how should the focusing feel???

J

juno_lau

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hello

i received my Jupiter-8 today

i have no experience on this before
but i found the focusing ring is quite tight, i will have to apply some force to turn it
which is more than the aperture ring in comparison
should it like that? :confused:

thanks for your answer
 
It should be smoov



like buttah.

You'll probably get more advice here later on how to disassemble, clean, and relube the lens. From what I understand, it should be easy; but I haven't had to do anything that drastic with a lens- yet. (knocks on wood)
 
It should feel good. ;)

Actually if you're thinking it's too hard, it probably is and needs to be relubed. The advantage though, is that you can change the aperture without the focus changing.
 
Is your J-8 an older chrome model, or one of the newer black ones?

I have a relatively new black one, and it's focusing is firm but smooth. The focus is tighter than the aperture. You shouldn't have to apply much force to focus, though. Odds are, especially if it's an older lens, that the original lubricants have gotten a little waxy. When you focus, does it feel uneven, going from loose to tight and back? That's probably what's happened. I had an Industar that was so tight, focusing could unmount the lens from the camera.

If you're brave and good with tools, you can try relubing the lens yourself using Kim Coxon's excellent instructions:
http://www.pentax-manuals.com/repairs.htm

Otherwise you'll have to send it somewhere.
 
Last edited:
FrankS said:
It should feel good. ;)

Actually if you're thinking it's too hard, it probably is and needs to be relubed. The advantage though, is that you can change the aperture without the focus changing.
Click to expand...

should the focus change with the aperture?!!! :eek:

brachal said:
Is your J-8 an older chrome model, or one of the newer black ones?

I have a relatively new black one, and it's focusing is firm but smooth. The focus is tighter than the aperture. You shouldn't have to apply much force to focus, though. Odds are, especially if it's an older lens, that the original lubricants have gotten a little waxy. When you focus, does it feel uneven, going from loose to tight and back? That's probably what's happened. I had an Industar that was so tight, focusing could unmount the lens from the camera.

If you're brave and good with tools, you can try relubing yourself using Kim Coxon's excellent instructions:
http://www.pentax-manuals.com/repairs.htm

Otherwise you'll have to send it somewhere.
Click to expand...

it is a chrome one
i think it is from the KMZ, with a "knob"? or "lever"? how do you call that thing?, on the focusing ring

i think i will consider relubing it...although i am not quite sure if it is wrong, but i am not that happy with it anyway...
there are lots of fine "scretch" on it, is that what people called "cleaning marks"?

i think i may buy a industar 61 LD or another copy of the jupiter-8 from Alex-photo...
i should buy the lens from him... :bang:
 
The newer black J-8s have a single focusing helical, so the entire front of the lens rotates when you focus. On these lenses, adjusting the aperture can affect the focus if the aperture ring is tight enough to cause the lens to rotate. My J-8 does this; I've learned to keep a finger on the focusing ring when I adjust the aperture. Older chrome Jupiters don't do this.

If you're not happy with the lens, it probably needs to be relubed. None of my chrome Jupiters are unpleasant to focus.

I don't think there's anything you can do about the cleaning marks on the front. Good luck, whatever you decide to do. When they're in good shape, the Industar 61 and Jupiter 8 are both very good lenses.
 
I have two old alloy (they aren't chrome, despite everyone calling them that) J-8s and they both have a lot of fine scratches and cleaning marks. Haven't tried them yet but I bet they are quite soft. I also have 2 newer, black ones that are nice and clean. Great lenses.

I'll second Kim Coxon's site for re-lube info, spot on!
 
juno_lau said:
should the focus change with the aperture?!!! :eek:


Sorry, my mistake. I've got a newer black one where the aperture ring turns with the focusing ring. Apparently the older alloy ones don't do that.
Click to expand...
 
how would the cleaning mark affect the image normally?
i have never encountered this before...

thanks for all of the info.
 
First off, if you have one with the tab, the problem is not the same as the black ones. Your lens sounds very much as though it is in dire need of a re-lube and clean. The main helix grease otherwise known as "yak spit", goes hard and causes the focus to feel tight and "notchy". In a similar vein, the grease which "damps" the apeture ring "shrinks". The end result is as you describe, the aperture ring turns too freely and the focus is too stiff. The guide on my site should help you with it if you decide to do it yourself. If you have any problems, drop me a line.

Kim
 
juno_lau said:
how would the cleaning mark affect the image normally?
i have never encountered this before...

thanks for all of the info.
Click to expand...

If they aren't too bad, they may not have a noticeable effect. If there are enough of them, they would cause the image to look soft or slightly out of focus.
 
it is really bad...
it seem they are also inside the lens... not only on the front element...

i should leave my 1st -ve feedback on ebay...
 
If it is this bad, I would be tempted to send it back for a refund.

Kim

juno_lau said:
it is really bad...
it seem they are also inside the lens... not only on the front element...

i should leave my 1st -ve feedback on ebay...
Click to expand...
 
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