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Focus problem roof prism binoculars (1 Viewer)

I

IvanVVV

New member
Hello,

i have a Pentax 10x43 DCF SP. The problem is that i have to adjust the diopter to " - " until the maximum, even though I don't have diopter. The problem has been accumulating, first I had to set diopter to - just a little bit. Now I can't get the focus because you can only adjust to a certain degree.

Is it possible that there is a problem with front lens? I saw there is a thread with two dents on the front lens. Is it possible to adjust that? I tried to screw it but it doesnt move. But i was pretty gentile as I don't want to break something ;)

Ivan
 
More likely is that the problem is with the focus drive slipping on one side (internally). --AP

Addendum:
Slipping focus is a problem that I've seen in several units of the Bushnell 8x42 Legend Ultra HD (as mentioned in the detailed thread on that bin http://www.birdforum.net/showthread.php?t=213464 ). The problem is that the focus drive slips a little bit on one side of the bin from time to time (I found that it happened at one of the limits of focus, I can't remember if the far or near, I think near), such that the diopter has to be used to compensate. This is a problem that I've seen in other cheap Chinese roofs. In fact, one of the first tests I conduct when evaluating a new bin is to run it back and forth, fairly hard, between its focus limits 20 or 30 times and then check that left-right focus synchrony (and diopter setting) is maintained. If not, I consider the bin faulty. The only high-end bins that I've tested with a similar problem were two units of early production Swarovski 8.5x42 EL (the original version, ~13 years ago).
 
Last edited:
Ivan,

Your diopter should be below the right eye piece on your binocular. See the picture of a Pentax 10x43 DCF SP in the link below.

According to the information given about your binocular in the link shown below the diopter on it can be locked in place after you set it. See the 4th paragraph down.

Did you lock the diopter in place each time after you set it?

http://www.cameralandny.com/optics/pentax.pl?page=dcfsp10x43

Bob
 
Hello, yes I do lock it but this is not the problem. Even if i try i cant get the two barrels on focus at the same time. I think there is a problem with the focus knob, it is becoming loose, the last time it happened similar and i had to give it on service for 100 euros, ...

Anybody knows if its is possible to fix the focus knob by myself?

p.s.

Alexis, I think you are right! That sounds like the problem I have. Do you know if there is any chance I can repair this by myself?
 
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Alexis Powell said:
More likely is that the problem is with the focus drive slipping on one side (internally). --AP

Addendum:
Slipping focus is a problem that I've seen in several units of the Bushnell 8x42 Legend Ultra HD (as mentioned in the detailed thread on that bin http://www.birdforum.net/showthread.php?t=213464 ). The problem is that the focus drive slips a little bit on one side of the bin from time to time (I found that it happened at one of the limits of focus, I can't remember if the far or near, I think near), such that the diopter has to be used to compensate. This is a problem that I've seen in other cheap Chinese roofs. In fact, one of the first tests I conduct when evaluating a new bin is to run it back and forth, fairly hard, between its focus limits 20 or 30 times and then check that left-right focus synchrony (and diopter setting) is maintained. If not, I consider the bin faulty. The only high-end bins that I've tested with a similar problem were two units of early production Swarovski 8.5x42 EL (the original version, ~13 years ago).
Click to expand...

To corroborate:

I had that issue on a pair of the discontinued Bushnell Hemispheres,
which have excellent optics and sloppy final assembly.
There is actually a slotted adjustment for the focuser lens pushrod
that makes it very easy to set the diopter side easily. It all starts with
the now-traditional pop-the-medallion entry. They settled in
beautifully after that. I think they were never checked.
Less hazardous than thunking for that extra .5D.

The slippage is interesting...they rely on the pushrod disk friction
not turning the adjustment thread. Grease missing from the pusher's disk
screws that up. Just an extra 5 seconds of assembly.

That is often the big difference...seconds of assembly instead of minutes.
 
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IvanVVV said:
So the best would be to take it to Pentax service?

Thank you for the answer!
Click to expand...


Ivan,

Yes, I would think so. While we have a number of people here who work on Porro Prism repairs there aren't too many who take Roof Prisms apart.

You should inquire about getting it serviced under warranty. I think that your binocular was faulty from the start.

Pentax, which is owned by Ricoh, has updated its line of binoculars although they don't seem to have changed too much. Here is a link from B&H Photo in New York City about it. Your binocular is the first one shown.

http://www.bhphotovideo.com/explora...tes-entire-pentax-sport-optics-binocular-line

Bob
 
"Yes, I would think so. While we have a number of people here who work on Porro Prism repairs there aren't too many who take Roof Prisms apart."

Ceasar:

I'm not saying he should send them to Cory, because he might get some mileage outta Pentax's warranty. But, just know Cory could do those in his sleep. When he worked for me, I've seen him totally disassemble a Leica Trinovid--including separating the proprietary prisms--and put everything in working order.

Bill
 
WJC said:
"Yes, I would think so. While we have a number of people here who work on Porro Prism repairs there aren't too many who take Roof Prisms apart."

Ceasar:

I'm not saying he should send them to Cory, because he might get some mileage outta Pentax's warranty. But, just know Cory could do those in his sleep. When he worked for me, I've seen him totally disassemble a Leica Trinovid--including separating the proprietary prisms--and put everything in working order.

Bill
Click to expand...

Hi Bill,

I expect Cory, or yourself, would be able to do this and it is good of you to confirm it.:t:

I was talking about the hobbyists here where he was seeking advice on how to do it himself.

He is from Slovenia. Maybe a forum member from Europe knows a repairman who could fix the problem for him?

Bob
 
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Ivan:

This looks to be a manufacturer defect, and I would contact Pentax and check into repair.

The diopter has slipped, and something is wrong. That is the first place to start.

Let us know how things go, with your repair.

Jerry
 
Agreed. It's new, under warrantee, and they need to know.

Just got carried away on the simplicity.
Cory might fall asleep first, then do it in his sleep. ;-)
 
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