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Where are the Mak-Newt people?

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#176 iKMN

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Posted 15 February 2019 - 12:55 PM

Has anyone here changed out the focuser on an ES comet hunter for a rack and pinion? Looking for options (or any option at all ;) ) to switch mine to get rid of crayford slippage with a heavy camera/fw/oag at some point (even though the standard focuser really isn't too bad) - does someone know what focuser(s) and mounting adapters work?

I would call ES and see if the focuser for the first light or truss dobs might fit. I “think” I recall someone posting how they put a Feathertouch on their CH but perhaps it was the MN190. I am very pleased with the Es Crayford but I’m visual only. It holds all my ES100 and 30/82. I love my CH scope it may even be my favorite scope.


Edit

http://starlightinst...&product_id=434

Found it!!

Edited by iKMN, 15 February 2019 - 12:57 PM.


#177 Eric Seavey

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Posted 18 February 2019 - 04:34 PM

I would call ES and see if the focuser for the first light or truss dobs might fit. I “think” I recall someone posting how they put a Feathertouch on their CH but perhaps it was the MN190. I am very pleased with the Es Crayford but I’m visual only. It holds all my ES100 and 30/82. I love my CH scope it may even be my favorite scope.


Edit

http://starlightinst...&product_id=434

Found it!!

The Comet Hunter from Explore Scientific and Skywatcher MN190 are currently the two most popular Maksutov-Newtonian Scopes. The MN190 definitely benefits from having the focuser replaced for astro imaging.  I believe the Comet Hunter has a better design right out of the box.



#178 RaulTheRat

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Posted 26 February 2019 - 08:44 AM

Excellent! Thanks, that's probably just cost me some money, but whatever! This may be a silly question, but the feathertouch is rack and pinion right? I don't just want a better crayford, I want something with zero slippage so even the best quality crayford design wouldn't really help.

#179 Eric Seavey

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Posted 26 February 2019 - 06:40 PM

Excellent! Thanks, that's probably just cost me some money, but whatever! This may be a silly question, but the feathertouch is rack and pinion right? I don't just want a better crayford, I want something with zero slippage so even the best quality crayford design wouldn't really help.

 

For my MN190 I bought the "FTF2025BCR" with the 2.5 inch draw tube, and the  "A20-200A-11---Adapter 2.0" for MEADE Lightbridge telescopes"  along with a 2-inch Televue extender.  It brings the total cost of the telescope to about $2000 range, and totally worth the cost if DSO imaging is your goal. 

I don't know too much about the Explore Scientific Comet Hunter, but it seems like a well designed system, though I cannot comment on the optics personally.  My DSO-Browser page has many shots taken with the MN190, with a larger APS-C sensor showing the great corner performance, and a small sensor showing the sharpness.  https://dso-browser....profile/eseavey



#180 RaulTheRat

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Posted 26 February 2019 - 09:22 PM

Nice images. Indeed, it looks like the MN-190 has excellent corner performance on that big chip - I've found the comet hunter equally good across the field, with a 4/3 sensor at least and as far as I understand it, the field is good for at least APS-C. I almost bought an MN-190 instead actually but then decided that wind load and weight would make it a bit of a challenge on my AZ-EQ-6, I think it would be doable, but I figured better to stick with something smaller to start with.

I've contacted starlight about the focusers, I see they have both crayford type and rack and pinion options, so hopefully they can confirm that their 2" R&P is compatible with the base. It is a lot of money as you mention, but optically I'm very pleased with the comet hunter and it's a useful focal length, so if I need to spend a bit on the focuser I'll probably suck it up and pay up.
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#181 Eric Seavey

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Posted 26 February 2019 - 11:22 PM

Nice images. Indeed, it looks like the MN-190 has excellent corner performance on that big chip - I've found the comet hunter equally good across the field, with a 4/3 sensor at least and as far as I understand it, the field is good for at least APS-C. I almost bought an MN-190 instead actually but then decided that wind load and weight would make it a bit of a challenge on my AZ-EQ-6, I think it would be doable, but I figured better to stick with something smaller to start with.

I've contacted starlight about the focusers, I see they have both crayford type and rack and pinion options, so hopefully they can confirm that their 2" R&P is compatible with the base. It is a lot of money as you mention, but optically I'm very pleased with the comet hunter and it's a useful focal length, so if I need to spend a bit on the focuser I'll probably suck it up and pay up.

Are you not satisfied with the focuser on the ES Comet Hunter?  I've seen some nice shots on astrobin taken with that scope with a Pentax K1.  That is full frame, and I think that is pushing it a bit.  4/3 sensor sounds perfect. What camera do you have?  The ZWO1600? or QHY163?



#182 Saj_37uk

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Posted 26 February 2019 - 11:28 PM

Anyone using a Nikon D5300 or similar with the 190MN? I'm thinking of getting one of these.

 

Also is OAG required? I noticed Eric is using one. 

 

 



#183 Eric Seavey

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Posted 27 February 2019 - 12:02 AM

 

Anyone using a Nikon D5300 or similar with the 190MN? I'm thinking of getting one of these.

 

Also is OAG required? I noticed Eric is using one. 

 

 

 

I use my Pentax K5 with the APS-C sensor and it covers the field nicely.  See my post above with the link to my DSO-browser page.  The primary mirror of the MN190 is fixed, and so I use a guide scope.  I use the OAG with my Celestron C11 when taking photos of small bright planetary nebulae.



#184 gnowellsct

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Posted 27 February 2019 - 08:15 AM

The mak newt people usually migrate to Mak Newt island this time of year.
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#185 RaulTheRat

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Posted 27 February 2019 - 09:36 PM

Are you not satisfied with the focuser on the ES Comet Hunter? I've seen some nice shots on astrobin taken with that scope with a Pentax K1. That is full frame, and I think that is pushing it a bit. 4/3 sensor sounds perfect. What camera do you have? The ZWO1600? or QHY163?


I have a ZWO 1600. With that, an OAG and filter wheel it slips, not badly enough to prevent imaging with it (generally it'll focus during a run of images), but it does slip - for example, when moving it around to put it away after imaging you have to be careful not to bump the imaging train or it would shift and prevent taking proper flats, and to get it to not slip during focusing when imaging you have to have the tension adjuster really locked down as hard as possible to the point where it hurts your fingers trying to do it up that tight.

It's not a bad focuser, there's little slop and for visual use it's adequate, but I'm not overly impressed for imaging.

Although I'm wary of any sort of crayford design, I'm also considering a baader steeltrack to replace it - the feather touch is just sooooo expensive, and I understand the diamond friction material on the baader is very good and they don't slip with heavy loads, so maybe I'll go that route, not sure yet, whatever happens I can't see much chance of sticking with the standard since as I said, it's not bad but neither is it any more than adequate if you're trying to focus something heavier than an eyepiece.

#186 Eric Seavey

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Posted 28 February 2019 - 12:42 AM

I have a ZWO 1600. With that, an OAG and filter wheel it slips, not badly enough to prevent imaging with it (generally it'll focus during a run of images), but it does slip - for example, when moving it around to put it away after imaging you have to be careful not to bump the imaging train or it would shift and prevent taking proper flats, and to get it to not slip during focusing when imaging you have to have the tension adjuster really locked down as hard as possible to the point where it hurts your fingers trying to do it up that tight.

It's not a bad focuser, there's little slop and for visual use it's adequate, but I'm not overly impressed for imaging.

Although I'm wary of any sort of crayford design, I'm also considering a baader steeltrack to replace it - the feather touch is just sooooo expensive, and I understand the diamond friction material on the baader is very good and they don't slip with heavy loads, so maybe I'll go that route, not sure yet, whatever happens I can't see much chance of sticking with the standard since as I said, it's not bad but neither is it any more than adequate if you're trying to focus something heavier than an eyepiece.

Wow. I am surprised!  From this image on their site, it looks like there is a thumbscrew for the tensioner and one to lock the focuser.  Looks like a good design actually. I am surprised it slips like you are saying.  Is it defective you think?

https://cdn.shopify....pg?v=1542072479

 

The feather touch is very nice, and I have no regrets.  Of course I only do imaging, so a good focuser was totally worth it for me.


Edited by Eric Seavey, 28 February 2019 - 12:44 AM.


#187 RaulTheRat

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Posted 28 February 2019 - 07:03 AM

Hi Eric

I don't think it's defective - I'll know for sure when I get the replacement scope shortly (due to a different problem - faults with the secondary mirror coating), but I think it's just what crayford focusers do...

The lock screw would prevent slipping yes, I have the focuser motorised though, so I could use the lock screw when moving the scope indoors I suppose to prevent any movement of the imaging train during handling and putting it down, but I can't use it during imaging and it doesn't help if the focuser actually slips during motor focusing such that the stepper motor thinks it's achieved a certain focuser position but really it's just turned the pinion while the tube has not moved the full amount. I don't think the second slippage has happened to me (yet?) but as I said, to prevent it I really have to crank down the tension adjuster very hard to the point where any more tension would be at risk of damaging something.

One more thing - I found a thread saying that some of the screws on the base are coarse adjustment of the tension, so if the new scope has the same slippage I will try adjusting those initially while I further research replacements. I think the feather touch would be great and it's a definite easy fitment with the adapter, but the steeltrack is a very good price albeit at the cost of having to drill the tube and fool around more trying to get a good fit.

#188 Eric Seavey

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Posted 28 February 2019 - 11:55 AM

 

Ah the baader focuser.  I looked at that one too, and for some reason would not fit, which is why I went with the feathertouch.  I can actually drive to the warehouse of the online store, where I brought in my scope and made everything fit, before purchasing.



#189 NHRob

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Posted 28 February 2019 - 12:02 PM

The Mak-Newt people are all hiding.

 

Have you checked under your bed??



#190 RaulTheRat

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Posted 28 February 2019 - 12:15 PM

 

 

Ah the baader focuser.  I looked at that one too, and for some reason would not fit, which is why I went with the feathertouch.  I can actually drive to the warehouse of the online store, where I brought in my scope and made everything fit, before purchasing.

 

 

Yes, I'm not sure if I can bring myself to spend literally twice as much, if not more than that, so as to not have to make it fit. Possibly it's worth just waiting a little while until I can afford the FT so as to not have to modify anything to get it to fit, like I said the supplied focuser isn't terrible at all, so perhaps I'll just make do for a while until I can get the FT.

 

How did you find recentering the secondary under the different focuser on your MN-190, was it necessary and if so was it difficult and what collimation method did you use?



#191 Eric Seavey

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Posted 28 February 2019 - 03:20 PM

How did you find recentering the secondary under the different focuser on your MN-190, was it necessary and if so was it difficult and what collimation method did you use?

I wasn't too worried about centering, that only gives a tiny bit of asymmetrical vignetting, and any vignetting is already small with my MN190.  For the most part it collimates like a newtonian, with the important difference to have the meniscus and PM parallel to each other.  Since so many people are asking me how to collimate the MN190, I plan on doing a video and putting it on Youtube.  The principle will apply to all mak-newts.

 

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#192 Saj_37uk

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Posted 28 February 2019 - 03:29 PM

Since so many people are asking me how to collimate the MN190, I plan on doing a video and putting it on Youtube. The principle will apply to all mak-newts.



Would really appreciate that!!

#193 Jeff B

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Posted 28 February 2019 - 04:27 PM

The mak newt people usually migrate to Mak Newt island this time of year.

That's not too far from Key Refractor.


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#194 RaulTheRat

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Posted 28 February 2019 - 06:35 PM

Thanks Eric, that's good to know - I only image with a 4/3 camera and the comet hunter field is wide enough for APS-C so probably I'd also not need to worry about any slight decentering of the secondary.

Please do post here if you make that video - I've not found my mak-newt particularly difficult to collimate but it'd be interesting to see how you do yours.

#195 AstroBruce

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Posted 28 February 2019 - 08:10 PM

 

I wasn't too worried about centering, that only gives a tiny bit of asymmetrical vignetting, and any vignetting is already small with my MN190.  For the most part it collimates like a newtonian, with the important difference to have the meniscus and PM parallel to each other.  Since so many people are asking me how to collimate the MN190, I plan on doing a video and putting it on Youtube.  The principle will apply to all mak-newts.

 

 

In order to get the optical axis in line with the mechanical axis, which will make the meniscus and primary parallel, the focuser must be properly centered over the secondary. That's why the focuser mount has elongated holes. This needs to be done, or you are wasting your time.

 

Bruce



#196 Saj_37uk

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Posted 28 February 2019 - 09:23 PM

Which focuser do you guys think is better for the 190MN? Moonlight or Feathertouch?

#197 Saj_37uk

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Posted 28 February 2019 - 09:51 PM

Also, has anyone imaged with a Nikon D5300? Should I be concerned about oversampling?

#198 Eric Seavey

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Posted 01 March 2019 - 12:34 AM

Which focuser do you guys think is better for the 190MN? Moonlight or Feathertouch?

I have the feathertouch and know it is great.  I haven't used the moonlight focuser, though I expect good quality.

 

 

Also, has anyone imaged with a Nikon D5300? Should I be concerned about oversampling?

No need to worry about over sampling.  I use my QHY224C that has 3.75um pixels.  I think the Nikon D5300 has 3.91um pixels.  And there is this site to help you: https://astronomy.to...ccd_suitability



#199 rkayakr

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Posted 02 March 2019 - 10:59 PM

I put a Moonlight on mine and it has served well. They make a plate specifically for the MN190 and installation was no problem. 


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#200 mgn

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Posted 13 April 2019 - 03:09 PM

Just bumping this up and I wanted to ask for some links to images taken through the MN190, or other Mak-Newts used for imaging. I have been doing alot of imaging lately using my new ZWO ASI1600MM cooled camera on the MN190 and am pretty pleased with the performance of the Mak-Newt.  It's a good match for the ASI1600 chip and pixel scale, and is giving me great resolution.  Importantly, the ASI1600 chip is a new generation CMOS device with high sensitivity and extremely low noise, making short exposure imaging, and video imaging, pretty easy for most of us. I am not an expert at imaging by any stretch but I do enjoy it, and this is my first serious astro camera after moving up from my old Canon 450D dslr. I have some images taken through the MN190, using both the ASi1600 and my Canon, in my public gallery on Astrobin, if anyone wishes to have a look they are here:

 

http://www.astrobin.com/users/glend/

 

The top couple of rows of the gallery thumbnails are all ASi1600 test images through the MN190, with many of those lower down taken with my cooled full spectrum DSLR on the MN190. To see larger images just click on the thumbnail to open the description page for that image and click of the image again to go to full screen mode.

 

I must admit the stock focuser concerns me, but I am still using it to produce these images, but I think I will swap over to a Moonlight now that Ron has got the correct adaptor for the MN190 in production.  Can we get some feedback from the guys beta testing that adaptor - Ron had indicated to me that there were some in the hands of testers now.

 

Remember, if your imaging through your Mak-Newt, send us a link.

My two scopes are the Intes Micro MN56 and MN86, and pretty much all the shots here are taken with one of those two.

 

http://www.mgnastro....trogallery.html

 

I installed a JMI low profile motorised focuser on my MN86 many years ago, and now that the kids are nearly grown up I'm coming back to these two, and am now putting a low profile motorised focuser on the MN56. I've upgraded my mount from an EQ6 to a CEM60 EQ (gosh what a difference) and upgraded my ancient SXVH-9 to a Trius 814. I am tempted to upgrade the MN86 to a 12" RC but I am undecided as yet. I need to build a third and hopefully final obs and that will decide what I purchase, if at all. I am very, very happy with my Mak newts and whatever I replace them with will have to be stellar in performance :=)

I will say that my little MN56 de-collumates itself more than I would like, which is an annoyance but the MN86 is rock solid.

 

regards
Martin 


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