156 replies to this topic

[Tom62e]

Yup. That's a hard pass for me.

With a Roki 135mm, at F2.8, I can get sharp stars throughout AND at half the cost.  William Optics selling the RC Mini at close to $1k is almost highway robbery.

Excuse my ignorance but I have to ask.  Is there a way to set up an auto-focuser like the ZWO EAF on the Roki/Samyang 135mm?

[Voyager_sr2]

Excuse my ignorance but I have to ask.  Is there a way to set up an auto-focuser like the ZWO EAF on the Roki/Samyang 135mm?

Of course, plenty of options. Here is first result from google https://agenaastro.c...-135-eaf-s.html

[Tom62e]

Of course, plenty of options. Here is first result from google https://agenaastro.c...-135-eaf-s.html

Nice.  This is good stuff.  I think I'm going to try one since I already have the EOS adapter for my astro-camera.  Hopefully I can find a good used one.

[Kevin_A]

Excuse my ignorance but I have to ask.  Is there a way to set up an auto-focuser like the ZWO EAF on the Roki/Samyang 135mm?

Sure is… Astrodymium cradle assembly with EAF adapter.

 

[markalot63]

Sure is… Astrodymium cradle assembly with EAF adapter.

 

 

Same, on the table for some flat frames at the moment.  I have the Nikon version and use the ZWO Nikon adapter with built in filter drawer.  I did have to use some thin spacers (also made by Astrodymium) for back focus but this setup is really reliable for me.  My version of the  lens needs to be stopped down to 3.X to fix bloated stars though.   

 

 

I was looking at the mini cat to solve the star spike issues I get with this lens being stopped down. 

Edited by markalot63, 31 October 2024 - 12:15 PM.

[fmendes]

Excuse my ignorance but I have to ask.  Is there a way to set up an auto-focuser like the ZWO EAF on the Roki/Samyang 135mm?

 

There are a number of ways. Beside the one with the ZWO EAF, I have made my own with worm mesh that can be engaged/disengaged any time (I didn't trust my first EAFs). 

 

I have modified mine to replace the bayonet by a M48 thread: https://www.cloudyni...-modifications/

[RetiredDave]

I returned my copy of the Minicat for an exchange, as I posted earlier. On APS-C, corner stars and even stars near the edges were really bad. BlurXterminator could not completely correct the stars in some images. I think I received a particularly bad one. In any case, the replacement was backordered, so I just decided to cancel. I'll wait until WO releases an improved version of this scope that does not require software to remedy the shortcomings of their hardware.

[fmendes]

I returned my copy of the Minicat for an exchange, as I posted earlier. On APS-C, corner stars and even stars near the edges were really bad. BlurXterminator could not completely correct the stars in some images. I think I received a particularly bad one. In any case, the replacement was backordered, so I just decided to cancel. I'll wait until WO releases an improved version of this scope that does not require software to remedy the shortcomings of their hardware.

 

I remember once I got a real bad session with the Rokinon 135mm. Stars were huge. "BXT will fix it", I thought. But BXT cannot reconstruct what was behind the stars; for small differences, it will "pull" data from surroundings, but for big differences it will leave a dark space between the star and the background.

 

[Astro-Goat]

I remember once I got a real bad session with the Rokinon 135mm. Stars were huge. "BXT will fix it", I thought. But BXT cannot reconstruct what was behind the stars; for small differences, it will "pull" data from surroundings, but for big differences it will leave a dark space between the star and the background.

 

 

That is true and can vouch for that. I've experienced that with btx.  
The way I minimized that was I used a step down ring, shoot it at f2.8, and used thin spacers at the back (i had a few spare spacers that came with a 294mc pro).

But at the end of the day, if you are posting the complete image on Instagram (like i do to get all the likes and to impress my family and friends in this "complex" hobby to make me look like an engineering genious) it isn't noticeable.  In fact, you'd have to pixel peek very very hard.

Overall, the Roki 135mm is far better than that Redcat Mini at 1/2 the cost.  Minus 1 point , for me, for William Optics. They should be ashamed of themselves for for selling that Mini. To me it's just a cash grab for them; very limited made. I can 99.9% tell you William Optics won't be doing a 2nd revision of the Mini Cat.

[rapture91]

A user on the German „Astronomie.de“ forum just posted a photo in the image gallery and said that his copy performed fine and stars were „pretty round“ in the corners.
I asked him if he could show an image of taken with PI‘s AberrationInspector before applying BlurXT.
As soon as he will reply, I‘ll post the picture here. Maybe the later production batches have been improved, since he got his copy a few days ago?

CS
Johannes

[Momerath]

Its been a bit for me. About 5 years (been too busy to image). I have extra time now and a little extra money to burn.  I was looking to get a new scope and a lighter mount. I currently have a AT65EDQ ( bought quite a few years ago and still quite awesome). Its mounted on an older CGEM DX that came with my Celestron 11 EdgeHD. My only experience with refractors is with the AT65EDQ. How would this compare? Image quality etc.

I was looking for something a little faster . I am also interested in something around the 80- 100 range. Open to suggestions. Im also looking for a mount/tripod that is way lighter than what I have. Something a little more portable and still handle well.

 

Thanks

Carl

[Voyager_sr2]

Received my scope, obviously got heavy clouds and rain too, so no optics test yet.

But I know now why it is so expensive: there is a multitool in the package while nothing to do with it, because scope is assembled, some expensive envelope for warranty paper and again the scope fully assembled so the case is twice as big as it should be.

Also there is a small piece of lie from the very beginning: inspection check list contains "dewshield retract smoothness" box checked while there is no retractable dew shield.

They also put some nice stickers though.

Edited by Voyager_sr2, 02 November 2024 - 09:19 PM.

[wheatgeneration]

I got one today. I was thinking I would send it back after all the fuss. I ordered it before this mess was apparent.

 

Recently I have been on a quest to find the best super wide what have you I can find. I am working on learning to make very big mosaics. I have been trying:

 

Zeiss Milvus 50mm 1.4, a $1400 lens. returned due to very bad corners. Zeiss recommended another that costs 4K. I may rent one.

Nikon Micro Nikkor PC85mm tilt-shift lens, relatively old but very sharp lens. A lens I already had.

Zeiss Makro 100mm f2, an older macro lens. Very sharp. Already had. Pretty good results.

Askar FMA135. Pretty good results.

Rokinon 135mm f2. The common wide lens. Okay results. Need to keep trying.

Askar FMA 180 pro. Okay results. 

 

So I decided to at least give the Mini a shot. I have also been trying various dual-band filters and the latest is the IDAS NBZ II. I did a test shoot of NGC7000 recently with all of the above, the last being the FMA 180. 

 

Tomorrow night I will shoot the same number of exposures with the Mini with the same camera, filter, etc. and compare them.

 

I have to say it's a cute lens. And shooting with a guide camera longer than the main one is fun. I do this regularly.

 

[wheatgeneration]

Shooting four minute subs right now. They look pretty good in the ASIAir app. I don't see anything obviously bad. The subs look a bit brighter than I got for the FMA180, which of course makes sense due to the bigger aperture.

 

The air plate solves the focal length at 174mm. Sharpness reminds me of the RedCat 51 I would say. 

 

Not quite as good as something like my favorite telescope, a Vixen VSD100 (380mm), but the fanciest scopes I have, which I guess are the Stellarvues, still need cleaning up. I won't be surprised if I end up keeping the mini.

 

I will process this shoot exactly the same as the FMA180 shoot I did recently and post aberration mosaics, etc. for both uncorrected and processed. And the final images. I try to be objective, not so I can be "right" but just for myself. I want to make the best images possible and the harder that is to achieve, the more fun I have.

[Kevin_A]

Same, on the table for some flat frames at the moment.  I have the Nikon version and use the ZWO Nikon adapter with built in filter drawer.  I did have to use some thin spacers (also made by Astrodymium) for back focus but this setup is really reliable for me.  My version of the  lens needs to be stopped down to 3.X to fix bloated stars though.   

 

 

I was looking at the mini cat to solve the star spike issues I get with this lens being stopped down. 

The only issue with super fast glass like a Roki is backfocus. Fast glass needs to be very precise. I have 4 different zwo cooled cameras and the official sensor to flange distance of all of these cameras is 17.5mm. Unfortunately zwo cameras can vary by as much as 0.3mm and this is not tolerable on a f2 lens setup. My 183 and 2600 are exactly at 17.5mm, my 533 is 17.3mm and my 585 is 17.7mm sensor to flange distance. I tested and measured all my cameras to verify due to swapping issues.  ZWO does not provide this undisclosed tolerance as most typical f7 scopes would not care. So when adding shims to offset for filters i had to test all my cameras first so I could compensate for this when using this lens. On my 183 and 2600 I add 0.61mm of shims for a 1.85mm thick filter and when using my 533 I add 0.81mm, my 585 comes in at 0.41mm for precise spacing. My images are fabulous now. The new WO scope should not have these issues, but then again there are disclaimers that leave me without confidence too. 

[wheatgeneration]

So these aberration mosaics represent a fairly close comparison between the FMA180 and the MiniCat. My impression of the processed images is the MiniCat collected more subtle data such as dust, but clearly the FMA image is far less distorted in the first place. The MiniCat image ends up a bit better I guess because it is faster, but the Askar is obviously cleaner to start with. I was hoping for better from the MiniCat. But honestly, if you look at images from the best optics, they all need a lot of work. We are shooting through miles of atmosphere and competing with a lot of light pollution, etc. Pixel scrutinizing is always a relative thing. Flaws are always there.

 

MiniCat stacked, color corrected and nothing else.

 

MiniCat processed.

 

FMA180 stacked and color corrected.

 

FMA180 processed.

[wheatgeneration]

These are the two minimally processed images. Rotation is close, but not exactly the same. Two hours through an IDAS NBZ II, ASI2600MC. Personally, I prefer mono or the Optolong L-Ultimate.

 

Processing was SPCC, BXT, AutomaticBackgroundExtractor, NXT, SXT, Photoshop camera raw on the starless image, screenstars.

 

MiniCat.

 

FMA180.

Edited by wheatgeneration, 04 November 2024 - 02:03 PM.

[markalot63]

These are the two minimally processed images. Rotation is close, but not exactly the same. Two hours through an IDAS NBZ II, ASI2600MC. Personally, I prefer mono or the Optolong L-Ultimate.

 

Processing was SPCC, BXT, AutomaticBackgroundExtractor, NXT, SXT, Photoshop camera raw on the starless image, screenstars.

 

MiniCat.

 

 

FMA180.

 

What is the oversharpening distortion around the stars in the Minicat image?  

 

[fmendes]

So these aberration mosaics represent a fairly close comparison between the FMA180 and the MiniCat. My impression of the processed images is the MiniCat collected more subtle data such as dust, but clearly the FMA image is far less distorted in the first place. The MiniCat image ends up a bit better I guess because it is faster, but the Askar is obviously cleaner to start with. I was hoping for better from the MiniCat. But honestly, if you look at images from the best optics, they all need a lot of work. We are shooting through miles of atmosphere and competing with a lot of light pollution, etc. Pixel scrutinizing is always a relative thing. Flaws are always there.

 

 

Thank you for putting these side by side. By comparison, this is the Rokinon at f/2.8, APS-C sensor. Only Graxpert and BXT, "Correct Only". I didn't even clip the edges.

 

 

And this is the final processed image:

 

 

 

One weird thing is that some very specific stars produce a very bright halo. Not any red, but a specific red.

Edited by fmendes, 04 November 2024 - 04:39 PM.

[wheatgeneration]

Thank you for putting these side by side. By comparison, this is the Rokinon at f/2.8, APS-C sensor. Only Graxpert and BXT, "Correct Only". I didn't even clip the edges.

I have the Rokinon. Mine isn't quite as good at yours.

 

For me at 135, the tiny Askar 135 is actually not bad.

[wheatgeneration]

Here is a stacked shot of IC1805 with the FMA135. SPCC and the background cleaned up a little. No correction.

 

[wheatgeneration]

What is the oversharpening distortion around the stars in the Minicat image?  

I think so? The images above are labelled. If that is the processed image, BXT was used once with default settings. That image does have a lot of dust behind many of the stars. I didn't put any fuss into processing. Just trying to get an idea what the lens can do.

[Drothgeb]

Considering it has 6 elements, and that WO has even mentioned adjusting the back focus with shims in the manual, it’s not really a Petzval. 
 

Has anyone tried adjusting the back focus on theirs to improve the stars?

[markalot63]

I think so? The images above are labelled. If that is the processed image, BXT was used once with default settings. That image does have a lot of dust behind many of the stars. I didn't put any fuss into processing. Just trying to get an idea what the lens can do.

If it was BXT then in my rather newbie opinion this is a clear sign the distortion is too much for BXT to correct without screwing up the background.  In my opinion one of the benefits to a fast lens is to grab the background (dust, etc) along with the main object.  

[fmendes]

I have the Rokinon. Mine isn't quite as good at yours.

 

For me at 135, the tiny Askar 135 is actually not bad.

 

Feel free to ask me on another topic, so we don't change the subject here. But it needs some attention to get good at wider apertures.