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02-26-2010, 08:32 PM   #1
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Is it worth fixing/cleaning on this Tamron 55BB 500mm f/8.0 mirror

Is this worth fixing? I bought a copy of the Tamron 55BB mirror lens and I saw quite a lot of dirt on the inside rear mirror. It does not look like fungus to me but I am not sure. Do you see this as fungus?




I don't know how difficult it is to open up from the rear and try to clean the inside mirror, any prior experience?

And I have not tried the mirror lens. It is likely going to marketplace but before I do, do you think it is worth cleaning.

Some confession to make to put you into my dilemma : I have some recent bad luck in destroying every single lens when I opened them. I have a count of 4 lens that are in a box waiting for the surgeon to finish the unfinished job. A lot of late night fixing ended up with grief not knowing how to put the lens back together as a single piece. It is a shame, I have some half-working lens and when I open them to try to repair them, they become totally unusable until I learn how to put them back to the original form.

Thanks,
Hin

02-26-2010, 09:56 PM   #2
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I would highly recommend send it to Eric for his professional opinion. I have sent him 4 lenses for both fixing and cleaning, it all came back as good as new. Two of the lenses I thought it has fungus but it turn out was just dust. His price is more than reasonable and if you don't want the work done, he will send it back to you no charge.

David
02-26-2010, 10:39 PM   #3
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I think MattGunn has cleaned one or two of these. I bet he can give you step by step instructions.
02-26-2010, 10:48 PM   #4
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QuoteOriginally posted by hinman Quote
Is this worth fixing? I bought a copy of the Tamron 55BB mirror lens and I saw quite a lot of dirt on the inside rear mirror. It does not look like fungus to me but I am not sure. Do you see this as fungus?


I don't know how difficult it is to open up from the rear and try to clean the inside mirror, any prior experience?

And I have not tried the mirror lens. It is likely going to marketplace but before I do, do you think it is worth cleaning.

Some confession to make to put you into my dilemma : I have some recent bad luck in destroying every single lens when I opened them. I have a count of 4 lens that are in a box waiting for the surgeon to finish the unfinished job. A lot of late night fixing ended up with grief not knowing how to put the lens back together as a single piece. It is a shame, I have some half-working lens and when I open them to try to repair them, they become totally unusable until I learn how to put them back to the original form.

Thanks,
Hin
I don't remember exactly how to get it apart to the point where I could tell you how to do it but it isn't difficult. The Trick, is Method. Whenever I take a lens apart, I always mark on the edge of a lens element which direction it faces and the order it goes in. Do so with a fine pencil.

I can't really tell from your photo. It could be dirt, Fungus, or the mirror surface silvering is damaged and flaking off. Most likely not the latter though.

I'd be willing to do a second if you want me to take a stab at it. PM me for info if you want to send it.



02-26-2010, 11:01 PM   #5
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QuoteOriginally posted by hinman Quote
And I have not tried the mirror lens. It is likely going to marketplace but before I do, do you think it is worth cleaning.
I was worried that the mirrored surface was similar to a camera's mirror, easy to scratch. I've been told it's not. These lenses sell for decent money on eBay, so it's probably still worth something to someone. I'm resisting making an offer myself.

QuoteQuote:
Some confession to make to put you into my dilemma : I have some recent bad luck in destroying every single lens when I opened them. I have a count of 4 lens that are in a box waiting for the surgeon to finish the unfinished job. A lot of late night fixing ended up with grief not knowing how to put the lens back together as a single piece. It is a shame, I have some half-working lens and when I open them to try to repair them, they become totally unusable until I learn how to put them back to the original form.
The main idea of the hobby is not to learn lens repair, but to take great photos. Don't let those lenses drag you down.
02-27-2010, 12:18 AM   #6
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It looks like fungus to me!
02-27-2010, 03:45 AM   #7
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I have fixed two of these lenses and they are amongst the easiest lenses I have ever worked on. The main reason for this is that there is no aperture and so no aperture mechanism. The only moving part in this lens is the focus helix and it isn't necessary to open this to get into the lens. If you realy arn't confident about fixing lenses then I would send it to someone who is, this a good lens and is worth repairing.
If you want to have a go yourself then it is posible to get at everything you need to from the front. With a spanner wrench (or an old pair of dividers or calipers etc) remove the retaining ring on the front. You should now be able to remove the front element and although it is a few inches inside the housing you can now get at the mirror front surface. You don't have to worry about damaging the reflecting coating as it is on the back of the glass mirror substrate (this is really a back silvered lens). I cleaned a lot (a LOT more than is visible in the photo above) of dirt and fungus of the mirror on one of mine this way using cotton buds (Q tips?) without any difficulty.
On my second one the previous owner had opened the lens to clean and had dropped the front element on a tiled floor (I will let you guess what happened) so try not to do this
If you want a mirror lens then this is definately the one to have.
02-27-2010, 01:49 PM   #8
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Thank you sincerely for all the inputs. It is great to have companions and get valuable inputs from you all. I will have a more thorough reply later on. Before I can make a decision, I probably find a chance to play with the lens on photos first and go from there.

Thanks,
Hin


Last edited by hinman; 02-27-2010 at 02:16 PM.
02-27-2010, 03:22 PM   #9
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I've got a Canon FD 500 mirror lens that has got fungus inside, so I asked a friend of mine who's spent the last 10 years repairing and adjusting military optics such as night vision equipment and rangefinders to have a look at it.

He dismantled it and discovered that the reflective surface is on the front of the elements and was affected by the fungus, it wasn't like a conventional mirror with the reflective surface behind the glass.

So, he was unable to clean the surface without damaging the mirror.

He was able to kill the fungus and has sealed the lens with ( I think ) nitrogen inside so it won't spread. But that was a bonus as he did the job at work and not every lens repair establishment would be able to do that.

It's probably worth asking and checking to ensure that anyone repairing your lens would be aware of that problem.
02-27-2010, 04:22 PM   #10
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Don't try to clean the mirror. The aluminum coating is very fragile. If you want to save it. Take it apart and send the mirror out to a astro shop that recoats mirrors.
02-27-2010, 11:42 PM   #11
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QuoteOriginally posted by wildlifephotog Quote
Don't try to clean the mirror. The aluminum coating is very fragile. If you want to save it. Take it apart and send the mirror out to a astro shop that recoats mirrors.
As MattGunn said before, the mirror in this lens is like a household mirror with glass front and silvered backside so unless the dirt/fungus is behind the mirror it can be cleaned like any other element.

QuoteOriginally posted by MattGunn Quote
You don't have to worry about damaging the reflecting coating as it is on the back of the glass mirror substrate (this is really a back silvered lens)
btw: optical diagram from adaptall-2.com
02-28-2010, 08:12 PM   #12
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Ovim and others, thank you for the follow up.

I examined my 55BB closely and it is both dirt and fungus. I don't have the tool and experience to open up from the frontal part and clean both mirrors. There are more fungus and dirt on the back than that on the front mirror.

I tried the lens with some casual shooting. Though the fungus and dirt , the lens surprises me especially in sharpness and performance in close up. Focusing is quite easy on the lens though the lens seems too light to hold steady in the shooting. All test shots are done hand-held with Pentax K-x in iso 400.





















Time to clean my sensor


I am undecided if I should take a loss and sell it cheap or fix it in some inexpensive way.

Hin

Last edited by hinman; 02-28-2010 at 08:18 PM.
03-02-2010, 05:54 PM   #13
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Thanks to Just1MoreDave to take over the ownership of my 55BB in marketplace. I played with the lens over the weekend and I go 'wow' with the 55BB with its performance. I will buy it again in the future when I recover a bit from my LBA mistakes. And as I mentioned, I have a box of lenses and cameras to fix, it will take me few months to get to most of them. Thank you Dave!

I highly recommend giving this 500mm a thought for the long lens need. It is very unlike the previous mirror lens that I have used from Vivitar 500mm f/8 mirror lens from Korea, likely Opteka or Kalimar related. Contrast and sharpness is quite good in the 55BB and what I like about is the handling in the focus ring and the ease of focusing. Though it may be too lightweight to feel well balanced in the K-x, I manage to shoot all the above hand-holding. Close up performance is a surprise for such a long focal lens. Bokeh is kind of an odd ball. Some good and some oddly busy looking with donuts shaped rendering especially when off focus objects are too close.

All in all, the 55BB is a good mirror lens to look for instead of the previous Vivitar that I have tried. It may be too slow to serve well in shooting birds in fly but it will do well in still objects in a distance.

@Dave, my Pentaxian friend IndianaDinos has many blog post documenting how he cleans up fungus in K10DPentax. Hope this helps you!

Thanks,
Hin

Last edited by hinman; 03-02-2010 at 07:08 PM.
03-02-2010, 06:42 PM   #14
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Nice shots, Hin.

The 55BB is well known as one of the top performing 3rd party mirror lenses.

It should be easy to take apart - the focusing ring should unscrew with the front element, exposing the insides with the inner mirror.
03-02-2010, 09:12 PM   #15
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QuoteOriginally posted by hinman Quote
Thanks to Just1MoreDave to take over the ownership of my 55BB in marketplace. I played with the lens over the weekend and I go 'wow' with the 55BB with its performance. I will buy it again in the future when I recover a bit from my LBA mistakes. And as I mentioned, I have a box of lenses and cameras to fix, it will take me few months to get to most of them. Thank you Dave!
Now the pressure is on me! I am reasonably confident in my repair abilities, but can I match the above "before" photos? Probably not!
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