Samyang 135 question

[Paul2019]

Hi all, 

Fun question! I’ve seen some Sony Samyang 135mm for sale considerably cheaper than the canon alternative. I was wondering if it is possible to use a Sony lens on a canon DSLR for Astro work? 
 

eventually I will upgrade to a Zwo camera then use a m48 mount but until that point will it work? Cost saving is around £200 

[Elp]

Not possible. Sony e mount backfocus is around 18mm, Canon EF is 44mm. You can use Canon on Sony, but not the other way around due to this distance difference. You can use either with an astro camera.

Edited August 15, 2023 by Elp

[tomato]

Yes you can use them with an astro camera but  it might not be as straight forward as using the Canon variety as I’m not sure if anyone sells a suitable adapter for this lens to mate with the camera. Myself and @Tomatobro have gone the Sony route by turning up suitable adapters.

I’m no DSLR expert but does anyone sell a Sony to Canon adapter and what does this do to the back focus spacing? Just read the previous post, looks like a non starter.

[Elp]

You can get a Sony e mount to m42 adaptor, I've got one. Unlike the ZWO Canon adaptors though there's little space to clamp on either lens or the adaptor, your best bet is getting a ring/clamp mount to hold the astro camera body and fashion some sort of support for the bottom of the lens if you're planning on using a Sony lens.

Edited August 15, 2023 by Elp

[Paul2019]

Had a Google for an adaptor, as previously mentioned it appears to be non possible. Thanks for the help

[tomato]

The Sony lens housing that the astro camera attaches to is thin plastic secured by three tiny screws. Some type of additional camera support is essential.

[Elp]

This is the one I've got, it's quite secure:

https://www.firstlightoptics.com/zwo-accessories/zwo-sony-adapter-for-asi-cameras.html

[tomato]

Here are mine, an initial lash up using whatever I had lying around and then a much improved properly engineered version which allows on mount adjustment for camera tilt.

 

[Elp]

Looks good, anywhere you can support it helps, depends on the lens being used, the SY135 is particularly heavyish.

[Raum]

On 15/08/2023 at 19:50, tomato said:

Yes you can use them with an astro camera but  it might not be as straight forward as using the Canon variety as I’m not sure if anyone sells a suitable adapter for this lens to mate with the camera. Myself and @Tomatobro have gone the Sony route by turning up suitable adapters.

I’m no DSLR expert but does anyone sell a Sony to Canon adapter and what does this do to the back focus spacing? Just read the previous post, looks like a non starter.

I am in the same postion as the original post. Except it is a sony a mount (should have a bit more backfocus then the canon version). Do you know anything about it? I plan on conneting it with the 2600mc.

[tomato]

I’m sure @Tomatobro will supply details but basically a m42 male adapter is screwed to end of the existing Sony lens adapter, as in the photo. As emphasised previously, this thin, plastic adapter is attached to the lens body by three small screws, and will not take the weight of an Astro camera alone, some form of additional camera support is required.

[Raum]

48 minutes ago, tomato said:

I’m sure @Tomatobro will supply details but basically a m42 male adapter is screwed to end of the existing Sony lens adapter, as in the photo. As emphasised previously, this thin, plastic adapter is attached to the lens body by three small screws, and will not take the weight of an Astro camera alone, some form of additional camera support is required.

Does he have the a-mount version? By the way, why don't you remove the plastic part you should gain a lot of backfocus that way by using a short 3d printed adapter.

Edited March 12 by Raum

[barbulo]

I'm not in favor of adding a camera support as it can be a source of induced tilt in this tilt-sensitive setup. Unless you manage to place and hold the sensor preciesly square to the optical train, you'll face tilt issues.

In my view, the best solution is to place the support somewhere between the lens and the camera.

[Tomatobro]

2 hours ago, Raum said:

will supply details

I have done four of these Sony mount Samyang lenses to date but as I recall the rear of this lens was different to the others. Not sure I have a record of why I did it this way.

[Raum]

5 minutes ago, Tomatobro said:

I have done four of these Sony mount Samyang lenses to date but as I recall the rear of this lens was different to the others. Not sure I have a record of why I did it this way.

Do you mean the e-mount or a-mount? I am talking about the a-mount which should have a backfocus of 44.5mm.

[Tomatobro]

1 minute ago, Raum said:

Do you mean the e-mount or a-mount

No idea. I purchase the Sony versions second hand because they are a lot cheaper than the Canon ones.

The mounting that Tomato has is different to the others probably due to the back focus of the Rising Cam camera but I don't know for sure. I have attached pictures of my dual setup for comparison

[Raum]

Thank you for the pictures, hopefully the a-mount doesn't have other screw designs.

[Elp]

Maybe try this, I dont know if it'll work as the adaptor technically isn't suited to the 2600 and whether you have enough room to add in adaptors in between.

Lens > a mount to e mount adaptor > zwo e mount to asi camera adaptor > various male female step up/down rings to attach to the 2600 > 2600.

I suspect the camera sensor may be too large for the lens adaptor aperture though, might be able to machine the internal out but it'll need a female thread putting back in as the back end of the adaptor is designed to sit over the nose of the smaller zwo dso cameras. 

Edited March 12 by Elp

[Elp]

I haven't got an a mount lens at hand, but there may be the slim chance you can take off the a mount bayonet fitting on the rear of the lens and swap to an e mount (or better yet an ef mount), this is largely dependent on the diameters between the mounts being the same, sourcing them can also be an issue though you may be able to take one off those standard lens adaptors you can buy, fixing hole positions will be the next issue.

Edited March 12 by Elp

[tomato]

I do find that some tilt adjustments are needed every time the camera goes on the lens, but the camera support facilitates this operation. I wish it was as easy to adjust tilt on my RASA8 set up.