dslr and Barlow

[Bungielad]

Hi all,

Just a quick question, do you use a Barlow lense when imaging with a dslr in your scope?

Cheers,

Bungielad.

[Leveye]

Absolutely!

[Alien 13]

Not for me i only have a std skywatcher barlow and the results are horrific with my scope.

Alan

[Mr TamiyaCowboy]

Yes and no. 

Some telescopes will need the use of a barlow to gain focus ( its the telescope being made for eyeball viewing no for digital imaging)

on my skywatcher 114-1 ( 1000mm ), i do not need to use a barlow.

But i do have a multifuntion canon DSLR adapter. 

the nose cap unscrews and fits a T-mount screw thread, this allows the camera to be used in the focuser alone.

but the adapter also has an extended body, inside there is space to slip a 25mm eyepiece, when the whole unit is screwed

to the t-mount it makes the camera into A-focal mode. 

for planets and the likes i will use the barlow lens fitted to fill the camera frame.

when i want to image galaxys like M31 i will use Prime focus and loose the barlow,

otherwise M31 would NOT fit on the cameras sensor. 

with webcams i only use a barlow for saturn and jupiter, the moon and sun with solar filtering you find they fill the image frame twice/three times over.

[Andy Milner]

Nice reply. That answers a few questions for me too!

Sent from my iPhone using Tapatalk

[Bungielad]

Thanks for the info, bit of a mix bag so I guess it's a bit of trial and error.

Bungielad.

[Alien 13]

It is a useful technique its a bit easier with slower scopes that do not require a high quality barlow but its allways worth trying.

Alan

[Cornelius Varley]

I tend to use a 2x TV Powermate when Lunar imaging (taken with Samsung NX100)

http://stargazerslounge.com/gallery/image/11807-appenines-2012-03-31-skymax-150-samsung-nx100-at-prime-focus-2x-powermate/

[carastro]

Don't use a Barlow for long exposure deep sky imaging as this makes the focal ratio too slow.

Carole

[Langy]

I do with my DSLR but I can really only use my DSLR in PF for lunar anything else is beyond my scope.

[glowingturnip]

I have done for small targets like the ring nebula and dumbbell nebula, but it does show up my guiding somewhat, amplifies those eggy stars.

I think the received wisdom is that you're not supposed to as it introduces more optics and makes the f ratio slower, but then I don't have a longer focal length scope to use instead.

[Russe]

Not usually. But you can. In a Skywatcher 130p or 130m you won't achieve focus without a Barlow. In a 130pds you do.

The problem with the Barlow is that it stops down your f/ratio - meaning it'll take longer to acquire your data in comparison to w/o a Barlow.

[Bungielad]

Could I just unscrew the lense and use the tube to reach focus in my scope?

Bungielad.

[Cornelius Varley]

Could I just unscrew the lense and use the tube to reach focus in my scope?

Bungielad.

The usual problem is that the point of focus is too close to the telescope for the camera  to reach focus with the barlow. By adding a barlow lens the point of focus is pushed outwards far enough to allow the camera to focus. By just adding an extension tube the camera is moved farther away from the point of focus, making things worse.

[happy-kat]

On my heritage if I use a Barlow I can't focus, to focus I have to drop the trusses down about an inch.