Blue cast using M prime lenses on K500

martbev · 06-22-2014, 03:10 PM

Hi,
I've have a Pentax ME (not the super) with 50mm f1.7, 28mm f2.8, and 120mm f2.8 lenses. I bought a K-500 to be able to use the lenses with a digital back. I followed the setup help I found on this forum, and it works fine, except that there seems to be a blue cast over all photos taken with the M series lenses compared to the kit DAL lens. Did I miss a setting (white point or something)? Or is it just the way the camera displays the image?

**eaglem** · 06-22-2014, 03:56 PM

Welcome to the forum, it may pay you to repost your question in the Lens section of the forum where you have a far better chance of getting the answers you require.

Adam · 06-22-2014, 04:05 PM

Originally posted by martbev

Hi,
I've have a Pentax ME (not the super) with 50mm f1.7, 28mm f2.8, and 120mm f2.8 lenses. I bought a K-500 to be able to use the lenses with a digital back. I followed the setup help I found on this forum, and it works fine, except that there seems to be a blue cast over all photos taken with the M series lenses compared to the kit DAL lens. Did I miss a setting (white point or something)? Or is it just the way the camera displays the image?

Also, be sure to upload some samples.

DeadJohn · 06-22-2014, 04:17 PM

Originally posted by martbev

Hi,
I've have a Pentax ME (not the super) with 50mm f1.7, 28mm f2.8, and 120mm f2.8 lenses. I bought a K-500 to be able to use the lenses with a digital back. I followed the setup help I found on this forum, and it works fine, except that there seems to be a blue cast over all photos taken with the M series lenses compared to the kit DAL lens. Did I miss a setting (white point or something)? Or is it just the way the camera displays the image?

Did you compare the DAL to the M lenses under the same lighting conditions and on multiple days? Does sun, shade, and indoors give a similar blue cast?

Are you shooting in JPEG or RAW? If RAW, what software are you using?

What is the white balance setting on your K-500? Auto should give reasonably good results in most lighting conditions.

And, as already mentioned, sample photos are very helpful to diagnose issues.

Kozlok · 06-22-2014, 06:00 PM

I have some M lenses that render a bit blue. I shoot raw and fix it in Lightroom.

**mattt** · 06-22-2014, 06:17 PM

I too have noticed the blue cast of M glass.. I have M 40mm f2.8 and M 85mm f2.0 and both exhibit this, particularly in highlights - I treat it like PF/CA and correct it in post.

stevebrot · 06-22-2014, 09:18 PM

Since this thread is taking on the flavor of a poll, I will add my lenses to the tally. Neither my M 50/1.7 nor my M200/4 have a blue cast, though it would not surprise me if other lenses in the series rendered that way. Few, if any, lenses are completely neutral in regards to color and it is seldom as simple as a general cast. As noted above, the solution is to correct in PP.

Steve

OregonJim · 06-22-2014, 11:12 PM

Originally posted by stevebrot

Since this thread is taking on the flavor of a poll, I will add my lenses to the tally.

Ok, guess I will, too. My M 50/1.4 does have a slight blue shift. S/N 7180xxx. I don't even bother to correct for it, unless skin tones are present. None of my other M's do this, as far as I can remember. The SMC coatings went through several formula changes in those days - I wouldn't be surprised if this was a characteristic of a specific coating formula.

wombat2go · 06-23-2014, 06:56 AM

Originally posted by mattt

I have M 40mm f2.8 and M 85mm f2.0 and both exhibit this, particularly in highlights

I just took color charts with both of these lenses in hazy sun, using the K-01 in raw+jpg
Indeed, the eyedroppers of both ufraw ( on the raw) and gimp ( on the jpg) report a slight cast of blue.
I checked some of the grays and the red patches

The 1:2 85mm raw, then jpg
https://app.box.com/s/uqrejz9uetc9p02a9uja
https://app.box.com/s/8ytbvdenjkafr2ry983x

The 1:2.8 40mm
https://app.box.com/s/iichwn6ghdqkhgzfq1yw
https://app.box.com/s/zh568nn45la3ahzri62d

**Kerrowdown** · 06-23-2014, 11:21 AM

I'll just say welcome aboard as you've enough replies of a technical nature to be getting on with.

**monochrome** · 06-23-2014, 12:40 PM

Well, I'll add that where I have duplicate focal lengths, my M lenses render cooler (blue) than their K counterparts (yellow) and I've known it for many years.

martbev · 06-23-2014, 04:07 PM

Thank you all for your very helpful responses. I will post sample photos tomorrow. I took a few shots in the same lighting conditions to compare the kit lens with the M lenses, both outdoors (full light) and indoors (low light). There was a pronounced blue cast in neutral (gray) areas. I shot with the factory defaults, so auto white balance and shooting jpeg.
I was wondering if I had missed something in the setup, but it looks like it's a characteristic of the lenses. Thanks again for clarifying it.

06-22-2014, 03:10 PM	#1
martbev New Member Join Date: Jun 2014 Posts: 9	Blue cast using M prime lenses on K500 Hi, I've have a Pentax ME (not the super) with 50mm f1.7, 28mm f2.8, and 120mm f2.8 lenses. I bought a K-500 to be able to use the lenses with a digital back. I followed the setup help I found on this forum, and it works fine, except that there seems to be a blue cast over all photos taken with the M series lenses compared to the kit DAL lens. Did I miss a setting (white point or something)? Or is it just the way the camera displays the image?

06-22-2014, 04:05 PM	#3
Adam Administrator Site Webmaster Join Date: Sep 2006 Location: Arizona Photos: Gallery \| Albums Posts: 51,595	Originally posted by martbev Hi, I've have a Pentax ME (not the super) with 50mm f1.7, 28mm f2.8, and 120mm f2.8 lenses. I bought a K-500 to be able to use the lenses with a digital back. I followed the setup help I found on this forum, and it works fine, except that there seems to be a blue cast over all photos taken with the M series lenses compared to the kit DAL lens. Did I miss a setting (white point or something)? Or is it just the way the camera displays the image? Also, be sure to upload some samples. 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:

06-22-2014, 11:12 PM	#8
OregonJim Veteran Member Join Date: Mar 2009 Location: Willamette Valley, Oregon Posts: 1,327	Originally posted by stevebrot Since this thread is taking on the flavor of a poll, I will add my lenses to the tally. Ok, guess I will, too. My M 50/1.4 does have a slight blue shift. S/N 7180xxx. I don't even bother to correct for it, unless skin tones are present. None of my other M's do this, as far as I can remember. The SMC coatings went through several formula changes in those days - I wouldn't be surprised if this was a characteristic of a specific coating formula. Last edited by OregonJim; 06-22-2014 at 11:23 PM.

06-23-2014, 04:07 PM	#12
martbev New Member Join Date: Jun 2014 Posts: 9 Original Poster	Thanks, everyone! Thank you all for your very helpful responses. I will post sample photos tomorrow. I took a few shots in the same lighting conditions to compare the kit lens with the M lenses, both outdoors (full light) and indoors (low light). There was a pronounced blue cast in neutral (gray) areas. I shot with the factory defaults, so auto white balance and shooting jpeg. I was wondering if I had missed something in the setup, but it looks like it's a characteristic of the lenses. Thanks again for clarifying it.

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06-22-2014, 03:56 PM	#2
eaglem Site Supporter Join Date: Feb 2009 Location: Perth Western Australia Photos: Gallery Posts: 43,146	Welcome to the forum, it may pay you to repost your question in the Lens section of the forum where you have a far better chance of getting the answers you require.

06-22-2014, 04:17 PM	#4
DeadJohn Pentaxian Join Date: Jan 2011 Location: New York Posts: 4,833	Originally posted by martbev Hi, I've have a Pentax ME (not the super) with 50mm f1.7, 28mm f2.8, and 120mm f2.8 lenses. I bought a K-500 to be able to use the lenses with a digital back. I followed the setup help I found on this forum, and it works fine, except that there seems to be a blue cast over all photos taken with the M series lenses compared to the kit DAL lens. Did I miss a setting (white point or something)? Or is it just the way the camera displays the image? Did you compare the DAL to the M lenses under the same lighting conditions and on multiple days? Does sun, shade, and indoors give a similar blue cast? Are you shooting in JPEG or RAW? If RAW, what software are you using? What is the white balance setting on your K-500? Auto should give reasonably good results in most lighting conditions. And, as already mentioned, sample photos are very helpful to diagnose issues.

06-22-2014, 06:00 PM	#5
Kozlok Pentaxian Join Date: Jun 2012 Location: Albuquerque Photos: Gallery Posts: 3,148	I have some M lenses that render a bit blue. I shoot raw and fix it in Lightroom.

06-22-2014, 06:17 PM	#6
mattt Site Supporter Join Date: Feb 2011 Location: Niagara Photos: Gallery \| Albums Posts: 3,907	I too have noticed the blue cast of M glass.. I have M 40mm f2.8 and M 85mm f2.0 and both exhibit this, particularly in highlights - I treat it like PF/CA and correct it in post.

06-22-2014, 09:18 PM	#7
stevebrot Otis Memorial Pentaxian Join Date: Mar 2007 Location: Vancouver (USA) Photos: Gallery \| Albums Posts: 42,007	Since this thread is taking on the flavor of a poll, I will add my lenses to the tally. Neither my M 50/1.7 nor my M200/4 have a blue cast, though it would not surprise me if other lenses in the series rendered that way. Few, if any, lenses are completely neutral in regards to color and it is seldom as simple as a general cast. As noted above, the solution is to correct in PP. Steve

06-23-2014, 06:56 AM	#9
wombat2go Veteran Member Join Date: Jan 2010 Location: Michigan Photos: Gallery Posts: 2,207	Originally posted by mattt I have M 40mm f2.8 and M 85mm f2.0 and both exhibit this, particularly in highlights I just took color charts with both of these lenses in hazy sun, using the K-01 in raw+jpg Indeed, the eyedroppers of both ufraw ( on the raw) and gimp ( on the jpg) report a slight cast of blue. I checked some of the grays and the red patches The 1:2 85mm raw, then jpg https://app.box.com/s/uqrejz9uetc9p02a9uja https://app.box.com/s/8ytbvdenjkafr2ry983x The 1:2.8 40mm https://app.box.com/s/iichwn6ghdqkhgzfq1yw https://app.box.com/s/zh568nn45la3ahzri62d

06-23-2014, 11:21 AM	#10
Kerrowdown PEG Moderator Join Date: Aug 2008 Location: Highlands of Scotland... "Hold Infinity in the palm of your hand" - William Blake Photos: Gallery Posts: 57,819	I'll just say welcome aboard as you've enough replies of a technical nature to be getting on with.

06-23-2014, 12:40 PM	#11
monochrome Loyal Site Supporter Join Date: Mar 2008 Location: Working From Home Photos: Gallery \| Albums Posts: 26,276	Well, I'll add that where I have duplicate focal lengths, my M lenses render cooler (blue) than their K counterparts (yellow) and I've known it for many years.