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08-16-2013, 09:56 PM   #1
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Bought a used lens off eBay - is this behavior normal?

I just purchased a used DA 35mm f/2.4 prime lens off ebay to use with my K30. I put the new lens on this evening and tried to taking photos throughout the house. There are a few things I noticed that seem odd with it:

First, when I would focus on a nearby object with depth, such as a stuffed animal or a cat, with the lens set at f/2.4 I noticed that in the resulting picture the area most in focus was not always what I focused in on. I might point the focus on the cats nose but it's ear would be most in focus in the resulting image.

Second, sometimes I would focus on a nearby object but the green focus icon in the viewfinder would stay flashing and I would be unable to take a picture for 4-6 seconds. It is almost as if the camera became temporarily frozen.

Third, I might more the camera and focus on something completely different at a different distance away from me. However, the viewfinder image would remain blurry. The lens would only autofocus if I turned the lens away and back to the object quickly. I almost had to shake it to make it focus. Sometimes it would autofocus quickly and sometimes it wouldn't at all.

Admittedly the only other lens I have experience with is the 18-135mm , however, I haven't experienced any these issues with it. Is there something awry with this lens or is this behavior normal for this 35mm lens and I'm terrible at using it?

08-16-2013, 10:09 PM   #2
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Could be a "regular" front focus/back focus issue, compounded by "low light" focus issues, augmented by "tungsten light" focus issues.

I'd try it outdoors tomorrow on a variety of subjects at different distances.
08-16-2013, 10:14 PM   #3
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QuoteOriginally posted by Newtophotos Quote
Is there something awry with this lens
Maybe, maybe not...

A few things to try. Go outside tomorrow in good light and try things again in a controlled environment. I know from experience that trying a new lens in a dim house at night does not always give the best results.

Second, be aware of the minimum focusing distance which is I think around 12" for that lens, if you are less than that it will not focus.

Third, what AF mode are you using? Center point, 5 point or 11 point? If not center point then it is quite possible that the AF system locked onto the cat's ear instead of it's nose.

Fourth, you are now using a lens with a relatively large maximum aperture which allows relatively small depth of focus. On your other lens it is hard to see this as the lens has a relatively small maximum aperture, but on this lens the 'slice' of the object that is in focus can be quite small.

So, do a proper test in good light, on a tripod if possible with a static focusing target. If you get the same results then the lens might be defective. You might also try cleaning the lens contacts with a soft cloth, I doubt that will help but it has been known to fix all manner of 'odd' behavior.
08-16-2013, 11:18 PM   #4
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QuoteOriginally posted by jatrax Quote
If not center point then it is quite possible that the AF system locked onto the cat's ear instead of it's nose.
...and even with center point, it may still miss focus depending on subject. That is just how things are. The camera does not "know" what you are wanting to be sharp.


Steve

08-17-2013, 03:08 AM   #5
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Um, those seem more like camera issues than lens issues to me. Or using it wrong.
1) Keep in mind that this lens will have, at f2.4, a much more shallow DoF than your 18-135mm. Secondly, the AF points are much bigger than the little indicators in the viewfinder. So maybe the AF point locked focus, but just not where you wanted it to. With a lens at f5.6 or f8, that might not even be visible, because the DoF will be so wide it will get even the stuff you wanted. But with a fast prime, its a little different. There might also be front or back focusing issues. Feel free to search for a thread on this, there are many threads about AF and AF adjustment, focus charts, etc.
2) Freezing? I really dont think the lens can do this. Check your menu, you might have one of the options enabled that prevents the camera from taking a photo if it doesnt lock focus. Also, update the firmware on your camera. Try using a different battery, make sure its full and keeps its charge normally. Make sure you dont have 2 sec timer enabled.
3) Thats hard to understand, because you dont give enough information. If the object is too close, it might not be able to focus on it (the kit lenses actually have better minimum focus capabilities than most other lenses). Also, if its too dark, the AF wont work. And make sure youre not holding the AF-lock button and that the MF/AF button is fully on AF. There is also a difference in whether you have AF.A, AF.S or AF.C selected.

Hope this helps

Edit: Here is what else I suggest you do. Update camera firmware. Make sure the lens mount and camera mount are clean, especially on the contacts. Try to AF in live view, see if that is accurate. Try to focus manually, see how that works out for you - use focus peaking.

Last edited by Na Horuk; 08-17-2013 at 05:02 AM.
08-20-2013, 07:45 PM   #6
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QuoteOriginally posted by Na Horuk Quote
Um, those seem more like camera issues than lens issues to me. Or using it wrong.
1) Keep in mind that this lens will have, at f2.4, a much more shallow DoF than your 18-135mm. Secondly, the AF points are much bigger than the little indicators in the viewfinder. So maybe the AF point locked focus, but just not where you wanted it to. With a lens at f5.6 or f8, that might not even be visible, because the DoF will be so wide it will get even the stuff you wanted. But with a fast prime, its a little different. There might also be front or back focusing issues. Feel free to search for a thread on this, there are many threads about AF and AF adjustment, focus charts, etc.
2) Freezing? I really dont think the lens can do this. Check your menu, you might have one of the options enabled that prevents the camera from taking a photo if it doesnt lock focus. Also, update the firmware on your camera. Try using a different battery, make sure its full and keeps its charge normally. Make sure you dont have 2 sec timer enabled.
3) Thats hard to understand, because you dont give enough information. If the object is too close, it might not be able to focus on it (the kit lenses actually have better minimum focus capabilities than most other lenses). Also, if its too dark, the AF wont work. And make sure youre not holding the AF-lock button and that the MF/AF button is fully on AF. There is also a difference in whether you have AF.A, AF.S or AF.C selected.

Hope this helps

Edit: Here is what else I suggest you do. Update camera firmware. Make sure the lens mount and camera mount are clean, especially on the contacts. Try to AF in live view, see if that is accurate. Try to focus manually, see how that works out for you - use focus peaking.
These responses have been very helpful. You guys nailed it, my main issue is that I was too close to the subject and hte lens wouldn't autofocus. Further away from the subject and outdoors the pictures are much better. I updated the firmware and will search on auto focusing.

I've noticed some small plastic shavings hanging out just inside lense mount ring on the camera body. Is this normal and where can this be coming from?
08-20-2013, 08:14 PM   #7
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QuoteOriginally posted by Newtophotos Quote
I just purchased a used DA 35mm f/2.4 prime lens off ebay
How much did you pay for it? A brand new one goes for $150. Just wondering.......
08-20-2013, 11:13 PM   #8
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QuoteOriginally posted by Driline Quote
How much did you pay for it? A brand new one goes for $150. Just wondering.......
Brand new ones are closer to $200 ($190 - $210, depending on region). Used ones normally go for between $140-$160.

I have bought two new ones (months apart) from two different stores (both had them on sale for $190. I returned one of them, and I'm still currently using the other one).

I bought a used one from these forums for $155 I think. I re-sold it for $145 later on. I lowered the price because I had tried to mod the lens (switch the plastic mount with a metal one - didn't work). It didn't affect the lens, but some people consider it important whether or not a lens has been opened up.

Those are the price ranges I would pay for a DA 35 2.4.

08-21-2013, 06:19 AM   #9
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QuoteOriginally posted by EarlVonTapia Quote
Brand new ones are closer to $200 ($190 - $210, depending on region). Used ones normally go for between $140-$160.

I have bought two new ones (months apart) from two different stores (both had them on sale for $190. I returned one of them, and I'm still currently using the other one).

I bought a used one from these forums for $155 I think. I re-sold it for $145 later on. I lowered the price because I had tried to mod the lens (switch the plastic mount with a metal one - didn't work). It didn't affect the lens, but some people consider it important whether or not a lens has been opened up.

Those are the price ranges I would pay for a DA 35 2.4.
Just last week these forums were promoting the Pentax store sale of the DA 35 2.4 for $150. You missed the sale man.....
08-21-2013, 07:19 AM   #10
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QuoteOriginally posted by Driline Quote
Just last week these forums were promoting the Pentax store sale of the DA 35 2.4 for $150. You missed the sale man.....
I don't know if that was supposed to be sarcasm, but I'll assume it wasn't.

Have you read that thread? Or the one which now exists over in "General Photography and Industry"?

It was a huge fiasco. No one is getting their lenses. Some of were put to even more trouble because the hold placed on our cards was the full retail price of the lens instead of the sale price.

Card holds were 5 days or more. People who paid with PayPal are just starting to get their money back today.
08-21-2013, 09:11 AM   #11
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QuoteOriginally posted by thornburg Quote
I don't know if that was supposed to be sarcasm, but I'll assume it wasn't.

Have you read that thread? Or the one which now exists over in "General Photography and Industry"?

It was a huge fiasco. No one is getting their lenses. Some of were put to even more trouble because the hold placed on our cards was the full retail price of the lens instead of the sale price.

Card holds were 5 days or more. People who paid with PayPal are just starting to get their money back today.
Yeah, I was one of them.
08-21-2013, 10:39 AM   #12
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QuoteOriginally posted by thornburg Quote
It was a huge fiasco. No one is getting their lenses. Some of were put to even more trouble because the hold placed on our cards was the full retail price of the lens instead of the sale price.
Then why would this forum promote such a boondoggle?
08-21-2013, 11:12 AM   #13
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QuoteOriginally posted by Driline Quote
Then why would this forum promote such a boondoggle?
Most we're not promoting it, we're giving them a tongue lashing for their ridiculous behavior.

As to why it was posted in the first place, the deal was on PentaxWebStore, the official US online store of the Pentax brand. Ricoh (who owns the Pentax brand) contracts a company called SureSource to run it.
08-21-2013, 04:04 PM   #14
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I feel oddly defensive every time I see this thread title.
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