Black at the top right of the frame?

ZombieArmy · 09-04-2014, 07:00 PM

I just got a pentax-F 35-70 to accompany my 18-55 zoom and I'm disappointed to find that at 70mm (and macro) that the top right of the frame has a black mark

It's also present at 60mm but nowhere else.

What could be causing this? And should I return it? I'd really hate to have to pay return shipping on yet another dud of a lens...

imgur: the simple image sharer

Last edited by ZombieArmy; 09-04-2014 at 07:07 PM.

**jatrax** · 09-04-2014, 07:20 PM

Is there a hood or filter on the lens?

ZombieArmy · 09-04-2014, 07:25 PM

Originally posted by jatrax

Is there a hood or filter on the lens?

No there isn't, but I think it was dust. I took the lens and smudged it on the rear element by accident, after cleaning it I noticed the spec actually moved and was a big ol circle in the frame. I shook the lens a bit and the spec is completely gone from the field of view now.

I wonder if I just have a big ass spec of dust in my lens somewhere, but I can't seem to find it.

70mm

70mm Macro

**jatrax** · 09-04-2014, 07:28 PM

That wasn't dust, that was a entire dust bunny

Glad you got it cleared, that is a nice lens. With all the others I own I still use it quite often when I want something small and light. Usually carry it as my "oh crap" backup lens, takes no space in the bag anyway.

Best,

ZombieArmy · 09-04-2014, 07:35 PM

Originally posted by jatrax

That wasn't dust, that was a entire dust bunny

Glad you got it cleared, that is a nice lens. With all the others I own I still use it quite often when I want something small and light. Usually carry it as my "oh crap" backup lens, takes no space in the bag anyway.

Best,

Yah I'm really liking the ability to shoot at 70mm

The autofocus is a bit iffy in a darker room but it usually gets it.

I assume this won't cause any notable loss in IQ? I mean since it's no longer on the frame

**jatrax** · 09-04-2014, 07:42 PM

Old lens collect dust, no way around that. Though I think your dust spot was a bit over the top. Honestly it is very hard to actually see a dust spot that is in the lens on a picture. Almost all the time the spot is actually on the sensor.

The rear element can have visible spots though and I'm guessing that is where yours was? Maybe it was not dust but a bit of lens blacking that was on the element and fell off. That lens has a glass rear cover, but inside that on the wall of the tube is a black anti-reflective material, like flocking. Sometimes a bit of that can come loose.

ZombieArmy · 09-04-2014, 07:58 PM

Originally posted by jatrax

Old lens collect dust, no way around that. Though I think your dust spot was a bit over the top. Honestly it is very hard to actually see a dust spot that is in the lens on a picture. Almost all the time the spot is actually on the sensor.

The rear element can have visible spots though and I'm guessing that is where yours was? Maybe it was not dust but a bit of lens blacking that was on the element and fell off. That lens has a glass rear cover, but inside that on the wall of the tube is a black anti-reflective material, like flocking. Sometimes a bit of that can come loose.

That's interesting, I didn't know that

Glad I got it to dislodge though, 23 dollars well spent on this lil lens

stevebrot · 09-04-2014, 07:59 PM

Originally posted by jatrax

Sometimes a bit of that can come loose.

...and if it falls on to the inside surface of the rear element, it can cast a shadow that can be pretty distinct.

Steve

**sergysergy** · 09-05-2014, 06:38 PM

I highly doubt that shadow was caused by dust.
Maybe it was something in the background (e.g. hanging on the wall) and out of focus?
I hate when I think my sensor is dirty and my "white wall" is not that white after all

ZombieArmy · 09-05-2014, 07:19 PM

Originally posted by sergysergy

I highly doubt that shadow was caused by dust.
Maybe it was something in the background (e.g. hanging on the wall) and out of focus?
I hate when I think my sensor is dirty and my "white wall" is not that white after all

No that black dot was present in many many shots in different areas.

09-04-2014, 07:00 PM	#1
ZombieArmy Pentaxian Join Date: Jun 2014 Location: Florida Posts: 3,210	Black at the top right of the frame? I just got a pentax-F 35-70 to accompany my 18-55 zoom and I'm disappointed to find that at 70mm (and macro) that the top right of the frame has a black mark It's also present at 60mm but nowhere else. What could be causing this? And should I return it? I'd really hate to have to pay return shipping on yet another dud of a lens... imgur: the simple image sharer Last edited by ZombieArmy; 09-04-2014 at 07:07 PM.

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09-04-2014, 07:20 PM	#2
jatrax Site Supporter Join Date: May 2010 Location: Washington Cascades Photos: Gallery \| Albums Posts: 12,991	Is there a hood or filter on the lens?

09-04-2014, 07:25 PM	#3
ZombieArmy Pentaxian Join Date: Jun 2014 Location: Florida Posts: 3,210 Original Poster	Originally posted by jatrax Is there a hood or filter on the lens? No there isn't, but I think it was dust. I took the lens and smudged it on the rear element by accident, after cleaning it I noticed the spec actually moved and was a big ol circle in the frame. I shook the lens a bit and the spec is completely gone from the field of view now. I wonder if I just have a big ass spec of dust in my lens somewhere, but I can't seem to find it. 70mm 70mm Macro

09-04-2014, 07:28 PM	#4
jatrax Site Supporter Join Date: May 2010 Location: Washington Cascades Photos: Gallery \| Albums Posts: 12,991	That wasn't dust, that was a entire dust bunny Glad you got it cleared, that is a nice lens. With all the others I own I still use it quite often when I want something small and light. Usually carry it as my "oh crap" backup lens, takes no space in the bag anyway. Best,

09-04-2014, 07:35 PM	#5
ZombieArmy Pentaxian Join Date: Jun 2014 Location: Florida Posts: 3,210 Original Poster	Originally posted by jatrax That wasn't dust, that was a entire dust bunny Glad you got it cleared, that is a nice lens. With all the others I own I still use it quite often when I want something small and light. Usually carry it as my "oh crap" backup lens, takes no space in the bag anyway. Best, Yah I'm really liking the ability to shoot at 70mm The autofocus is a bit iffy in a darker room but it usually gets it. I assume this won't cause any notable loss in IQ? I mean since it's no longer on the frame

09-04-2014, 07:42 PM	#6
jatrax Site Supporter Join Date: May 2010 Location: Washington Cascades Photos: Gallery \| Albums Posts: 12,991	Old lens collect dust, no way around that. Though I think your dust spot was a bit over the top. Honestly it is very hard to actually see a dust spot that is in the lens on a picture. Almost all the time the spot is actually on the sensor. The rear element can have visible spots though and I'm guessing that is where yours was? Maybe it was not dust but a bit of lens blacking that was on the element and fell off. That lens has a glass rear cover, but inside that on the wall of the tube is a black anti-reflective material, like flocking. Sometimes a bit of that can come loose.

09-04-2014, 07:58 PM	#7
ZombieArmy Pentaxian Join Date: Jun 2014 Location: Florida Posts: 3,210 Original Poster	Originally posted by jatrax Old lens collect dust, no way around that. Though I think your dust spot was a bit over the top. Honestly it is very hard to actually see a dust spot that is in the lens on a picture. Almost all the time the spot is actually on the sensor. The rear element can have visible spots though and I'm guessing that is where yours was? Maybe it was not dust but a bit of lens blacking that was on the element and fell off. That lens has a glass rear cover, but inside that on the wall of the tube is a black anti-reflective material, like flocking. Sometimes a bit of that can come loose. That's interesting, I didn't know that Glad I got it to dislodge though, 23 dollars well spent on this lil lens

09-04-2014, 07:59 PM	#8
stevebrot Otis Memorial Pentaxian Join Date: Mar 2007 Location: Vancouver (USA) Photos: Gallery \| Albums Posts: 42,007	Originally posted by jatrax Sometimes a bit of that can come loose. ...and if it falls on to the inside surface of the rear element, it can cast a shadow that can be pretty distinct. Steve

09-05-2014, 06:38 PM	#9
sergysergy Site Supporter Join Date: Jan 2011 Photos: Gallery Posts: 5,175	I highly doubt that shadow was caused by dust. Maybe it was something in the background (e.g. hanging on the wall) and out of focus? I hate when I think my sensor is dirty and my "white wall" is not that white after all

09-05-2014, 07:19 PM	#10
ZombieArmy Pentaxian Join Date: Jun 2014 Location: Florida Posts: 3,210 Original Poster	Originally posted by sergysergy I highly doubt that shadow was caused by dust. Maybe it was something in the background (e.g. hanging on the wall) and out of focus? I hate when I think my sensor is dirty and my "white wall" is not that white after all No that black dot was present in many many shots in different areas.