samyang 85mm as if overexposure

ghigoblin · 10-23-2018, 01:14 AM

hi guys,

after a while in a box, i've decided to re-use my sammy 85mm manual. it was there because in the last years i've taking picture in harh mountain enviroments and i've found more reliable using the combo k70/k5IIs and pentax da 18-135mm and pentax da-hd 20-40mm. so i've started taking pictures with the sammy attached on the k70 and it appears a bad overexposure;i've tried different combination, using info taken by the manual and tryin to find some reading around the web, but nothing. the only way to have a balanced picture was using something like ISO100 F16 and 1/8000s(!).
so i've switched to the K5IIs with the exact same results.and this is my question ma i doing something wrong with the camera settings or is it some really bad behaviour of the lens? eventually, what should i do? i've attached some pics to clearified.
thank you for your time
federico

Attached Images

View Picture EXIF

View Picture EXIF

**PJ1** · 10-23-2018, 04:01 AM - **1 Like**

The EXIF says the focus range is "distant". These look to be out of focus. All I can suggest is that it is a manual focus lens so the question is whether they images look sharp before you press the shutter. Once you have a subject clearly in focus you can address the exposure issue. Or if you cannot get a sharp image, the problem may be something different.

steve_k · 10-23-2018, 04:09 AM - **1 Like**

Looking at the photos and data my best guess is you have an issue with the aperture staying wide open. Do you see the aperture blades close when you press the shutter. I’m not familiar with the lens but I believe it has an aperture ring. What if you use the lens in manual mode setting the aperture by the ring?

pschlute · 10-23-2018, 05:00 AM - **1 Like**

Originally posted by steve_k

Looking at the photos and data my best guess is you have an issue with the aperture staying wide open

This.

**UncleVanya** · 10-23-2018, 05:18 AM - **1 Like**

Try taking the lens off the camera. Set to A does the aperture look like a very small opening? Take your aperture ring and turn it to open the blades up and the back to the A position. Do the blades open and clouds smoothly and quickly? Take your lens, set to A and use a finger to push the aperture lever so the blades are open wide, the release the lever. If all is well the blades will snap shut very quickly. My guess is this won't happen... It will be jerky and sluggish or won't close automatically because the spring is weak or disconnected or the aperture mechanism has corrosion causing friction.

ghigoblin · 10-23-2018, 08:07 AM

hi guys,

thank you all for the advices. back from work now, and, first, i've tried to put the lens out and control the blades, the easy one. it appears that the aperture lever is totally freezed. it doesen't move. now i need to make it work!

---------- Post added 10-23-18 at 08:16 AM ----------

after a few shot it seems that it'all fine.

Originally posted by PJ1

The EXIF says the focus range is "distant". These look to be out of focus. All I can suggest is that it is a manual focus lens so the question is whether they images look sharp before you press the shutter. Once you have a subject clearly in focus you can address the exposure issue. Or if you cannot get a sharp image, the problem may be something different

those were just to show the matter, but you think tha a bad focus can influence the overall exposure?

thank all of you again for the advices.

Snafu711 · 10-23-2018, 11:59 AM

comparing the exif of your first picture (ok expose) and your last picture (heavily overexposed) I see: exposure is all manual. Both pics have been taken using F= 16. The main difference is the exposure time of 1/8000s to 1/500s.

So my diagnosis is: if 1/8000s is the shutter speed is needed to get decent exposure, you can expect to get overexposure of 4 EV at 1/500s - just what you've got.

In order to check for slow aperture I suggest AV mode with F = 11 or F = 16 selected. When the camera picks the shutter speed needed and you still get significant overexpose you can blame it on the lens - especially if this issue shows for different lighting situations.

**UncleVanya** · 10-23-2018, 12:59 PM

Originally posted by Snafu711

comparing the exif of your first picture (ok expose) and your last picture (heavily overexposed) I see: exposure is all manual. Both pics have been taken using F= 16. The main difference is the exposure time of 1/8000s to 1/500s.

So my diagnosis is: if 1/8000s is the shutter speed is needed to get decent exposure, you can expect to get overexposure of 4 EV at 1/500s - just what you've got.

In order to check for slow aperture I suggest AV mode with F = 11 or F = 16 selected. When the camera picks the shutter speed needed and you still get significant overexpose you can blame it on the lens - especially if this issue shows for different lighting situations.

You seem to have missed this:

Originally posted by ghigoblin

hi guys,

thank you all for the advices. back from work now, and, first, i've tried to put the lens out and control the blades, the easy one. it appears that the aperture lever is totally freezed. it doesen't move. now i need to make it work!

---------- Post added 10-23-18 at 08:16 AM ----------

after a few shot it seems that it'all fine.

Aperture was totally frozen up non-responsive - now he has freed it up and it works.

richfam · 10-23-2018, 06:03 PM - **1 Like**

Originally posted by ghigoblin

after a few shot it seems that it'all fine.

I had a similar issue with my Rokinon 85mm f/1.4 (made by Samyang).

The lens worked perfectly when I first got it, but gradually the aperture lever started to stick in the wide open position. It eventually got so bad that I had to take the lens off after every shot, tap the aperture lever to unstick it, then remount the lens for my next shot.

It felt like a friction problem, so I figured that it might eventually work itself out, and that's what happened: the aperture lever started sticking less and less, and now it doesn't stick at all anymore. The lens is working perfectly now (several hundred exposures with no problems).

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10-23-2018, 04:01 AM - 1 Like	#2
PJ1 Loyal Site Supporter Join Date: Jul 2012 Location: Toowoomba, Australia Photos: Gallery \| Albums Posts: 5,483	The EXIF says the focus range is "distant". These look to be out of focus. All I can suggest is that it is a manual focus lens so the question is whether they images look sharp before you press the shutter. Once you have a subject clearly in focus you can address the exposure issue. Or if you cannot get a sharp image, the problem may be something different.

10-23-2018, 04:09 AM - 1 Like	#3
steve_k Site Supporter Join Date: Dec 2016 Location: Shelton, CT Photos: Albums Posts: 708	Looking at the photos and data my best guess is you have an issue with the aperture staying wide open. Do you see the aperture blades close when you press the shutter. I’m not familiar with the lens but I believe it has an aperture ring. What if you use the lens in manual mode setting the aperture by the ring?

10-23-2018, 05:00 AM - 1 Like	#4
pschlute Moderator Loyal Site Supporter Join Date: Mar 2007 Location: Surrey, UK Photos: Gallery Posts: 8,198	Originally posted by steve_k Looking at the photos and data my best guess is you have an issue with the aperture staying wide open This.

10-23-2018, 05:18 AM - 1 Like	#5
UncleVanya Loyal Site Supporter Join Date: Jul 2014 Photos: Gallery \| Albums Posts: 28,398	Try taking the lens off the camera. Set to A does the aperture look like a very small opening? Take your aperture ring and turn it to open the blades up and the back to the A position. Do the blades open and clouds smoothly and quickly? Take your lens, set to A and use a finger to push the aperture lever so the blades are open wide, the release the lever. If all is well the blades will snap shut very quickly. My guess is this won't happen... It will be jerky and sluggish or won't close automatically because the spring is weak or disconnected or the aperture mechanism has corrosion causing friction.

10-23-2018, 08:07 AM	#6
ghigoblin New Member Join Date: May 2014 Location: livorno (leghorn) Photos: Albums Posts: 9 Original Poster	hi guys, thank you all for the advices. back from work now, and, first, i've tried to put the lens out and control the blades, the easy one. it appears that the aperture lever is totally freezed. it doesen't move. now i need to make it work! ---------- Post added 10-23-18 at 08:16 AM ---------- after a few shot it seems that it'all fine. Originally posted by PJ1 The EXIF says the focus range is "distant". These look to be out of focus. All I can suggest is that it is a manual focus lens so the question is whether they images look sharp before you press the shutter. Once you have a subject clearly in focus you can address the exposure issue. Or if you cannot get a sharp image, the problem may be something different those were just to show the matter, but you think tha a bad focus can influence the overall exposure? thank all of you again for the advices.

10-23-2018, 11:59 AM	#7
Snafu711 Veteran Member Join Date: Sep 2017 Posts: 307	comparing the exif of your first picture (ok expose) and your last picture (heavily overexposed) I see: exposure is all manual. Both pics have been taken using F= 16. The main difference is the exposure time of 1/8000s to 1/500s. So my diagnosis is: if 1/8000s is the shutter speed is needed to get decent exposure, you can expect to get overexposure of 4 EV at 1/500s - just what you've got. In order to check for slow aperture I suggest AV mode with F = 11 or F = 16 selected. When the camera picks the shutter speed needed and you still get significant overexpose you can blame it on the lens - especially if this issue shows for different lighting situations.

10-23-2018, 12:59 PM	#8
UncleVanya Loyal Site Supporter Join Date: Jul 2014 Photos: Gallery \| Albums Posts: 28,398	Originally posted by Snafu711 comparing the exif of your first picture (ok expose) and your last picture (heavily overexposed) I see: exposure is all manual. Both pics have been taken using F= 16. The main difference is the exposure time of 1/8000s to 1/500s. So my diagnosis is: if 1/8000s is the shutter speed is needed to get decent exposure, you can expect to get overexposure of 4 EV at 1/500s - just what you've got. In order to check for slow aperture I suggest AV mode with F = 11 or F = 16 selected. When the camera picks the shutter speed needed and you still get significant overexpose you can blame it on the lens - especially if this issue shows for different lighting situations. You seem to have missed this: Originally posted by ghigoblin hi guys, thank you all for the advices. back from work now, and, first, i've tried to put the lens out and control the blades, the easy one. it appears that the aperture lever is totally freezed. it doesen't move. now i need to make it work! ---------- Post added 10-23-18 at 08:16 AM ---------- after a few shot it seems that it'all fine. Aperture was totally frozen up non-responsive - now he has freed it up and it works.

10-23-2018, 06:03 PM - 1 Like	#9
richfam Forum Member Join Date: Oct 2017 Location: Lindsborg, Kansas Photos: Gallery Posts: 89	Originally posted by ghigoblin after a few shot it seems that it'all fine. I had a similar issue with my Rokinon 85mm f/1.4 (made by Samyang). The lens worked perfectly when I first got it, but gradually the aperture lever started to stick in the wide open position. It eventually got so bad that I had to take the lens off after every shot, tap the aperture lever to unstick it, then remount the lens for my next shot. It felt like a friction problem, so I figured that it might eventually work itself out, and that's what happened: the aperture lever started sticking less and less, and now it doesn't stick at all anymore. The lens is working perfectly now (several hundred exposures with no problems).

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