Help : K-85-210mm-F3.5-Zoom spots in image

bmf · 12-10-2020, 01:05 PM

Hi Folks,

I have an old copy of this lens.

SMC Pentax 85-210mm F3.5 Reviews - K Zoom Lenses - Pentax Lens Reviews & Lens Database

Someone dropped it on a beach a long time ago and I got given it. I took it apart and cleaned it up, got it back together and calibrated and it worked well.

I've not used it for a year or two and have started to play with it again (it's on my k7). When at full zoom I get some weird spots on the pictures (besides the obvious hair :-)).

Does anyone have a feel of where I should go to try and clean the lens, cant see anything obvious on glass or just looking through it. Which of the groups / elements would come into focus like that at full zoom?

Or might it be on the sensor?

One pic show it the next one nothing.

Thanks a million for any ideas.

Brett

Attached Images

pschlute · 12-10-2020, 01:19 PM

Looks like sensor dust to me. Were both shots taken at the same aperture ? Spots show up more at small apertures.

pentasonic49 · 12-10-2020, 01:21 PM

I would also suspect dust on the sensor, you need to try another lens to confirm this.

crazy4oldcars · 12-10-2020, 01:25 PM

Take a picture of a well-lit, single, light colored area like the sky, on manual focus, and turn the focus all the way to the closest setting. In other words, severely defocused, and an minimum zoom. Check that image for spots. If they're there, it's dust on the sensor.

Kirk B.

**MossyRocks** · 12-10-2020, 01:35 PM

Originally posted by crazy4oldcars

Take a picture of a well-lit, single, light colored area like the sky, on manual focus, and turn the focus all the way to the closest setting. In other words, severely defocused, and an minimum zoom. Check that image for spots. If they're there, it's dust on the sensor.

Similar to my standard advise is minimum focus, max f-stop and pointed at a wall. It is great for finding spots that need cleaning on the sensor.

If it were something on or in the lens looking through the lens it would clearly be visible likely on the back element.

pentasonic49 · 12-10-2020, 02:08 PM

The marks on the first photo are remarkably similar in size. The plain background, as advised would be best, your second picture is much darker in parts which might hide the spots.

**Michail_P** · 12-10-2020, 02:11 PM

If you’re confident that you cleaned the lens well, then it is certainly sensor dust. Looks like it. If it was lens dust, then it should be at a rear element.

**othar** · 12-10-2020, 02:23 PM

I think it's on the sensor. Alternatively it could be on a lenselement close to the sensor. The easiest way to test would be a picture of a blue sky with another lens

MikeMcE · 12-10-2020, 02:54 PM

Suspect sensor more than glass in tube.... sensors can grab chunks quickly if we don’t pay attention.

Always hated standing and swapping glass outside.

Hang up and DRIVE!

**dms** · 12-10-2020, 05:56 PM

Unquestionably IMO dust on the sensor, as stated above.
The best way of dealing with it is a strong blast of air using (for example) large Giottos Rocket Blaster Dust-Removal Tool.
I have (knock on wood) had to use the Giotto many times, and never needed to do any further cleaning of the sensor(s).

BTW how do you like this lens?
I have it and find (for my intended purpose of theatre photography) the contrast was low and focussing was too hard. Otherwise it was physically very large to carry around. So I never gave it a real use/evaluation.

**DWS1** · 12-10-2020, 06:13 PM

Sure looks like sensor dust to me as well.

**pentaxus** · 12-11-2020, 01:45 PM

Something in the lens isn't going to be that clear. A hair on the sensor or hanging somewhere inside the mirror box when the mirror is up.

bmf · 12-11-2020, 09:15 PM

Thanks folks you were on the money! in the end I was forced to get out the sensor cleaning kit.

Unfortunately I forgot to take a "sensor dust image" before trying to blow the dust away,but I did afterwards and there was still a spot. I could swear that there was nothing visible on the sensor after looking REAL close, but I swabbed the sensor once each way with a different side of the swab as they recommend and it's crystal clean now.

DMS I like the lens a lot, but I don't really travel with it except when it's in the trunk of the car. (the definition of a bad lens right, the one you dont have with you all the time ;-))

Here in switzerland I'm normally on the train......

Thanks

12-10-2020, 01:05 PM	#1
bmf Junior Member Join Date: Nov 2010 Posts: 40	Help : K-85-210mm-F3.5-Zoom spots in image Hi Folks, I have an old copy of this lens. SMC Pentax 85-210mm F3.5 Reviews - K Zoom Lenses - Pentax Lens Reviews & Lens Database Someone dropped it on a beach a long time ago and I got given it. I took it apart and cleaned it up, got it back together and calibrated and it worked well. I've not used it for a year or two and have started to play with it again (it's on my k7). When at full zoom I get some weird spots on the pictures (besides the obvious hair :-)). Does anyone have a feel of where I should go to try and clean the lens, cant see anything obvious on glass or just looking through it. Which of the groups / elements would come into focus like that at full zoom? Or might it be on the sensor? One pic show it the next one nothing. Thanks a million for any ideas. Brett Attached Images

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12-10-2020, 01:19 PM	#2
pschlute Moderator Loyal Site Supporter Join Date: Mar 2007 Location: Surrey, UK Photos: Gallery Posts: 8,202	Looks like sensor dust to me. Were both shots taken at the same aperture ? Spots show up more at small apertures.

12-10-2020, 01:21 PM	#3
pentasonic49 Veteran Member Join Date: Oct 2012 Location: weston-super-mare Posts: 395	I would also suspect dust on the sensor, you need to try another lens to confirm this.

12-10-2020, 01:25 PM	#4
crazy4oldcars Senior Member Join Date: Jan 2017 Location: Beaumont, Texas Posts: 218	Take a picture of a well-lit, single, light colored area like the sky, on manual focus, and turn the focus all the way to the closest setting. In other words, severely defocused, and an minimum zoom. Check that image for spots. If they're there, it's dust on the sensor. Kirk B.

12-10-2020, 01:35 PM	#5
MossyRocks Loyal Site Supporter Join Date: Nov 2017 Location: Minnesota Photos: Gallery \| Albums Posts: 2,982	Originally posted by crazy4oldcars Take a picture of a well-lit, single, light colored area like the sky, on manual focus, and turn the focus all the way to the closest setting. In other words, severely defocused, and an minimum zoom. Check that image for spots. If they're there, it's dust on the sensor. Similar to my standard advise is minimum focus, max f-stop and pointed at a wall. It is great for finding spots that need cleaning on the sensor. If it were something on or in the lens looking through the lens it would clearly be visible likely on the back element.

12-10-2020, 02:08 PM	#6
pentasonic49 Veteran Member Join Date: Oct 2012 Location: weston-super-mare Posts: 395	The marks on the first photo are remarkably similar in size. The plain background, as advised would be best, your second picture is much darker in parts which might hide the spots.

12-10-2020, 02:11 PM	#7
Michail_P Site Supporter Join Date: Nov 2019 Location: Kalymnos Photos: Gallery Posts: 3,006	If you’re confident that you cleaned the lens well, then it is certainly sensor dust. Looks like it. If it was lens dust, then it should be at a rear element.

12-10-2020, 02:23 PM	#8
othar Site Supporter Join Date: May 2014 Location: Linz Photos: Albums Posts: 3,098	I think it's on the sensor. Alternatively it could be on a lenselement close to the sensor. The easiest way to test would be a picture of a blue sky with another lens

12-10-2020, 02:54 PM	#9
MikeMcE Pentaxian Join Date: Jun 2020 Photos: Albums Posts: 1,093	Suspect sensor more than glass in tube.... sensors can grab chunks quickly if we don’t pay attention. Always hated standing and swapping glass outside. Hang up and DRIVE!

12-10-2020, 05:56 PM	#10
dms Site Supporter Join Date: Aug 2011 Location: New York, NY Photos: Gallery Posts: 2,192	Unquestionably IMO dust on the sensor, as stated above. The best way of dealing with it is a strong blast of air using (for example) large Giottos Rocket Blaster Dust-Removal Tool. I have (knock on wood) had to use the Giotto many times, and never needed to do any further cleaning of the sensor(s). BTW how do you like this lens? I have it and find (for my intended purpose of theatre photography) the contrast was low and focussing was too hard. Otherwise it was physically very large to carry around. So I never gave it a real use/evaluation.

12-10-2020, 06:13 PM	#11
DWS1 Site Supporter Join Date: Aug 2018 Location: Arkansas, USA Posts: 1,169	Sure looks like sensor dust to me as well.

12-11-2020, 01:45 PM	#12
pentaxus Site Supporter Join Date: Jun 2010 Location: Central Coast, CA Posts: 1,315	Something in the lens isn't going to be that clear. A hair on the sensor or hanging somewhere inside the mirror box when the mirror is up.

12-11-2020, 09:15 PM	#13
bmf Junior Member Join Date: Nov 2010 Posts: 40 Original Poster	Thanks folks you were on the money! in the end I was forced to get out the sensor cleaning kit. Unfortunately I forgot to take a "sensor dust image" before trying to blow the dust away,but I did afterwards and there was still a spot. I could swear that there was nothing visible on the sensor after looking REAL close, but I swabbed the sensor once each way with a different side of the swab as they recommend and it's crystal clean now. DMS I like the lens a lot, but I don't really travel with it except when it's in the trunk of the car. (the definition of a bad lens right, the one you dont have with you all the time ;-)) Here in switzerland I'm normally on the train...... Thanks