Bargain Pentaz smc-f 50mm 1.7 lens Broken :(

Hi guys, this is my first post i hoped it was in better circumstances.

i just came back from lisbon and went to a famous brickabrack market. there was a guy selling antique camera equipment and he had some pentax lenses, unfortunately i had left my camera at the hotel, so i couldnt check it there.

to cut a long story short i managed to get the lens down to 10 euros which is about 7 pounds not bad eh?

Ok the problem---it dosent work, it can take at f1.7 but when i try to set the aperture using the camera in av mode ( pentax k10d) the images are blown out, and it seems like the aperture is not decreasing in size.

same when i use the manual av ring --- would love some help if anyone has any ideas!!1

should i open it!!

or get it repaired or leave it and just use it a 1.7!! ok cant wait to get stuck into this forum

ayaz

certainly don't open it up unless you know exactly what you are doing. Most lenses are extremely complicated in construction and only a select few (mostly old and Soviet) designs can be easily repared by the uninitiated.

It sounds like the iris is stuck. The easy way to tell is to take the lens off the camera with the aperture ring set on A. The lens should stop all the way down. If it does not, then the iris is stuck and you'll either need to have it repaired, put up with it being stuck wide open or get rid of it

It sounds like the the SMC Pentax-A 1:1.7 50mm, which is the only Pentax lens which consistently suffers from aperture ring failure.

If you paid seven euros, then you paid about seven euros too much.

However, I think somebody here managed to repair one once. It's a fiddly job.

G

thanks, for the help!!!

i am a bit dissapointed though,

however i looked at the lens and it is a smc pentax f 50mm

so not as bad as the pentax A i hope.

do you have any suggestions of a good lens that does a similar job but not a ridiculous price!!

check your settings on your camera?
in the custom function area, under aperture set to "ok"?
if so don't chuck that lens, reverse mount it and usit for xtreme macros!

The SMC Pentax-F 50mm 1:1.7 is a fine lens, I have one and it produces excellent results. Don't bin it yet.

I repaired an A series 50mm 1:1.7 lens once, but I wouldn't attempt it again. It had a different problem to yours though, the aperture ring would only move part way round the scale due to a broken leaf-spring mount.

With the aperture ring set to "A", your lens should work in all exposure modes. It could be that you simply have dirty or damaged contacts on the lens. Put no more than one (1) drop of WD-40 or similar onto a piece of paper kitchen towel and clean the lens mount a few times. Then take another dry kitchen towel and clean the mount again to remove any excess WD-40.

With the lens in your hand and the aperture ring set to A, the aperture should be fully stopped down (small hole). Manually move the aperture actuator on the rear of the lens and check that the iris moves thoughout it's entire range. Inspect the iris blades for oil. If it has any it'll need professional (but inexpensive) cleaning.

If the aperture feels nice 'n snappy during this test, it could be that the actuator is bent such that it fouls when mounted on the camera. If you attempt to straighten it, be prepared for it to break (another repair job).

I have an old 28mm f2.8 RMC Tokina which i found had the iris stuck wide open. The aperture ring moved around freely enough but the iris stayed opened.
I opened it up and and gave it a nudge and got it to close but the blades were covered in oil.
I just use it for reversing as you suggest.

I took this shot of a dead baby Daddy long legs which was ony a couple of millimetres in body length.

I once bought a "damaged" SMCP 28mm. The aperture ring would not move.

I got hold of it firmly, twisted hard, and suddenly, it was in perfect condition.

It had obviously lain unused for twenty years and just seized up.

G

I have a 1 page expoded view illustration of the SMC A 1.7. which shows you how to dismantle it.
Trouble is I don't have a scanner.
Let me know if you want it and i will get it scanned at the mother in laws.

You have a camera! Just Photocopy it!

DOH

A lot of information! ill try cleaning the contacts. if that dosent work reversing it may have to do!!

Still upset thought it was a bargain but got screwed


if cleaning dosent work i may send it to get checked cost me 10pound but if its simple then maybe worth it !!

thanks for the advice

Okay, so i had a play around with the lens, at A it is still wide open but wheni play with a little slider on the fitment of the lens i can open and close the aperture, then when increase the aperture it opens as it should using the manual ring, but when i turn it back to A it dosent reduce the size

and i have to use the slide thing protruding out
i hope this helps you more learned to diagnose the problem

great!

Sounds to me like a spring is broken. With the lens in your hand and the aperture ring set to 'A', the iris should be closed by a spring. When you move the actuator to open it, it should then close itself under spring pressure. Does this happen?

If not, it's manual aperture only I'm afraid unless you have it repaired.

You'll need to use the camera in manual exposure mode, 'M' on your mode dial. If you use any other mode it'll still work, but only wide open.

Regards,

Yeah dosent spring back, is it expensive to fix!!


Cracking lens quality though much better then my kit lens and teaches you to move about more to get a better shot then using a change in the focal length


thanks for the advice