera can recognize and write to the EXIF the aperture value if the aperture ring is in A position. Otherwise you can set the EXIF's registered value manually in the camera menu (K3-lll only).

but how does a lens with a maximum aperture of 2.8 get read as 1.4 ?

[Just1MoreDave]

but how does a lens with a maximum aperture of 2.8 get read as 1.4 ?

When you have the aperture ring off the A position, you're in this weird area where Pentax tried for 100% backward compatibility and maybe got 95%. The lens is supposed to act like a KA lens under those circumstances. The camera doesn't actually see the aperture ring setting. The technical explanation for how a KA lens works is on this page. Skip down to "Electric Lens-Body Communication" to save time.

Features and Operation of the KA Mount | The K-Mount Page

Although that tech is cool and backward compatible in its time, it was almost instantly obsolete. It couldn't handle variable-aperture zooms (e.g. A35-70 f3.5-4.5) or lenses with maximum apertures that weren't exact half-stops (e.g. A*135 f1.8). So when you switch to the A position on the aperture ring, none of the contact pattern logic applies. They added a data pin and a chip in the lenses, which the camera reads for all it needs to know.

Probably the K-3 III adds more complications when it tries to be more compatible with old lenses. Does your lens do the same thing with an older digital body?

The most likely result of the error is the camera won't set the aperture exactly right, but it might be close enough so you don't notice. Note that your EXIF shows a different metering mode (center-weighted) when you move off the A position.

If you look at the chart in my link, you can see that changing contact R1 can change a lens from the f1.4-f22 range to f2.8-f32. Maybe wiggle contact R1 and see what happens.

[UncleVanya]

but how does a lens with a maximum aperture of 2.8 get read as 1.4 ?

I don’t have the k3iii but in M mode don’t you specify the aperture the lens is set to in the menu? Could the lens be sent to 2.8 but your setting be 1.4 which is what gets in EXIF?

[PJ1]

But what about

Focal Length 100.0mm (35mm equivalent: 154mm)

??

Surely it should be APS-C field of view equivalent 154mm?

And f1.4 is two stops faster than f2.8. To state the obvious, (unless it is peculiar to this particular lens sample and /or body) this is probably a glitch in the body's lens recognition programming. Maybe someone with a K-3iii and the same lens could see if they get the same readings. If they do, it is one for Ricoh. (Shouldn't have turned the work experience kid loose on the programming.)

[pschlute]

but how does a lens with a maximum aperture of 2.8 get read as 1.4 ?

Off the "A" position the exif will record whatever you have set the camera up to display. The camera will never record the actual aperture setting (unless by coincidence you have set that up)

[aslyfox]

just did two samples

first jpeg

K 3 III set for Tav

lens set at 2.8 mark on lens

upper screen far right corner ( flashing ) F ( solid ) 1.4 before shutter triggered

EXIF

Resolution 1350 x 900 pixels
Focal Length 100.0mm (35mm equivalent: 154mm)
Exposure Time 1/80s (0.013)
Aperture F/1.4
ISO Equivalent 3200
White Balance Auto
Metering Mode Center weight
Focus Range Close
JPEG Quality 85
Lens ID Smc PENTAX-D FA 100mm F2.8 Macro




second jpeg

K 3 III set for Tav

lens set at " A " position on lens

upper screen far right corner ( solid ) F 2.8 before shutter triggered

EXIF

Resolution 1350 x 900 pixels
Focal Length 100.0mm (35mm equivalent: 154mm)
Exposure Time 1/60s (0.017)
Aperture F/2.8
ISO Equivalent 3200
White Balance Auto
Metering Mode Pattern
Focus Range Close
JPEG Quality 85
Lens ID Smc PENTAX-D FA 100mm F2.8 Macro

only setting I changed " 2.8 " for " A "

nothing else

exposure time and metering mode made by camera automatically ??????

what does ( Flashing ) F mean ??

[UncleVanya]

With the k3iii you have to set the aperture on the camera to match the aperture on the lens IF you want the EXIF data to be correct. Setting aperture in the camera doesn’t charge the exposure in any mode outside Av. Setting the ring on the lens sets the actual aperture - but the camera does not know the value selected so it flashes asking you to set it. This doesn’t affect the exposure - just the Exif.

[pschlute]

lens set at 2.8 mark on lens

EXIF
Aperture F/1.4

These two things are not compatible. See previous responses

[Not a Number]

When the ring is off the "A" position the camera treats the lens as a lens without electrical connections (K-mount or screw mount). As such it will ignore even the "passive" aperture range settings from the contacts on the lens. So the camera won't be able to determine the minimum and maximum f-stops for the lens.

Similarly when the lens is off the "A" setting you have to enter in the focal length - and you can enter something other than 100mm.

[aaacb]

It couldn't handle variable-aperture zooms

sorry for the off topic, but thanks so much for this explanation and link. i think i finally understand why my vivitar s1 70-210 shows funny exposures in Av mode on the k1, especially at longer focal lengths. I'll try using Tv instead and see if the issues go away, as the article implies

[Fogel70]

But what about ??

Surely it should be APS-C field of view equivalent 154mm?

No, you are reading it backwards. A 100mm lens on a APS-C has the FOV of a 154mm lens on 35mm format.
It is a 100mm lens, so you can only get a 100mm FOV on every camera you use it on. But the FOV will be equivalent to other focal length on other formats.

[mlag]

The behaviour ressembles a lot the one I have with a 3th party extension ring + a K3 II (2) that detects any vintage manual lens (without aperture contacts) as a lens with minimum f1.2 and showing this in the EXIF data.
(it should indicate nothing for aperture - indicating a manual metering --
note that the extender ring works fine on all newer lenses with contacts: it's main use case as a "modern" extension ring with all contacts ! for more see Caruba Extension Tube Pentax Chrome : ET PC reviews - Pentax Camera Accessory Review Database ).

In my case, the reason is that the 3rd contact is always connected (due to the extension ring different implementation of the 3rd contact), hence any manual lens is perceived as a lens with contacts passing aperture information. As these manual lenses have a metal mount , all other contact points are shorted which my camera reads as minimum aperture f1.2 and as a lens with automatic aperture.

So my guess is that somewhere you do an incorrect mix of lens/aperture ring settings & manual or automated metering camera menu settings in the camera, and this yields a "default" minimum aperture info....
One difference that can influence is on the lens side: there are three types of lenses: manual vintage lenses (only fnumbers) and modern lenses where you can set the aperture ring to A or a manual f-number and then there are modern lenses that only do A (do not have aperture ring as it is camera controlled). As the K3-3 introduced some new settings to work both with old manual and both types newer (aperture controlled) lenses, I guess you found a way or a combination to confuse the camera.
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