200p DSLR focus

[miguel87]

I have minimal expectations for AP.

I am primarily interested in observing but every now and then I like to take a photo.

I have a driven EQ5 with a 200p (f5).

When I pit my DSLR into the focusser with T ring adaptor I can only achieve focus if I also screw the Tal barlow lens (the removable bit you can use for 1.25mag with eyepieces) into the end of the camera adapter.

I'm thinking that essentially I am turning an f5 (good for AP) into something slower just to achieve focus..

Can I avoid this without putting money into AP? It's a road I dont really fancy starting on.

Thanks

[alacant]

Hi

You've probably still got the eyepiece adapter attached. Can you post a photo of the focuser with camera attached?

 

[miguel87]

Will do when I get a chance in a couple of hours. What do you mean about probably having the eyepiece adaptor attached? That's the only way of connecting my camera to the telescope?

Edited April 22, 2020 by miguel87

[scitmon]

You won't achieve focus with standard tube length of the 200p unless you use a barlow.  This is what the 200 P-DS is for: https://www.firstlightoptics.com/reflectors/skywatcher-explorer-200p-ds-ota.html

[miguel87]

12 minutes ago, scitmon said:

You won't achieve focus with standard tube length of the 200p unless you use a barlow.  This is what the 200 P-DS is for: https://www.firstlightoptics.com/reflectors/skywatcher-explorer-200p-ds-ota.html

Thanks. I guess I was lucky that I had the tal barlow then. 

Does it make a difference if I slide the whole barlow on or just use the screw off lens? If so, which is better?

Mike

[alacant]

10 minutes ago, miguel87 said:

Does it make a difference if I slide the whole barlow

Hi. yes. No need to use a Barlow; the quality of your images will be worse. 

Much better to attach the camera directly to the telescope. Unscrew the eyepiece holder first. See here for details, but send a photo anyway. You may have the wrong adapter.

cheers

[Cornelius Varley]

39 minutes ago, miguel87 said:

Will do when I get a chance in a couple of hours. What do you mean about probably having the eyepiece adaptor attached? That's the only way of connecting my camera to the telescope?

This video probably explains it

 

[miguel87]

1 minute ago, alacant said:

Hi. yes. No need to use a Barlow; the quality of your images will be worse. 

Much better to attach the camera directly to the telescope. Unscrew the eyepiece holder first. See here for details, but send a photo anyway. You may have the wrong adapter.

cheers

I think I am not explaining myself well. I have my telescope and camera attached to each other and they work fine with the correct adaptor.

As somebody has informed me, I cant get focus with the camera without using either the tal barlow 2x or the barlow screw off lens 1.25x on it's own.

So now I wonder which of these two options is best to use or if it makes no difference.

[david_taurus83]

The stock focuser is too tall for the camera to focus at the prime length of 1000mm. You need to move the mirror up the tube or fit a low profile focuser.

By using the barlow you are trying to take an image at 2000mm which will be very difficult.

[alacant]

5 minutes ago, david_taurus83 said:

The stock focuser is too tall

Which is why you need to unscrew the  1.25 eyepiece holder first. This then reveals a male t thread which attaches to the t ring of the camera. The camera then focuses fine. No Barlow needed nor recommended.

HTH.

 

Edited April 22, 2020 by alacant

[almcl]

+1 for what Alacant said.  With a T mount to EOS adapter you can easily reach focus on a 200P - although you may want to add a coma corrector when you see the star shapes.

I did it like this:

[miguel87]

Ok people,

Fact 1, you CANNOT focus a 200p with a camera attached because the physical length of the focusser is wrong. Therefore,

Fact 2, I HAVE to use my barlow and I know it works perfectly fine and I have a few good photos. The way I think of it is that the barlow reaches down the focusser and grabs the image to bring it all the way up to the camera sensor.

I just wondered if anybody would recommend having the WHOLE barlow attached and having it slide onto the camera nose piece just like it would a normal eyepiece OR take just the little screw off lens from the barlow and thread it directly into the camera's nose piece thread.

Edited April 22, 2020 by miguel87

[CloudMagnet]

You really dont need a Barlow at all to focus. I have been using my 200p for months with a DSLR and coma corrector and it has about 15mm of focus left over. Just attach the coma corrector to a M48 adapter and then attach that straight on to the DSLR.

[david_taurus83]

18 minutes ago, miguel87 said:

Ok people,

Fact 1, you CANNOT focus a 200p with a camera attached because the physical length of the focusser is wrong. Therefore,

Fact 2, I HAVE to use my barlow and I know it works perfectly fine and I have a few good photos. The way I think of it is that the barlow reaches down the focusser and grabs the image to bring it all the way up to the camera sensor.

I just wondered if anybody would recommend having the WHOLE barlow attached and having it slide onto the camera nose piece just like it would a normal eyepiece OR take just the little screw off lens from the barlow and thread it directly into the camera's nose piece thread.

I'll take your word for it as it's your scope! I had the old blue tube and I had to fit a low profile focuser for my 600D.

A bit confused though, is it the 200p in your profile photo? The one with the dual speed focuser? I thought that these only came on the 200PDS or have you fitted it yourself?

 

[Cornelius Varley]

@miguel87 What type of focuser do have on your 200P. The standard focuser supplied can take either 2" or 1.25" eyepieces depending on which eyepiece adapter is attached. Removing the adapter reveals a t-thread on the other part to allow a DSLR to be connected.. Can you upload a photo of the telescope showing a close up of the focuser so we confirm the type of focuser.

[miguel87]

24 minutes ago, david_taurus83 said:

I'll take your word for it as it's your scope! I had the old blue tube and I had to fit a low profile focuser for my 600D.

A bit confused though, is it the 200p in your profile photo? The one with the dual speed focuser? I thought that these only came on the 200PDS or have you fitted it yourself?

 

Fitted the dual speed Crayford myself.

People saying I dont need a barlow I need a T ring to EOS or something. Why would I buy something I dont have instead of using a barlow that I do have?

Just wanted to know out of my 2 options, not buying any extras, is it better to use whole barlow or half barlow.

Sorry just trying to simplify things 

Edited April 22, 2020 by miguel87

[miguel87]

25 minutes ago, Cornelius Varley said:

@miguel87 What type of focuser do have on your 200P. The standard focuser supplied can take either 2" or 1.25" eyepieces depending on which eyepiece adapter is attached. Removing the adapter reveals a t-thread on the other part to allow a DSLR to be connected.. Can you upload a photo of the telescope showing a close up of the focuser so we confirm the type of 

Which way would you do it...

[Anthony1979]

I just untread the 1.25 eye piece hold and screws the t ring to the piece which goes into the focuser... But i use the 150p

Edited April 22, 2020 by Anthony1979

[david_taurus83]

15 minutes ago, miguel87 said:

Fitted the dual speed Crayford myself.

People saying I dont need a barlow I need a T ring to EOS or something. Why would I buy something I dont have instead of using a barlow that I do have?

Just wanted to know out of my 2 options, not buying any extras, is it better to use whole barlow or half barlow.

Sorry just trying to simplify things 

Because your doubling the focal length and effectively making it f10. What are you trying to take pictures of?

[CraigT82]

Using the Barlow lens on it's own should give you less of a magnification increase than using the whole Barlow.

The further away from a Barlow lens you get the greater the magnification increase. 

[miguel87]

So all these camera t rings are a standard 2 inch thread?

Thus should go straight onto my focusser?

Why do people have issues with focussing a 200p and dslr then?

[miguel87]

2 minutes ago, david_taurus83 said:

Because your doubling the focal length and effectively making it f10. What are you trying to take pictures of?

So you're saying that all 3 methods should be able to achieve focus. And that it will give me 3 different magnifications?

[Cornelius Varley]

1 hour ago, miguel87 said:

Fact 1, you CANNOT focus a 200p with a camera attached because the physical length of the focusser is wrong.

The standard 2"/1.25" does focus with a DSLR, its called a direct DSLR connection

15 minutes ago, miguel87 said:

Fitted the dual speed Crayford myself.

It might have been helpful if you had mentioned that earlier.

1 minute ago, miguel87 said:

So all these camera t rings are a standard 2 inch thread?

Thus should go straight onto my focusser?

Why do people have issues with focussing a 200p and dslr then?

The t-thread is M42x0.75mm. I don't think many do have problems, the standard focuser on the 200P allows a camera to reach focus.

[miguel87]

4 minutes ago, CraigT82 said:

Using the Barlow lens on it's own should give you less of a magnification increase than using the whole Barlow.

The further away from a Barlow lens you get the greater the magnification increase. 

So of I can thread straight onto the focusser that will be my minimum magnification?

Then half barlow

Then full barlow lens will be most zoomed in (highest f number)?

[miguel87]

2 minutes ago, Cornelius Varley said:

The standard 2"/1.25" does focus with a DSLR, its called a direct DSLR connection

It might have been helpful if you had mentioned that earlier.

The t-thread is M42x0.75mm. I don't think many do have problems, the standard focuser on the 200P allows a camera to reach focus.

Not with the standard 1.25 inch focus tube it doesnt. It's quite well discussed on astronomy forums.