156 replies to this topic

[Foobaria]

At least they are trying to be honest.   That's enough for me, pass on this one. 

 

There is now some interesting information on the WO website for the Minicat 51.

 

It says “Due to the nature of MiniCat’s fast aperture optical design, edge stars may not be as round as with other RedCats. However, our tests show it still outperforms conventional lenses. With aberration correction software like BXT, peripheral distortions can be perfectly corrected on APS-C sensors, while Full Frame may need some fine-tuning for even better results.”

https://williamoptic...re_after_NfE4EE

 

One of the images shown, an aberration inspector taken from an image of M24 using a APS-C sensor, shows pretty poor star shapes in the edges and corners.  Possibly this is why they recommend using BXT software.

 

Although the Minicat is called a Petzval design, the manual has a short section called “Ultra Flat Back Focus Adjustment” and shows the insertion of a pvc gasket into the optical train as a means of adjusting backfocus, along with a picture of what happens with the wrong backfocus.  

https://support.will...ocus-adjustment

The aberration inspector image of M24 actually looks to me as if the back focus distance was incorrect (camera sensor too close).

 

Andy

[gspinin]

Yikes! That not good. I’m seriously considering a purchase. Ugh.

[Tom62e]

Mine is due to arrive on Tuesday but I'm traveling until the following Saturday, so I won't be home to receive it.  Life is so cruel!

 

Did anyone receive theirs yet?

[Foobaria]

Mine is due to arrive on Tuesday but I'm traveling until the following Saturday, so I won't be home to receive it.  Life is so cruel!

 

Did anyone receive theirs yet?

Please share your experiences here.  Good luck!

[rapture91]

My copy arrived on Wednesday. Fortunately, I‘m going to use the Minicat with the ZWO ASI533 MC and its 1“ sensor, where peripheral distortions should be minimized.

I‘m using BlurXT anyways, so shouldn‘t be a problem.

As a happy user of the Askar FMA180 Pro, what got me was the larger aperture and faster f ratio.

Three hours of imaging with the Minicat at f/3.5 would translate to over 8 hours of data acquisition with the Askar at f/4.5. This way I hope to get the most out of the limited clear sky time we have here in south Germany

I recently imaged M31 with the Askar and plan on revisiting this object with the Minicat maybe today.
Will be interesting to see the differences.

[Tom62e]

My copy arrived on Wednesday. Fortunately, I‘m going to use the Minicat with the ZWO ASI533 MC and its 1“ sensor, where peripheral distortions should be minimized.

I‘m using BlurXT anyways, so shouldn‘t be a problem.

As a happy user of the Askar FMA180 Pro, what got me was the larger aperture and faster f ratio.

Three hours of imaging with the Minicat at f/3.5 would translate to over 8 hours of data acquisition with the Askar at f/4.5. This way I hope to get the most out of the limited clear sky time we have here in south Germany

I recently imaged M31 with the Askar and plan on revisiting this object with the Minicat maybe today.
Will be interesting to see the differences.

Yes, please keep us posted!   And clear skies!

[rapture91]

So I was lucky and got clear skies yesterday. Setting up the Minicat on my AZ-GTi was no different to the Askar FMA180 Pro. The Minicat to me seems to be of even higher quality than the Askar. I also like that it comes with the soft carry case, really handy.
With the Askar, I found it difficult to quickly achieve focus in each new session due to the helical focuser. With the Minicat’s new WIFD design and the built in bahtinov mask, focus was readily obtained.
Another nice feature, the interior of the dew cap is flocked, efficiently preventing dew formation over the entire night (around 10 hours at 7 to 10 °C).
Like the Askar, the built-in rotator makes it easy to perfectly frame the object.

On my 1“ sensor, stars looked pretty good in the corners. Although I still might have to tweak backfocus a bit from the applied 55 mm, to get even better results.

Other than that, I‘ll try to process my images of M31 in the next days and hopefully will be able to post a comprising to the Askar.

So far, I‘m really pleased with the little cat.

CS
Johannes

[Foobaria]

So I was lucky and got clear skies yesterday. Setting up the Minicat on my AZ-GTi was no different to the Askar FMA180 Pro. The Minicat to me seems to be of even higher quality than the Askar. I also like that it comes with the soft carry case, really handy.
With the Askar, I found it difficult to quickly achieve focus in each new session due to the helical focuser. With the Minicat’s new WIFD design and the built in bahtinov mask, focus was readily obtained.
Another nice feature, the interior of the dew cap is flocked, efficiently preventing dew formation over the entire night (around 10 hours at 7 to 10 °C).
Like the Askar, the built-in rotator makes it easy to perfectly frame the object.

On my 1“ sensor, stars looked pretty good in the corners. Although I still might have to tweak backfocus a bit from the applied 55 mm, to get even better results.

Other than that, I‘ll try to process my images of M31 in the next days and hopefully will be able to post a comprising to the Askar.

So far, I‘m really pleased with the little cat.

CS
Johannes

You said "from the applied 55mm" ... does it have a backfocus requirement??  Do you have any pics to share?

[Dan Starr]

I received my MiniCat on 10/10 and of course tried it that night.  I am a total Newb to deep sky astro imaging however having caught the bug when I purchased a Seestar.  I have since traded for an 8" RASA with a ZWO 585 MC Pro.  Finding this to be great fun and able to capture images very quickly but not able to take it anywhere except out of the garage I was looking to get something a little more portable but still relatively fast aperture wise.  Anyhow, I've purchased a second ASI 585MC so very small sensor.

 

For the MiniCat on the back I have ZWO filter drawer and a Optolog light pollution filter of the next to highest grade.  Was hoping to "install" this inside the MiniCat but seems that isn't possible?  If someone knows it is and I'm missing please share instructions.  I have an SWO AM3 this and the ASI AIR 256GB version ride on.  ZWO 30f4 guide scope and their guide camera.

 

Anyhow, with the filter drawer and filter in place everything fits together with no extra step up or down rings required.  For me I am just live stacking and so far I am not seeing any edge problems...then again I've never been a pixel peeper with digital photography.

 

I have a 40 minutes LIVE view stacking of 1 minute exposures straight out of the ASI Air application on my phone of Andromeda.  I of course need to learn pix in sight at some point and will probably try some curves adjustment in photoshop at some point but figured send you folks the unedited image and let you discuss as you want.

 

Likewise, if someone wants to send me a larger sensor I'd be all for that lol.

 

Specifics on image collection, middle of the driveway, moon was out and very bright, two street lights left and right to the point where it wasn't dark at all outside...plenty of shadows and what not.  Crazy to me I can capture anything in such conditions.  

 

Seems uploading here only always postage stamp size to be imported?  Anyhow if someone wants to look at it and mess around with the file send me a message here with your e-mail and I can send it to you for your review...posting for me.

 

Thanks and feel free to let me know of any questions or comments.

 

This all works flawlessly together with the ASI AIR ap, AM3, guide scope and so on.  PA is a breeze once focused which wasn't bad once I realized I blew by the focus point...the scale on the side reads 22 for my arrangement btw.  Only piece I've added is the ZWO filter drawer and ASI 585MC Pro.

 

Dan

[Foobaria]

Please share your pix here, we'd love to see them. 

[BlakPhoenix]

So I was lucky and got clear skies yesterday. Setting up the Minicat on my AZ-GTi was no different to the Askar FMA180 Pro. The Minicat to me seems to be of even higher quality than the Askar. I also like that it comes with the soft carry case, really handy.
With the Askar, I found it difficult to quickly achieve focus in each new session due to the helical focuser. With the Minicat’s new WIFD design and the built in bahtinov mask, focus was readily obtained.
Another nice feature, the interior of the dew cap is flocked, efficiently preventing dew formation over the entire night (around 10 hours at 7 to 10 °C).
Like the Askar, the built-in rotator makes it easy to perfectly frame the object.

On my 1“ sensor, stars looked pretty good in the corners. Although I still might have to tweak backfocus a bit from the applied 55 mm, to get even better results.

Other than that, I‘ll try to process my images of M31 in the next days and hopefully will be able to post a comprising to the Askar.

So far, I‘m really pleased with the little cat.

CS
Johannes

Petzfal scopes don't have backfocus requirements like other designs. So long as you can bring the stars to focus, then they are as sharp as they will be (unless you have tilt issues). The idea of the design is that adjusting the focus ring simply moves the focus point in an out, there is no change in star shape along that plane. Try it yourself. Removing/adding spacers will just mean you focus further in or out, but the stars will stay as they are.

[Dan Starr]

OK looks like I figured out to upload larger images...now to link them here.

 

 

 

Let me know of any questions or comments.  

 

Dan

[rapture91]

Soo I finally have two pictures to share with you. 

After closer inspection of the sensor corners, stars don't look as good as I had imagined for a ~1000 € telescope. After checking back with WO support, they told me that there was some minor tilt and stars were slightly out of focus. I will of course pay attention to perfectly nail focus the next time I get the chance.

 

 

Fortunately, after applying BlurXT in PixInsight amongst others, this is what the final result looked like with the uncooled ZWO ASI533 MC (around 4.2 hours integration time):

 

The little cat is indeed an imaging machine and I'm happy with the end result. However, I don't like the fact that my copy did not work as intended "out of the box" and there's some tweaking to do ...

 

Looks like Dan had more luck? Or is it maybe the smaller chip of the 585?

CS
Johannes

Edited by rapture91, 14 October 2024 - 07:52 AM.

[Peds]

Getting rid of elongation at the corners in aps-c might not be an easy task... WO themselves say this here: "Correctable Corner Imperfections - Due to the nature of MiniCat’s fast aperture optical design, edge stars may not be as round as with other RedCats."

 

They go on to say "With aberration correction software like BXT, peripheral distortions can be perfectly corrected on APS-C sensors, while Full Frame may need some fine-tuning for even better results."

 

Their example shows quite a bit of elongation prior to using BXT.

[rapture91]

Thanks for the info, which I had already read. The 533 sensor is 1“, so I expected better results than what I got …
I will probably send the scope back to the retailer for closer inspection.

CS
Johannes

[Dan Starr]

Yes Johannes I think the small sensor is probably helping quite a bit...you could look at my FOV and trim yours to about the same and then look at your new edge stars.

 

Kind of like the RASA I knew I didn't want a super large sensor after seeing all the posts about tilt, corner elongations and what not.  Figuring I'll take a small field of view and less hassles.

 

 

Good luck with your scope...I'm happy with mine so far just from portability standpoint and oh my the ASI Air just nailing whatever I go to being dead centered in the frame...so much time gained nudging left/right up/down!  

 

Dan

[rapture91]

Hey Dan,

I just had a look at image of NGC 7000 on Astrobin, where the uploaded provided the raw stack before post-processing —> Minicat with ZWO ASI2600 (APS-C sensor)

https://app.astrobin...FmIzk=&i=m2kptc

In PixInsight, I compared the raw stack with my 1“ 533 sensor and noticed even more severe coma in the corners.

However, even that got sorted using BlurXT.

Having done that comparison, I find the coma for my system way less distracting and will probably keep the scope due to its immense light-gathering power

CS
Johannes

[rapture91]

Yes Johannes I think the small sensor is probably helping quite a bit...you could look at my FOV and trim yours to about the same and then look at your new edge stars.

 

Kind of like the RASA I knew I didn't want a super large sensor after seeing all the posts about tilt, corner elongations and what not.  Figuring I'll take a small field of view and less hassles.

 

 

Good luck with your scope...I'm happy with mine so far just from portability standpoint and oh my the ASI Air just nailing whatever I go to being dead centered in the frame...so much time gained nudging left/right up/down!  

 

Dan

Could you provide the raw stack of your M31 image? I‘d like to have a look at those corners

 

The raw stack of my M31 using the 533 sensor can be found here, for those who are interested:

 

https://1drv.ms/u/s!...wmjMkrLxto7Zhe-

[Dan Starr]

Sure Johannes PM sent please let me know your e-mail...I could also upload to g drive if you wish.

 

Dan

[Dan Starr]

Here's the region around Sadr...20 minutes or so live stacked.

 

 

Thoughts and comments appreciated.

 

I've set up a google drive with the originals...send me a PM with your e-mail and I can share.

 

Clear skies.

 

Dan

Edited by Dan Starr, 15 October 2024 - 10:14 AM.

[AGrayson]

Thanks for all the information and images people!

Please, keep em coming.

[Foobaria]

Thank you Dan, nice pix!  That comet is wow. 

 

OK looks like I figured out to upload larger images...now to link them here.

 

 

 

 

 

Let me know of any questions or comments.  

 

Dan

[RetiredDave]

 Here is an image of M31 (stack of ~70 60 second images with a 2600MCP) I took on 13 Oct with the Minicat 51 I received earlier this week. On the left is the uncorrected image, and on the right is after BlurXterminator correct only. I Included the FWHM/Eccentricity and Abberation Inspector images. Other than some left right tilt, what do you make of these images before and after (other than BlurX is indistinguishable from magic). Thanks,

 

Dave

Attached Thumbnails

• 

Edited by RetiredDave, 15 October 2024 - 02:13 PM.

[Sergio_2014]

There is now some interesting information on the WO website for the Minicat 51.

 

It says “Due to the nature of MiniCat’s fast aperture optical design, edge stars may not be as round as with other RedCats. However, our tests show it still outperforms conventional lenses. With aberration correction software like BXT, peripheral distortions can be perfectly corrected on APS-C sensors, while Full Frame may need some fine-tuning for even better results.”

https://williamoptic...re_after_NfE4EE

 

One of the images shown, an aberration inspector taken from an image of M24 using a APS-C sensor, shows pretty poor star shapes in the edges and corners.  Possibly this is why they recommend using BXT software.

 

Although the Minicat is called a Petzval design, the manual has a short section called “Ultra Flat Back Focus Adjustment” and shows the insertion of a pvc gasket into the optical train as a means of adjusting backfocus, along with a picture of what happens with the wrong backfocus.  

https://support.will...ocus-adjustment

The aberration inspector image of M24 actually looks to me as if the back focus distance was incorrect (camera sensor too close).

 

Andy

Wow, IMO it's quite shameless for a manufacturer to tell customers: "Oh well, stars are not too good at the corners, but hey, you can use BXT". Come on, is it well corrected for an APSC format or not? Unbelievable!

[Andy Lucy]

Wow, IMO it's quite shameless for a manufacturer to tell customers: "Oh well, stars are not too good at the corners, but hey, you can use BXT". Come on, is it well corrected for an APSC format or not? Unbelievable!

Looking at the various images that have been posted in this thread, and the images on the WO website, it is clear that the Minicat produces poor quality stars on the edges and corners of an APS-C sensor.  This is roughly in line with the WO description of the scope.

 

I think that this may be the first time a telescope manufacturer has marketed its product as only able to achieve good results through the use of software corrections.  However, the use of software lens corrections for conventional (terrestrial) photography has been widely used for around a decade so, in a sense, it is already normal to compensate for imaging hardware deficiencies through the use of software.  

 

The results from software correction of poor hardware potentially won’t be as good as results from decent hardware (using a lower degree of software correction or no correction), so there is still an incentive to buy decent hardware.

 

There is a good discussion on the pros and cons of using BXT in this CN thread:

https://www.cloudyni...blurxterminator

 

Andy