Finger print visible in viewfinder new K-50

LOBO RSA · 10-20-2014, 08:00 AM

Hi I have a fingerprint mark that becomes visible when looking through the viewer that comes and goes depending on the light and focus . It is normal according to the dealer ? I have a new K50

AldaCZ · 10-20-2014, 08:24 AM

Normal

It won't be noticeable which a fast/bright lens.

**Another dyemention** · 10-20-2014, 08:38 AM

I can't be sure without seeing your VF but all vfs have a pattern to them. It looks just like a finger print. It's from when they grind them. It's much more visible with certain lenses than with others.

stevebrot · 10-20-2014, 10:08 AM

Originally posted by Another dyemention

It looks just like a finger print. It's from when they grind them. It's much more visible with certain lenses than with others.

The focus screen incorporates a Fresnel lens on its lower surface to focus and concentrate light to the viewfinder*. The pattern of concentric grooves looks a bit like a finger print to some users while other users complain about a grainy/smeary look. The grooves are particularly apparent at narrower maximum apertures when looking at the blank sky. The are less apparent when shooting with faster (wider maximum aperture) lenses.

Steve

* Fresnel lens focus screens have been the norm for SLR cameras for a long time. I remember the first time I looked into a SLR viewfinder in the late 1960s. I immediately asked the camera's owner, "What are those funny lines?"

shaX 07 · 10-20-2014, 10:23 AM

I think there are fingers inside your camera....

bobpur · 10-20-2014, 10:50 AM

I thought I knew what it is but I can't put my finger on it right now.

LOBO RSA · 10-20-2014, 10:54 AM

Originally posted by stevebrot

The focus screen incorporates a Fresnel lens on its lower surface to focus and concentrate light to the viewfinder*. The pattern of concentric grooves looks a bit like a finger print to some users while other users complain about a grainy/smeary look. The grooves are particularly apparent at narrower maximum apertures when looking at the blank sky. The are less apparent when shooting with faster (wider maximum aperture) lenses.

Steve

* Fresnel lens focus screens have been the norm for SLR cameras for a long time. I remember the first time I looked into a SLR viewfinder in the late 1960s. I immediately asked the camera's owner, "What are those funny lines?"

Hi Steve Thanks for that excellent reply You are spot-on and have made my day

Wolfgang

rawr · 10-20-2014, 11:14 AM

Originally posted by LOBO RSA

Hi I have a fingerprint mark that becomes visible when looking through the viewer that comes and goes depending on the light and focus .

It could be the fresnel screen built into the focus screen. or it could indeed actually be a dirty fingerprint. It happens. Check it out carefully with a bright LED torch to make sure you understand what it really is..

I remember when I go my new K-5, there was a clear dirty thumb-print on the focus screen straight out of the box. it looked like whoever had installed the focus screen forgot to wear gloves, or something. I took the camera back to the dealer, and they exchanged it for a new camera on the spot. I checked the new body with a LED torch before accepting it though. Luckily all was clean.

AldaCZ · 10-20-2014, 12:27 PM

There are nice problems

When I used a SLR...it was not just dirty but I could see the wires to the "metering" sensor in the middle (Praktica MTL3)

It's OT but ..This will never happen again (not my photo, neither camera)

Schick · 10-20-2014, 06:37 PM

Originally posted by LOBO RSA

Hi I have a fingerprint mark that becomes visible when looking through the viewer that comes and goes depending on the light and focus . It is normal according to the dealer ? I have a new K50

Oh good, it wasn't just me thinking the same thing.

A few weeks back I was very curious about why it seemed covered in prints. Was delighted to find it was just the viewing screen too.

stevebrot · 10-20-2014, 09:36 PM

Originally posted by LOBO RSA

Hi Steve Thanks for that excellent reply You are spot-on and have made my day

It is my pleasure and the same for the other helpful people on this site.

Steve

Suleeto · 01-09-2015, 03:23 PM

Just to note, that focus screen is removable for those who didn't notice. Mine had a legit fingerprint on it... not the ridges in the nylon that make the Fresnel lens (if we're talking about the same piece). You could see the crooked fingerprint in the viewfinder. I ended up carefully unhinging the retaining bracket and letting the nylon focus screen fall out into my hand. Then I gently cleaned it with sensor cleaner and using a pair of tweezers replaced it back into the retaining bracket, and locked it back down. It actually has a little tiny plastic tab that I suspect serves no other purpose than to handle it with tweezers.

But it is nylon (or looks to be) so I'd be careful not to scratch it. I wonder how much a replacement costs. Replacing takes seconds.

stevebrot · 01-09-2015, 05:09 PM

Originally posted by Suleeto

It actually has a little tiny plastic tab that I suspect serves no other purpose than to handle it with tweezers.

That is one of the tab's functions. The other is to serve as an index for correct placement. If the tab is on the wrong side, the screen will be upside-down and manual focus will not be possible. The tab should be oriented to the left (towards the grip-side of the camera).

I would use caution if you are planning on cleaning it again in the future. I am not sure what is in sensor cleaner, but what is safe for sensors may not be safe for a focus screen. Solvent erosion of the Fresnel surface will result in a dimmer view and may also shift the plane of focus such that accurate focus may not be possible. KatzEye has included a cleaning tutorial with the information on their Web site detailing how they clean screens:

cleaning - KatzEye Optics

Steve

Juiceheadgorilla · 01-10-2015, 12:36 AM

I have no experience with this =[

vonBaloney · 02-01-2015, 06:58 AM

Originally posted by Suleeto

Then I gently cleaned it with sensor cleaner

Did that work? Focusing screens seem to get damaged by *anything*...

10-20-2014, 08:00 AM	#1
LOBO RSA New Member Join Date: Oct 2014 Location: Cape Town Posts: 13	Finger print visible in viewfinder new K-50 Hi I have a fingerprint mark that becomes visible when looking through the viewer that comes and goes depending on the light and focus . It is normal according to the dealer ? I have a new K50

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10-20-2014, 08:24 AM	#2
AldaCZ Veteran Member Join Date: Nov 2013 Location: North Bohemia Photos: Gallery Posts: 1,251	Normal It won't be noticeable which a fast/bright lens.

10-20-2014, 08:38 AM	#3
Another dyemention Site Supporter Join Date: Apr 2014 Posts: 432	I can't be sure without seeing your VF but all vfs have a pattern to them. It looks just like a finger print. It's from when they grind them. It's much more visible with certain lenses than with others.

10-20-2014, 10:08 AM	#4
stevebrot Otis Memorial Pentaxian Join Date: Mar 2007 Location: Vancouver (USA) Photos: Gallery \| Albums Posts: 42,007	Originally posted by Another dyemention It looks just like a finger print. It's from when they grind them. It's much more visible with certain lenses than with others. The focus screen incorporates a Fresnel lens on its lower surface to focus and concentrate light to the viewfinder. The pattern of concentric grooves looks a bit like a finger print to some users while other users complain about a grainy/smeary look. The grooves are particularly apparent at narrower maximum apertures when looking at the blank sky. The are less apparent when shooting with faster (wider maximum aperture) lenses. Steve Fresnel lens focus screens have been the norm for SLR cameras for a long time. I remember the first time I looked into a SLR viewfinder in the late 1960s. I immediately asked the camera's owner, "What are those funny lines?"

10-20-2014, 10:23 AM	#5
shaX 07 Veteran Member Join Date: Sep 2013 Location: Maine Posts: 331	I think there are fingers inside your camera....

10-20-2014, 10:50 AM	#6
bobpur Inactive Account Join Date: Jul 2010 Photos: Gallery Posts: 328	I thought I knew what it is but I can't put my finger on it right now.

10-20-2014, 10:54 AM	#7
LOBO RSA New Member Join Date: Oct 2014 Location: Cape Town Posts: 13 Original Poster	Originally posted by stevebrot The focus screen incorporates a Fresnel lens on its lower surface to focus and concentrate light to the viewfinder. The pattern of concentric grooves looks a bit like a finger print to some users while other users complain about a grainy/smeary look. The grooves are particularly apparent at narrower maximum apertures when looking at the blank sky. The are less apparent when shooting with faster (wider maximum aperture) lenses. Steve Fresnel lens focus screens have been the norm for SLR cameras for a long time. I remember the first time I looked into a SLR viewfinder in the late 1960s. I immediately asked the camera's owner, "What are those funny lines?" Hi Steve Thanks for that excellent reply You are spot-on and have made my day Wolfgang

10-20-2014, 11:14 AM	#8
rawr Veteran Member Join Date: Jun 2009 Posts: 11,913	Originally posted by LOBO RSA Hi I have a fingerprint mark that becomes visible when looking through the viewer that comes and goes depending on the light and focus . It could be the fresnel screen built into the focus screen. or it could indeed actually be a dirty fingerprint. It happens. Check it out carefully with a bright LED torch to make sure you understand what it really is.. I remember when I go my new K-5, there was a clear dirty thumb-print on the focus screen straight out of the box. it looked like whoever had installed the focus screen forgot to wear gloves, or something. I took the camera back to the dealer, and they exchanged it for a new camera on the spot. I checked the new body with a LED torch before accepting it though. Luckily all was clean.

10-20-2014, 12:27 PM	#9
AldaCZ Veteran Member Join Date: Nov 2013 Location: North Bohemia Photos: Gallery Posts: 1,251	There are nice problems When I used a SLR...it was not just dirty but I could see the wires to the "metering" sensor in the middle (Praktica MTL3) It's OT but ..This will never happen again (not my photo, neither camera)

10-20-2014, 06:37 PM	#10
Schick Forum Member Join Date: Sep 2014 Location: Saskatchewan Canada Posts: 57	Originally posted by LOBO RSA Hi I have a fingerprint mark that becomes visible when looking through the viewer that comes and goes depending on the light and focus . It is normal according to the dealer ? I have a new K50 Oh good, it wasn't just me thinking the same thing. A few weeks back I was very curious about why it seemed covered in prints. Was delighted to find it was just the viewing screen too.

10-20-2014, 09:36 PM	#11
stevebrot Otis Memorial Pentaxian Join Date: Mar 2007 Location: Vancouver (USA) Photos: Gallery \| Albums Posts: 42,007	Originally posted by LOBO RSA Hi Steve Thanks for that excellent reply You are spot-on and have made my day It is my pleasure and the same for the other helpful people on this site. Steve

01-09-2015, 03:23 PM	#12
Suleeto Senior Member Join Date: Nov 2014 Location: Southern California Photos: Gallery \| Albums Posts: 113	Just to note, that focus screen is removable for those who didn't notice. Mine had a legit fingerprint on it... not the ridges in the nylon that make the Fresnel lens (if we're talking about the same piece). You could see the crooked fingerprint in the viewfinder. I ended up carefully unhinging the retaining bracket and letting the nylon focus screen fall out into my hand. Then I gently cleaned it with sensor cleaner and using a pair of tweezers replaced it back into the retaining bracket, and locked it back down. It actually has a little tiny plastic tab that I suspect serves no other purpose than to handle it with tweezers. But it is nylon (or looks to be) so I'd be careful not to scratch it. I wonder how much a replacement costs. Replacing takes seconds.

01-09-2015, 05:09 PM	#13
stevebrot Otis Memorial Pentaxian Join Date: Mar 2007 Location: Vancouver (USA) Photos: Gallery \| Albums Posts: 42,007	Originally posted by Suleeto It actually has a little tiny plastic tab that I suspect serves no other purpose than to handle it with tweezers. That is one of the tab's functions. The other is to serve as an index for correct placement. If the tab is on the wrong side, the screen will be upside-down and manual focus will not be possible. The tab should be oriented to the left (towards the grip-side of the camera). I would use caution if you are planning on cleaning it again in the future. I am not sure what is in sensor cleaner, but what is safe for sensors may not be safe for a focus screen. Solvent erosion of the Fresnel surface will result in a dimmer view and may also shift the plane of focus such that accurate focus may not be possible. KatzEye has included a cleaning tutorial with the information on their Web site detailing how they clean screens: cleaning - KatzEye Optics Steve

01-10-2015, 12:36 AM	#14
Juiceheadgorilla Inactive Account Join Date: Jan 2015 Posts: 13	I have no experience with this =[

02-01-2015, 06:58 AM	#15
vonBaloney Pentaxian Join Date: Oct 2011 Location: Albuquerque, NM Posts: 6,029	Originally posted by Suleeto Then I gently cleaned it with sensor cleaner Did that work? Focusing screens seem to get damaged by anything...