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10-26-2010, 07:08 PM   #1
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Lens issues | DA 70mm/2.4

I got a DA 70/2.4 today from KEH. It was used, condition identified as "EX+." Looks to be in great shape cosmetically, and the elements are nice and clean. However, upon close inspection, I can see some oil on the blades. Just a very small amount. If I look through the rear element with a flashlight, I don't see anything with the aperture stopped down. But as I start to open it slowly, I can see traces of oil film.

I have many older lenses that have a similar very small amount of oil visible, that work fine, and I don't worry about it. But I was surprised to see this on such a new lens. Does this seem odd to you guys? Is this lens known to have any such problems?

Additionally, I'm pretty sure the lens is backfocusing, but I can't do any tripod tests to confirm because I don't have an Arca-Swiss plate for the camera yet. But hand held at shutter speeds around 1/160 or so, at roughly 2x minimum focus distance, I am getting backfocus fairly consistently. If I set the AF adjust to +10, I think it's about right, but possibly still slightly backfocused. I suspect I may have to return this lens.

I just got the camera today, and it's the only lens I have. I should be getting a couple of other lenses in the next day or two, so I can test them to be sure there isn't an issue with the camera.

10-26-2010, 08:34 PM   #2
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My understanding is the oil on the blades usually results from heat exposure; age doesn't matter, its just that one day the previous owner left it in the glove box.

What body is this on? Is the body a used model too? Without other lenses, it's hard to say if it's the lens or body with the focus issue. I don't have the focus compensation option, is ten the limit?

I've only bought from them twice, but I'm be surprised to hear that KEH sold an EX+ with oil on the aperture. That said, everything I've heard is their return policy is fantastic, so you should be ok if you need to send it back.

On the plus side, if you do send it back, the DA 40 has recently become available for considerably less than usual, maybe Pentax is starting to lower lens prices? Fingers crossed!
10-26-2010, 09:04 PM   #3
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That's weird, I just bought a DA70 from Henry's on ebay and it also has oil on the blades.
10-26-2010, 09:23 PM   #4
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I'd definitely send it back if there's oil on the blades...

Sorry to hear you're having a frustrating first experience.

10-26-2010, 09:25 PM   #5
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This is on a brand new K-7, which I just received today. I've never used a Pentax body before this, so it's very possible I'm just doing something wrong. I tried with SR on and off. Only shooting in AF-S mode. 10 is indeed the adjustment limit.

I was surprisd to see the oil, considering KEH's ratings are always very conservative. But it's a very superficial amount, and I would not likely send it back for that. But if it's not focusing right for me, I will definitely be sending it back.

I need to post some shots, to see what others think of the sharpness, too, I am not that impressed thus far, but I haven't had any good light since being able to try it, and maybe I am just impatient.

I don't have a way to mount it on my tripod, either. I've tried for the last two days to order an L-bracket, but the RRS web site seems kinda hosed. I'll call them in the morning.
10-26-2010, 09:28 PM   #6
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QuoteOriginally posted by deadwolfbones Quote
I'd definitely send it back if there's oil on the blades...

Sorry to hear you're having a frustrating first experience.
Yeah, it's a bit of a bummer, but...oh well. The camera seems awesome. I am getting the hang of all the settings, and I feel like I pretty much know what I'm doing. It seemed comically small at first, after rockin' the D3, but it still feels good in my hand, and I think I could really get used to having a small camera.

I was supposed to get another lens from KEH tomorrow, but I never got a ship notification, so not really sure...
10-26-2010, 09:34 PM   #7
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I love the ergonomics of the K-7/K-5. That grip is a little rubberized slice of heaven, IMO.
10-26-2010, 09:52 PM   #8
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I seriously doubt it's anything you're doing wrong. Oil suggests the lens has been mistreated to some degree, so it'd be my main suspect, but there's always a chance your body fell just outside the tolerance range they were supposed to be built in. It happens with all of the manufacturers. Best information I've seen was from one of the camera/lens rental outfits that went nuts testing the models they had on hand. Found some relatively large deviations for what we all consider precision camera gear.

One of the advantages to the Pentax bodies beyond the k100d is the ability to store the focus compensation for a number of lenses, but that won't do you much good if the body is outside the range.

There's also the chance that the body is within spec, but barely, and the lens is on the far opposite side of the specification. If in doubt, I'd return it, but I'd want to test the body against a couple other lenses relatively soon to see if it has an issue requiring repair/replacement.

I'm very envious of your new camera; the K-7 is the first camera I really wish I had instead of my k100d.

10-26-2010, 10:01 PM   #9
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Yeah, I'm really hoping it's not the body. Got it from Amazon, so no worries if I have to return it. BUT, I am already really digging it. I NEEEED to get out and shoot with it, but it won't do me any good if I don't have a lens that works. The other lens that's coming from them is the DA 35/2.8 Macro. From what I've read, there's definitely something wrong if I can't get sharp pics from that!

I'll call them tomorrow to check on the status of the 35, then I think I will get return auth for the 70 and just go ahead and buy the LN- copy they currently have of the 77/1.8. Didn't want to spend that much, but it's my most-used focal length, so....why not? LOL

This Pentax thing was supposed to be an experiment, and I'm already in for over $2K. Geez!
10-27-2010, 10:04 AM   #10
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Well, my 35 won't be arriving until Friday, so I have no lenses at the moment. I just called KEH. Their service seems great, of course, friendly and cooperative with returns. They didn't have another 70/2.4, conveniently, so that made the decision to grab the 77/1.8 pretty easy.

Should be back to the business of evaluating the K-7 by Friday, with the DA 35/2.8 and the A 50/1.7, with the lens I reeeeally want (since I am first and foremost a portrait guy) arriving some time next week.
10-27-2010, 10:34 AM   #11
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I'm also returning mine for refund. Too bad, I liked it.
10-27-2010, 10:36 AM   #12
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I don't know about you, but for me the short telephoto is about way more than portraits. I recently got myself one of the Samyang 85mm rebrands, and I've found it matches how I see the world 85% of the time.

In the past few months I've chosen to upgrade my kit a bit, and so far I've put down 350 in lenses, 330 in support upgrades, and about 100 in quick release upgrades. Add in a few bits here and there and I'm sure I've hit a round 800, considerably more than I meant to. I think that's what happens to photographers; our money magically becomes glass and photographic paraphernalia. On the plus side, the new tripod setup I just ordered is being covered completely with credit card bonus points.

I do have to say I'm a bit perplexed by this concept of "autofocus" as you call it. What purpose does it serve? Is it nice? Does it make for a benevolent god?

My k100d has an AF (actuate on focus) switch, but that controls the focus not the shutter. :-P
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