RedGreenBlue
29-Nov-2020, 21:40
210016210017210018210019
I have this Petzval lens that I find odd, but then maybe it's not. I'd appreciate feedback.
All measurements are approximate. The focal length appears to be 195mm, the entrance pupil is 43mm or so, indicating an aperture of 4.53. The engraved stops are 4.5 5 5.5 6 8 11 16 22. Pretty much a modern sequence. The image circle is 11 inches. The barrel length seems short to me at 52mm, with attached cells it's 62mm. I also have the flange - not shown.
The aperture engraving is shallow. I thought there was no maker's name but then I noticed what looked like scratches at the front edge of the barrel. I tried to show these in the first photo. I'm pretty sure they are the remains of an engraving which, if so, would lead me to think that the barrel had been shortened. So I took other photos with the cells removed to show the condition of the barrel openings and threads.
The lens shows lots of swirl moving away from center wide open, and is moderately sharp at center. Stopped down the center is sharper and sharpness extends farther out. I removed the lenses from the cells so I know it's a Petzval. Only slight corner vignetting on 8x10 and it fully covers 8x10 stopped down a bit.
Besides the question of the barrel, the other thing I noticed is it seems to me that the angle of view is quite wide. I can only say that it covers a field that's equivalent to a 24mm lens on 24x36mm format in the narrow dimension.
Scott
I have this Petzval lens that I find odd, but then maybe it's not. I'd appreciate feedback.
All measurements are approximate. The focal length appears to be 195mm, the entrance pupil is 43mm or so, indicating an aperture of 4.53. The engraved stops are 4.5 5 5.5 6 8 11 16 22. Pretty much a modern sequence. The image circle is 11 inches. The barrel length seems short to me at 52mm, with attached cells it's 62mm. I also have the flange - not shown.
The aperture engraving is shallow. I thought there was no maker's name but then I noticed what looked like scratches at the front edge of the barrel. I tried to show these in the first photo. I'm pretty sure they are the remains of an engraving which, if so, would lead me to think that the barrel had been shortened. So I took other photos with the cells removed to show the condition of the barrel openings and threads.
The lens shows lots of swirl moving away from center wide open, and is moderately sharp at center. Stopped down the center is sharper and sharpness extends farther out. I removed the lenses from the cells so I know it's a Petzval. Only slight corner vignetting on 8x10 and it fully covers 8x10 stopped down a bit.
Besides the question of the barrel, the other thing I noticed is it seems to me that the angle of view is quite wide. I can only say that it covers a field that's equivalent to a 24mm lens on 24x36mm format in the narrow dimension.
Scott