Tamron 23A mystery

guardian · Joined: 18 Mar 2009 Posts: 1747

I own too many lenses. Bought a Tamron 23A from a party down in Alabama. It arrived in absolutely pristine shape, except the rear element was badly peripherally fogged, something I attributed to separation. This was a real disappointment given the splendid condition of virtually every other aspect of this beautiful lens.

I determined to buy a second 23A, a beater, in hope of scavenging its rear element and replacing my bad one.

Well, things do not always go as planned. I've still not been able to buy the second copy. Meanwhile, the first 23A being so nice otherwise, I gave it the same treatment I give all my lenses: Double seal baggie containing lens and a seriously sized bag of silica gel desiccant. I make the bags myself using paper towels and a desk stapler. Each bag contains at least four teaspoons of silica gel.

Anyway that's what I did. I sealed up the lens, together with the desiccant, and put it away for safekeeping in one of my lens drawers.

Time passes. I do not really know how much time . . but at least four or five months would be my guesstimate. So today I see an auction for another 23A which appears to be going cheap. I have too many lenses so I retrieve my own 23A just to be certain my memory is not playing tricks and that I have the right lens in mind.

Lo and behold I take the lens out of the baggie and the rear element is clear! Surprised? Yeah, I was really surprised. It tends to be very humid in Alabama. Maybe moisture somehow had crept into the rear element and fogged it, only later to be drawn out over such a long time by the silica gel? I really dunno. But I am very happy.

I do have one remaining qualm. Am only about 90% sure I have the right lens. But if there is another Tamron SP lens around here with a bad rear element, well, I've not been able to locate it yet; but there are so many lenses . . . . it could be hiding. Wink

Roka · Expire: 2017-04-07

cooltouch · Joined: 15 Jan 2009 Posts: 9109 Location: Houston, Texas

Since you put the lens away, essentially forgotten for 4-5 months with your big bag of desiccant, it occurs to me that the lens's fog may have cleared much sooner than your estimate. Maybe only a few days was all that was necessary. I've had the 23a apart on more than one occasion, but I don't recall offhand if there was anything about a rear group that might have caused it to be slow to reach ambient relative humidity.

The 23a has been one of my most used lenses over the years, by the way. I've used it in all sorts of climates and have never had a fogging problem with mine.

guardian · Joined: 18 Mar 2009 Posts: 1747

I enjoyed your responses. Yeah, I really need to go into "ALL OUT SEARCH" mode and go through my entire lens collection to try to find if I am confusing my 23A with another Tamron SP lens. Finding the time for such an all out search is an issue, and I really have more pressing lens issues right now like: where to store all these new lenses that I've recently bagged.

There are so many lenses and it was months ago, but I don't think I bagged my 23A right away. I remember fretting about it for perhaps a week or two. When I retrieved it yesterday, seeing it for the first time in a while, I was like "OMG that's a brand new lens!". So if I do have the right lens and if the rear element cleared spontaneously, or with the aid of the silica gel whichever, I'm a pretty fortunate guy.

I really like the 23A. Another Tamron SP lens I had been wanting for several years is the 19AH, supposedly also a fine lens. Then, about two months ago and after having waited a really long time, I lucked into two 19AH lenses in nice shape on the same day, each having the CORRECT TAMRON HOOD, for less than US$50 each. That was a good day.

Thing is, aside from the 23A and now the two 19AH lenses, I really do not think I own any other lenses from the "larger" Tamron SP group. I don't own, for example, any of the really expensive large Tamron SP lenses. At least that's my best recollection, and it's why I think the 23A more than likely (but not for certain) actually cleared up.

ETA

This is the "Equipment Care and Repairs" board after all. In that spirit I want to mention, for whatever help it might be to others, that I buy my silica gel in bulk in the form of kitty litter. It comes in large four pound containers. The individual granules are mostly white, but with some blue granules in there, too. On the container it says:

Ingredients: Silica Gel

Made in China

Crystallized Cat Litter

Non-Toxic

I do not own a feline. But I know, having searched, that most cat litter is not silica gel. You have to seek it out, and you will not find it in every store. I buy mine in a grocery store, but you might have better luck in a pet store. I dunno.

My cost for a four pound container is around US$5. But you can desiccate quite a few lenses with that much silica gel, and the needed paper towels are not expensive at all. Using half a towel (I buy the ones that are perforated half sheet at a time) I fold and staple closed the edges to form a pouch, spoon in the silica gel, than staple closed the opening. So far, no spills or accidents. And moisture can travel through the paper towel without impediment, while the silica gel is contained.

cooltouch · Joined: 15 Jan 2009 Posts: 9109 Location: Houston, Texas

What is the brand name of this silica gel "kitty litter" you buy?

Regarding Tamron: I have a largish collection of Tamron lenses, including a few premium ones, such as the 30a, 31a, and 60b. They were worth the price I had to pay for them, every penny. But I shopped around for a while and kept an eye out on eBay for good deals before I picked them up.

guardian · Joined: 18 Mar 2009 Posts: 1747

cooltouch · Joined: 15 Jan 2009 Posts: 9109 Location: Houston, Texas

Thanks, I consider myself fortunate to have those Tamrons as well, along with all the other Tamrons I own. I have Tamrons ranging from 17mm to 500mm.

Your silica gel comments just caused me to recall something. Silica gel is used a lot in labs for various purposes. You can buy it in bulk from chemistry supplies. Heck, you can even buy it from Amazon.com (I just googled it):

http://www.amazon.com/ACTIVA-Silica-Flower-Drying-Pound/dp/B001H7HA80/ref=sr_1_6?ie=UTF8&qid=1461775484&sr=8-6&keywords=silica+gel
http://www.amazon.com/Quality-White-Silica-Desiccant-Beads/dp/B01BLYLUSY/ref=sr_1_18?ie=UTF8&qid=1461775643&sr=8-18&keywords=silica+gel

guardian · Joined: 18 Mar 2009 Posts: 1747

visualopsins · Expire: 2021-06-22

My environment is brutal to lenses. Wild swings of temperature and humidity. Lenses grow fungus if I screw up only a little. But what does work is fine, no problems for 10 years. Only when I have been careless using this system. Pelican cases -- these are air-tight. Three. One for drying lenses fresh from field/market on the way to case 2. for oft used lenses, or BIG case 3. for long-term storage. EDV 300 and 500 from http://www.eva-dry.com/ and inexpensive temp/humidity gauges. Utilize indicator silica gel on de-humidifiers to keep them maintained -- plug in outlet for a few hours to cook off moisture. Use less than 300F oven to renew loose silica gel packets; over 300F silica gel begins to release toxic gas...

Please search the forum for tons more info about lens storage, de-humidifiers, silica gel sources, & etc..

https://www.theruststore.com/Silica-Gel-FAQ-W40C2.aspx

guardian · Joined: 18 Mar 2009 Posts: 1747

I need to buy still more cat litter . . . at US$5 for four pounds! . . . .

. . . . while I still can. Good grief!!

The prices other sources are asking for silica gel are astronomical!!

Exclamation

ETA

Regarding "recharging" of silica gel:

I plan to avoid it. It's said recharged gel is less effective in pulling moisture. But the real reason is that I'm buying fresh silica gel so cheaply that recharging is more of a nuisance than it is worth. I've never had an indicator bead go pink. But if it happens I will just discard that gel and use fresh.

visualopsins · Expire: 2021-06-22

Money talks. I would investigate why the price difference. Probably something to do with market volume, producing with less expensive resources, or better, waste from another process, or just less processing for lower quality product, etc..

They don't say that, really? Silica Gel has been proven in lab to have no "memory" effect with re-use...it doesn't wear out. Laughing

I guess I put in more humid lenses and open cases more often in harsher environment than you -- reason I get pink indicators -- most often in the #1 drying box that gets humid lens put inside to dry and gets opened most...

How is the used cat litter disposed? I think to help conserve the resource(s) including those required to get the stuff to market.