Diffraction in pentax 67 lenses

Herb · 02-13-2010, 12:44 PM

I have a lot of time in LF, not much in MF, and my small format friends are worrying about diffraction in their lenses at small aperatures.
Question: do the Pentax lenses, say 55 or 105 have diffraction problems at f22? This would show up as soft edges most likely, and some of the threads i read about the lenses talk about soft edges in some but do not say what f stop they are shooting.

tuco · 02-13-2010, 01:36 PM

Well, you can always shoot them all the way stopped down and find out

I shoot both those lenses at ƒ16 and ƒ19 all the time in my long exposures shots. And I know I've shot the 55 at ƒ22 several times. I didn't notice anything standing out but the edges in those shots didn't have much to show. I don't have one to post at the moment. If there is any softness on the edges, I think you'd be picking fly crap out of the pepper to find it. Big deal. And I find there are not too many situations where you need ƒ22 on the 55mm. You get around 8 feet to infinity at ƒ16 on it- on the SMC 67 generation of that lens, anyway.

My digital friend is always trying to shoot at the cherry aperture. I never even think about it. I shoot at whatever aperture the scene requires for what I want.

Ben_Edict · 02-13-2010, 01:39 PM

Visible Diffraction effects are format dependent. When people are complaing, they mostly complain about diffraction visibly setting in at around f/11 and smaller for APS-C sized sensors.

With a genuine 6x7 format, diffraction at f/22 should not be a really important problem. In LF (4x5 for instance) we use routinely f/32 and smaller without visible problems.

Ben

Wheatfield · 02-13-2010, 03:23 PM

Diffraction is a problem if you go looking for it.
Otherwise it's just another thing for the measurbators to get their pants wet about.

Here's an exercise for you:
Set oyur camera up on a tripod.
Take a picture at f/4 where you know the lens is performing well.
Take another picture at f/8.
Take another picture at f/16.
Take another picture at f/22.

Make prints of each file and see if you can spot the diffraction.

Get back to me with your results.

desertscape · 02-13-2010, 06:07 PM

I find it odd that people worry about diffraction but not so much about aberrations. They are both distructive to the image, just at opposite ends of the aperture continuum. If I were to obsses about either one while shooting, it would limit what I shoot. I don't worry about it. I shoot the 300 Takumar, 400, 600 and 90-180 zoom at f/45 on a regular basis. Having the right composition trumps diffraction loss every time. Concerning the shorter lenses at f/22; no problem.

Steve

Wheatfield · 02-13-2010, 08:37 PM

Originally posted by desertscape

I find it odd that people worry about diffraction but not so much about aberrations. They are both distructive to the image, just at opposite ends of the aperture continuum. If I were to obsses about either one while shooting, it would limit what I shoot. I don't worry about it. I shoot the 300 Takumar, 400, 600 and 90-180 zoom at f/45 on a regular basis. Having the right composition trumps diffraction loss every time. Concerning the shorter lenses at f/22; no problem.

Steve

If there were more of me, I'd give you a standing ovation.

tuco · 02-13-2010, 10:43 PM

Originally posted by desertscape

... Having the right composition trumps diffraction loss every time.

I think that about sums it up!

Herb · 02-14-2010, 11:26 AM

Ok, pretty much as I suspected. My LF lenses are capable of down to f128 in some cases, but the diameter of the opening is pretty big at f32 and f45.
I think the comment about "measurebaturs" was pretty accurate.
My comment was pertinent as I am pretty new to MF and do mostly scanning for b/w.

tuco · 02-14-2010, 11:41 AM

Herb I have a Schneider Super-Angulon 90mm/f8 and for an economical lens, it does great at ƒ64

Wisner 4x5 TF, TXT 4164, PMK Pyro

Ben_Edict · 02-14-2010, 01:12 PM

Originally posted by tuco

Herb I have a Schneider Super-Angulon 90mm/f8 and for an economical lens, it does great at ƒ64

Very nice image - would love to see it really large.

Ben

tuco · 02-14-2010, 05:53 PM

Thanks, Ben. The largest I have is a 16x20 hanging on my wall. I need to tool up and get a 20x24 tray and easel to do that size.

brkl · 02-19-2010, 10:35 AM

The more area you have to store a picture, the less perceivable effect diffraction has. You'd probably notice it if you mounted that Super-Angulon on an APS-C camera and took a shot at f64.

Another fantastic shot, Tuco!

Jonson PL · 02-19-2010, 12:33 PM

Originally posted by tuco

Herb I have a Schneider Super-Angulon 90mm/f8 and for an economical lens, it does great at ƒ64

Wisner 4x5 TF, TXT 4164, PMK Pyro

Sweet shot !

Ansel Adams, Edward Weston and others, even had the f/64 club.

tuco · 02-19-2010, 04:14 PM

Originally posted by brkl

The more area you have to store a picture, the less perceivable effect diffraction has. You'd probably notice it if you mounted that Super-Angulon on an APS-C camera and took a shot at f64.

Another fantastic shot, Tuco!

Thanks. But wouldn't the image circle projected by that lens be larger than the camera and the APS-C sensor would only be seeing the cherry center of the lens?

Ben_Edict · 02-20-2010, 04:36 AM

Originally posted by tuco

Thanks. But wouldn't the image circle projected by that lens be larger than the camera and the APS-C sensor would only be seeing the cherry center of the lens?

Yes, that's correct. But diffraction is the same all over the image circle - it is not concentrated in the center.

Ben

02-13-2010, 12:44 PM	#1
Herb Inactive Account Join Date: Jan 2010 Location: Raleigh North Carolina Posts: 18	Diffraction in pentax 67 lenses I have a lot of time in LF, not much in MF, and my small format friends are worrying about diffraction in their lenses at small aperatures. Question: do the Pentax lenses, say 55 or 105 have diffraction problems at f22? This would show up as soft edges most likely, and some of the threads i read about the lenses talk about soft edges in some but do not say what f stop they are shooting.

02-13-2010, 01:36 PM	#2
tuco Pentaxian Join Date: Jul 2009 Location: Pugetopolis Posts: 11,020	Well, you can always shoot them all the way stopped down and find out I shoot both those lenses at ƒ16 and ƒ19 all the time in my long exposures shots. And I know I've shot the 55 at ƒ22 several times. I didn't notice anything standing out but the edges in those shots didn't have much to show. I don't have one to post at the moment. If there is any softness on the edges, I think you'd be picking fly crap out of the pepper to find it. Big deal. And I find there are not too many situations where you need ƒ22 on the 55mm. You get around 8 feet to infinity at ƒ16 on it- on the SMC 67 generation of that lens, anyway. My digital friend is always trying to shoot at the cherry aperture. I never even think about it. I shoot at whatever aperture the scene requires for what I want. Last edited by tuco; 02-13-2010 at 02:04 PM.

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02-13-2010, 01:39 PM	#3
Ben_Edict Veteran Member Join Date: Jul 2007 Location: SouthWest "Regio" Photos: Albums Posts: 3,309	Visible Diffraction effects are format dependent. When people are complaing, they mostly complain about diffraction visibly setting in at around f/11 and smaller for APS-C sized sensors. With a genuine 6x7 format, diffraction at f/22 should not be a really important problem. In LF (4x5 for instance) we use routinely f/32 and smaller without visible problems. Ben

02-13-2010, 03:23 PM	#4
Wheatfield Moderator Join Date: Apr 2008 Location: The wheatfields of Canada Posts: 15,975	Diffraction is a problem if you go looking for it. Otherwise it's just another thing for the measurbators to get their pants wet about. Here's an exercise for you: Set oyur camera up on a tripod. Take a picture at f/4 where you know the lens is performing well. Take another picture at f/8. Take another picture at f/16. Take another picture at f/22. Make prints of each file and see if you can spot the diffraction. Get back to me with your results.

02-13-2010, 06:07 PM	#5
desertscape Pentaxian Join Date: Feb 2009 Location: Arizona Posts: 1,272	I find it odd that people worry about diffraction but not so much about aberrations. They are both distructive to the image, just at opposite ends of the aperture continuum. If I were to obsses about either one while shooting, it would limit what I shoot. I don't worry about it. I shoot the 300 Takumar, 400, 600 and 90-180 zoom at f/45 on a regular basis. Having the right composition trumps diffraction loss every time. Concerning the shorter lenses at f/22; no problem. Steve

02-13-2010, 08:37 PM	#6
Wheatfield Moderator Join Date: Apr 2008 Location: The wheatfields of Canada Posts: 15,975	Originally posted by desertscape I find it odd that people worry about diffraction but not so much about aberrations. They are both distructive to the image, just at opposite ends of the aperture continuum. If I were to obsses about either one while shooting, it would limit what I shoot. I don't worry about it. I shoot the 300 Takumar, 400, 600 and 90-180 zoom at f/45 on a regular basis. Having the right composition trumps diffraction loss every time. Concerning the shorter lenses at f/22; no problem. Steve If there were more of me, I'd give you a standing ovation.

02-13-2010, 10:43 PM	#7
tuco Pentaxian Join Date: Jul 2009 Location: Pugetopolis Posts: 11,020	Originally posted by desertscape ... Having the right composition trumps diffraction loss every time. I think that about sums it up!

02-14-2010, 11:26 AM	#8
Herb Inactive Account Join Date: Jan 2010 Location: Raleigh North Carolina Posts: 18 Original Poster	Ok, pretty much as I suspected. My LF lenses are capable of down to f128 in some cases, but the diameter of the opening is pretty big at f32 and f45. I think the comment about "measurebaturs" was pretty accurate. My comment was pertinent as I am pretty new to MF and do mostly scanning for b/w.

02-14-2010, 11:41 AM	#9
tuco Pentaxian Join Date: Jul 2009 Location: Pugetopolis Posts: 11,020	Herb I have a Schneider Super-Angulon 90mm/f8 and for an economical lens, it does great at ƒ64 Wisner 4x5 TF, TXT 4164, PMK Pyro

02-14-2010, 01:12 PM	#10
Ben_Edict Veteran Member Join Date: Jul 2007 Location: SouthWest "Regio" Photos: Albums Posts: 3,309	Originally posted by tuco Herb I have a Schneider Super-Angulon 90mm/f8 and for an economical lens, it does great at ƒ64 Very nice image - would love to see it really large. Ben

02-14-2010, 05:53 PM	#11
tuco Pentaxian Join Date: Jul 2009 Location: Pugetopolis Posts: 11,020	Thanks, Ben. The largest I have is a 16x20 hanging on my wall. I need to tool up and get a 20x24 tray and easel to do that size.

02-19-2010, 10:35 AM	#12
brkl Veteran Member Join Date: Oct 2008 Posts: 497	The more area you have to store a picture, the less perceivable effect diffraction has. You'd probably notice it if you mounted that Super-Angulon on an APS-C camera and took a shot at f64. Another fantastic shot, Tuco!

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02-19-2010, 12:33 PM	#13
Jonson PL Veteran Member Join Date: Dec 2006 Location: Copenhagen Photos: Gallery Posts: 1,842	Originally posted by tuco Herb I have a Schneider Super-Angulon 90mm/f8 and for an economical lens, it does great at ƒ64 Wisner 4x5 TF, TXT 4164, PMK Pyro Sweet shot ! Ansel Adams, Edward Weston and others, even had the f/64 club.

02-19-2010, 04:14 PM	#14
tuco Pentaxian Join Date: Jul 2009 Location: Pugetopolis Posts: 11,020	Originally posted by brkl The more area you have to store a picture, the less perceivable effect diffraction has. You'd probably notice it if you mounted that Super-Angulon on an APS-C camera and took a shot at f64. Another fantastic shot, Tuco! Thanks. But wouldn't the image circle projected by that lens be larger than the camera and the APS-C sensor would only be seeing the cherry center of the lens?

02-20-2010, 04:36 AM	#15
Ben_Edict Veteran Member Join Date: Jul 2007 Location: SouthWest "Regio" Photos: Albums Posts: 3,309	Originally posted by tuco Thanks. But wouldn't the image circle projected by that lens be larger than the camera and the APS-C sensor would only be seeing the cherry center of the lens? Yes, that's correct. But diffraction is the same all over the image circle - it is not concentrated in the center. Ben