Imaging with the 130pds

[Uranium235]

Just spent the night tinkering with this to remove the stars.... very tedious work indeed!

[simmo39]

A quick last shot for 2015, hope you like.

[JimFR]

A quick last shot for 2015, hope you like.

Bubble nebula! Prime focus?

[simmo39]

Bubble nebula! Prime focus?

Hi, yep. Canon 600d (modded)

[toxic]

very nice image Simmo

[JimFR]

Hi, yep. Canon 600d (modded)

Very nice. Just need some clear nights!

[Viv]

Loving this thread & some incredible images !!

Hope to add to it soon

[Thalestris24]

Not posted on here in a while tho not had many imaging opportunities anyway...

Did this M3 on NYE and last night, 4 x 360s and 6 x 480s with the 130pds/qhy8l and mostly processed in Startools. I never seem to quite get nice pin sharp stars... Also, there are some odd lighter patches at the bottom of the image (and the top!). If I try and get rid of the I start losing the fainter stars... Anyway, I think this counts as a work in progress

Resized to about 50%:

And a crop resized to 60%:

Louise

Edited January 8, 2016 by Thalestris24

[simmo39]

M1 from last night, v pleased with this one.

[JimFR]

M1 from last night, v pleased with this one.

Glad you got use of the clear skies... both my camera and my drives' batteries were flat! Got a good gawp at M42/3 in though...

[Herbby]

Wow just wow all of you the images in this thread are pure inspiration to me and I only to be a quarter as good one day.

I have patiently read through all of the 35 pages today as I have been trying to start astrophotography with just my dslr and tripod and I am looking for a scope to progress onto when the time is right and to be honest looked at the 130 due to cost sorry to go off topic and not sure were to post this question but can this scope work well with a dslr as from what I have read here the majority of images are all via cdd camera's and we'll out of my budget.

Sorry again if this the wrong place and please keep this thread going into have absolutely loved reading it today and viewing your images.

Darrell.

[halli]

Nice crab Simmo - good size for 130pds - was it cropped ? What was the exposure length and number of lights ?

I also managed to make use of a full clear sky the other night without the moon !   I am still getting used to using a mono CCD with filters and LRGB processing so I thought I would select a cluster in this case the beehive M44 where there were some different colours in the stars.

Still mastering flats with the 383l so there were none !

6x1000s L

6x600 r,g and B

I have just got a Skywatcher Coma Corrector but haven't fitted it yet to the 130pds so there is a little coma in the cornerss of the attached even though it was cropped to get rid of the majority.

I would appreciate if any one has any advice about fitting the CC with the 383l.

I hope you like the cluster (at least the right colours appear to have emerged ...........)

Any advice/comment on the processing welcome !

Ian

[Uranium235]

When taking flats with the 130, use a large lightsource (ie: a big monitor running notepad or Al's virtual lightbox), back it away by about 10 inches and diffuse the light with some copier paper - that will help prevent stray light from bypassing the primary/secondary and going straight up the drawtube.

In regard to the CC, try to stay as close to the 55mm spacing as possible as going over that will increase the reduction factor, but increase coma in the far corners. It also helps to have three thumbscrews fitted rather than the standard two, that will help prevent the CC from flapping about in the drawtube under the combined weight of your imaging train (a CC, FW and 383 is a bit heafty).

[Uranium235]

Wow just wow all of you the images in this thread are pure inspiration to me and I only to be a quarter as good one day.

I have patiently read through all of the 35 pages today as I have been trying to start astrophotography with just my dslr and tripod and I am looking for a scope to progress onto when the time is right and to be honest looked at the 130 due to cost sorry to go off topic and not sure were to post this question but can this scope work well with a dslr as from what I have read here the majority of images are all via cdd camera's and we'll out of my budget.

Sorry again if this the wrong place and please keep this thread going into have absolutely loved reading it today and viewing your images.

Darrell.

Should work well enough with a DSLR, its a fairly quick telescope so its quite a good match. Actually, it would be a good deal less complicated becuase the weight of your average DSLR isnt putting much strain on the focuser.

[simmo39]

Nice crab Simmo - good size for 130pds - was it cropped ? What was the exposure length and number of lights ?

Hi Ian,  yep its cropped, total exposure is just under an hour, 10 x 600  at 800.( modded 600d ) with a master bias and master dark. I havent carcked the lights thing yet.

Btw, v nice image too. must try for that myself.

Edited January 10, 2016 by simmo39

[halli]

When taking flats with the 130, use a large lightsource (ie: a big monitor running notepad or Al's virtual lightbox), back it away by about 10 inches and diffuse the light with some copier paper - that will help prevent stray light from bypassing the primary/secondary and going straight up the drawtube.

In regard to the CC, try to stay as close to the 55mm spacing as possible as going over that will increase the reduction factor, but increase coma in the far corners. It also helps to have three thumbscrews fitted rather than the standard two, that will help prevent the CC from flapping about in the drawtube under the combined weight of your imaging train (a CC, FW and 383 is a bit heafty).

Thanks for the advice Rob.  

I have bought an A3 LED display for flats and am experimenting with this.  Because of the shutter on the 383 it means that the right amount of light reduction needs to be made to increase the exposure time -  which is a bit fiddly.  Unfortunately the panel can be dimmed but does not dim enough !  Its a question of diffusing the light enough to get to the right exposure I guess. I am also going to look at the T shirt method outdoors but again its getting the right thickness of material to get a long enough exposure !  Bring back AV DSLR flats anyday !

I believe a figure of 25-30k ADU and above 5s should be achieved  to avoid the shutter affect ?

Wrt the coma corrector yes the drawtube focusser scews arent the best and I thought of replacing the complete unit which holds the screws  as it is difficult to tighten the screws with the filter wheel in situ as it is. Haven't researched this yet though.  

From the Atik site the backfocus for the 383 is quoted as 17mm which I assume is from the chip to the 383 mating interface - I guess this is the distance I add to the EFW thickness and then add the CC internal distance to the lens and then also add a spacer if required to get 55mm     Does this sound about right to you ?

[halli]

Hi Ian,  yep its cropped, total exposure is just under an hour, 10 x 600  at 800.( modded 600d ) with a master bias and master dark. I havent carcked the lights thing yet.

Btw, v nice image too. must try for that myself.

  Thanks.  I will certainly have a go as well myself at M1.       I have a GSO RC8 so probably try that out on it as it has a longer focal length - but good to see its reasonably tolerant to cropping as it is a small object.  

You captured some nice detail  !

[sidelight]

I found 22500 ADU about right for my 383 so that's what I aim for.

Cheers

Ross

Sent from my SM-N9005 using Tapatalk

[halli]

Thanks Ross. I'll try that value out.

[Pompey Monkey]

Thanks for the advice Rob.  

I have bought an A3 LED display for flats and am experimenting with this.  Because of the shutter on the 383 it means that the right amount of light reduction needs to be made to increase the exposure time -  which is a bit fiddly.  Unfortunately the panel can be dimmed but does not dim enough !  Its a question of diffusing the light enough to get to the right exposure I guess. I am also going to look at the T shirt method outdoors but again its getting the right thickness of material to get a long enough exposure !  Bring back AV DSLR flats anyday !

I believe a figure of 25-30k ADU and above 5s should be achieved  to avoid the shutter affect ?

Wrt the coma corrector yes the drawtube focusser scews arent the best and I thought of replacing the complete unit which holds the screws  as it is difficult to tighten the screws with the filter wheel in situ as it is. Haven't researched this yet though.  

From the Atik site the backfocus for the 383 is quoted as 17mm which I assume is from the chip to the 383 mating interface - I guess this is the distance I add to the EFW thickness and then add the CC internal distance to the lens and then also add a spacer if required to get 55mm     Does this sound about right to you ?

I've had good results with ADUs in the range 14,000 to 30,000. I don't think that it's mega-critical as long as you are well out of the noise floor and not saturating the sensor. Flat field corrections in software are multiplictive so, in theory at least, as long as you are not clipped at the black or white ends the corrected results should be the same as long as the sensor is linear. The KAF 8300 is, apparently, quite linear and is used for scientific work.

With regards to the back focus distance, you'll have a fun time sourcing all the spacers that you'll need to get it exact. I found Telescop-Express to be a very useful resource.

The third screw in the eyepiece holder is an absolutely must with the weight of the coma corrector, filter wheel and camera hanging off of the PDS focuser if you want any kind of orthogonality at your chip! I used an M6 allen-head bolt that I have in abundance. There's plenty of metal in the eyepiece holder to take the bolt. Taps and dies are cheap and you just need to find a buddy with a pillar drill (every astronomer should have access to a pillar drill! ). You can see the bolt in this close up:

You might also consider tightening up the focuser a bit too. See here: http://www.teleskop-shop.at/testphotos/w-erbung/Crayford_adjustment_Synta_microfoc.pdf I found that the weight of the imaging gear would slowly unwind the focuser over the evening until I had "corrected" the tension in mine.

[richyrich_one]

Thanks for the advice Rob.  

I have bought an A3 LED display for flats and am experimenting with this.  Because of the shutter on the 383 it means that the right amount of light reduction needs to be made to increase the exposure time -  which is a bit fiddly.  Unfortunately the panel can be dimmed but does not dim enough !  Its a question of diffusing the light enough to get to the right exposure I guess. I am also going to look at the T shirt method outdoors but again its getting the right thickness of material to get a long enough exposure !  Bring back AV DSLR flats anyday !

I believe a figure of 25-30k ADU and above 5s should be achieved  to avoid the shutter affect ?

Is it a 12v LED display? Could you drop the voltage with a dc-dc convertor to lower the brightness further?

[halli]

Is it a 12v LED display? Could you drop the voltage with a dc-dc convertor to lower the brightness further?

Interesting thought Rich yes it is 12V and therefore it is worth trying to reduce the input voltage as you suggest  -  I'll certainly look into that thanks for the idea !

I've had good results with ADUs in the range 14,000 to 30,000. I don't think that it's mega-critical as long as you are well out of the noise floor and not saturating the sensor. Flat field corrections in software are multiplictive so, in theory at least, as long as you are not clipped at the black or white ends the corrected results should be the same as long as the sensor is linear. The KAF 8300 is, apparently, quite linear and is used for scientific work.

With regards to the back focus distance, you'll have a fun time sourcing all the spacers that you'll need to get it exact. I found Telescop-Express to be a very useful resource.

The third screw in the eyepiece holder is an absolutely must with the weight of the coma corrector, filter wheel and camera hanging off of the PDS focuser if you want any kind of orthogonality at your chip! I used an M6 allen-head bolt that I have in abundance. There's plenty of metal in the eyepiece holder to take the bolt. Taps and dies are cheap and you just need to find a buddy with a pillar drill (every astronomer should have access to a pillar drill! ). You can see the bolt in this close up:

focuser.PNG

You might also consider tightening up the focuser a bit too. See here: http://www.teleskop-shop.at/testphotos/w-erbung/Crayford_adjustment_Synta_microfoc.pdf I found that the weight of the imaging gear would slowly unwind the focuser over the evening until I had "corrected" the tension in mine.

Thanks also for your response Paul.  Its good to know that the ADU value isn't so critical !   I have used the SGP flat calibration wizard which finds the exposure for  an ADU value which seems to work quite well.   The fiddly bit is dimming the light source so that the exposure values are high enough for the 383.   

Not sure what I am going to do about the third screw !   I guess I may be able to use a hand drill  - not sure .  Certainly longer bolts are needed in my case as it is difficult tightening them by hand because of the proximity of the filter wheel body.  An Allen head seems to definitely be needed when trying to hold the weight of all the gubbins.  

I was thinking whether there was a brass compression ring adaptor that could be screwed onto the end of the drawtube to replace the current assembly.  The focuser seems ok at the moment if I use the locking screw after focussing,  but thanks for the link  - Im sure that will come useful in the future at some point

Cheers

Ian

Edited January 10, 2016 by halli

[Pompey Monkey]

 An Allen head seems to definitely be needed when trying to hold the weight of all the gubbins.  

I only do it up finger tight! As tempting as it is to use an allen key, the coma corrector is a delicate optical assembly

[Skyline]

Wow just wow all of you the images in this thread are pure inspiration to me and I only to be a quarter as good one day.

I have patiently read through all of the 35 pages today as I have been trying to start astrophotography with just my dslr and tripod and I am looking for a scope to progress onto when the time is right and to be honest looked at the 130 due to cost sorry to go off topic and not sure were to post this question but can this scope work well with a dslr as from what I have read here the majority of images are all via cdd camera's and we'll out of my budget.

Sorry again if this the wrong place and please keep this thread going into have absolutely loved reading it today and viewing your images.

Darrell.

Of course you can use a DSLR with it, the scope is optimised to be used for a DSLR, you'll be surprised what you can achieve with this scope and a DSLR coupled with a coma corrector.

[JimFR]

Of course you can use a DSLR with it, the scope is optimised to be used for a DSLR, you'll be surprised what you can achieve with this scope and a DSLR coupled with a coma corrector.

And a clear night! [emoji16]