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Forum: General Photography 05-25-2019, 12:18 PM  
Could anyone recommend a good set of JIS screwdrivers and spanner?
Posted By mccririck
Replies: 21
Views: 1,129
Hmm. I'll have another look. Bit on the from of the 50/1.7 there are two small screw sizes and the 00 is too big.
Forum: General Photography 05-25-2019, 02:44 AM  
Could anyone recommend a good set of JIS screwdrivers and spanner?
Posted By mccririck
Replies: 21
Views: 1,129
Guys just a heads up on sizing. I ordered a set with 00 and 0 JIS sizes and they are too big for the Pentax-M 50mm f1.7 I want to dismantle. Looks like I need 000 and 0000.
Forum: Digital Processing, Software, and Printing 05-07-2019, 12:33 PM  
Android Pentax Image Sender
Posted By mccririck
Replies: 11
Views: 2,283
Personally I think this is the best app for android.
Forum: Digital Processing, Software, and Printing 05-06-2019, 04:24 AM  
Android Pentax Image Sender
Posted By mccririck
Replies: 11
Views: 2,283
Just wanted to mention this app as it's the best I've found for sending images from your DSLR to your phone. Beats all the other apps imo.
Forum: Pentax K-70 05-06-2019, 03:11 AM  
what do you set your programable buttons for?
Posted By mccririck
Replies: 2
Views: 554
Thanks. It's good to have a reply to this at last!
Forum: Pentax SLR Lens Discussion 05-04-2019, 10:17 AM  
Best or most-interesting old manual Pentax lenses to use on a crop body?
Posted By mccririck
Replies: 54
Views: 2,360
What's the difference between a Pentax-A and a Takumar-A?
Forum: Pentax SLR Lens Discussion 05-01-2019, 02:00 PM  
Best or most-interesting old manual Pentax lenses to use on a crop body?
Posted By mccririck
Replies: 54
Views: 2,360
Which of the macros would you recommend getting first?
Forum: Pentax SLR Lens Discussion 04-29-2019, 01:54 PM  
Best or most-interesting old manual Pentax lenses to use on a crop body?
Posted By mccririck
Replies: 54
Views: 2,360
Nice collection!
Forum: General Photography 04-29-2019, 01:46 PM  
Could anyone recommend a good set of JIS screwdrivers and spanner?
Posted By mccririck
Replies: 21
Views: 1,129
Struggling to find a set with a P000 JIS driver. P0 and P00 very common.
Forum: Pentax K-70 04-29-2019, 01:23 PM  
is the K-70 likely to get another firmware update?
Posted By mccririck
Replies: 38
Views: 1,513
No it's just off topic. End of.
Forum: Pentax SLR Lens Discussion 04-29-2019, 12:01 PM  
Best or most-interesting old manual Pentax lenses to use on a crop body?
Posted By mccririck
Replies: 54
Views: 2,360
The Super Takumar 135 f/3.5 and 200 f/4 are both stellar. And neither are radioactive.

I have the M-28 f/2.8 and it's a good focal length to have, I think it lacks micro-contrast though.
Forum: Pentax K-70 04-29-2019, 11:48 AM  
is the K-70 likely to get another firmware update?
Posted By mccririck
Replies: 38
Views: 1,513
Why are people talking about the GR III here?
Forum: General Photography 04-28-2019, 08:15 AM  
Could anyone recommend a good set of JIS screwdrivers and spanner?
Posted By mccririck
Replies: 21
Views: 1,129
What JIS sizes are most regularly required for lenses? I have a Pentax M 135mm and an M 50mm I. Wed to clean.
Forum: Pentax SLR Lens Discussion 04-28-2019, 06:37 AM  
prime, prime, everywhere a prime...
Posted By mccririck
Replies: 6,741
Views: 345,885
I need one of those.
Forum: Pentax SLR Lens Discussion 04-27-2019, 08:40 AM  
The "Angry Photographer" Was Right About This 135mm Lens...
Posted By mccririck
Replies: 35
Views: 4,169
Why should Ken post his photos on the internet. He chooses to post specific photos to illustrate points, rather than his best shots.

And the thing most people like about Ken is his knowledge of lenses and cameras. He knows more about vintage lenses than anyone else I know - I've bought some of his recommendations and they have been fantastic.

You do not have to be the world's best, most artistic photographer to know the stuff Ken knows and shares on YouTube. He has masses of experience using equipment, and he knows what he's talking about.

I would say I find his magnetism and other off topic videos not so good, although they can be enjoyable.
Forum: Pentax SLR Lens Discussion 04-27-2019, 01:29 AM  
Which lenses are radioactive and are they dangerous?
Posted By mccririck
Replies: 65
Views: 2,421
There were, I'm not sure if it was you but certainly people were comparing to a banana and I was showing stats to show why this was an odd comparison. And someone claimed the banana was beta and gamma and the lenses are alpha and I disproved that. In science you need to be accurate and making nonsense comparisons is unhelpful
Forum: Pentax SLR Lens Discussion 04-26-2019, 08:11 AM  
Which lenses are radioactive and are they dangerous?
Posted By mccririck
Replies: 65
Views: 2,421
Look at my replies to find what issues I had with some of the comments in this thread. I think I made some reasonable points.
Forum: Pentax SLR Lens Discussion 04-26-2019, 03:49 AM  
Which lenses are radioactive and are they dangerous?
Posted By mccririck
Replies: 65
Views: 2,421
I'm not saying it is extremely dangerous. I was taking issue with some of the statements you made which were not really true.
Forum: Pentax SLR Lens Discussion 04-25-2019, 03:26 PM  
Which lenses are radioactive and are they dangerous?
Posted By mccririck
Replies: 65
Views: 2,421
P.S. the Thorium decay in lenses is an alpha, beta and gamma emitter. (Yes there is some gamma too, in the same way as potassium. And the Thorium decay series is longer than potassium - there are more steps.

As for the person who commented that it is Thorium dioxide used in lenses. Well that makes only a small difference to the calculation since the atomic weight of Thorium is 232 and the atomic weight of oxygen is only 16.
Forum: Pentax SLR Lens Discussion 04-25-2019, 01:56 PM  
Which lenses are radioactive and are they dangerous?
Posted By mccririck
Replies: 65
Views: 2,421
Well, as I've pointed out, beta radiation is present in the Thorium decay, and it goes through skin. If you watch the angry photographer video on youtube with the highly radioactive Kodak lens, it goes through his hand, and through some copper sheeting. Try doing that with a banana. There is far less radioactivity in a banana for the reasons I have already stated.
Forum: Pentax SLR Lens Discussion 04-25-2019, 11:45 AM  
Which lenses are radioactive and are they dangerous?
Posted By mccririck
Replies: 65
Views: 2,421
I'm not convinced. Hold a geyger counter next to a pealed banana and then at the front or rear of a radioactive lens.

Thoriated glass - Wikipedia


- Thoriated glass can contain up to 30% Thorium by mass.


- average banana peeled weighs 116g. Of that 334mg is Potassium. 0.334/116 x 100 = 0.29%

So there is 100 times more Thorium in the glass than Potassium in a banana, and nearly 10,000 times more radioactive isotopes in Thorium than Potassium.


As well as that there are several beta decays in the Thorium decay series:

Forum: Pentax SLR Lens Discussion 04-25-2019, 10:59 AM  
Which lenses are radioactive and are they dangerous?
Posted By mccririck
Replies: 65
Views: 2,421
regarding the banana K-40 makes up 0.012% of potassium atoms.

Th-232 makes up 99.98% of Thorium atoms, and all Thorium isotopes are radioactive.
Forum: Pentax SLR Lens Discussion 04-25-2019, 10:14 AM  
Which lenses are radioactive and are they dangerous?
Posted By mccririck
Replies: 65
Views: 2,421
I guess the important thing is not to look into the lens close up. Don't hold it up to your eye and stare into it!

Has anyone measure the radiation from the front of the lens, from the rear, from the sides, and then from the rear when it is attached to a camera? It would be interesting to see the differences.
Forum: Pentax K-70 04-24-2019, 12:14 PM  
is it possible to fit a hand strap to the K-70?
Posted By mccririck
Replies: 12
Views: 609
A wrist strap and a hand strap are two different things. One goes round your wrist and the other you put your hand into it and it goes round the back of your hand.
Forum: Pentax K-70 04-24-2019, 12:11 PM  
is it possible to fit a hand strap to the K-70?
Posted By mccririck
Replies: 12
Views: 609
That's a wrist strap rather than a hand strap.
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