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Forum: Troubleshooting and Beginner Help
07-13-2013, 04:26 PM
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Indeed. This thing is so much fun. Didn't expect that a MF macro lens will serve me well even for action shots :) Of course I'm usually front- or back-focusing a bit, but who cares, I love the final result.
Handheld, 1/250, f/2.5, flash bounced off ceiling:
OK, so now at least I have purpose in life: tighten these damn screws. After a week of playing with this lens the dimming_while_focusing thing turned out to be really annoying. Especially while focusing for the shots like the one above. It's quite possible that I might play the doctor much sooner then expected. I've found this helpful site where someone shares his experiences from opening his Tamron 52BB:
Category: Adaptall 2 - wiratama.net
Maybe it'll help someone else so I'm sharing.
Anyway, the thing I haven't mention before is that shortly after buying this lens I purchased a second copy. Mostly because of the price ($100) and because of the bundled items. It came here few days ago and turned out to be issue-free. So, for now I'll just shoot with this one and when in the right mood I'll think about cracking open the one from Slip.
Two observations:
- the second copy also has irregular aperture iris shape. This thing doesn't seem to affect the image in any way, even the bokeh shape looks pretty regular to me
- the aperture not stepping down past the f/13 is definitely adapter's fault. Right now I have 2 genuine Tamron Adaptall mounts: for P/K and for Olympus (that came on the other lens). On both the aperture works fine.
I've contacted big_is (the seller/manufacturer on eBay) and they promised they'd send me a different copy to test and see if the issue persist. Because of a busy week I still haven't tried the trick with masking tape but one more idea came to my mind. If I succeed in any way, I'll share the solution here.
I thought of that too. Then I realized this would require the auto-aperture compatibility on both (camera and lens) sides and I'm pretty sure that this Tammy has no idea what are those electric contacts on the camera side :D
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Forum: Troubleshooting and Beginner Help
07-07-2013, 08:47 PM
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That's it, mystery solved! It's the adapter, not the lens. Thanks for pointing that out.
In case this could help someone else, here are the details:
The original P/K => Adaptall adapter that came with the lens is equipped with a spring loaded aperture lever:
Moving the lever causes this tab (located on the lens side of the adapter) to go up and down:
The tab from the photo above pushes another spring loaded lever located inside the lens. This causes the aperture to open/close:
It's a precise mechanism so every mm counts. The big_is Adaptall => EOS adapter has no spring loaded anything:
It's just a piece of metal that exerts a constant pressure on the lever inside the lens. This alone should keep the aperture closed at the set value. Don't know if that's a design flaw or they couldn't make the flange any higher without running into some kind of trouble. All I know by now is that the pressure coming from the adapter dimensions alone is not enough to make the aperture fully close, hence the aperture effective range of f/2.5-f/13.
In a spare time I'll do some experiments stacking masking tape on the adapter and checking if that changes anything. The lever inside the lens goes up and down a bit as you turn the aperture ring. The first permanent solution that occurred to me was a tiny leaf spring in the right place on the adapter... but it may as well be that the masking tape will become my permanent solution :)
OK, so the extension tube issue was my lack of knowledge and the aperture not fully closing is caused by the adapter. I'm glad I started this thread :) The only issue left is the focus ring causing the aperture diameter to change.
I did another video showing what effect this issue has on light (filmed the live view screen on my camera since it's more readable than filming VF) :
It doesn't make the lens unusable but it's a bit annoying. Two more things I've noticed:
- when you turn the lens upside down, sometimes one of the blades seems to fall off a bit. Not by much but it's different from all the others. After moving the aperture ring it gets back in line.
- when you manipulate the lens a delicate sound can be heard, like if some tiny piece was rolling inside. Difficult to guess from the sound alone but it could very well be a tiny screw or spring
Does it help with the diagnosis or nothing will be certain until opening the lens?
After I've done some reading I imagine it can be indeed. Well, as I wrote before, for now I'd like to know what the illness is. This doesn't necessarily mean I'll start playing the doctor right away :) In the meantime I'll just try not to pay too much attention to the focus ring/aperture issue, practice my MF skills and enjoy this great lens.
The first attempt on my cat's whiskers
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Forum: Troubleshooting and Beginner Help
07-06-2013, 08:40 PM
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Thank you Steinback for your input. I've kind of suspected that's the case since the extension doesn't have any optical elements. I believe this one is matched for the lens since it's Tamron made and it says "for SP 90/2.5 1:2 1:1" on it. The focusing range is pretty narrow but images are really sharp so apparently it does its job.
I've also purchased th 2x TC, still waiting for it to arrive.
I'm not really that concerned about the iris shape. More so about the iris reacting when the focus ring is moved (you can perceive a slight dimming in the viewfinder while you're focusing) and the iris not reacting to the aperture ring between f/13 and f/32.
I provided all the detail I thought of as relevant. Maybe someone will be able to come up with a suggestion as to what needs to be fixed. Who knows, since I already started the whole adventure with MF lenses (last month I bought 6 as my starter kit :) ), maybe this one will be the first one I'll tinker with.
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Forum: Troubleshooting and Beginner Help
07-06-2013, 04:15 PM
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As some of you may remember I bought the Tamron 90mm f2.5 52BB listed here:
https://www.pentaxforums.com/forums/sold-items/224630-sale-sold-tamron-90mm-f...pic-added.html
It arrived some time ago but it took much longer for the Adaptall > EOS (I shoot Canon 60D) big_is adapter, so the lens was just sitting on the shelf, waiting for its turn. Yesterday I finally got to test it. It fitted nicely with the adapter, focus ring works pretty smooth, maybe there is a bit more CA wide open than I expected but pictures look sharp and tasty. Anyways, after I've done some testing, I'm stuck with several concerns.
Given that I'm an absolute beginner in MF lenses, and not so experienced photographer either, I decided to ask for some expert opinion to solve this puzzle.
1. Irregular aperture shape:
What could have caused it? Bad servicing, manufacturer's error? Don't know if it really affects the image in any way but it's there: a bit out of center and out of the shape it should probably have.
2. There are 13 stops on the aperture ring. Moving the ring only affects the iris between f/2.5 and f/13. Apertures: f/13, f/16, f/22, f/32 look pretty much the same to me:
f/2.5
f/3.3
f/4.0
f/4.8
f/5.6
f/6.7
f/8.0
f/9.5
f/11
f/13 (from now on, you can see the the aperture ring moving but no effect on the iris)
f/16
f/22
f/32
3. There is a slight play on the focusing ring. It would be nothing to write home about if moving the focus ring wouldn't affect the aperture iris. As I said, I'm an absolute beginner in MF lenses but I guess it shouldn't work that way. Even if I didn't care that, let's say: f/4.0 is really f/4.0, such behavior affects light repeatability in a series of photos.
Here is a short video to demonstrate what I'm talking about:
https://vimeo.com/69810889
4. Don't know what am I doing wrong but I can't get the lens to work with the 1:1 extension tube. I'm installing it the same way I do the adapter: aligning the aperture tabs and screwing the tube in, until the silver button clicks. When I'm using the lens solo it seems to focus correctly, however with the extension tube I get about 10cm of the effective focusing range:
MFD at 4.0
∞ at 4.0 (the blurred gray area to the bottom of this photo is the black stripe from the photo above)
I'll appreciate every comment on why the things are the way they are :) Am I doing something wrong, am I overreacting or does this lens have some issues? If so, what illness are the symptoms pointing to and can it be cured?
Here are some more shots:
f/2.5
f/5.6
f/11 (the famous blue spot starting to show up)
f/16
f/32
f/2.5
f/5.6
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Forum: Welcomes and Introductions
06-03-2013, 03:40 PM
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Hello everyone! Thank you for the warm welcome. The Tamron 90mm f2.5 I wanted has already been paid for and shipped. Can't wait to put my hands on it :)
Hola Francisco! It's not only the availability but the prices down here are absurdly high, Nikon being the most insane at 2x - 2.5x the price in the US. That's precisely why I bought every single piece of equipment (except for bags and backpack) in North America, Asia and Europe. Thank you Internet!
BTW, I'm pretty new to photography, this Tamron will be my second lens. Right now I'm shooting (my lovely cats mostly :D ) with Canon 60D equipped with the kit 18-200 f/3.5-5.6 lens.
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Forum: Welcomes and Introductions
06-02-2013, 04:14 PM
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Hi, my name is Maria and not being a Pentax user I'm still interested in buying one particular item in the Marketplace. Since I'm required to write 2 posts before being able to contact the seller, thought this section would be the best place to start.
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Forum: Sold Items
06-02-2013, 04:05 PM
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Hi, I'm interested in that lens and have just registered on this forum to be able to contact you. Since I'm required to write two postsbefore being able to contact you directly, here goes the first one.
Maria
---------- Post added 06-02-13 at 04:06 PM ----------
Here goes the second one, I've just sent you PM
---------- Post added 06-02-13 at 04:09 PM ----------
:D Well, I didn't .... it seems that the forum joins the following posts submitted by the same user.
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