Exposure data of AF film lens on DSLR

lotech · 12-28-2018, 11:19 PM

Please excuse my dumb question, I use 2 old film lenses on my K3, namely the Tamron 28-200mm and the Pentax 80-320mm, I don't see focal length data shown on the playback only aperture, shutter speed and ISO is that normal ?

Unregistered User 8 · 12-28-2018, 11:32 PM

Hi lotech, I believe the lenses in question predate the internal chips required to " communicate " with your DSLR.

lotech · 12-28-2018, 11:48 PM

Yes, I just thought even film camera will need such information to produce proper exposure especially will flash

Unregistered User 8 · 12-28-2018, 11:57 PM

The sensor ( or film ) don't really need/rely on the focal length, just the amount of light reaching either of them. So aperture, shutter speed and ISO ( ASA ) are the only critical information needed for manual operation or AUTO.

Adam · 12-29-2018, 12:06 AM

If the lenses are autofocus, you should be getting focal length info. Perhaps cleaning the contacts on the camera mount would help.

lotech · 12-29-2018, 12:43 AM

I've 2 lenses lacking that info but digital lens ok so I guess that's compatibility problem nothing major

**TwoUptons** · 12-29-2018, 09:23 AM

I don’t know which vintage your Tamron is, but I had the ‘Tamron-inspired’ Pentax 28-200, and it did fine.

I’d have thought the 80-320 would have also provided FL, since it’s a FA lens... I’d check the contacts and turn the camera off then on again with the lens mounted...

As an addendum, I was told years ago that all Pentax lenses from the F-series on encoded focus distance as well as FL.

-Eric

**twilhelm** · 12-29-2018, 09:41 AM

The 80-320 should provide focal length to the camera. I don't know about the other lens. Clean the lens mount carefully, I use a bit of isopropal alcohol on a Q-tip or cloth. Then check to make sure all the "bearings" are able to be pressed in and snap back out. One may be stuck and not making contact with the camera mount.

**ffking** · 12-29-2018, 10:01 AM

Just as a a sort of reversal of the original question, I'm assuming that lens identification came in with the MTF optimisation programmed exposure, since there were no data recoded on film 25 years or so back - is this correct?

ne! · 12-29-2018, 10:17 AM - **1 Like**

Hmmm, I’m not sure if this will help, but from reading your question I wonder if you need to switch info modes on image play back?

On my K-1, the standard information page shows the parameters you mention, but if I hit the info button and switch to a detailed page, I can see the focal length as well as other information. There is also a histogram-view mode on image playback.

lotech · 12-29-2018, 10:45 AM

Oh yes you are right, I completely forgot where I saw the detail info., I only recall from memory without actually check with a DA lens, there is not enough room to jam in the full detail on the playback screen, now I can see the FL detail of the shots I shoot with the old lens on the info. page , sorry guys for misleading !

Originally posted by ne!

Hmmm, I’m not sure if this will help, but from reading your question I wonder if you need to switch info modes on image play back?

On my K-1, the standard information page shows the parameters you mention, but if I hit the info button and switch to a detailed page, I can see the focal length as well as other information. There is also a histogram-view mode on image playback.

johnha · 01-01-2019, 06:02 PM

Originally posted by ffking

Just as a a sort of reversal of the original question, I'm assuming that lens identification came in with the MTF optimisation programmed exposure, since there were no data recoded on film 25 years or so back - is this correct?

I'm not sure about lens identification as such, but the F lenses provided the set focal length to the SFX/SF7 cameras - they used it for tweaking the standard program mode (wide, standard or tele as shown on the LCD) and for warning if flash coverage wouldn't cover the whole frame.

12-28-2018, 11:19 PM	#1
lotech Pentaxian Join Date: Apr 2012 Posts: 1,312	Exposure data of AF film lens on DSLR Please excuse my dumb question, I use 2 old film lenses on my K3, namely the Tamron 28-200mm and the Pentax 80-320mm, I don't see focal length data shown on the playback only aperture, shutter speed and ISO is that normal ?

12-29-2018, 12:06 AM	#5
Adam Administrator Site Webmaster Join Date: Sep 2006 Location: Arizona Photos: Gallery \| Albums Posts: 51,595	If the lenses are autofocus, you should be getting focal length info. Perhaps cleaning the contacts on the camera mount would help. Adam PentaxForums.com Webmaster (Site Usage Guide \| Site Help \| My Photography) PentaxForums.com server and development costs are user-supported. You can help cover these costs by donating or purchasing one of our Pentax eBooks. Or, buy your photo gear from our affiliates, Adorama, B&H Photo, KEH, or Topaz Labs, and get FREE Marketplace access - click here to see how! Trusted Pentax retailers:

12-29-2018, 10:01 AM	#9
ffking Site Supporter Join Date: Nov 2015 Location: Old South Wales Posts: 6,038	Just as a a sort of reversal of the original question, I'm assuming that lens identification came in with the MTF optimisation programmed exposure, since there were no data recoded on film 25 years or so back - is this correct? Last edited by ffking; 12-29-2018 at 10:33 AM.

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12-28-2018, 11:32 PM	#2
Unregistered User 8 Closed Account Join Date: Mar 2015 Photos: Gallery Posts: 8,694	Hi lotech, I believe the lenses in question predate the internal chips required to " communicate " with your DSLR.

12-28-2018, 11:48 PM	#3
lotech Pentaxian Join Date: Apr 2012 Posts: 1,312 Original Poster	Yes, I just thought even film camera will need such information to produce proper exposure especially will flash

12-28-2018, 11:57 PM	#4
Unregistered User 8 Closed Account Join Date: Mar 2015 Photos: Gallery Posts: 8,694	The sensor ( or film ) don't really need/rely on the focal length, just the amount of light reaching either of them. So aperture, shutter speed and ISO ( ASA ) are the only critical information needed for manual operation or AUTO.

12-29-2018, 12:43 AM	#6
lotech Pentaxian Join Date: Apr 2012 Posts: 1,312 Original Poster	I've 2 lenses lacking that info but digital lens ok so I guess that's compatibility problem nothing major

12-29-2018, 09:23 AM	#7
TwoUptons Loyal Site Supporter Join Date: Nov 2015 Photos: Albums Posts: 4,213	I don’t know which vintage your Tamron is, but I had the ‘Tamron-inspired’ Pentax 28-200, and it did fine. I’d have thought the 80-320 would have also provided FL, since it’s a FA lens... I’d check the contacts and turn the camera off then on again with the lens mounted... As an addendum, I was told years ago that all Pentax lenses from the F-series on encoded focus distance as well as FL. -Eric

12-29-2018, 09:41 AM	#8
twilhelm Loyal Site Supporter Join Date: Feb 2009 Location: Florida Photos: Gallery \| Albums Posts: 2,369	The 80-320 should provide focal length to the camera. I don't know about the other lens. Clean the lens mount carefully, I use a bit of isopropal alcohol on a Q-tip or cloth. Then check to make sure all the "bearings" are able to be pressed in and snap back out. One may be stuck and not making contact with the camera mount.

12-29-2018, 10:17 AM - 1 Like	#10
ne! Forum Member Join Date: Dec 2016 Posts: 57	Hmmm, I’m not sure if this will help, but from reading your question I wonder if you need to switch info modes on image play back? On my K-1, the standard information page shows the parameters you mention, but if I hit the info button and switch to a detailed page, I can see the focal length as well as other information. There is also a histogram-view mode on image playback.

12-29-2018, 10:45 AM	#11
lotech Pentaxian Join Date: Apr 2012 Posts: 1,312 Original Poster	Oh yes you are right, I completely forgot where I saw the detail info., I only recall from memory without actually check with a DA lens, there is not enough room to jam in the full detail on the playback screen, now I can see the FL detail of the shots I shoot with the old lens on the info. page , sorry guys for misleading ! Originally posted by ne! Hmmm, I’m not sure if this will help, but from reading your question I wonder if you need to switch info modes on image play back? On my K-1, the standard information page shows the parameters you mention, but if I hit the info button and switch to a detailed page, I can see the focal length as well as other information. There is also a histogram-view mode on image playback.

01-01-2019, 06:02 PM	#12
johnha Veteran Member Join Date: Apr 2012 Location: Lancashire, UK Photos: Albums Posts: 1,155	Originally posted by ffking Just as a a sort of reversal of the original question, I'm assuming that lens identification came in with the MTF optimisation programmed exposure, since there were no data recoded on film 25 years or so back - is this correct? I'm not sure about lens identification as such, but the F lenses provided the set focal length to the SFX/SF7 cameras - they used it for tweaking the standard program mode (wide, standard or tele as shown on the LCD) and for warning if flash coverage wouldn't cover the whole frame.