Samyang 135mm rear lens missing or not

[Elp]

Acquired a t2.2 135mm lens from a reputable camera company only to find there's a lens missing, the one that would be most close to the sensor and whatever holds it in place. A brief test with a DSLR seems to focus, did a test last night and will process shortly but wondering if there was ever a design change or is the rear lens genuinely missing.

 

 

Edited December 16, 2022 by Elp

[vlaiv]

There seems to be at least 9 different models of Samyang 135 F/2.0 - and on top of that - you have cinema version T2.2

It could be that what you see in top image is say Canon EF mount, and you have some other mount?

Each of those different mounts have different flange focal distance - and could have different rear end. Sometimes, optical element is used to move focus position closer or further.

[barbulo]

6 minutes ago, vlaiv said:

could have different rear end

+1 for that. See the official web page.

Perhaps this is yours:

Edited December 15, 2022 by barbulo
Add pic

[Elp]

29 minutes ago, vlaiv said:

you have some other mount?

Definitely it's a canon EF as I tested it with my 600d and my Eos to m42 adaptors. Focus seems to be found (until I process my star images to see in more detail), the FL was calculated as 130mm too after plate solving so I'm wondering what that last lens actually does. Backspacing also seemed correct at around 44.5mm.

The one thing I did notice was the infinity focus point was in a different area from that of my other lens which is all present and correct.

Edited December 15, 2022 by Elp

[vlaiv]

I guess that best course of action would be to contact that reputable company and see if they know the reason for missing last lens (or if it is supposed to be there in the first place).

Unless someone here happens to have exact same model so you can compare.

[Elp]

Ive contacted them, see what they say.

This is a stacked result, focus isn't quite right, toward the right maybe a little tilt, I have this problem with both of my O3 filters, the general speed one and the fast speed, both Baader.

[vlaiv]

30 minutes ago, Elp said:

This is a stacked result

Was this at full aperture? Try stopping it to F/2.8 and see if that improves corners

[Elp]

10 minutes ago, vlaiv said:

Was this at full aperture? Try stopping it to F/2.8 and see if that improves corners

T2.8, always shoot at that with this lens. I get the o3 one sided flaring issue with my refractor and SCT too. Need to do more testing with the filters.

[Ratlet]

Something funky going on with the star shapes.  They're all flaring towards the centre of the image.  Might be the backfocus is too close?

[ollypenrice]

Certainly experiment with backfocus.

Olly

[Elp]

Think I might, when it's a little warmer...