Imaging with the 130pds

[alacant]

1 hour ago, Atreta said:

so i'd need just another 10mm

Hi. Yeah, the link I posted includes a 30mm ring which should be fine: low profile eos > 30mm m48 > GSOcc > telescope. The main problem with the GSO is that it needs over 5cm of front focus at the recommended 75mm spacing so you may need an extension tube to reach focus. HTH.

[StamosP]

On 19/4/2017 at 16:01, mAnKiNd said:

However, since I use a IDAS LPS-D1 filter, which has a glass thickness of 2.2mm, then if I understand correctly, I can subtract that value from the total distance, giving me a "true" distance of 52.8mm, which is not a far cry from the recommended 52.5mm.

Hello Minos,

this is the answer i got some time ago from Ted Ishikawa of Hutech regarding the thickness of clip EOS filter:

"Hi Stamatis,
Current D1-EOS is 0.5mm thick.
Ted"

[mAnKiNd]

On 29/04/2017 at 10:13, StamosP said:

Hello Minos,

this is the answer i got some time ago from Ted Ishikawa of Hutech regarding the thickness of clip EOS filter:

"Hi Stamatis,
Current D1-EOS is 0.5mm thick.
Ted"

Hi Stamatis,

Thank you so much for this information, it is very helpful! The TS website for this filter states 2.2mm under the specs. I will get in touch with them and confirm this as I bought it from them. I wonder if the 2.2mm is not for the glass thickness, but some other measurement. Thanks again??

[dyfiastro]

Hi everyone.
First time out last night and got everything running in the new obsy, took a little longer due to software issues so lost a little time.
Its been weeks since I have been able to do anything due to bad weather and its the first time I have actually attempted to image comets with the scope.

Comet C/2015 V2 (Johnson) - 7x180s, ISO1600, Canon 600D

Comet 41P/Tuttle-Giacobini-Kresak -  4x180s, ISO1600, Canon 600D

Now the obsy is build I am hoping to be able to get out a lot more now and have more imaging time rather than spending time setting up etc...

Thanks in advance

[richyrich_one]

Nice shots.

Congrats on getting the obsy finished, I couldn't bear the thought of having to setup each time.

You've inspired me to have a go at Johnson... Oh wait, its cloudy.

[alacant]

On 1/5/2017 at 07:13, mAnKiNd said:

The TS website for this filter states 2.2mm under the specs.

Hi. Was there ever a solution or answer to this? I just installed a 1mm thick clip filter. Is this enough to make a difference to the cc spacing? TIA.

[richyrich_one]

21 minutes ago, alacant said:

Hi. Was there ever a solution or answer to this? I just installed a 1mm thick clip filter. Is this enough to make a difference to the cc spacing? TIA.

If it's 1mm thick then it will require 0.3mm extra spacing.

Most likely it won't have any real effect, but I guess it depends how close you are to the limit before adding the filter.

[Adam J]

7 hours ago, richyrich_one said:

If it's 1mm thick then it will require 0.3mm extra spacing.

Most likely it won't have any real effect, but I guess it depends how close you are to the limit before adding the filter.

I have been wanting to better understand this as I self modified my DSLR removing both filters to make it full spectrum. I have a clip filter after the coma corrector.

I have been working on the assumption that if I have removed glass (overall) from between the CC and the sensor that this would result in the optimal spacing from CC to sensor reducing?

As such I am considering moving my CC closer to the sensor using the spring loaded adjustment screws on my 550D DSLR.

I have also been getting an effect that appears like squashed stars radially around the centre of the image, kind of the opposite to coma appearing squashed as opposed to stretched radially. I am lead to believe this is as a result of the CC being too far from the sensor and hence over compensating for the coma and going past round stars to stars that are squished in the opposite plane. This is again in line with my understanding that removing the filters will have reduced the effective focal length requiring that the distance to the sensor be reduced. 

Any opinions on this?

 

[mAnKiNd]

Hi AdamJ,

FWIW, when I image with my unmodded 450D on my short refractor, i use a CC <70mm> CMOS spacing for good correction, but with my full spectrum 1200D, I use a CC <65.3mm> CMOS spacing. I believe the reason for this reduction, is as you've described it, in that all glass filters inside the full spectrum camera are removed, which reduces the effective focal length required. Therefore, if you minimise your spacing as you say, would probably work better. Try it and see

On a different note, a threaded connection to the focuser is assuredly always more likely to be optically aligned with the collimation than a clamped connection, with less flexure and more stability. I wonder if many of the aforementioned chromatic aberrations and bloating reported in certain CC's where also in part, due to being clamped in the focuser rather than threaded..

I understand that the drawtubes in Synta focusers found on the common newtonians utilise an M54x1mm female thread that usually houses the removable 2" clamp. Furthermore, all previously discussed CC's such as the SW 0.9x, MPCC, GPU aplanatic etc.. utilise a male M48x0.75mm to connect with a DSLR. Therefore, one would require an M54x1mm Male to M48x0.75mm female adapter, and they could adapt the Drawtube + CC + Spacer + DSLR combo in a threaded fashion. Uranium has successfully demonstrate this concept after loads of DIY with the SW0.9X CC.

Such an adapter would not only ensure an improved connection, but also would provide a little more backfocus, allowing the drawtube to be racked out further, thereby minimising the intrusion that causes D-shapes on bright stars and negating the need to trim it down. Fortunately for us, the Hungarians at Lacerta make such an adapter (I've ordered one!) and there is also a T2 version (though it looks less secure). 

Food for thought..

EDIT: I saw on another thread here that the good folk at FLO used to do a bespoke adapter service. Maybe that's still on?

Edited May 4, 2017 by mAnKiNd

[richyrich_one]

31 minutes ago, mAnKiNd said:

Hi AdamJ,

FWIW, when I image with my unmodded 450D on my short refractor, i use a CC <70mm> CMOS spacing for good correction, but with my full spectrum 1200D, I use a CC <65.3mm> CMOS spacing. I believe the reason for this reduction, is as you've described it, in that all glass filters inside the full spectrum camera are removed, which reduces the effective focal length required. Therefore, if you minimise your spacing as you say, would probably work better. Try it and see

On a different note, a threaded connection to the focuser is assuredly always more likely to be optically aligned with the collimation than a clamped connection, with less flexure and more stability. I wonder if many of the aforementioned chromatic aberrations and bloating reported in certain CC's where also in part, due to being clamped in the focuser rather than threaded..

I understand that the drawtubes in Synta focusers found on the common newtonians utilise an M54x1mm female thread that usually houses the removable 2" clamp. Furthermore, all previously discussed CC's such as the SW 0.9x, MPCC, GPU aplanatic etc.. utilise a male M48x0.75mm to connect with a DSLR. Therefore, one would require an M54x1mm Male to M48x0.75mm female adapter, and they could adapt the Drawtube + CC + Spacer + DSLR combo in a threaded fashion. Uranium has successfully demonstrate this concept after loads of DIY with the SW0.9X CC.

Such an adapter would not only ensure an improved connection, but also would provide a little more backfocus, allowing the drawtube to be racked out further, thereby minimising the intrusion that causes D-shapes on bright stars and negating the need to trim it down. Fortunately for us, the Hungarians at Lacerta make such an adapter (I've ordered one!) and there is also a T2 version (though it looks less secure). 

Food for thought..

EDIT: I saw on another thread here that the good folk at FLO used to do a bespoke adapter service. Maybe that's still on?

Same thing but cheaper from here. Got one, on practice not what I was hoping for.

 

Edited May 4, 2017 by richyrich_one
Comments added

[mAnKiNd]

3 minutes ago, richyrich_one said:

 Got one, on practice not what I was hoping for.

How so?

[richyrich_one]

13 minutes ago, mAnKiNd said:

How so?

I found using the locking ring to adjust rotation difficult to tighten without the t-ring/cc connection loosening. I ended up adding a thumb screw that locked down on the cc thread and also gave a lever to help hold it when tightening.

I got it to solve my tilt problems but it didn't change anything. Still currently unresolved.

You are also forced to use the M42 connection to the cc so vignetting could be an issue.

I've abandoned it for now, I may try it again.

[mAnKiNd]

Thanks Rich for taking the time to reply.

Vignetting with T2 did cross my mind when I was thinking of this adapter in use with the MPCC, as that's the connecting thread it uses. However, i'll be using the adapter with the GPU aplanatic CC, which has the wider M48 and would therefore avoid possible vignetting on APS-C sensor. This gave me hope that perhaps this Lacerta adapter is actually better suited for the GPU CC rather than it's advertised use with the MPCC. 

My concern is whether or not this adapter combination will give a secure enough connection to the DSLR flange ring, being that a 4mm long M48 male thread on the coma corrector hides approximately 2mm's inside the adapter. I think 2mm left over is sufficient to lock into the DSLR flange ring, but I don't think it will hold a lot of weight. Nevertheless, as soon as it arrives, i'll be using my 130PDS with DSLR + CC only, so not too much weight.

Thanks again

Edited May 4, 2017 by mAnKiNd

[richyrich_one]

Sounds like the GPU CC wins again(are you listening Baader?!). The M48 thread on the MPCC finishes flush to the adapter forcing you to use M42 on the t-ring.

When using the locking ring, there is some play in both the thread on the ring and the draw tube, I was never confident that it was square when it was tightened. I guess it should be.

It always bothered me that I wasn't mounting the camera in the same manner as I was collimating. I tried to collimate with a threaded connection using a self-centering adapter but the results where never repeatable. This confirmed my suspicions about the adapter.

Hopefully you'll have a better experience. It seems when you start with the GPU CC you are already on to a winner.

[alacant]

42 minutes ago, richyrich_one said:

The M48 thread on the MPCC finishes flush to the adapter forcing you to use M42 on the t-ring.

??? The m48 connection works fine. It just needs a m48 to camera ring. Screw it home, it sits square and avoids the dark corners on the light frames. Any tilt placing it in the focuser however and you've had it. Which reminds me...

...+1 for the idiotic undercut on the Baader; I needed to remove the lining in the 2" adaptor so they the screws bore directly onto the surface of the cc, otherwise it 'pushes' itself outwards as the band is tightened against it. Hopeless! HTH and clear skies.

** the gpu can threaded only in its original configuration, not after sw have ruined it.

[richyrich_one]

2 minutes ago, alacant said:

??? The m48 connection works fine. It just needs a m48 to camera ring. Screw it home, it sits square and avoids the dark corners on the light frames.

This in relation to the FUFMPCC adapter, are you using one?

[alacant]

19 minutes ago, richyrich_one said:

are you using one?

Dunno. The methods I've tried are:

1. mpcc - Baader t2 adaptor - t2 ring - camera

2. mpcc - m48 ring - camera

At both 55 and 53mm.

The only one I could get working without xs vignetting was method 2. HTH.

 

[mAnKiNd]

There seems to be many M54x1mm male to T2 adapters on sale, but I have only found the Lacerta adapter provides an M54x1mm to M48x0.75mm female thread, but that adapter sounds like it has issues with its rotating functionality. Baader makes these adapters but the M54 side has a 0.75mm pitch (for filters) not the 1mm needed for the Synta drawtube.

Perhaps the FLO bespoke adapter service is still in effect and people can order a straight-up M54x1mm male to M48x0.75mm female adapter (with no rotation functionality like the Lacerta adapter) for using M48 threaded CC's on synta focusers, like the one on the 130PDS. There should be enough market for this i presume, considering synta scopes are so widespread in the imaging world, and of which many imagers use M48 threaded CC's.

Edited May 5, 2017 by mAnKiNd

[richyrich_one]

2 minutes ago, alacant said:

Dunno.

You cannot use the M48 connection of the MPCC with this and use an M48 t-ring, the thread is too short. If the GPU has a longer thread(I don't have one but sounds like it does) then it will protrude through the FUFMPCC enough to connect one.

You are right about the SW incarnation. Why did they do that?! Does that extra shoulder unscrew?

So get this one:

http://www.teleskop-express.de/shop/product_info.php/language/en/info/p6706_TS-Optics-GPU-Superflat-2--Komakorrektor-fuer-Newton-Teleskope--4-elementig.html

And not this one:

http://www.teleskop-express.de/shop/product_info.php/language/en/info/p5836_GPU-Aplanatic-Koma-Korrector-4-element-fuer-Newton-Teleskope-ab-f-4.html

[richyrich_one]

2 minutes ago, mAnKiNd said:

There seems to be many M54x1mm male to T2 adapters on sale, but I have only found the Lacerta adapter provides an M54x1mm to M48x0.75mm female thread, but that adapter sounds like it has issues with its rotating functionality. Baader makes these adapters but the M54 side has a 0.75mm pitch (for filters) not the 1mm needed for the Synta drawtube.

Perhaps the FLO bespoke adapter service is still in effect and people can order a straight-up M54x1mm male to M48x0.75mm female adapter (with no rotation functionality like the Lacerta adapter) for using M48 threaded CC's on synta focusers, like the one on the 130PDS. There should be enough market for this i presume, considering synta scopes are so widespread in the imaging world, and of which many imagers use M48 threaded CC's.

How would rotate the camera for framing the object?

[mAnKiNd]

The ring on the SW equivalent of the GPU CC is an M50 thread and should screw off.

[alacant]

3 minutes ago, richyrich_one said:

Does that extra shoulder unscrew?

No. Get the proper Hungarian variety. HTH.

[richyrich_one]

1 minute ago, mAnKiNd said:

The ring on the SW equivalent of the GPU CC is an M50 thread and should screw off.

 

Just now, alacant said:

No. Get the proper Hungarian variety. HTH.

Which is it?

[mAnKiNd]

3 minutes ago, richyrich_one said:

How would rotate the camera for framing the object?

You are correct, in that you wouldn't be able to rotate the camera and live with it's final position, which I do with my short refractor as I prefer the threaded connection to clamping but with rotation ability. 

[mAnKiNd]

http://www.teleskop-express.de/shop/product_info.php/language/en/info/p5836_GPU-Aplanatic-Koma-Korrector-4-element-fuer-Newton-Teleskope-ab-f-4.html

 

In the technical specifications for this product, it specifies an M50 connection behind the M48 thread, see it in the picture. The SW seems to have a ring in place on the M50 thread, so I presume it unscrews..

 

EDIT: i meant this product, which is essentially the same as the above without the ring. http://www.teleskop-express.de/shop/product_info.php/info/p6706_TS-Optics-GPU-superflat-2--Coma-Correktor-for-Newtonian-telescopes--4-element.html

Edited May 5, 2017 by mAnKiNd