What are these red and purple lines?

bessa-66 · 06-11-2016, 06:27 PM

G'day everyone, how are you? I have a SMC Pentax K 300mm F4 lens, and the aperture doesn't stop down when it's on the camera (pentax k-x dslr). When I touch the aperture lever off the camera, however, it stops down. Does anyone know what the problem is? Is it repairable?

My photos taken with this camera also have red and purple lines running around the subjects, as seen in the crops below- does anyone know what they are?

Thank you!

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Adam · 06-11-2016, 06:33 PM - **1 Like**

Originally posted by bessa-66

G'day everyone, how are you? I have a SMC Pentax K 300mm F4 lens, and the aperture doesn't stop down when it's on the camera (pentax k-x dslr). When I touch the aperture lever off the camera, however, it stops down. Does anyone know what the problem is? Is it repairable?

My photos taken with this camera also have red and purple lines running around the subjects, as seen in the crops below- does anyone know what they are?

Thank you!

This behavior is normal. The lens should stop down when you go to take a photo, otherwise it will stay open.

Make sure you follow these instructions to meter correctly:
https://www.pentaxforums.com/forums/54-pentax-lens-articles/110657-how-use-me...k-x-k-7-a.html

What you're seeing in the photo are chromatic aberrations, which are common on older telephoto lenses that do not employ corrective elements. Stop down to reduce their severity. Also, while I won't go in detail, things that aren't in focus typically exhibit more aberrations than things that are. That's why the boat has all those halos, while the houses just have a small amount of fringing.

**sergysergy** · 06-11-2016, 06:37 PM

https://en.wikipedia.org/wiki/Chromatic_aberration

you can correct them in post processing too

bessa-66 · 06-11-2016, 06:43 PM

Thanks for the reply guys! Adam, the lens doesn't stop down when the photo is taken- it stays wide open for some reason. I've put the camera into bulb mode and set the ring to f22 and didn't see it close down like on my other lenses. Any ideas?

**Quartermaster James** · 06-11-2016, 07:02 PM

Originally posted by bessa-66

Thanks for the reply guys! Adam, the lens doesn't stop down when the photo is taken- it stays wide open for some reason. I've put the camera into bulb mode and set the ring to f22 and didn't see it close down like on my other lenses. Any ideas?

Did you set your camera's aperture ring custom function to allowed? See the instructions at the link Adam provided.

bessa-66 · 06-11-2016, 07:33 PM

Originally posted by Quartermaster James

Did you set your camera's aperture ring custom function to allowed? See the instructions at the link Adam provided.

Sure did!

**Quartermaster James** · 06-11-2016, 07:49 PM

Originally posted by bessa-66

Sure did!

And you are metering with the green button?

stevebrot · 06-11-2016, 09:06 PM

Originally posted by bessa-66

Sure did!

If so, the lens should stop down to the setting on the aperture ring for exposure. If it does not, you should confirm that the body is able to consistently stop down other lenses that you might have.

Steve

bessa-66 · 06-11-2016, 09:31 PM

Hi Steve, I meter using the green button, and the shutter speed changes accordingly. But when I twist the aperture ring to another value, the shutter speed doesn't change (if I'm pointing at the same subject). There is no clicking noise as with my other lenses. Checking now just to be sure

**Quartermaster James** · 06-11-2016, 09:51 PM

Originally posted by bessa-66

Hi Steve, I meter using the green button, and the shutter speed changes accordingly. But when I twist the aperture ring to another value, the shutter speed doesn't change (if I'm pointing at the same subject). There is no clicking noise as with my other lenses. Checking now just to be sure

If I understand what you are saying correctly, everything is operating as it should. The shutter speed isn't going to change again until you meter with the green button again. If you meter, then change the aperture, then your exposure is going to be off.

stevebrot · 06-11-2016, 10:11 PM

Originally posted by bessa-66

Hi Steve, I meter using the green button, and the shutter speed changes accordingly. But when I twist the aperture ring to another value, the shutter speed doesn't change (if I'm pointing at the same subject). There is no clicking noise as with my other lenses. Checking now just to be sure

Originally posted by Quartermaster James

If I understand what you are saying correctly, everything is operating as it should. The shutter speed isn't going to change again until you meter with the green button again. If you meter, then change the aperture, then your exposure is going to be off.

What he said. You are in manual mode. The green button stops the lens down for a moment and changes the shutter speed to match, but when it opens back up you are fully manual again.

Steve

bessa-66 · 06-11-2016, 11:58 PM

I think it might be the aperture linkage for this 300mms lens... Maybe it's out of alignment or something- in manual mode, I tested with another lens and it did stop the aperture down. The 300mm is 45 years old after all!

elvinhaak · 06-12-2016, 12:13 AM

Is the mount black or powdered or something? If the contacts are not making contact the body might think you are having an 'A' on the lens since the 'A'-contact (which should be making contact) is not contacting.
Of course I guess you are using the body in using the lens in the setting that it would use 'non-A' lenses? Although I mainly shoot with manual lenses withouth 'A', I sometimes forget the setting... and then it stays open during exposure (and if the body experiences an 'A'-lens it uses the calculated value of the body/the movement that would go with the aperture-setting on the body).
You can try in lifeview what the lens does: if it closes down, the linkage is working as it should ( I don't remember if the K-x does has lifeview though)

**Kerrowdown** · 06-12-2016, 12:28 AM

Originally posted by bessa-66

is 45 years old after all!

What's your point here, I'm older than that and I still work... well most of the time.

bessa-66 · 06-12-2016, 01:30 AM

Hi guys, just tried to stop down my other manual lenses, and I can see the diaphragm stop down when I press the button. Not so with the 300... it does stick when I press it down off the camera- is there any chance that this can be fixed with a little oil or something?

---------- Post added 06-12-16 at 01:30 AM ----------

Originally posted by Kerrowdown

What's your point here, I'm older than that and I still work... well most of the time.

Aaah, but you're not a glass tube! :P

---------- Post added 06-12-16 at 01:32 AM ----------

Originally posted by elvinhaak

Is the mount black or powdered or something? If the contacts are not making contact the body might think you are having an 'A' on the lens since the 'A'-contact (which should be making contact) is not contacting.
Of course I guess you are using the body in using the lens in the setting that it would use 'non-A' lenses? Although I mainly shoot with manual lenses withouth 'A', I sometimes forget the setting... and then it stays open during exposure (and if the body experiences an 'A'-lens it uses the calculated value of the body/the movement that would go with the aperture-setting on the body).
You can try in lifeview what the lens does: if it closes down, the linkage is working as it should ( I don't remember if the K-x does has lifeview though)

Hi Elvinhaak, this lens has no A setting on the ring at all

06-11-2016, 06:33 PM - 1 Like	#2
Adam Administrator Site Webmaster Join Date: Sep 2006 Location: Arizona Photos: Gallery \| Albums Posts: 51,609	Originally posted by bessa-66 G'day everyone, how are you? I have a SMC Pentax K 300mm F4 lens, and the aperture doesn't stop down when it's on the camera (pentax k-x dslr). When I touch the aperture lever off the camera, however, it stops down. Does anyone know what the problem is? Is it repairable? My photos taken with this camera also have red and purple lines running around the subjects, as seen in the crops below- does anyone know what they are? Thank you! This behavior is normal. The lens should stop down when you go to take a photo, otherwise it will stay open. Make sure you follow these instructions to meter correctly: https://www.pentaxforums.com/forums/54-pentax-lens-articles/110657-how-use-me...k-x-k-7-a.html What you're seeing in the photo are chromatic aberrations, which are common on older telephoto lenses that do not employ corrective elements. Stop down to reduce their severity. Also, while I won't go in detail, things that aren't in focus typically exhibit more aberrations than things that are. That's why the boat has all those halos, while the houses just have a small amount of fringing. 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: Last edited by photolady95; 06-11-2016 at 06:45 PM.

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06-11-2016, 06:37 PM	#3
sergysergy Site Supporter Join Date: Jan 2011 Photos: Gallery Posts: 5,175	https://en.wikipedia.org/wiki/Chromatic_aberration you can correct them in post processing too

06-11-2016, 06:43 PM	#4
bessa-66 Senior Member Join Date: Dec 2015 Posts: 137 Original Poster	Thanks for the reply guys! Adam, the lens doesn't stop down when the photo is taken- it stays wide open for some reason. I've put the camera into bulb mode and set the ring to f22 and didn't see it close down like on my other lenses. Any ideas?

06-11-2016, 07:02 PM	#5
Quartermaster James Loyal Site Supporter Join Date: Oct 2014 Location: Anchorage, Alaska Posts: 653	Originally posted by bessa-66 Thanks for the reply guys! Adam, the lens doesn't stop down when the photo is taken- it stays wide open for some reason. I've put the camera into bulb mode and set the ring to f22 and didn't see it close down like on my other lenses. Any ideas? Did you set your camera's aperture ring custom function to allowed? See the instructions at the link Adam provided.

06-11-2016, 07:33 PM	#6
bessa-66 Senior Member Join Date: Dec 2015 Posts: 137 Original Poster	Originally posted by Quartermaster James Did you set your camera's aperture ring custom function to allowed? See the instructions at the link Adam provided. Sure did!

06-11-2016, 07:49 PM	#7
Quartermaster James Loyal Site Supporter Join Date: Oct 2014 Location: Anchorage, Alaska Posts: 653	Originally posted by bessa-66 Sure did! And you are metering with the green button?

06-11-2016, 09:06 PM	#8
stevebrot Otis Memorial Pentaxian Join Date: Mar 2007 Location: Vancouver (USA) Photos: Gallery \| Albums Posts: 42,007	Originally posted by bessa-66 Sure did! If so, the lens should stop down to the setting on the aperture ring for exposure. If it does not, you should confirm that the body is able to consistently stop down other lenses that you might have. Steve

06-11-2016, 09:31 PM	#9
bessa-66 Senior Member Join Date: Dec 2015 Posts: 137 Original Poster	Hi Steve, I meter using the green button, and the shutter speed changes accordingly. But when I twist the aperture ring to another value, the shutter speed doesn't change (if I'm pointing at the same subject). There is no clicking noise as with my other lenses. Checking now just to be sure

06-11-2016, 09:51 PM	#10
Quartermaster James Loyal Site Supporter Join Date: Oct 2014 Location: Anchorage, Alaska Posts: 653	Originally posted by bessa-66 Hi Steve, I meter using the green button, and the shutter speed changes accordingly. But when I twist the aperture ring to another value, the shutter speed doesn't change (if I'm pointing at the same subject). There is no clicking noise as with my other lenses. Checking now just to be sure If I understand what you are saying correctly, everything is operating as it should. The shutter speed isn't going to change again until you meter with the green button again. If you meter, then change the aperture, then your exposure is going to be off.

06-11-2016, 10:11 PM	#11
stevebrot Otis Memorial Pentaxian Join Date: Mar 2007 Location: Vancouver (USA) Photos: Gallery \| Albums Posts: 42,007	Originally posted by bessa-66 Hi Steve, I meter using the green button, and the shutter speed changes accordingly. But when I twist the aperture ring to another value, the shutter speed doesn't change (if I'm pointing at the same subject). There is no clicking noise as with my other lenses. Checking now just to be sure Originally posted by Quartermaster James If I understand what you are saying correctly, everything is operating as it should. The shutter speed isn't going to change again until you meter with the green button again. If you meter, then change the aperture, then your exposure is going to be off. What he said. You are in manual mode. The green button stops the lens down for a moment and changes the shutter speed to match, but when it opens back up you are fully manual again. Steve

06-11-2016, 11:58 PM	#12
bessa-66 Senior Member Join Date: Dec 2015 Posts: 137 Original Poster	I think it might be the aperture linkage for this 300mms lens... Maybe it's out of alignment or something- in manual mode, I tested with another lens and it did stop the aperture down. The 300mm is 45 years old after all!

06-12-2016, 12:13 AM	#13
elvinhaak Junior Member Join Date: Apr 2016 Posts: 33	Is the mount black or powdered or something? If the contacts are not making contact the body might think you are having an 'A' on the lens since the 'A'-contact (which should be making contact) is not contacting. Of course I guess you are using the body in using the lens in the setting that it would use 'non-A' lenses? Although I mainly shoot with manual lenses withouth 'A', I sometimes forget the setting... and then it stays open during exposure (and if the body experiences an 'A'-lens it uses the calculated value of the body/the movement that would go with the aperture-setting on the body). You can try in lifeview what the lens does: if it closes down, the linkage is working as it should ( I don't remember if the K-x does has lifeview though)

06-12-2016, 12:28 AM	#14
Kerrowdown PEG Moderator Join Date: Aug 2008 Location: Highlands of Scotland... "Hold Infinity in the palm of your hand" - William Blake Photos: Gallery Posts: 57,867	Originally posted by bessa-66 is 45 years old after all! What's your point here, I'm older than that and I still work... well most of the time.

06-12-2016, 01:30 AM	#15
bessa-66 Senior Member Join Date: Dec 2015 Posts: 137 Original Poster	Hi guys, just tried to stop down my other manual lenses, and I can see the diaphragm stop down when I press the button. Not so with the 300... it does stick when I press it down off the camera- is there any chance that this can be fixed with a little oil or something? ---------- Post added 06-12-16 at 01:30 AM ---------- Originally posted by Kerrowdown What's your point here, I'm older than that and I still work... well most of the time. Aaah, but you're not a glass tube! :P ---------- Post added 06-12-16 at 01:32 AM ---------- Originally posted by elvinhaak Is the mount black or powdered or something? If the contacts are not making contact the body might think you are having an 'A' on the lens since the 'A'-contact (which should be making contact) is not contacting. Of course I guess you are using the body in using the lens in the setting that it would use 'non-A' lenses? Although I mainly shoot with manual lenses withouth 'A', I sometimes forget the setting... and then it stays open during exposure (and if the body experiences an 'A'-lens it uses the calculated value of the body/the movement that would go with the aperture-setting on the body). You can try in lifeview what the lens does: if it closes down, the linkage is working as it should ( I don't remember if the K-x does has lifeview though) Hi Elvinhaak, this lens has no A setting on the ring at all