Noob question on Caltar 90mm f8

[JesseJ]

Hello, I just got one off ebay and it has a pentagon shaped aperture. I've never seen that in other formats. Is this normal for this lens? I also got a 180mm Sironar N which I was hoping to compare against, but it has a hexagon aperture. Appreciate any input on this. Thank you, Jesse

[Tin Can]

Welcome!

Compare Bokeh wide open and stopped down

[JesseJ]

Thank you, and thank you for your reply. I'll do that, hopefully it's normal for this lens.

[BrianShaw]

Normal for that brand of shutter, and many other shutters in all formats.

[JesseJ]

@BrianShaw, Thank you.

[Oren Grad]

What Brian said. Many small- and medium-format lenses have five-bladed diaphragms, and some shutters for view camera lenses do as well. For example, I have an old 90mm f/8 Super-Angulon in Compur 00 that has a five-bladed diaphragm. What shutter is your lens mounted in?

[JesseJ]

@Oren Grad. Thanks. It's in a Copal N0.0. I forgot that the shutter is separate

[Chauncey Walden]

If you would be so kind, what is the full marking on the lens?

[Bernice Loui]

Five bladed iris in the shutter is common and typical for a shutter of this size..

Would a five bladed iris for a wide angle LF view camera lens be significant, most likely no. This is due to the way most LF wide angle images are made which is majority of the image in "sharp" perceived focus. Out of focus rendition and in to out of focus rendition ala "Bokeh". Majority of these wide angle LF view camera lenses are optimized at f16, negating the value of a really round iris.

~Five bladed pentagon shaped iris on a wide angle LF view camera lens, use it in creative/expressive image making with narray-A-care.~

In the case of normal to longer than normal focal lengths, a really round iris can and does make a Significant difference if out of focus rendition and in to out of focus rendition is valued.

Majority of lenses using this shutter size have a five bladed iris, including Hazzelblad-Zeiss CF lenses with Prontor shutters (renders pentagon shaped out of focus items) and many others.

If out of focus and in to out of focus rendition is an important aspect of the image to be made, Choosing/using an non modern plasmat lens design like Tessar, Dialyte (APO artar, APO ronar, APO nikkor), Heilar, Dagor, in a non-modern shutter like older compur, compound, Ilex or in barrel with a really round iris will go a significant ways to aid in rounder-smoother out of focus rendition and in to out of focus rendition.

Completely depends on what the image goals and intent is, this drives lens choice then camera needed to properly support the requirements of the lens.
Bernice

[Corran]

Related to this discussion - many Nikon lenses in Copal shutters came with 5-blade irises. Then at some point they had 7-blade irises instead. These were denoted with an "S" in a circle on the shutter. Nikon's lenses also often had 7-bladed irises. Related? I don't know, and neither do I know if it was requested by Nikon or just done by Copal.

I have a 90mm f/8 with 7-blade and 120mm f/8 with 5-blade.