Vivitar 28mm F2.5 Lens

[Affinity]

Hello Forum,

I'm a long time lurker here. This is one of my favorite forums.

I recently obtained a 28mm lens that was labeled as T-mount in the listing. However, after obtaining it, it doesn't appear to be T-mount. In fact, there are no threads at all at the base. It's smooth on the sides and tops (see pictures). Can anyone help me identify what lens mount this is?

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[visualopsins]

The smooth part is the inner ring of a T2 adapter screwed onto the T2 mount.

[Alun Thomas]

As per Visualopsins' comment, the part you can see 'should' unscrew, however I have had lenses where I could not manage to do this, I ended up getting another T2 lens mount and separating the inner and outer rings, and then fitting it to the lens I neeeded it on. The outer connects to the inner using typically 3 grub screws. This arrangement allows the user to rotate the lens so that it sits in the correct orientation on the camera, i.e. with the focus and aperture marks facing upward.

[marcusBMG]

I had a lens like this where this inner t-mount part was epoxied on! But I still managed to get it off by judicious heating with an air gun.

[Affinity]

Thank you everyone for the replies and clarification.

Does anyone have a tool in mind that could grip this ring without scratching it?

[Affinity]

[visualopsins]

[Affinity]

Took this lens for a walk. It will focus beyond affinity by a little bit. Is that the fault of the adapter or lens? This lens has a unique feature I haven't encountered before. You can set the limit on the aperture and then there is a hard stop at that particular aperture.

The aperture ring is also stepless.

This lens seemed to handle flaring better than most others I own of the same era. But I didn't get to test this enough.

I bought this lens for video mostly. The results on my D850 for pictures are acceptable to me and somewhat as you expect -- soft wide open, improves with stopping down. It wouldn't be a goto for landscape shots for me however.

Pictures are SOOC but resized and compressed.

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[Alun Thomas]

Your lens is typical of third party lenses in the mid to late 60s, many of which had preset aperture mechanisms. Your particular example is a Vivitar 'Pyramid Preset'
http://camera-wiki.org/wiki/Vivitar#Compatible_T_System_Family
I have a copy of the same lens, as well as a later 28/2.5 automatic copy. I kept the earlier copy and sold the automatic version, the earlier copy seemed just that slight bit better in IQ.

[Affinity]

Thanks for the information Alun.

This lens hasn’t enticed me yet despite being useable but I have not tried it for video. What is your opinion of it?

[Alun Thomas]

I always voice my opinion on a lens in terms of what else was available at the time. A good copy of the Vivitar/Kiron 28/2.5 is perhaps not quite as good at F8 as a Camera manufacturers (Nikkor-H, Auto-Rokker, Canon FLII, Super Takumar) 28/3.5 lens, but it doesn't lag by far, and has a wider aperture if needed. I chose that comparison because I believe that is what the Vivitar was aimed to compete with.
The build quality of that lens line is also very good, every bit as good as a Camera Manufacturer was capable of.
The Kiron is one of my favourite three 28s from a third party manufacturer of that era, the other two being the Makinon 28/2.8 from the early 70s and the Sun manufactured 28/2.8 from around 1969.

[D1N0]

These also come with a slightly wider filter thread (67mm instead of 62). Probably to deal with vignetting when using filters rather than a larger front element.