DSLR / 130pds connection

[Simon Dunsmore]

Hi Folks, 

I just received my new shiny 130pds yey! 

Up until now I've been using a Skywatcher 72ED and attached my dslr via a field flattener. Question, what is the best way to attach the dslr to the 130pds? I've got two options so far please see pictures. 1. Use the field flattener from the 72ED or 2. T adapter screwed into eyepiece holder. Thanks for your help. 

 

Cheers 

Simon 

[david_taurus83]

You won't achieve focus with the flattener and it's designed for correcting a refractors field curvature. Coma correctors are used for Newtonians and the lens element is located in the nosepiece enabling you to have correct back spacing while keeping the camera close to the focuser.

[fozzybear]

8 minutes ago, david_taurus83 said:

You won't achieve focus with the flattener and it's designed for correcting a refractors field curvature. Coma correctors are used for Newtonians and the lens element is located in the nosepiece enabling you to have correct back spacing while keeping the camera close to the focuser.

yep agree with David you will need a  Baader Mpcc  or and OVL or SW equiv sorry it hurts the purse.. . 

[Simon Dunsmore]

13 minutes ago, fozzybear said:

yep agree with David you will need a  Baader Mpcc  or and OVL or SW equiv sorry it hurts the purse.. . 

Thanks for your help. Would I be able to obtain focus using the t adapter attached to the eyepiece holder. I appreciate the comma corrector is a necessary expense but is it absolutely necessary? Clutching at straws here

[fozzybear]

2 minutes ago, Simon Dunsmore said:

Thanks for your help. Would I be able to obtain focus using the t adapter attached to the eyepiece holder. I appreciate the comma corrector is a necessary expense but is it absolutely necessary? Clutching at straws here

strange artefacts if not using the CC at the edges of the images but for visual nada... and yes 55mm I've never used well yet to try my OVL FF on my ED72 you've got nothing to try it in the 130pds as the same back focus 55mm as per a CC so give it a try you have nothing to loose.

[fozzybear]

4 minutes ago, fozzybear said:

strange artefacts if not using the CC at the edges of the images but for visual nada... and yes 55mm I've never used well yet to try my OVL FF on my ED72 you've got nothing to try it in the 130pds as the same back focus 55mm as per a CC so give it a try you have nothing to loose.

no not at all the stars in the image without the CC will be elongated at the extremities of the image

[fozzybear]

15 minutes ago, Simon Dunsmore said:

Thanks for your help. Would I be able to obtain focus using the t adapter attached to the eyepiece holder. I appreciate the comma corrector is a necessary expense but is it absolutely necessary? Clutching at straws here

stars in the periphery will be affected  ie outer edges if that helps also depends if you can get focus

Edited June 10, 2020 by fozzybear

[alacant]

Hi

If it will reach focus, try with your field flattener. It may go some way to correct the coma. Or go glassless with -can't tell if your second shot already has- one of these.

HTH

 

Edited June 10, 2020 by alacant

[Simon Dunsmore]

1 minute ago, alacant said:

Hi

Try with your field flattener first. It should go some way to correct the coma. Or go glassless with one of these.

HTH

 

Hi, 

Thanks for this. I'm concerned about obtaining focus. I'll definitely try the FF first. Can I ask what the benefit of the glass less item would be, is this needed to obtain focus? 

I have actually saved some pennies for a Skywatcher CC and T adapter, but don't want to spend the money if a coma corrector isn't really needed. 

I've read quite a few threads on here about how people have added comma correctors but can't seem to establish if it's essential for focus or just comma correction. Just how bad is the coma (sorry that was a lot of questions) 

[alacant]

2 minutes ago, Simon Dunsmore said:

needed to obtain focus? 

Hi. It replaces the field flattener but with far less optical path and in so doing guarantees focus.

4 minutes ago, Simon Dunsmore said:

coma corrector isn't really needed. 

Only you can decide. Many of us can't cope with coma. Others struggle to see it. If you're lucky, you may fall into the latter category!

 

[Simon Dunsmore]

10 hours ago, alacant said:

Hi

If it will reach focus, try with your field flattener. It may go some way to correct the coma. Or go glassless with -can't tell if your second shot already has- one of these.

HTH

 

Hi Alacant, 

Thanks so much for your assistance. I've ordered one of the glass less adapters and I'll give it a try first. I'm assuming that it just drops into the 2" eyepiece adapter? 

Hopefully, as you say, I won't notice the coma and save myself some cash 😊

Thanks again 

Simon 

[alacant]

2 hours ago, Simon Dunsmore said:

it just drops into the 2" eyepiece adapter? 

Hi. Yes.

Screw the threaded end of the adapter into your t2 ring and attach the bayonet to your camera. Now introduce the other end of the adapter into the ds focuser and tighten the thumb screws whilst keeping the camera pushed up against the focuser tube to keep it as square as possible.

Actually, once you've screwed it into your t-ring, it will become obvious what to do.

2 hours ago, Simon Dunsmore said:

Hopefully, as you say, I won't notice the coma

Here's hoping:)

Edited June 11, 2020 by alacant