Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
01-14-2015, 03:24 AM   #1
Senior Member




Join Date: Dec 2012
Location: Exeter, Devon
Posts: 137
Aperture issue with 10-17mm f/3.5-4.5 fisheye

I just received a second hand (via an eBay seller) copy of the SMC DA 10-17mm f/3.5-4.5 fisheye lens yesterday, and gave it a bit of a test.

Almost everything seems to be in order; optics are clean, autofocus is fine, images are sharper than expected and the distortion is juicy.

However, the maximum aperture is not behaving quite how I thought it would; I of course expected a maximum aperture of f/3.5 at 10mm, f/4.5 at 17mm, and f/4.0 at some point inbetween.

However, at 10mm the maximum aperture is reported as f/4.0. At 17mm the maximum aperture is still reporting as f/4.0. And everywhere else ... yes, f/4.0.

Any thoughts? Anyone seen this behaviour before, on this or any other lens?

01-14-2015, 04:15 AM   #2
Veteran Member
EarlVonTapia's Avatar

Join Date: Oct 2012
Location: Vancouver
Photos: Gallery
Posts: 1,207
QuoteOriginally posted by NeilGratton Quote
I just received a second hand (via an eBay seller) copy of the SMC DA 10-17mm f/3.5-4.5 fisheye lens yesterday, and gave it a bit of a test.

Almost everything seems to be in order; optics are clean, autofocus is fine, images are sharper than expected and the distortion is juicy.

However, the maximum aperture is not behaving quite how I thought it would; I of course expected a maximum aperture of f/3.5 at 10mm, f/4.5 at 17mm, and f/4.0 at some point inbetween.

However, at 10mm the maximum aperture is reported as f/4.0. At 17mm the maximum aperture is still reporting as f/4.0. And everywhere else ... yes, f/4.0.

Any thoughts? Anyone seen this behaviour before, on this or any other lens?
I've owned 2 separate copies of the DA 10-17, and never experienced that sort of behavior.

It sounds like maybe the contacts are dirty. Clean them off with some alcohol and see if the camera and lens start talking to each other again.

If that fails, and your camera body works fine with other lenses, then perhaps the computer stuff inside the lens is damaged. I would contact the seller and get a return.
01-14-2015, 05:15 AM   #3
Senior Member




Join Date: Dec 2012
Location: Exeter, Devon
Posts: 137
Original Poster
QuoteOriginally posted by EarlVonTapia Quote
It sounds like maybe the contacts are dirty. Clean them off with some alcohol and see if the camera and lens start talking to each other again.
Thanks, I'll give it a go.

However, the rest of the communication works fine - set the aperture on the camera and it stops down fine. No problem with autofocus. It's just the reported maximum aperture that's the problem (and if that's the only issue I ever have, I'm happy to live with it, given the bargain price I paid for the lens).
01-14-2015, 05:34 AM   #4
Veteran Member
EarlVonTapia's Avatar

Join Date: Oct 2012
Location: Vancouver
Photos: Gallery
Posts: 1,207
QuoteOriginally posted by NeilGratton Quote
Thanks, I'll give it a go.

However, the rest of the communication works fine - set the aperture on the camera and it stops down fine. No problem with autofocus. It's just the reported maximum aperture that's the problem (and if that's the only issue I ever have, I'm happy to live with it, given the bargain price I paid for the lens).
That's not a bad way to look at it, and depending on the final price, that might be the course of action I would take.

I do see glitchy electronics as a sign of possible impending failure though. I had an old F series zoom die a slow death that way (first the autofocus was erratic, then it just stopped). Also, my Tamron 17-50 (reported every focal length as 40mm, then one day the zoom mechanism broke!).

The DA 10-17 doesn't have an aperture ring, so if the aperture control does die at some point, it will really limit its usefulness.

Did the seller mention any sort of problems with the lens?

Anyways, what matters in the end is if you're happy with it. I'm holding on to a couple of janky lenses myself, simply because the price I paid was really good for them.

E

01-14-2015, 05:39 AM   #5
Site Supporter
Site Supporter




Join Date: May 2012
Location: Adelaide
Photos: Gallery | Albums
Posts: 1,248
Just had a play with my copy on a K-3. What behaviour you get seems to depend on where you were zoomed when you spin the rear control wheel to request maximum aperture. If you do it at say 14mm, you see F4 reported. Then if you move the zoom to 10mm you still get F4 reported. The camera thinks you want F4 'cause that's what you told it. Now while staying zoomed at 10mm spin the rear control wheel one more click to the left and F3.5 will be reported. That's cause you told the camera you want the next wider aperture (which at 10mm it was able to give you).

Now if you zoom back towards 17mm you will get F4 and then F4.5 reported. Now zoom down to 10mm and it will step down to F3.5. So if the camera is told 'aperture wide open please' at the wide end of the zoom, it remembers that and does its best to keep giving you that as you zoom up and down. I get F3.5 to around 11.5mm, then F4 though to just before 17mm when it moves to F4.5.

When I think about it, there is an inherent programming logic dilemma present with variable aperture zooms. How Pentax has resolved it kind of makes sense.
01-14-2015, 06:09 AM   #6
Senior Member




Join Date: Dec 2012
Location: Exeter, Devon
Posts: 137
Original Poster
QuoteOriginally posted by EarlVonTapia Quote
I do see glitchy electronics as a sign of possible impending failure though.
The thought had crossed my mind :-/

QuoteQuote:
Did the seller mention any sort of problems with the lens?
He put on the listing: "The lens cap has some damage to it as it was damaged separately but the lens is in perfect working order."
(And the lens cap isn't actually that bad)

QuoteOriginally posted by southlander Quote
Just had a play with my copy on a K-3.
The behaviour you described is what I would have expected. What actually happens is if I set the maximum aperture available at 10mm, it's (reported as) f/4.0. If I then zoom in to 17mm, it's still (reported as) f/4.0.

I'll do some exposure tests when I get home later, to check how the actual aperture changes. (If I'm in manual and spot metering, and zoom in wide open from 10mm to 17mm, I should see see it drop by 2/3 a stop if it's actually going from f/3.5 to f/4.5.

Last edited by NeilGratton; 01-14-2015 at 06:22 AM.
01-14-2015, 07:03 AM - 1 Like   #7
Pentaxian
Na Horuk's Avatar

Join Date: Feb 2012
Location: Slovenia, probably
Photos: Gallery | Albums
Posts: 11,183
Hm, but is the lens wide open, or do you see the aperture blades stopped down to f4? Just look at the front of the lens and choose the widest aperture at the widest angle.What do the aperture blades do? The question is, are you shooting at f3.5 and the camera labels it f4, or are you shooting actually at f4 and the camera displays the correct information?

Also, you can take the standard precautions:
- charge the battery overnight, leave it outside of the camera for some hours
- make sure the camera and lens mount contacts are clean, free of particles and grime
- make sure the aperture lever on the lens moves normally and snaps into position as it should
- UPDATE the camera firmware to the latest one
01-14-2015, 07:19 AM   #8
Pentaxian
kh1234567890's Avatar

Join Date: Sep 2010
Location: Manchester, UK
Photos: Gallery
Posts: 2,616
What it should do is that if you set the aperture to f/3.5 @ 10mm in the Av mode and then zoom in, the reported aperture should change to f/4 just before you hit 12mm and then to f/4.5 just before 17mm. If you then zoom out, it should revert to f/4 and then to f/3.5 at about the same FL points. I would suspect a problem with the sliding contacts inside the lens barrel - does the EXIF show the correct FL ? Maybe 'exercising' it for a while may help ...

---------- Post added 14-01-15 at 14:19 ----------

QuoteOriginally posted by Na Horuk Quote
Hm, but is the lens wide open, or do you see the aperture blades stopped down to f4?
Hard to see with a fisheye

01-21-2015, 05:01 AM   #9
Site Supporter
Site Supporter




Join Date: May 2012
Location: Adelaide
Photos: Gallery | Albums
Posts: 1,248
QuoteOriginally posted by NeilGratton Quote
I just received a second hand (via an eBay seller) copy of the SMC DA 10-17mm f/3.5-4.5 fisheye lens yesterday, and gave it a bit of a test.
Any update on the aperture problem?
01-21-2015, 07:04 AM   #10
Senior Member




Join Date: Dec 2012
Location: Exeter, Devon
Posts: 137
Original Poster
Not really. I tested exposures with spot exposure mode against an evenly lit section of wall, and can confirm that set in manual with the aperture at maximum (but reporting f/4.0), it gets about a stop darker when zooming in from 10mm to 17mm. Based on that I assume it's setting the aperture properly, but reporting it incorrectly.
01-24-2015, 02:16 AM   #11
Junior Member




Join Date: Dec 2014
Location: Riga
Photos: Gallery | Albums
Posts: 47
You should check EXIF for detailed info, particularily if lens model and other lens-related information is shown. If not, there is problem in lens-body communication (contacts, internal wiring etc).

If EXIF values are about OK, check what FL is reported when lens is zoomed to extremes and inbetween. If FL indicated doesn't change, possibly the encoder that reads FL is worn/damaged, and lens IC thinks that lens is always set to middle zoom, thus reports incorrect aperture.
Reply

Bookmarks
  • Submit Thread to Facebook Facebook
  • Submit Thread to Twitter Twitter
  • Submit Thread to Digg Digg
Tags - Make this thread easier to find by adding keywords to it!
10-17mm, 10mm, 17mm, aperture, aperture issue, av mode, f/3.5, f/3.5-4.5, f/4, f/4.0, fisheye, fl, issue with 10-17mm, k-mount, lens, pentax lens, slr lens
Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
For Sale - Sold: Pentax SMCP-DA 10-17mm f/3.5-4.5 ED (IF) Lens Dat_Bokeh Sold Items 4 01-27-2015 01:19 AM
Pentax DA f/3.5-4.5 10-17mm Lens $450 Takumar55 Pentax Price Watch 7 08-15-2013 03:21 PM
For Sale - Sold: Pentax DA 10-17mm f/3.5-4.5 Fish-eye HSV Sold Items 3 06-03-2013 01:49 PM
PENTAX DA 10-17mm f/3.5-4.5 ED FishEye Zoom Price JackProton Pentax SLR Lens Discussion 18 02-24-2009 12:44 PM
For Sale - Sold: Pentax DA-Fisheye 10-17mm 3.5-4.5 Cmanuel86 Sold Items 5 01-15-2009 09:06 PM



All times are GMT -7. The time now is 03:15 PM. | See also: NikonForums.com, CanonForums.com part of our network of photo forums!
  • Red (Default)
  • Green
  • Gray
  • Dark
  • Dark Yellow
  • Dark Blue
  • Old Red
  • Old Green
  • Old Gray
  • Dial-Up Style
Hello! It's great to see you back on the forum! Have you considered joining the community?
register
Creating a FREE ACCOUNT takes under a minute, removes ads, and lets you post! [Dismiss]
Top