[dadipentak]

Ah, ok--something to consider. Thanks!

[excanonfd]

Ah, ok--something to consider. Thanks!

Following up von Baloney's explanation: Place a piece of 3M Invisible Scotch Tape as shown in the picture and you will get f5.6 showing up as the maximum aperture. Any non metallic tape will do but the 3M Invisible tape is readily available and is very thin. Burnish the tape well with a blunt piece of plastic rod or a piece of 'popsicle' stick to insure that the piece of tape is truly and well stuck to the adapter.

[dadipentak]

Following up von Baloney's explanation: Place a piece of 3M Invisible Scotch Tape as shown in the picture and you will get f5.6 showing up as the maximum aperture. Any non metallic tape will do but the 3M Invisible tape is readily available and is very thin. Burnish the tape well with a blunt piece of plastic rod or a piece of 'popsicle' stick to insure that the piece of tape is truly and well stuck to the adapter.

Really? That's it? Even I can do that!

[Stone G.]

Really? That's it? Even I can do that!

Well, if I did that I would surely know where to look for it next time I changed lenses: Stuck to my sensor.......

But then, a bit more seriously:

Most of my adaptalls don't mind one stop or so of underexposure from what the meter says on my PENTAX DSLRs and I regularly have to set exposure compensation accordingly. Now, I have one of those half-faulty PK/A Custom Mounts that cannot open wider than to f/4 and that mount is permanently on my 54B. I have never had any visible under exposure whenever the camera thought the lens was at f/4 while actually being at f/5.6.

[excanonfd]

Well, if I did that I would surely know where to look for it next time I changed lenses: Stuck to my sensor.......

But then, a bit more seriously:

Most of my adaptalls don't mind one stop or so of underexposure from what the meter says on my PENTAX DSLRs and I regularly have to set exposure compensation accordingly. Now, I have one of those half-faulty PK/A Custom Mounts that cannot open wider than to f/4 and that mount is permanently on my 54B. I have never had any visible under exposure whenever the camera thought the lens was at f/4 while actually being at f/5.6.

You won't be able to remove that little piece of tape without an Exacto knife. I have two PK/A adapters that do not report wider than f4.0, one is on the 54B and the other on the 23A. I sometimes get a hankering to try fixing them and I had to use an exacto knife to lift off as much as I can of the tape then wipe it down with naptha soaked cloth to get the adhesive residue off.

You are right about the non-exposure problem even if the adapter reports f4.0 instead of f5.6 but the 'fix' require minimal effort and recording of the correct exposure value in the exif, makes this mod worth doing.

[vonBaloney]

You won't be able to remove that little piece of tape without an Exacto knife. I have two PK/A adapters that do not report wider than f4.0, one is on the 54B and the other on the 23A. I sometimes get a hankering to try fixing them and I had to use an exacto knife to lift off as much as I can of the tape then wipe it down with naptha soaked cloth to get the adhesive residue off.

Acetone will take that sticky stuff right off.

[pacerr]

Acetone will take that sticky stuff right off.

It's also used as cement for some types of plastics - naptha/lighter fluid is a safer bet.

Don't know if any of the Pentax plastic is susceptible (an' I don't plan on finding out) but a drop of acetone on some things softens the plastic enough you can leave a finger print on the surface - a permanent ID tag when it works.

H2

[dadipentak]

Some more test shots from the 300/5.6.




I'm favorably impressed. The handling is reminiscent of my old Tokina 400/5.6. This lens is sharper though. It is somewhat prone to green/magenta fringing, however.

[nextimelah]

I recently bought a cheap 46A (70-210mm f3.8-4.0) for the PKA mount (like most people) and took it out for a test run today.

I am very pleasantly surprised at how well the lens performed! I own a 19AH and this is half it's size and weight, and only 0.4 stops slower (f3.5 vs f4-ish), making it a poor man's constant aperture telephoto zoom lens. My only gripe is that the lens hood is screwed on and not bayonet (and my purchase did not come with one) and the focus ring is very stiff (maybe it's just mine).

The photos below are just resized and untouched otherwise. You can see that wide open (picture 1), it is already very sharp vs f8 in the second picture. The third one is wide open as well. Macro performance is also not bad.

For the price vs performance, IMHO this is a seriously underrated lens!

[Stone G.]

For the price vs performance, IMHO this is a seriously underrated lens!

I think the lessons to be learned with your and many others' examples are: 1) Tamron didn't really ever make a crappy adaptall (that I know of - whether SP or not) and they all have their uses to this very day; 2) you cannot really use today's prices for adaptall lenses as a measure of "rating" as far as image and manufacturing qualities are concerned. Lenses like the 46A and 103A were very popular and they sold well for a reason in their time. Therfore, they are abundant on the used market today and not "highly rated (collectors') items".

[pacerr]

I have to agree. It wasn't the optical quality that killed the Adaptall line; it was the inability to economically provide AF adapters for all the auto-focus variants coming into vogue at that time.

Many of the SP lenses and more than a few of the AD-2 lenses were as good as any top quality OEM lens of the era -- and still are if you can do without auto-focus.

H2

[dadipentak]

I recently acquired the converter--this is from the trial outing. I'm pleased.

[kacansas03]

I recently acquired the converter--this is from the trial outing. I'm pleased.

Wow, I really like the image from your "new" 600mm lens Dave!! I wonder how that competes with images from the very expensive Canon 600mm. I keep reading how Pentax lenses do not perform as well as Canon who is better than Nikon. And now we see a wonderful bird picture from an "old" Tamron SP Adaptall 2 lens plus it's preferred 2X teleconverter! So many times at photo group outings I get asked what is that lens you are using? And it is an Adaptall and they OOO and AhAh over the images that little lens produces! We usually don't get to the price of the lens. It is my opinion that Canon users who have spent so much money on their camera bodies plus so much on their top of the market lenses must justify the expense somehow. It could be a terrible blow to their egos if Pentax comes out with a great full frame that works with Adaptall lenses.

[dadipentak]

Thanks, Alan! Dunno about the Canon but I'd say the IQ isn't far off my Sigma 500/4.5. There was some strong PF at the black/white boundary but it wasn't hard to fix in PP.

[pacerr]

I recently acquired the [ BBAR MC 2X ] converter--

In passing, I'll note that the IQ results from both the Adaptall 140F 1.4x TC and the Tamron Pz-AF 1.4x TC are indistinguishable when used on my 360B. The Pz-AF is MUCH more convenient to use but it also costs about 6-8 times as much these days.

H2