144 replies to this topic

[Jinux]

I have had that issue where the lens hits the hard stop with the EAF, sometimes it does cause problems, sometimes not. With the Samyang 135mm it is possible to adjust the focus ring and extend the beyond infinity focus throw, which eliminates that problem. If you don't want to undertake that task you have two options, decrease the step size and hope the focus curve can still be accomplished accurately over a smaller focus distance OR decrease the back focus distance which will make the camera come to focus before the infinity distance on the lens. Obviously the second one is only possible if there's an even thinner lens adapter, which isn't the case here. You might get lucky and the lens might come to focus a little before the infinity mark and you won't have any issues, otherwise you'll have to decrease step size or adjust the focus collar.

Rokinon 135mm seems to have enough margin over infinity focus. Probably 0.1mm margin I added (0.1mm thinner)  also contributed as well.

On field test, autofocus ran well without hitting hard stop.

All CNC'ed components including ring, clamps and holding plates worked well on the field but critical focus zone was too narrow for this fast optics. 

 

CFZ = 1.6 * lamda * F^2, where lamda is wavelength of green = 500nm

 

With F/2.8 setting on Rokinon, CFZ is mere 6.3um which is lower than my CNC tolerance (I don't know how much precision typical manufacturing has.)

So, I need to adjust some tilt plate using screw. I don't know how Eric got that flat with minor tilt with my 3D printed plate. 

 

Also, light pollution on my backyard is quite high and change over time in frame, so it's very difficult to process.

So, I designed 77mm filter to M48/0.75 2" filter adapter and plan to put this filter in front of the objective lens. This will handle light pollution and step down the F ratio to increase CFZ.

 

Need clear nights to test this out but rain is coming. Should've done this during summer days when temperature is tolerable, abundant clear days, and long list of wide field objects in the sky.

Attached Thumbnails

• 
• 

[Jinux]

It would be interesting to add 2" EFW in front of objective lens to have automated NB imaging.

I think it's easy to model and CNC. 

[erictheastrojunkie]

 I don't know how Eric got that flat with minor tilt with my 3D printed plate. 

 

 

Complete blind luck is all it was. Obtaining critical focus with the lens can be quite difficult, also if your autofocus program selects a focus star that is more towards the edge vs centrally that can also play a big role, imaging with fast optics like this can be VERY difficult when it comes to focus and tilt. One thing I will say is that that Rokinon 135mm holds focus very well over the course of a night, l had looked at some logs saved from multiple imaging sessions and even with big temperature swings the focus point barely shifted 10 steps over the course of multiple nights worth of imaging. If your temps aren't shifting by more than maybe 20 degrees in a night it may not even be worth running the autofocus because it could make focus worse if it happens to be off by a little bit. That's just something you have to test for yourself though. 

 

Gradients with a lens like this can be a beast to remove, especially complex light pollution gradients WITH filters. You also have to be careful with this lens and filters on the front of the lens, I know when I used a filter in front of one of my copies of the lens I got some nasty concentric circles that could not be fixed, maybe filter specific, but I've heard multiple people state the same. 

 

I really like the "retro" look of having wood elements on the setup, something about the modern element of imaging with the mount/lens/camera/computer goes well with the wooden components. 

[Jack’sDad]

As someone heavily entrenched in the ZWO & Sony environments who just stumbled upon this thread (and didn’t read it all, yet), color me interested. Looks like I’ve got some reading to do.

[Jinux]

Gradients with a lens like this can be a beast to remove, especially complex light pollution gradients WITH filters. You also have to be careful with this lens and filters on the front of the lens, I know when I used a filter in front of one of my copies of the lens I got some nasty concentric circles that could not be fixed, maybe filter specific, but I've heard multiple people state the same. 

I designed 3D printed filter mount for 2" filters and used IDAS NBZ filter for the second light shot. 

 

 

and I got a decent pictures out of it. Background gradient is okay and not as nasty as no filter one and easily removed by all my processing tools (Siril, Startools and GraXpert) without much differences. 

When I had no filter, only GraXpert was able to deal with that uneven gradients. And of course, background noise is much less.

One of the improvement was to add flocking on lens hood. My club members recommended to do it when I consulted about nasty concentric circle gradient on my first light image.

 

Only 88min available to picture before it sets down over my house roof.  

 

 

Now I'm convinced and will attach filter wheel in front of the objective lens. This scheme has many advantages over filters before the sensor.

First, 48mm aperture with 135mm focal length lens means 135/48 = F2.81 It's still blazing fast, so I'm not concerned about getting less lights with reduced aperture. Even 36mm filter, opening is 34mm and it would yield F3.97 and many people use this 135mm/F2 at F4 to get better sharpness. 

Second, filter in front of objective lens means, no filter induced halo, no refocus due to filter change, no worry on dusts on filters, no separate flats per filter, no fast optics optimized filter required. Sounds like dream to me.

 

Of course, I would add an UVIR filter on "telescope" side opening of filter wheel with some 3D printed hood to screw in to block sideway lights and dusts.

This is a project until coming two series of storms go away in California. 

[KLWalsh]

This might be useful for some:

https://www.amazon.c...,aps,131&sr=8-5

This inexpensive extension tube set includes a section with a bayonet interface for Sony A lenses. The different sections of the tube set screw together using an M57 thread. (That’s what I measured with calipers.) The M57 is an oddball size. Preferably, an M57 to M48 adapter would allow the bayonet section to be mated to an ASI camera.
From my searches online, it appears that Borg telescopes use M57 threads. So perhaps Borg has an adapter that would work.

[Tbuckley94]

This might actually be possible. And you might actually be making your adapter thinner than it needs to be because your lens doesn’t need to be so close to reach infinity.

While in air the backfocus of a Sony E mount lens might not be nearly enough to reach the focal plane, if we lived in a world where air had a much higher refractive index it could.

So my thought is, fill the air gap with a higher refractive index material like glass. machine the adapter out of metal, make sure your tolerances are tight. Add a pocket for a thick optical flat/window with an AR coating just behind the lens but before the sensor, so that it fills the air gap with as much glass as possible. But not too much that your lens crashes into it at infinity (assuming it moves).

With a bit of math/ray tracing, or perhaps trial and error if it’s easier, you could move the backfocus onto the chip so it reaches focus without introducing any abberation to the rays and without any additional shaving of the thickness of your mount or camera.

If you are dubious of abberation free claim consider the effect of the sensors cover glass on your PSF… pretty trivial. Same with on chip filters.

This change in backfocus is actually something you need to routinely account for when designing cooled infrared cameras since the cover glass is commonly made of silicon a material with a high refractive index that shifts the focus appreciably compared to what you’d expect from a CAD model alone or if the window was made of sapphire.

[Chiefsmith]

BTW, I created another model for small ASI camera that has T-thread in front.

 

https://www.thingive...m/thing:4664592

 

More than 30 folks downloaded but didn't get any feedback whether it's working or not. Interesting.

I sent these to one of CN'er who promised to give me feedback. I'll report later.

I bought the ZWO adapter for Sony Nex lens thinking I could use an M42/M42 adapter to connec the ZWO adapter to my Altair269C and ASI678MC cameras. I just received the ZWO adapter the other day and it does not work. The ZWO adapter works as an extension tube for close-up just like the extension tubes I used in the 70's for that kind of work. I completely forgot how that worked; however, my Meike 35mm f/1.7 mounted on the ASI678MC with the ZWO adapter and the M42/M42 adapter produces very sharp images when focused down to about 30cm or so - not quite able to focuse on anything farther away than that but the close focus is really sharp.

 

Your second adapter that you posted way back in December 2020 is exactly what I think I need to make my two cameras work with the wide angle Meike lenses that I have. These are fully manual lenses that I have used on Canon cameras. I now have a wide-angle Meike lens with the Sony e-mount. I set all of this up specifically to use the Altair269C for wide field imaging - think 35mm f/1.7 mounted on the Altair269C with SAO70355 as the center of the image.

 

If your second adpater allows for sharp focusing on stars, and you are willing, I would very much be interested in either testing one of these or maybe buying one from you. I think it is possible to send private email messages but I am not too sure how to do that. Please let me know what you think.

 

 

 

Food for thought: You could probably have these made by one of the companies in China for not too much money. The ZWO version only works on their cameras that have that black 11mm ring. Your second design, if you have it working, will work on just about every other ZWO camera as well as cameras from Altair of any other that have the female M42 threading for attaching to a telescope. 

 

I just read on your designer page that you are unable to test this adapter with your Sony lens because of the electronic focusing issue. Again, I would very much like to try your second adapter!

Edited by Chiefsmith, 12 September 2024 - 11:29 AM.

[Jinux]

It's been a while I have updated this thread. I was frustrated by the precision and repeatability of my desktop CNC.

Long story short, I bite the bullet and invested proper CNC "mill" and now it really cuts in precision easy.

So, my test project was converting Rokinon 135 E-mount lens back flange to M42/0.75 to directly screw into faceplate of 2600MC.

It replaces existing bayonet and achieves infinity focus with 17.5mm 2600MC's backfocus.

 

Rokinon 135/F2 with M42/0.75

 

When screwed in to 2600MC's faceplate it would look like this. 

 

Screwed into 2600MC. 

 

I haven't blackened internal threads yet, so it was hand held moon shot to check infinity focus and it does with a bit of rotation margin which is desirable for autofocus run.

 

I still need to test tilt testing with stars but that would be later. First, I have to blacken the inner tube.

Also, if I have 4th axis, I may be able to remove one more back piece of the lens and make it possible to add filter slider or even filter wheel application. 

Good thing about this is that this may work for all Rokinon lens regardless of mount type or focal length. Downside is that this is very Rokinon lens specific design.

 

I'm expecting using this to take C2023/A3. Gotta run to blacken the inner tube!

 

 

[Jinux]

I bought the ZWO adapter for Sony Nex lens thinking I could use an M42/M42 adapter to connec the ZWO adapter to my Altair269C and ASI678MC cameras. I just received the ZWO adapter the other day and it does not work. The ZWO adapter works as an extension tube for close-up just like the extension tubes I used in the 70's for that kind of work. I completely forgot how that worked; however, my Meike 35mm f/1.7 mounted on the ASI678MC with the ZWO adapter and the M42/M42 adapter produces very sharp images when focused down to about 30cm or so - not quite able to focuse on anything farther away than that but the close focus is really sharp.

 

Your second adapter that you posted way back in December 2020 is exactly what I think I need to make my two cameras work with the wide angle Meike lenses that I have. These are fully manual lenses that I have used on Canon cameras. I now have a wide-angle Meike lens with the Sony e-mount. I set all of this up specifically to use the Altair269C for wide field imaging - think 35mm f/1.7 mounted on the Altair269C with SAO70355 as the center of the image.

 

If your second adpater allows for sharp focusing on stars, and you are willing, I would very much be interested in either testing one of these or maybe buying one from you. I think it is possible to send private email messages but I am not too sure how to do that. Please let me know what you think.

 

nex m42 adapter.jpg

 

 

Food for thought: You could probably have these made by one of the companies in China for not too much money. The ZWO version only works on their cameras that have that black 11mm ring. Your second design, if you have it working, will work on just about every other ZWO camera as well as cameras from Altair of any other that have the female M42 threading for attaching to a telescope. 

 

I just read on your designer page that you are unable to test this adapter with your Sony lens because of the electronic focusing issue. Again, I would very much like to try your second adapter!

Yes and no and it depends. I checked the original design writing and I made the adapter 0.3mm longer than the required spec of 18mm backfocus. And one user tried and was not able to focus to infinity. But some lens has margin on infinity focus, so it depends.

To fix this properly, I have to reduce bayonet to camera body margin and move this to strengthen the body. I think it's doable but still 0.4mm thick backplate that connects camera body and lens, a little bit uncomfortable zone.

 

On the other hands, I may ditch this design and create completely new one. 

ASI small camera has top plate as screwed into the body. If we replace this whole thing, there may be even a room for a filter to slide in!

[Chiefsmith]

Yes and no and it depends. I checked the original design writing and I made the adapter 0.3mm longer than the required spec of 18mm backfocus. And one user tried and was not able to focus to infinity. But some lens has margin on infinity focus, so it depends.

To fix this properly, I have to reduce bayonet to camera body margin and move this to strengthen the body. I think it's doable but still 0.4mm thick backplate that connects camera body and lens, a little bit uncomfortable zone.

 

On the other hands, I may ditch this design and create completely new one. 

ASI small camera has top plate as screwed into the body. If we replace this whole thing, there may be even a room for a filter to slide in!

Since my first post to you concerning the adapter I went ahead and bought the ZWO Nex/ASI adapter and the ASI533MC-Pro. I am using Meike manual lenses (25mm, 35mm, and 50mm) with this and everything is working. The weather here is really bad so I have only had one good night to test this setup with SAO70355 as the target center using the 25mm f/1.8 lens. The first shots, as few as they were, were quite good. The Meike manual lens are very good for this. 

 

This is the setup. The filter size on the lens is 49mm so a 49mm to 52mm adapter ring was required for the IDAS Nebula Booster NBZ 52mm IGAD (not attached but always used) filter and lens hood. The filter is threaded to accept the 52mm attachements.

 

[calypsob]

It's been a while I have updated this thread. I was frustrated by the precision and repeatability of my desktop CNC.

Long story short, I bite the bullet and invested proper CNC "mill" and now it really cuts in precision easy.

So, my test project was converting Rokinon 135 E-mount lens back flange to M42/0.75 to directly screw into faceplate of 2600MC.

It replaces existing bayonet and achieves infinity focus with 17.5mm 2600MC's backfocus.

 

Rokinon 135/F2 with M42/0.75

135_back.jpg

 

When screwed in to 2600MC's faceplate it would look like this. 

assembly.jpg

 

Screwed into 2600MC. 

2600_assy.jpg

 

I haven't blackened internal threads yet, so it was hand held moon shot to check infinity focus and it does with a bit of rotation margin which is desirable for autofocus run.

moon_testing.jpg

 

I still need to test tilt testing with stars but that would be later. First, I have to blacken the inner tube.

Also, if I have 4th axis, I may be able to remove one more back piece of the lens and make it possible to add filter slider or even filter wheel application. 

Good thing about this is that this may work for all Rokinon lens regardless of mount type or focal length. Downside is that this is very Rokinon lens specific design.

 

I'm expecting using this to take C2023/A3. Gotta run to blacken the inner tube!

Ive been following along with increasing interest as I buy more lenses for Sony Fe only.

What aluminum are you using? If 6061, definitely try 2011 instead, it has very fine chips. Better imo for camera parts. 
 

Also, regarding that flange you made on the samyang. I use Ef mount, it eould be amazing if you could do a m48 or m54 male thread bayonet replacement. To take it a step further, if you could make a 3mm thick stainless plate that mounts to the lens bayonet, and make a second plate with the bayonet mount that uses an array of bolts to fix it to the 3mm plate. This would allow you to use shims to permanently adjust tilt in the lens. A tilt plate is great, but imo shims tightened by a beam wrench are superior.

Edited by calypsob, 16 October 2024 - 09:14 AM.

[Jinux]

Ive been following along with increasing interest as I buy more lenses for Sony Fe only.

What aluminum are you using? If 6061, definitely try 2011 instead, it has very fine chips. Better imo for camera parts. 
 

Also, regarding that flange you made on the samyang. I use Ef mount, it eould be amazing if you could do a m48 or m54 male thread bayonet replacement. To take it a step further, if you could make a 3mm thick stainless plate that mounts to the lens bayonet, and make a second plate with the bayonet mount that uses an array of bolts to fix it to the 3mm plate. This would allow you to use shims to permanently adjust tilt in the lens. A tilt plate is great, but imo shims tightened by a beam wrench are superior.

Thanks for the interesting idea. M48 is certainly possible. It's just another 0.75mm pitch threads on different diameters but M54 would be a problem as thread location is overlapping with existing 3 screw mounting holes. But if you don't mind cut off threads on 3 locations, it would be doable too. It will screw in just fine anyway.

 

I'm not clear about 3mm plate and another bayonet plate idea as tilt corrector. First, this would work only to the lenses with long enough flange to focal planes like Canon. Second, I guess you don't want to mess with existing bayonet, so cover them with a SS plate (I guess bayonet is 3mm thick in EF mount?) then create new bayonet with tilt fix hole patterns. 

I think this would be already realizable using off the shelve item. Just buy EF to M42 adapter, drill 3 holes to insert grub screws on female bayonet plate (of course disassemble it first and do tapping after) , then you have permanent tilt adjusting adapter.

[calypsob]

Thanks for the interesting idea. M48 is certainly possible. It's just another 0.75mm pitch threads on different diameters but M54 would be a problem as thread location is overlapping with existing 3 screw mounting holes. But if you don't mind cut off threads on 3 locations, it would be doable too. It will screw in just fine anyway.

I'm not clear about 3mm plate and another bayonet plate idea as tilt corrector. First, this would work only to the lenses with long enough flange to focal planes like Canon. Second, I guess you don't want to mess with existing bayonet, so cover them with a SS plate (I guess bayonet is 3mm thick in EF mount?) then create new bayonet with tilt fix hole patterns.
I think this would be already realizable using off the shelve item. Just buy EF to M42 adapter, drill 3 holes to insert grub screws on female bayonet plate (of course disassemble it first and do tapping after) , then you have permanent tilt adjusting adapter.

There are some good ideas brewing here.

I’ll make s drawing of the plate idea. Essentially I want to bypass shimming the samyang bayonet screws because the tubes the bayonet screw into are plastic. So id like a flat piece of metal to replace the bayonet and drill it to replace the factory bayonet. Additionally I would drill and thread this plate to accept an additional plate which would be a m54 or m48 thread. This second plate would thread onto the flat baseplate at 5 points. You could put shims between the baseplate snd this plate.

This as you say is ideal on canon and nikon mirrored mounts. It could carry over to pentax 645 too.
Honestly you could make a permanent tilt plate for a telescope this way as well.

Heres how the do it in cinema https://m.youtube.co...h?v=7XvdMCuhEEg

[Chiefsmith]

Yes and no and it depends. I checked the original design writing and I made the adapter 0.3mm longer than the required spec of 18mm backfocus. And one user tried and was not able to focus to infinity. But some lens has margin on infinity focus, so it depends.

To fix this properly, I have to reduce bayonet to camera body margin and move this to strengthen the body. I think it's doable but still 0.4mm thick backplate that connects camera body and lens, a little bit uncomfortable zone.

 

On the other hands, I may ditch this design and create completely new one. 

ASI small camera has top plate as screwed into the body. If we replace this whole thing, there may be even a room for a filter to slide in!

I just looked at the Rokinon lenses available in my country and I must say they are quite expensive compared to the Meike lens. The lens mounts on the two lens brands appear to be identical and I would not be surprised if they were interchangeable. I have been very impressed with the quality of images produced using the Meike manual lenses that I own. Admittedly, there are many more focal lengths available under the Rokinon label than under the Meike label.

 

 

 

 

In the private message I sent you I stated that the filter was not attached. This shows the 49mm to 52mm adapter, the 52mm filter, and the 52mm lens hood. These are, of course, tightened only enough so that the sizes are visible. The ZWO/Nex adapter takes the place of the ZWO 11mm spacer and acts as an 11mm spacer to provide the necessary 17.5mm backspace for the ASI533MC and the Meike lens. I offered the Meike 35mm because that lens on your ASI2600 provides a very interesting FOV.

 

 

 

 

 

[Shinken]

A Samyang/Rokinon 135mm F2.0 Lens to M42/T2 Adapter already exists and is commertially available:

 

https://ensoptical.c...roduct_id=13220

 

It replaces the Samyanf bayonet for M42 threads allowing enough backfocus space to fit a QHY2600M with its SLIM 7 position filter wheel. I am currently using this setup which produces a 130mm field of view with very good images.

You must use a Canon mount Samyang lens for this to work. I own many Sony lenses but I can't use those in this way so I bit the bullet and bought the Canon-mount lens to make this work.

[Chiefsmith]

A Samyang/Rokinon 135mm F2.0 Lens to M42/T2 Adapter already exists and is commertially available:

 

https://ensoptical.c...roduct_id=13220

 

It replaces the Samyanf bayonet for M42 threads allowing enough backfocus space to fit a QHY2600M with its SLIM 7 position filter wheel. I am currently using this setup which produces a 130mm field of view with very good images.

You must use a Canon mount Samyang lens for this to work. I own many Sony lenses but I can't use those in this way so I bit the bullet and bought the Canon-mount lens to make this work.

I just ordered this on the off-chance that the adapter will work with my Meike lens. The mounts appear to be identical so time will tell!!! If it does not work with my Meike lenses then I will just order a Samyang lens in the focal length that I prefer. A rather expensive way to do business but it gets the job done - I hope.

 

Thank you for this bit of information!

[Jinux]

A Samyang/Rokinon 135mm F2.0 Lens to M42/T2 Adapter already exists and is commertially available:

 

https://ensoptical.c...roduct_id=13220

 

It replaces the Samyanf bayonet for M42 threads allowing enough backfocus space to fit a QHY2600M with its SLIM 7 position filter wheel. I am currently using this setup which produces a 130mm field of view with very good images.

You must use a Canon mount Samyang lens for this to work. I own many Sony lenses but I can't use those in this way so I bit the bullet and bought the Canon-mount lens to make this work.

I can see how this is made and how it would work. The reason it works only to Canon mount is they made it thickness to match with Canon EF mount's 44mm spec. With this much of back-focus, you can do a lot of things. There are even ZWO's EOS to ASI or EOS to ASI filter slider designs on the market. 

Happened to be the one I had is Sony E-mount one that has 18mm backfocus, so the adapter is about 1.5mm thin and probably not suitable for 3-D printing model unless you use better printing material like carbon fiber.

 

I think the best design is the one that Julian is introduced in this forum before. https://www.cloudyni...5#entry13236995

This is universal to all Samyang/Rokinon regardless of camera type and gives room to attach all sort of necessary with enough backfocus distance.

Only drawback is that user has to unscrew 4 screws that hold inner pieces. I think it's doable but I'm not comfortable for doing that.

The reason he designed that way is because it's 3D printing design and can't handle 1.7mm screw on the side, I guess. And my next goal is to make this design in CNC with side holes, so that I don't have to touch inner pieces but just outer tubes. 

[Jinux]

There are some good ideas brewing here.

I’ll make s drawing of the plate idea. Essentially I want to bypass shimming the samyang bayonet screws because the tubes the bayonet screw into are plastic. So id like a flat piece of metal to replace the bayonet and drill it to replace the factory bayonet. Additionally I would drill and thread this plate to accept an additional plate which would be a m54 or m48 thread. This second plate would thread onto the flat baseplate at 5 points. You could put shims between the baseplate snd this plate.

This as you say is ideal on canon and nikon mirrored mounts. It could carry over to pentax 645 too.
Honestly you could make a permanent tilt plate for a telescope this way as well.

Heres how the do it in cinema https://m.youtube.co...h?v=7XvdMCuhEEg

I watched the video and it's related with the calibration between actual focus distance vs focus ring distance by shimming. This is very important for Cinema lens but not for normal lens. 

I still don't fully capture what you want to achieve. A photo of the "plastic piece" and simple drawing of what you want to have would be helpful.

[Markp910]

I bought the ZWO adapter for Sony Nex lens thinking I could use an M42/M42 adapter to connec the ZWO adapter to my Altair269C and ASI678MC cameras. I just received the ZWO adapter the other day and it does not work. The ZWO adapter works as an extension tube for close-up just like the extension tubes I used in the 70's for that kind of work. I completely forgot how that worked; however, my Meike 35mm f/1.7 mounted on the ASI678MC with the ZWO adapter and the M42/M42 adapter produces very sharp images when focused down to about 30cm or so - not quite able to focuse on anything farther away than that but the close focus is really sharp.

 

Your second adapter that you posted way back in December 2020 is exactly what I think I need to make my two cameras work with the wide angle Meike lenses that I have. These are fully manual lenses that I have used on Canon cameras. I now have a wide-angle Meike lens with the Sony e-mount. I set all of this up specifically to use the Altair269C for wide field imaging - think 35mm f/1.7 mounted on the Altair269C with SAO70355 as the center of the image.

 

If your second adpater allows for sharp focusing on stars, and you are willing, I would very much be interested in either testing one of these or maybe buying one from you. I think it is possible to send private email messages but I am not too sure how to do that. Please let me know what you think.

 

nex m42 adapter.jpg

 

 

Food for thought: You could probably have these made by one of the companies in China for not too much money. The ZWO version only works on their cameras that have that black 11mm ring. Your second design, if you have it working, will work on just about every other ZWO camera as well as cameras from Altair of any other that have the female M42 threading for attaching to a telescope. 

 

I just read on your designer page that you are unable to test this adapter with your Sony lens because of the electronic focusing issue. Again, I would very much like to try your second adapter!

AMAZING thank you