Diaphragm problem

Poliyoyo · 05-09-2012, 01:53 PM

I have a Kx body and a Smc-M 50mm 1.7 and just recently bought a 44M 58mm f2 Helios.
The lens is in great condition and works just fine.

After using the 50mm for a few months in a bokeh frenzy at about 1.7-2.8, i decided to finally compare it's sharpness to my 18-55 kit lens at 50 mm. I noticed it works just fine from F1.7 to about 4, the dof increases and the shutter speed decreases, as they should.
The problem is after F4 in the 50mm M, all the pictures tend to have the same depth of field, nothing comes even close to what the 18-55 at f.5.6 can do.
The same thing goes for the Helios lens too.

The guy i bought the Helios from said he had the same problem with his K10 with manual lens.
Does anybody else here have the same problem?

alphanerd · 05-09-2012, 02:04 PM

Originally posted by Poliyoyo

I have a Kx body and a Smc-M 50mm 1.7 and just recently bought a 44M 58mm f2 Helios.
The lens is in great condition and works just fine.

After using the 50mm for a few months in a bokeh frenzy at about 1.7-2.8, i decided to finally compare it's sharpness to my 18-55 kit lens at 50 mm. I noticed it works just fine from F1.7 to about 4, the dof increases and the shutter speed decreases, as they should.
The problem is after F4 in the 50mm M, all the pictures tend to have the same depth of field, nothing comes even close to what the 18-55 at f.5.6 can do.
The same thing goes for the Helios lens too.

The guy i bought the Helios from said he had the same problem with his K10 with manual lens.
Does anybody else here have the same problem?

When you adjust the aperture of the helios past f4, does the viewfinder continue to get darker? If you take it off the camera and do the same thing, does the aperture continue to get smaller?

Poliyoyo · 05-09-2012, 02:16 PM

Yes, it does.

Also with the M 50mm, when using the green button for metering, the viewfinder gets darker and darker as i increase the F number. Also the aperture gets smaller when the lens is taken off.

alphanerd · 05-09-2012, 03:16 PM

Are you focusing to the same distance with the lenses? Distance to subject matters a lot with regard to depth of field.

Poliyoyo · 05-09-2012, 09:44 PM

Yes, i'm focusing on the same object from the same vantage point.

05-09-2012, 01:53 PM	#1
Poliyoyo Inactive Account Join Date: May 2012 Posts: 3	Diaphragm problem I have a Kx body and a Smc-M 50mm 1.7 and just recently bought a 44M 58mm f2 Helios. The lens is in great condition and works just fine. After using the 50mm for a few months in a bokeh frenzy at about 1.7-2.8, i decided to finally compare it's sharpness to my 18-55 kit lens at 50 mm. I noticed it works just fine from F1.7 to about 4, the dof increases and the shutter speed decreases, as they should. The problem is after F4 in the 50mm M, all the pictures tend to have the same depth of field, nothing comes even close to what the 18-55 at f.5.6 can do. The same thing goes for the Helios lens too. The guy i bought the Helios from said he had the same problem with his K10 with manual lens. Does anybody else here have the same problem?

05-09-2012, 02:16 PM	#3
Poliyoyo Inactive Account Join Date: May 2012 Posts: 3 Original Poster	Yes, it does. Also with the M 50mm, when using the green button for metering, the viewfinder gets darker and darker as i increase the F number. Also the aperture gets smaller when the lens is taken off. Last edited by Poliyoyo; 05-09-2012 at 02:21 PM.

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05-09-2012, 02:04 PM	#2
alphanerd Senior Member Join Date: Mar 2011 Posts: 119	Originally posted by Poliyoyo I have a Kx body and a Smc-M 50mm 1.7 and just recently bought a 44M 58mm f2 Helios. The lens is in great condition and works just fine. After using the 50mm for a few months in a bokeh frenzy at about 1.7-2.8, i decided to finally compare it's sharpness to my 18-55 kit lens at 50 mm. I noticed it works just fine from F1.7 to about 4, the dof increases and the shutter speed decreases, as they should. The problem is after F4 in the 50mm M, all the pictures tend to have the same depth of field, nothing comes even close to what the 18-55 at f.5.6 can do. The same thing goes for the Helios lens too. The guy i bought the Helios from said he had the same problem with his K10 with manual lens. Does anybody else here have the same problem? When you adjust the aperture of the helios past f4, does the viewfinder continue to get darker? If you take it off the camera and do the same thing, does the aperture continue to get smaller?

05-09-2012, 03:16 PM	#4
alphanerd Senior Member Join Date: Mar 2011 Posts: 119	Are you focusing to the same distance with the lenses? Distance to subject matters a lot with regard to depth of field.

05-09-2012, 09:44 PM	#5
Poliyoyo Inactive Account Join Date: May 2012 Posts: 3 Original Poster	Yes, i'm focusing on the same object from the same vantage point.

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