Super-Takumar 55/1.8 questions - yellowing, white balance, exposure

**BigMackCam** · 07-30-2016, 04:45 AM

I just picked up a beautiful example of the Super-Takumar 55/1.8 and I've been playing with it on my K5.

Although the glass isn't badly yellowed, there is a definite amber tint to it. The K5's AWB occasionally gets confused and ends up giving me a blue-ish cast on images, though choosing an appropriate preset or setting a custom white balance works perfectly. Also, I notice that, wide open, the camera tends to under expose with this lens by around one stop.~~.. gradually improving as I stop down. At f/5.6 it seems about right.~~

Re the yellowing, I know I can reduce this by exposing the glass to UV for a period, but I'm wondering whether there's much benefit in doing so? With white balance set to compensate, colour reproduction seems - at least from my early tests - very nice indeed. Am I missing out in any way by not giving it the UV treatment? Is this likely to be causing the under-exposure?

Thanks in advance!

Last edited by BigMackCam; 07-30-2016 at 05:18 AM.

pathdoc · 07-30-2016, 05:42 AM

Use the muted setting and be done.

IIRC, Digitalis once said that the downside of leaving the yellowing alone is that it impairs sharpness as well as affects colour cast.

I think the main problem with the exposure is that the lens mount contacts aren't closed, leading to metering issues. When I use flash (especially a thyristor unit), an external meter or Sunny Sixteen, it seems I have less of a problem.

D1N0 · 07-30-2016, 05:44 AM

I get under exposure with all my m42 glass on the K-5. yellow or not. So I tend to shoot it with +0.7 or +1 ev. Auto white balance isn't really a problem, with my yellowed s-m-c tak 50 1.4 I get a bit warmer pics. Sometimes in low light it get's it wrong with too much magenta.

**BigMackCam** · 07-30-2016, 06:00 AM

Originally posted by pathdoc

IIRC, Digitalis once said that the downside of leaving the yellowing alone is that it impairs sharpness as well as affects colour cast.

I think the main problem with the exposure is that the lens mount contacts aren't closed, leading to metering issues. When I use flash (especially a thyristor unit), an external meter or Sunny Sixteen, it seems I have less of a problem.

Thanks, that's good to know... Well, I certainly don't see any sharpness issues. That's not to say it couldn't be sharper, but I wasn't expecting it to be as sharp as it is already; surprisingly usable wide open if focused accurately, and bitingly sharp at f/5.6.

Interestingly, I just tried the lens on a chrome flanged adapter, and the exposure seemed better... I'll have to do some more controlled tests.

EDIT: Well, I'll be darned. I just tested between the normal Pentax adapter and the chrome flanged adapter... Digitalis seems to be onto something. With the flanged adapter (which covers the mount contacts) it's only under-exposing by a third of a stop, as opposed to a full stop with the proper adapter. Fascinating

Originally posted by D1N0

I get under exposure with all my m42 glass on the K-5. yellow or not. So I tend to shoot it with +0.7 or +1 ev. Auto white balance isn't really a problem, with my yellowed s-m-c tak 50 1.4 I get a bit warmer pics. Sometimes in low light it get's it wrong with too much magenta.

Thanks for that. Yes, I also get under-exposure to varying degrees on my M42 lenses, so I guess this one isn't unusual in that respect.

I think I'll leave the lens well alone for now. I'm very happy with the IQ, the white balance isn't really an issue, and if the yellowing *is* contributing to the under-exposure, it's not too significant.

Thanks again, fellas

Last edited by BigMackCam; 07-30-2016 at 06:12 AM.

**k0og** · 07-30-2016, 06:35 AM

The yellowing also reduces the total light throughput by a fraction of a stop. I don't know how much. It's probably not much of a real-life issue though.

I cleared my lenses using an Ikea LED lamp, as detailed in this thread. It really does work! I used it for about a week on mine, and it is a good lamp for general workbench close-up work anyway.

-Joe-

**UncleVanya** · 07-30-2016, 07:13 AM

Some people have had luck adding an o-ring to their setup to block dust and light leaking in around the mount. The ring goes outside on the lens barrel covering the gap by rolling it against the adapter and leaving it there.

D1N0 · 07-30-2016, 07:23 AM

Yeah I wonder who that was.

**BigMackCam** · 07-30-2016, 07:32 AM

Originally posted by UncleVanya

Some people have had luck adding an o-ring to their setup to block dust and light leaking in around the mount. The ring goes outside on the lens barrel covering the gap by rolling it against the adapter and leaving it there.

Originally posted by D1N0

Yeah I wonder who that was.

Hmm. Seems like a really smart idea!

Thanks again...

stevebrot · 07-30-2016, 11:16 AM

Originally posted by k0og

I cleared my lenses using an Ikea LED lamp, as detailed in this thread. It really does work! I used it for about a week on mine, and it is a good lamp for general workbench close-up work anyway.

+1 for this technique. It works and is not expensive. I cleared my ST 55/1.8 and Auto-Rikenon 55/1.4 with excellent results.

Steve

**BigMackCam** · 07-30-2016, 11:34 AM - **1 Like**

Originally posted by k0og

I cleared my lenses using an Ikea LED lamp, as detailed in this thread. It really does work! I used it for about a week on mine, and it is a good lamp for general workbench close-up work anyway.

Originally posted by stevebrot

+1 for this technique. It works and is not expensive. I cleared my ST 55/1.8 and Auto-Rikenon 55/1.4 with excellent results.

Thanks Joe & Steve - that sounds ideal. I was just going to live with it, but this is a nice straightforward fix... and there's a depressingly massive IKEA store about 20 mins from where I live!

EDIT: I just checked and they have them in stock at my local IKEA "retail torture facility"

Going to head over on Monday to buy one.

Every time I visit IKEA, I always seem to come back with yet more drinking glasses, rye crispbreads (which I think contain cement) and lingonberry jam... I'd better make space in the cupboards in advance

stevebrot · 07-30-2016, 05:17 PM - **1 Like**

Originally posted by BigMackCam

Every time I visit IKEA, I always seem to come back with yet more drinking glasses, rye crispbreads (which I think contain cement) and lingonberry jam... I'd better make space in the cupboards in advance

Herring...don't forget the pickled herring...

Steve

**BigMackCam** · 08-01-2016, 04:11 AM

Originally posted by stevebrot

Herring...don't forget the pickled herring...

I just got back from IKEA, with a black JANSJÖ work lamp (I checked to see if they did a red one, Steve, but no joy

)...

I forgot the pickled herring, but - as predicted - I did acquire some sundry items... KNÄCKEBRÖD RÅG rye crispbreads, KALLES cod's roe in a tube (which I shall open, consume one portion on a rye crispbread, then place the tube back in the fridge where it will sit untouched until I clean the fridge out at the end of the year

), a BLASKA plastic dustpan and brush, BÄSTIS lint roller refills, and some SÖTSAK DAMMSUGARE pastries with almond paste.

That aside... I'll set up the lamp this evening and see if I can't get the ST55/1.8 back to its original tint-free state

**BigMackCam** · 08-01-2016, 10:11 AM

OK, I'm set up to go

Couldn't find a small, flat mirror in the house (not without taking something down off the wall

), so I'm going with aluminium foil for now...

This is how I have the lens and lamp arranged... this is the minimum distance I can get between lamp and lens to get the circle of light fully covering the rear element (and the edge of the mount). Does it look OK?

**k0og** · 08-02-2016, 05:46 PM

Originally posted by BigMackCam

OK, I'm set up to go

Couldn't find a small, flat mirror in the house (not without taking something down off the wall

), so I'm going with aluminium foil for now...

This is how I have the lens and lamp arranged... this is the minimum distance I can get between lamp and lens to get the circle of light fully covering the rear element (and the edge of the mount). Does it look OK?

That's probably good enough. I put my lamp right up nearly touching the rear element and it works well. If you get a little closer it might work faster since less light will be outside the rear element glass.

The aluminum foil should be plenty good for a reflector.

-Joe-

07-30-2016, 04:45 AM	#1
BigMackCam Digitiser of Film Join Date: Mar 2010 Location: North East of England Posts: 20,673	Super-Takumar 55/1.8 questions - yellowing, white balance, exposure I just picked up a beautiful example of the Super-Takumar 55/1.8 and I've been playing with it on my K5. Although the glass isn't badly yellowed, there is a definite amber tint to it. The K5's AWB occasionally gets confused and ends up giving me a blue-ish cast on images, though choosing an appropriate preset or setting a custom white balance works perfectly. Also, I notice that, wide open, the camera tends to under expose with this lens by around one stop.~~.. gradually improving as I stop down. At f/5.6 it seems about right.~~ Re the yellowing, I know I can reduce this by exposing the glass to UV for a period, but I'm wondering whether there's much benefit in doing so? With white balance set to compensate, colour reproduction seems - at least from my early tests - very nice indeed. Am I missing out in any way by not giving it the UV treatment? Is this likely to be causing the under-exposure? Thanks in advance! Last edited by BigMackCam; 07-30-2016 at 05:18 AM.

07-30-2016, 11:34 AM - 1 Like	#10
BigMackCam Digitiser of Film Join Date: Mar 2010 Location: North East of England Posts: 20,673 Original Poster	Originally posted by k0og I cleared my lenses using an Ikea LED lamp, as detailed in this thread. It really does work! I used it for about a week on mine, and it is a good lamp for general workbench close-up work anyway. Originally posted by stevebrot +1 for this technique. It works and is not expensive. I cleared my ST 55/1.8 and Auto-Rikenon 55/1.4 with excellent results. Thanks Joe & Steve - that sounds ideal. I was just going to live with it, but this is a nice straightforward fix... and there's a depressingly massive IKEA store about 20 mins from where I live! EDIT: I just checked and they have them in stock at my local IKEA "retail torture facility" Going to head over on Monday to buy one. Every time I visit IKEA, I always seem to come back with yet more drinking glasses, rye crispbreads (which I think contain cement) and lingonberry jam... I'd better make space in the cupboards in advance Last edited by BigMackCam; 07-30-2016 at 11:41 AM.

08-01-2016, 04:11 AM	#12
BigMackCam Digitiser of Film Join Date: Mar 2010 Location: North East of England Posts: 20,673 Original Poster	Originally posted by stevebrot Herring...don't forget the pickled herring... I just got back from IKEA, with a black JANSJÖ work lamp (I checked to see if they did a red one, Steve, but no joy )... I forgot the pickled herring, but - as predicted - I did acquire some sundry items... KNÄCKEBRÖD RÅG rye crispbreads, KALLES cod's roe in a tube (which I shall open, consume one portion on a rye crispbread, then place the tube back in the fridge where it will sit untouched until I clean the fridge out at the end of the year ), a BLASKA plastic dustpan and brush, BÄSTIS lint roller refills, and some SÖTSAK DAMMSUGARE pastries with almond paste. That aside... I'll set up the lamp this evening and see if I can't get the ST55/1.8 back to its original tint-free state Last edited by BigMackCam; 08-01-2016 at 10:11 AM.

08-01-2016, 10:11 AM	#13
BigMackCam Digitiser of Film Join Date: Mar 2010 Location: North East of England Posts: 20,673 Original Poster	OK, I'm set up to go Couldn't find a small, flat mirror in the house (not without taking something down off the wall ), so I'm going with aluminium foil for now... This is how I have the lens and lamp arranged... this is the minimum distance I can get between lamp and lens to get the circle of light fully covering the rear element (and the edge of the mount). Does it look OK? Attached Images Last edited by BigMackCam; 08-01-2016 at 10:30 AM.

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07-30-2016, 05:42 AM	#2
pathdoc Pentaxian Join Date: Mar 2015 Photos: Gallery \| Albums Posts: 6,381	Use the muted setting and be done. IIRC, Digitalis once said that the downside of leaving the yellowing alone is that it impairs sharpness as well as affects colour cast. I think the main problem with the exposure is that the lens mount contacts aren't closed, leading to metering issues. When I use flash (especially a thyristor unit), an external meter or Sunny Sixteen, it seems I have less of a problem.

07-30-2016, 05:44 AM	#3
D1N0 Pentaxian Join Date: May 2012 Location: --- Photos: Gallery Posts: 6,802	I get under exposure with all my m42 glass on the K-5. yellow or not. So I tend to shoot it with +0.7 or +1 ev. Auto white balance isn't really a problem, with my yellowed s-m-c tak 50 1.4 I get a bit warmer pics. Sometimes in low light it get's it wrong with too much magenta.

07-30-2016, 06:00 AM	#4
BigMackCam Digitiser of Film Join Date: Mar 2010 Location: North East of England Posts: 20,673 Original Poster	Originally posted by pathdoc IIRC, Digitalis once said that the downside of leaving the yellowing alone is that it impairs sharpness as well as affects colour cast. I think the main problem with the exposure is that the lens mount contacts aren't closed, leading to metering issues. When I use flash (especially a thyristor unit), an external meter or Sunny Sixteen, it seems I have less of a problem. Thanks, that's good to know... Well, I certainly don't see any sharpness issues. That's not to say it couldn't be sharper, but I wasn't expecting it to be as sharp as it is already; surprisingly usable wide open if focused accurately, and bitingly sharp at f/5.6. Interestingly, I just tried the lens on a chrome flanged adapter, and the exposure seemed better... I'll have to do some more controlled tests. EDIT: Well, I'll be darned. I just tested between the normal Pentax adapter and the chrome flanged adapter... Digitalis seems to be onto something. With the flanged adapter (which covers the mount contacts) it's only under-exposing by a third of a stop, as opposed to a full stop with the proper adapter. Fascinating Originally posted by D1N0 I get under exposure with all my m42 glass on the K-5. yellow or not. So I tend to shoot it with +0.7 or +1 ev. Auto white balance isn't really a problem, with my yellowed s-m-c tak 50 1.4 I get a bit warmer pics. Sometimes in low light it get's it wrong with too much magenta. Thanks for that. Yes, I also get under-exposure to varying degrees on my M42 lenses, so I guess this one isn't unusual in that respect. I think I'll leave the lens well alone for now. I'm very happy with the IQ, the white balance isn't really an issue, and if the yellowing is contributing to the under-exposure, it's not too significant. Thanks again, fellas Last edited by BigMackCam; 07-30-2016 at 06:12 AM.

07-30-2016, 06:35 AM	#5
k0og Site Supporter Join Date: Nov 2008 Location: Rolla, Missouri Photos: Gallery \| Albums Posts: 699	The yellowing also reduces the total light throughput by a fraction of a stop. I don't know how much. It's probably not much of a real-life issue though. I cleared my lenses using an Ikea LED lamp, as detailed in this thread. It really does work! I used it for about a week on mine, and it is a good lamp for general workbench close-up work anyway. -Joe-

07-30-2016, 07:13 AM	#6
UncleVanya Loyal Site Supporter Join Date: Jul 2014 Photos: Gallery \| Albums Posts: 28,403	Some people have had luck adding an o-ring to their setup to block dust and light leaking in around the mount. The ring goes outside on the lens barrel covering the gap by rolling it against the adapter and leaving it there.

07-30-2016, 07:23 AM	#7
D1N0 Pentaxian Join Date: May 2012 Location: --- Photos: Gallery Posts: 6,802	Yeah I wonder who that was.

07-30-2016, 07:32 AM	#8
BigMackCam Digitiser of Film Join Date: Mar 2010 Location: North East of England Posts: 20,673 Original Poster	Originally posted by UncleVanya Some people have had luck adding an o-ring to their setup to block dust and light leaking in around the mount. The ring goes outside on the lens barrel covering the gap by rolling it against the adapter and leaving it there. Originally posted by D1N0 Yeah I wonder who that was. Hmm. Seems like a really smart idea! Thanks again...

07-30-2016, 11:16 AM	#9
stevebrot Otis Memorial Pentaxian Join Date: Mar 2007 Location: Vancouver (USA) Photos: Gallery \| Albums Posts: 42,007	Originally posted by k0og I cleared my lenses using an Ikea LED lamp, as detailed in this thread. It really does work! I used it for about a week on mine, and it is a good lamp for general workbench close-up work anyway. +1 for this technique. It works and is not expensive. I cleared my ST 55/1.8 and Auto-Rikenon 55/1.4 with excellent results. Steve

07-30-2016, 05:17 PM - 1 Like	#11
stevebrot Otis Memorial Pentaxian Join Date: Mar 2007 Location: Vancouver (USA) Photos: Gallery \| Albums Posts: 42,007	Originally posted by BigMackCam Every time I visit IKEA, I always seem to come back with yet more drinking glasses, rye crispbreads (which I think contain cement) and lingonberry jam... I'd better make space in the cupboards in advance Herring...don't forget the pickled herring... Steve

08-02-2016, 05:46 PM	#14
k0og Site Supporter Join Date: Nov 2008 Location: Rolla, Missouri Photos: Gallery \| Albums Posts: 699	Originally posted by BigMackCam OK, I'm set up to go Couldn't find a small, flat mirror in the house (not without taking something down off the wall ), so I'm going with aluminium foil for now... This is how I have the lens and lamp arranged... this is the minimum distance I can get between lamp and lens to get the circle of light fully covering the rear element (and the edge of the mount). Does it look OK? That's probably good enough. I put my lamp right up nearly touching the rear element and it works well. If you get a little closer it might work faster since less light will be outside the rear element glass. The aluminum foil should be plenty good for a reflector. -Joe-