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02-13-2016, 07:09 PM   #1
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Remove front Objective?

Does anyone know if it's possible to use a lens spanner wrench to remove the front element of the 10-17mm Fisheye lens?

02-13-2016, 10:34 PM   #2
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And exactly what do you hope to accomplish by doing this?
02-14-2016, 03:57 PM   #3
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QuoteOriginally posted by Digitalis Quote
And exactly what do you hope to accomplish by doing this?
I was hoping to clean some larger dust particles from the lens.
02-14-2016, 04:06 PM   #4
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Unless they are visible in your images I would simply leave them where they are. Dust in lenses is very common.

And in any event I would get the lens serviced by a professional, and leave a note about the dust particles that need to be eliminated. Tinkering with lenses isn't for amateurs.

02-14-2016, 07:09 PM   #5
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QuoteOriginally posted by Digitalis Quote
Unless they are visible in your images I would simply leave them where they are. Dust in lenses is very common.

And in any event I would get the lens serviced by a professional, and leave a note about the dust particles that need to be eliminated. Tinkering with lenses isn't for amateurs.
Thanks for the concern. I am aware of the implications of opening the lens. I've done this before. I just am not certain how this lens is put together.
02-14-2016, 09:58 PM   #6
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QuoteOriginally posted by Butch5 Quote
I am aware of the implications of opening the lens. I've done this before.
disassembly of a M42,K,A.F,FA lenses are generally pretty straightforward, but fisheye lenses are tricky.

QuoteOriginally posted by Butch5 Quote
I just am not certain how this lens is put together.
There might be a schematic somewhere on the internet that could guide you - but the odds are stacked against you, as the 10-17mm is a rather specialized lens.
02-15-2016, 12:39 AM   #7
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QuoteOriginally posted by Butch5 Quote
I am aware of the implications of opening the lens. I've done this before. I just am not certain how this lens is put together.
The wider the lens, the harder it is to calibrate for proper focus. I would think, however, that if you can't loosen the front group by rotating the lens hood with your hand, you're likely not able to do it with a wrench.

Here's a link to a YouTube video where a guy has a Tokina partially disassembled. I believe that these are optically similar or identical to the Pentax but that doesn't mean they're mechanically similar or identical.

02-15-2016, 11:25 AM   #8
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QuoteOriginally posted by Digitalis Quote
disassembly of a M42,K,A.F,FA lenses are generally pretty straightforward, but fisheye lenses are tricky.



There might be a schematic somewhere on the internet that could guide you - but the odds are stacked against you, as the 10-17mm is a rather specialized lens.
Thanks! I have searched the internet and not really found much. I did find the video mentioned here but he had the same issue I do, how to remove the from element. I thought about having it serviced, but by the time all is said and done it would probably be almost what I paid for it.

---------- Post added 02-15-2016 at 01:26 PM ----------

QuoteOriginally posted by K David Quote
The wider the lens, the harder it is to calibrate for proper focus. I would think, however, that if you can't loosen the front group by rotating the lens hood with your hand, you're likely not able to do it with a wrench.

Here's a link to a YouTube video where a guy has a Tokina partially disassembled. I believe that these are optically similar or identical to the Pentax but that doesn't mean they're mechanically similar or identical.

How do I disassemble the Tokina 10-17mm Fisheye lens? - YouTube

Thanks! I have tried to loosen the lens hood to no avail. I did watch this video and he has run into the same problem, how to get into the front.

02-15-2016, 02:41 PM   #9
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QuoteOriginally posted by Butch5 Quote
Thanks! I have searched the internet and not really found much. I did find the video mentioned here but he had the same issue I do, how to remove the from element. I thought about having it serviced, but by the time all is said and done it would probably be almost what I paid for it.

---------- Post added 02-15-2016 at 01:26 PM ----------




Thanks! I have tried to loosen the lens hood to no avail. I did watch this video and he has run into the same problem, how to get into the front.
Hi Butch

Pentax probably glued the retainer ring into place, as they've done with other lenses too. In the past I repaired several lenses, even complicated ones (like the 28mm shift) and had to heat the retainers to soften the glue. I wouldn't do it with the fish-eye, though. I would guess, you need to work your way from behind, removing the zoom and focus rings in order to get to the real lens barrel. From there you might be able to unscrew the whole front assembly, which should enable you, to unmount the front lens. I don't believe (but cannot prove it), that the front element cannot be loosened, by just removing the retainer ring. The only hints I have found so far is the schematics on BDimitrovs site. Though usually I won't hesitate to disassemble lenses, when necessary, I would not come near the front lens with a spanner tool. I would in all probability scratch the element, when the spanner slips, which ought to happen...

Ben
02-15-2016, 07:11 PM   #10
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QuoteOriginally posted by Ben_Edict Quote
I would in all probability scratch the element, when the spanner slips, which ought to happen
which is exactly what i'm getting at, spanners slip and even a nick on the front element of a fisheye is going to be visible... more so than the dust trapped inside.

So take that into consideration when you attempt to remove the front element - do I really want to ruin this lens? because if you are inexperienced the chances are extremely high that it will happen.

QuoteOriginally posted by Ben_Edict Quote
had to heat the retainers to soften the glue
A good soak in acetone does the trick. I would be wary of using heat around metal/glass interfaces.
02-16-2016, 05:00 PM   #11
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QuoteOriginally posted by Digitalis Quote
which is exactly what i'm getting at, spanners slip and even a nick on the front element of a fisheye is going to be visible... more so than the dust trapped inside.

So take that into consideration when you attempt to remove the front element - do I really want to ruin this lens? because if you are inexperienced the chances are extremely high that it will happen.

A good soak in acetone does the trick. I would be wary of using heat around metal/glass interfaces.
The problem with acetone is, that it will sip into the lens and might also dissolve the lens cement in the first cemebted group (directly behind the fron element). But ofcourse you are right, that using heat is a dangerous path. I more or less mentioned it, to dissuade the TO from that operation, because removing dust specks is hardly worth the risc.

Ben
02-16-2016, 06:32 PM   #12
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QuoteOriginally posted by Ben_Edict Quote
The problem with acetone is, that it will sip into the lens and might also dissolve the lens cement in the first cemebted group
A few drops are unlikely to seep past that interface, moderation is key here. Besides I have the equipment and skills needed to re-cement and re-center elements so it isn't such a big deal.

QuoteOriginally posted by Ben_Edict Quote
But ofcourse you are right, that using heat is a dangerous path. I more or less mentioned it, to dissuade the TO from that operation, because removing dust specks is hardly worth the risc.
These days it is more than likely to encourage them. Idle hands( and idle heads) being the devils plaything and all that...
02-18-2016, 08:07 PM   #13
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QuoteOriginally posted by Ben_Edict Quote
Hi Butch

Pentax probably glued the retainer ring into place, as they've done with other lenses too. In the past I repaired several lenses, even complicated ones (like the 28mm shift) and had to heat the retainers to soften the glue. I wouldn't do it with the fish-eye, though. I would guess, you need to work your way from behind, removing the zoom and focus rings in order to get to the real lens barrel. From there you might be able to unscrew the whole front assembly, which should enable you, to unmount the front lens. I don't believe (but cannot prove it), that the front element cannot be loosened, by just removing the retainer ring. The only hints I have found so far is the schematics on BDimitrovs site. Though usually I won't hesitate to disassemble lenses, when necessary, I would not come near the front lens with a spanner tool. I would in all probability scratch the element, when the spanner slips, which ought to happen...

Ben
Hi Ben,

Thanks for the reply. My fear was that the wrench might slip. That is one reason I asked if anyone knew how to remove it. I've tried using a rocket blaster to blow air in from the rear but it doesn't seem to make it the front. I think a burst of air would probably dislodge the particles. I just don't know if there is a path in the lens through which the air could travel all the way to the front. I would be afraid to use anything more powerful than the rocket blaster as it may cause damage or blow grease onto the elements.
02-20-2016, 03:12 AM   #14
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HI BUtch

I don't think, seeing the lens' layout, that a rocket blower would provide enough air pressure, to dislodge a particle on the inside of the front element. The elements are usually contained within a secondary, tight barrell, which you will only see, when you remove the moving parts (aka focus and zoom rings) of the lens. I haven't disassembled my own 10-17 though. Unless, the dust specks really are visible in the images, I wouldn't care.

Ben
02-25-2016, 06:22 PM   #15
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QuoteOriginally posted by Ben_Edict Quote
HI BUtch

I don't think, seeing the lens' layout, that a rocket blower would provide enough air pressure, to dislodge a particle on the inside of the front element. The elements are usually contained within a secondary, tight barrell, which you will only see, when you remove the moving parts (aka focus and zoom rings) of the lens. I haven't disassembled my own 10-17 though. Unless, the dust specks really are visible in the images, I wouldn't care.

Ben
Thanks Ben,

They are not visible in the images. It just bugs me knowing they are there. I just purchased the lens used. So far I'm not sure if I like it or not. It'st the first fish eye I've ever had. I mean the lens is a good solid lens. I'm just not sure if I like the fish eye effect. I mainly wanted a diagonal fish eye for macro work. I haven't used it for that yet so time will tell.
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