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06-21-2009, 06:43 PM   #1
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Just bought Tamron 300mm f2.8 (360b). how do i test it?

As the title suggests i just bought a tamrom 300mm f2.8 (model 360b) for what i thought was a good price of US$550 (firstly is that an ok price?).

I'm still waiting for my pk adapter to turn up but once it does i want to be able to test this lens to make sure everything works as should. On first inspection the glass appears very clean and i couldn't see any marks, blemishes, dust etc internal. But what is the best way to test to make sure the apperature blades are responding appropriately? and what else should i be looking out for/checking?

Does anyone know the differences between the earlier 60b version and this newer 360b model?

any ideas/comments would be appreciated.

06-21-2009, 07:31 PM   #2
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To test the functioning of the aperture, set the camera to the AV mode and change the aperture from the largest to the smallest aperture while taking a picture at each aperture. The exposures ideally will all be identical. If you have a sticking aperture - you will get some over exposures. You will need a tripod because at the smaller apertures you will get some really long exposures.

If the lens is not a PKA lens - you will need to set the camera to manual and change the aperture while pressing the green button between each exposure.

Tom
06-21-2009, 08:13 PM   #3
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Adaptall-2 ref

QuoteOriginally posted by InKeepingSecrets Quote

Does anyone know the differences between the earlier 60b version and this newer 360b model?

You'll find all three versions here:

Adaptall-2.com

H2
06-21-2009, 09:18 PM   #4
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QuoteOriginally posted by InKeepingSecrets Quote
As the title suggests i just bought a tamrom 300mm f2.8 (model 360b) for what i thought was a good price of US$550 (firstly is that an ok price?).

I'm still waiting for my pk adapter to turn up but once it does i want to be able to test this lens to make sure everything works as should. On first inspection the glass appears very clean and i couldn't see any marks, blemishes, dust etc internal. But what is the best way to test to make sure the apperature blades are responding appropriately? and what else should i be looking out for/checking?

Does anyone know the differences between the earlier 60b version and this newer 360b model?

any ideas/comments would be appreciated.
Seems like a fair price at least, and depending on what accessories you got (TCs, Hood, filters, cases, etc...), and the final proof of a good copy, it could even be a better than average price (I think).

You can test the aperture/diaphragm for sticking without the adapter by pressing in on the spring loaded push rod/actuator that's in the edge of the mount end. From memory (my adaptall 400mm's not with me right now ), pressing the actuator should open the aperture though I may have that backwards. Either way, you should be able to set the f/32 position on the aperture ring to see the blades when they're stopped down.

Another thing to check is whether the tube behind the tripod collar is loose in it's connection to the rest of the lens body. Again, I'm assuming a similarity in the construction which may be wrong, but my 400mm had a problem when I first got it where the six (I think six) screws which join these two pieces would work loose quite often. On model 65b (400mm), these screws are visible through the 3/8" tripod mount hole, one at a time as you rotate the tripod collar 'round the lens. I've even heard of a case where one or more of these screws had backed out so far the lens wouldn't even turn 90 in it's collar 'cause the collar was hanging up on a screw head... My issue was resolved with a good screwdriver and the application of a very small amount of loctite to each screw before tightening it down firmly.

BTW, you probably know this, but there are both pk and pk/a adapters available, with the pk mount costing approx $20+ and necessitating green button metering like an "M" lens while the pk/a version which costs closer to $90+ allows auto aperture modes like modern lenses.

Congrats on the lens - most likely you'll love it and probably soon find yourself on the lookout for the Pentax-F 1.7x AF adapter .

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