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APM 0.75x 82mm Riccardi reducer not working

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#26 juliangeorgeshaw

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Posted 22 May 2020 - 06:26 AM

The drastic solution is to replace the APM-Riccardi reducer with the Astro-physics QUADTCC. It costs almost 3 times as much but has an extra element. This is what I did.

 

This is the best I could do with the APM reducer, the new ASI6200 full frame camera and the LZOS 152mm triplet:

https://www.astrobin...fmw1dn/?nc=user

 

This is my first light with the same gear but using the QUADTCC reducer:

(Edit) https://www.astrobin...sethvz/?nc=user

(FWIW my best spacing, discovered by experiment, for the QUADTCC is 99.5mm)

 

Good luck getting your money back. I am resigned to owning an expensive APM paper weight.


Edited by juliangeorgeshaw, 22 May 2020 - 11:13 PM.


#27 maxmir

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Posted 22 May 2020 - 02:08 PM

The drastic solution is to replace the APM-Riccardi reducer with the Astro-physics QUADTCC. It costs almost 3 times as much but has an extra element. This is what I did.

 

This is the best I could do with the APM reducer, the new ASI16200 full frame camera and the LZOS 152mm triplet:

https://www.astrobin...fmw1dn/?nc=user

 

This is my first light with the same gear but using the QUADTCC reducer:

https://www.astrobin...fmw1dn/?nc=user

(FWIW my best spacing, discovered by experiment, for the QUADTCC is 99.5mm)

 

Good luck getting your money back. I am resigned to owning an expensive APM paper weight.

 

You are showing the link to same image. 

 

I looked at the other image on astrobin. Yes, looks great in comparison.

The LZOS 152mm is sold by APM?

 

I am looking at the QUADTCC but it was not designed for the oil spaced AP 130mm EDF F6.

I seen someone who is using this combination on Astrobin. Images are ok but the sensor is not full frame.

 

(Anyone finding QUADTCC with AP 130 F6 EDF example please post images)

 

Max



#28 juliangeorgeshaw

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Posted 22 May 2020 - 07:41 PM

- Link corrected, thank you

 

- Yes, the lens is inscribed "LZOS for APM" and I think the lens design is by Thomas M Brack. (Note: the APM-LZOS triplets are not to be confused with APM's new "APO doublets")

 

- Oil spaced problem? According to Roland Christen the QUADTCC works fine with the oil spaced TEC-140, F7. However I think Roland is using an 8300 chipped camera, not a full frame camera. 

https://astromart.co...-quad-tcc-59475

 

Also I think I read him saying that getting perfectly round stars with a small-pixel, full frame camera is not easy.



#29 maxmir

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Posted 22 May 2020 - 08:09 PM

- Link corrected, thank you

 

- Yes, the lens is inscribed "LZOS for APM" and I think the lens design is by Thomas M Brack. (Note: the APM-LZOS triplets are not to be confused with APM's new "APO doublets")

 

- Oil spaced problem? According to Roland Christen the QUADTCC works fine with the oil spaced TEC-140, F7. However I think Roland is using an 8300 chipped camera, not a full frame camera. 

https://astromart.co...-quad-tcc-59475

 

Also I think I read him saying that getting perfectly round stars with a small-pixel, full frame camera is not easy.

Indeed, not easy.  I am going to start another thread to see if there full frame examples out  their.



#30 juliangeorgeshaw

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Posted 22 May 2020 - 09:03 PM

To start your collection, full frame images with QUADTCC and AP130 GTX by Manuelj (a superb imager who has been very helpful to me)

https://www.flickr.c...57655986839001/

https://www.flickr.c...57655986839001/



#31 maxmir

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Posted 23 May 2020 - 09:02 AM

To start your collection, full frame images with QUADTCC and AP130 GTX by Manuelj (a superb imager who has been very helpful to me)

https://www.flickr.c...57655986839001/

https://www.flickr.c...57655986839001/

Need an example with the older AP130 F6 EDF. It is the older lens design( oil spaced).

I have the 3.5 FT focuser so the QUADTCC will fit.

 

No one knows if it will work well enough with the older F6 EDF



#32 alan.dang

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Posted 21 August 2020 - 06:05 PM

Hi Maxmir,

Even though the reducer does not work, have you had any luck with a prime focus flattener for the 130 EDF (that’s not the official AP one).

#33 ManuelJ

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Posted 21 August 2020 - 10:58 PM

Need an example with the older AP130 F6 EDF. It is the older lens design( oil spaced).

I have the 3.5 FT focuser so the QUADTCC will fit.

 

No one knows if it will work well enough with the older F6 EDF

Have you asked AP? This reducer works with oil spaced lenses. 

 

Well, the oil space thing looks like a bit on the invent side. At least you learned something from this. I also followed the hard path. 



#34 StephenW

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Posted 27 August 2020 - 03:19 PM

>This is the best I could do with the APM reducer, the new ASI6200 full frame camera and the LZOS 152mm triplet:

 

Curious what spacing you ended up with to get your best results with the Ricardi?

 

My Precise Parts adapter finally arrived putting me at 70.6mm for my TMB152 + M82 Ricardi + 6200, and the results are not pretty :).   The aberrations in the corners are significantly worse than without the Ricardi...

 

And a side note:  Anyone know of a US source for an M82-M68 adapter?    I see Teleskop Express carries one, but shipping from EU can be painful...

 

thanks!

 

Steve



#35 sn2006gy

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Posted 27 August 2020 - 03:38 PM

 

 

And a side note:  Anyone know of a US source for an M82-M68 adapter?    I see Teleskop Express carries one, but shipping from EU can be painful...

 

 

Shipping from EU is actually faster than much of US shipping.  DHL doesn't seem to be hampered as much as UPS/USPS is.



#36 StephenW

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Posted 27 August 2020 - 06:37 PM

Yep, went ahead and ordered - $30 shipping via DHL is painful, but hopefully it will arrive quickly enough! :)

 

@Julian - still curious what spacing you ended up with for your best results with the Riccardi.



#37 Vaud

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Posted 09 September 2020 - 03:22 AM

I own one of those, to use on a TMB 130 f/6 astrograph, but it is at a distant property, and I have yet to make or buy the adapter to mate it with my 3.5" FeatherTouch focuser.  So I can't vouch for its quality, other than to note that its designer is well respected, and that it is designed to fill a 52 mm imaging circle.  I've attached its nominal spot diagram out to 52 mm diameter.  The BFL info is detailed (also attached as an Excel spreadsheet), but it is also a bit confusing, so you might want to double check your spacing.  What scope are you pairing it with?  That matters a lot in setting the BFL.

 

All the best,

 

Kevin

 

attachicon.gifApo 130_780+075x reducer.pdf

 

attachicon.gifRiccardi Reducer Info May 2014.xls

May I ask where is the xls coming from? Interesting enough there is a note on TEC140 I'm using and it says BF = 76.96mm.

As per AP documentation (RiccardiAdapation.pdf) and manual calculation the right distance to Atik383L is 73.5mm.

 

The background of this post is a nuuuumber of nights I spent to determine right BF for Riccardi attached to my TEC140 ( + two cameras ASI071 and Atik383 - both having same BF of 17.5mm).

So far no success for any distance between 69 and 76mm (where 76 distance image is already a disaster and this is probably the only solid conclusion that I have).

Hence, I'm also confused what am i doing wrong or... if there is an issue with the Riccardi M63...

 

Q1... in the RiccardiAdaptaion.pdf there is no notion of the scope. Out of this thread I understand that actually the distance may differ between the scopes (f-ratio as this determines light cone angle that enters the reducer) so that this 73.5mm is just a theory?. Do I read you Guys right?

Q2. Is there anyone working with TEC140 + small Riccardi 0.75x who could advice your own, well working distance?


Edited by Vaud, 09 September 2020 - 05:01 AM.


#38 LPA

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Posted 09 September 2020 - 09:44 AM

I got the smaller Riccardi 0.75x for my AT130EDT + ASI6200MM. The recommended spacing for a 130mm f/7 scope is 73.5mm. I have the ASI6200MM attached to an EFW with the M68 OAG but without the tilt plate so the BF of this combo is 50mm. I obtained a 23.5mm spacer from PP to go directly from the Riccardi to the OAG so there would be no possible vignetting of the light path. The Riccardi claims a 40mm fully corrected image circle for this FF/FR and the diagonal of the ASI6200 is 43mm. I tested this combination using M31 as my target. I still need more blue subs along with lum subs, and my PA is slightly off, so this is not my final version of this target. Here are the 4 corners of the raw image before any PP. Please ignore the registration errors.

 

M31_4corners.jpg

 

Here is the result after PP and cropping to 9000x6000, then downsizing for CN:

 

M31_RGB_HTcsmall.jpg

 

I'm happy with this result. I also have the ASI2600MC setup the same way using the 5-position EFW + M68 OAG. Right now I just have an Ha filter for that camera. Eventually I'll add OIII or else get one of the multi-band filters. But since the BF of these cameras is the same, I can conveniently swap them between my EdgeHD11 and the AT130EDT without having to change any spacers. Note: I replaced the stock focuser on the AT130EDT with a 2.5" FeatherTouch. The Riccardi won't focus with the stock focuser and the Riccardi screws directly into the FT.

 

Larry


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#39 Vaud

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Posted 09 September 2020 - 10:58 AM

Thanks Larry,

That's Full-Frame, I guess the corners could have been better but no drama.

Both cams I have i.e. Atik383 and ASI071 (22.5mm and 28.3mm accordingly) are far below declared quality of 42mm and results are worse than on your FF corners.

 

Anybody has a mix of TEC140 + Riccardi 0.75x (small i.e. M63), who could advice on BF working fine?

K


Edited by Vaud, 09 September 2020 - 11:03 AM.


#40 LPA

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Posted 09 September 2020 - 12:54 PM

This discussion made me curious about what is the actual focal length of my AT130EDT. Its nominal FL with the 0.75x Riccardi is 910*.75 = 682.5, giving an image scale of 1.1353"/px with the ASI6200. When I plate-solved my integrated subs, I got a scale of 1.1270"/px which corresponds to an effective FL of 688.16, slightly longer than the nominal FL. Obviously I would need to repeat this without the Riccardi to determine the effective FL of just the scope. Then I could determine the effective FL reduction by the Riccardi. I doubt this is meaningful, but what is the effective FL of your scope based on plate-solving?

 

Larry


Edited by LPA, 09 September 2020 - 12:56 PM.


#41 Vaud

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Posted 09 September 2020 - 03:55 PM

For TEC140 should be 980 x .75 = 735 but plate-solve says 742.26. It's then 7.26 longer.

Your Full Frame result cropped to 28mm diagonal (like my ASI071) would probably give a nice flat field.

Not sure if that's a good catch but I'm more than happy to explore this path.

7mm is <1% of FL. Do you think this kind of difference/shift of curvature center could result in significant image quality (bear in mind we're taking about 28 diagonal, not full 42mm declared)?

What do you think?

Maybe others have some observations i.e. plate solve based FL with reducer being longer than theoretical value (out of equation) but field still nice and flat?

Krzysztof


Edited by Vaud, 09 September 2020 - 03:58 PM.


#42 LPA

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Posted 09 September 2020 - 08:17 PM

I don't really know, but your results aren't far off from nominal so I'd be surprised if that is causing any problems. I was thinking that if there was an assembly issue with the Riccardi, it would show up in the FL. But that doesn't seem to have happened.

 

I expect that most ASI6200 images will need to be cropped for composition, but I hope not to need cropping all the way down to APS-C which is the size of the ASI2600. I like to print my best images, usually 20x16". If I crop to 7200x5760, the image would print at 360 dpi. Even if I crop to 6000x4800, the dpi for printing would be 300 dpi, more than enough for a good print.

 

Larry



#43 5th Gin

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Posted 12 September 2020 - 02:33 PM

I got the smaller Riccardi 0.75x for my AT130EDT + ASI6200MM. The recommended spacing for a 130mm f/7 scope is 73.5mm. I have the ASI6200MM attached to an EFW with the M68 OAG but without the tilt plate so the BF of this combo is 50mm. I obtained a 23.5mm spacer from PP to go directly from the Riccardi to the OAG so there would be no possible vignetting of the light path. The Riccardi claims a 40mm fully corrected image circle for this FF/FR and the diagonal of the ASI6200 is 43mm. I tested this combination using M31 as my target. I still need more blue subs along with lum subs, and my PA is slightly off, so this is not my final version of this target. Here are the 4 corners of the raw image before any PP. Please ignore the registration errors.

 

M31_4corners.jpg

 

Here is the result after PP and cropping to 9000x6000, then downsizing for CN:

 

M31_RGB_HTcsmall.jpg

 

I'm happy with this result. I also have the ASI2600MC setup the same way using the 5-position EFW + M68 OAG. Right now I just have an Ha filter for that camera. Eventually I'll add OIII or else get one of the multi-band filters. But since the BF of these cameras is the same, I can conveniently swap them between my EdgeHD11 and the AT130EDT without having to change any spacers. Note: I replaced the stock focuser on the AT130EDT with a 2.5" FeatherTouch. The Riccardi won't focus with the stock focuser and the Riccardi screws directly into the FT.

 

Larry

That's very helpful! Why doesn't the AT130EDT stock focuser focus with the Riccardi? Is it too short or too long?

 

And I assume it needs a M63-M68 adapter to connect the reducer to the M68 OAG?



#44 LPA

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Posted 20 September 2020 - 08:30 PM

The stock focuser is too long for the Riccardi. The FeatherTouch also has threads that allow the Riccardi to screw directly into the barrel after removing the 2" adapter. I obtained a spacer from PP that goes from the Riccardi directly to the oag w/o tilt plate (63-68mm, length=23.5mm). The flat frames show very little light dropoff with this arrangement and no vignetting. Here is my final image of M31, uncropped and down-sized for CN, LRGB+Ha+OIII.

Subs: R: 20x150sec, G: 36x120s, B: 40x120s, L: 56x60s, Ha: 35x300s, OIII: 29x300s

Camera: ASI6200MM + EFW

Filters: Astrodon (2" LRGB + 5nm Ha + 5nm OIII)

Scope: AT130EDT + Riccardi 0.75x FF/FR

Mount: CEM60

Imaging and mount control: TheSkyX on Raspberry Pi 4

PP: PI + PS

 

M31_NBRGBcsmall.jpg

 

Larry


Edited by LPA, 20 September 2020 - 08:50 PM.

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#45 StephenW

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Posted 20 September 2020 - 08:45 PM

I've also been playing with the spacing for the M82 Riccardi and my ASI 6200.

 

I had previously set the spacing to 70.6mm based on this: https://www.apm-tele...diBackfocus.pdf

 

That had worked fine with the small chip in my STF-8300, but had massive distortion in the corners with the 6200

 

After some experimentation last night it looks like 76.5mm is the optimum spacing to use.  If skies stay clear I'll do some proper test images tonight.

 

Based on last nights' testing though, there is still some distortion at the edges, and I'm facing some tilt.   Maybe I do just need to start saving up for the QUADTCC... :-!




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