Lens Tamron 300 mm f/ 5.6 Adapt-A-Matic - Loose Focus

[teredactle]

Hi everyone,

I picked up one of these lenses from a local pawn shop and noticed that the focus ring on it is VERY easy to move, to the point that if I don't keep it level (horizonta) it will move by itself - I think this is called "creep"? Is there any chance that this could be tightened to prevent movement after focus is achieved?

Also, I noticed that that even though it came with M42 mount, this is actually an adapter (from what I've read these lenses can basically be put on many camera mounts); is there a place where I can find any documentation on how this adapter should be mounted?

Thanks in advance!!

[marcusBMG]

i think most of us with one of these have noticed that the focus movement is light. if I were you I would diy something to add a bit of friction - a litle bit of leather glued under the edge of the focus sleeve for example. Certainly this should be an easier problem to deal with than stiff focus.
The mount unscrews to change for a different one. Adaptamatic mounts were made for nikon F, M42, Miranda, minolta, canon fl... but this predates PK for example. M42 is the most common and versatile with lots of adapters available for most cameras. if you're using nikon then finding an adaptamatic F mount is the trick, your focus range with the M42 mount on a nikon will be limited to relatively close range only due to the longer registration distance of Nikon.

[luisalegria]

Yes, thats creep and yes this lens tends to creep.
There is no tightness adjustment I know of. The only fix here are artificial means as marcus suggests or by renewing the grease on the helical screw.

There are no illustrated guides online (that I know of) on how to install/uninstall the Adaptamatic mount, but its pretty straightforward.

To remove unscrew the retaining ring and the mount just falls out.
To put it back -

Set Manual-Auto switch to A

line up the slot on the mount side with the peg/screw head on the lens body, at the same time making sure the "arm" on the mount goes in the slot.

make sure the adapter has gone all the way in - it should just drop in, no need for force. make sue its on straight.

Screw on the retaining ring.

[Lloydy]

The 300 / 5.6 is a very good lens, it's certainly the lightest 300 I've used which helps a lot. Mine isn't adaptamatic ( it'a adaptall ) but I have a few adaptamatics and can only agree with luisalegria, it's a bit of fiddle at first but it's actually easy enough - and never force it.

[teredactle]

Thanks for all your replied. I will take a look at this on the weekend and see what if anything can be done. I will also take some pictures of the lens and if I take any WITH it.

"renewing the grease on the helical screw. " not sure where this helical screw is...will have to google that..


-Set Manual-Auto switch to A
-line up the slot on the mount side with the peg/screw head on the lens body, at the same time making sure the "arm" on the mount goes in the slot.
-make sure the adapter has gone all the way in - it should just drop in, no need for force. make sue its on straight.
-Screw on the retaining ring.

Good info here. I quickly tried it on a M42 adapter, and it was a bit loose. I fiddled with the retaining ring and it seemed to make it tight on the M42 adapter.

Both the focus and cap is very loose, I think I read that this is common. I think on the cap I can squish it slightly so that it's not perfectly round and it will prevent it from moving itself so easy.

I will try the helical screw suggestion for the focus - any recommended grease to use? I'm really new with all of this.

Thanks again!

[marcusBMG]

If you browse the threads in the equipment care and repairs section you will find a number of examples of disassembling a prime lens, and pictures of helicoids, to give you a perspective on what is involved.
I don't know of anyone who has worked on this particular lens.

[teredactle]

Thanks, upon a second look, the zoom while it moves very easily, doesn't tend to open itself if pointed downwards as I initially though.

I took a little bit of time today and took a couple of pictures from my window with this lens, the focusing was in live view because I really can't focus well through the viewfinder with these manual lenses - is this something that one gets better with time at??

Anyway, here's a couple of snaps. https://www.flickr.com/photos/128517069@N07/sets/72157649352214886

[luisalegria]

Yes, manual focusing on a usually lousy DSLR finder is difficult and takes quite a lot of practice.
After a couple of thousand shots you will get the hang of it!
Heck, its not all that easy to focus a 300mm with a proper old SLR either.
In my experience getting a new focus screen may not help that much, and there is a lot of fiddly work getting it shimmed correctly.

[luisalegria]

Also, lighting conditions make a huge difference. Your samples are taken in weather that makes this one especially difficult to use.
This lens is best in good light, not just because of its taking aperture but because of limited brightness in the finder and difficulty in distinguishing the best point of focus even when its wide open.
They sell 300mm f/2.8 lenses for a reason.

[marcusBMG]

Focussing - yeah! Luis comments +1
I, if not swear by, certainly lean on my tenpa 1.36x VF magnifier, particularly with tp's. Lives on the camera.
You can check out this ongoing discussion on viewfinder screens in this pentax forums thread:
http://www.pentaxforums.com/forums/115-pentax-k-5/142241-best-screen-ever-manual-focus-canon-ee-s.html

[RAART]

I think that I posted here (mflenses) the instructions already but since the server crash the instructions are gone. If I find again scanned file I will repost again.

[RAART]

here it is: http://forum.mflenses.com/viewtopic,p,1265621.html#1265621

and the file itself. Found it in my email! (click on it to get readable size)

[teredactle]

Wow, how great are you guys!!! Thanks so much for this RAART!!

marcusBMG I looked at the link, lots of info there, thank you! I will decide down the road if replacing the screen may be something that I want to do, some of them are pretty costly so I need to prioritize.

Thanks again!!