GSO 2" 42mm Camera Projection Eyepiece, excellent value at the moment.
Hi all,
I ordered a 2" 42mm Superview CPL from Andrews on Friday and received it today. I will definitely also get a 2" 32mm Superview CPL when they are back in stock. They are so versatile, well made and optics are great quality
Even if they are used as an eyepiece (not CPL) they represent great value and quality for the price for such a versatile eyepiece. Not trying to give Andrew's a plug here but....if your after a super cheap, excellent quality 2" eyepiece that has 68 degree AFOV and a free T1 Thread adapter to connect a camera (with seperate T-ring), take it from me, you should definitely check'em out. Normally ,the T1 thread adapter alone cost you what the eyepiece costs. You will not be disappointed once you see the price!
If you are after a bargain though, check'em out!
It absolutely ceases to amaze me how Andrew's keep servicing the Amateur Astronomy community with such great service, quality stuff and most excellent prices!
Have you had some experience with this camera projection eyepiece that you could share with us? I bought the 1.25" versions of these eyepieces and have tried a few photos with it during the Venus transit and also yesterday, but am having a few issues - which I am working on.
Have you had some experience with this camera projection eyepiece that you could share with us? I bought the 1.25" versions of these eyepieces and have tried a few photos with it during the Venus transit and also yesterday, but am having a few issues - which I am working on.
-John
Hi John,
I am looking at buying one of the 2" 30mm ones. What issues were you having?
I was having some issues with floaters and I think some off-axis blurring. Due to projection, it seems to highlight anything in the focal plane, i.e. dust, lint etc. Once I checked the eyepieces, and everything else - most of these floaters went away. This issue can be a problem with any eyepiece but is magnified due to projection.
The other issue - which I haven't resolved yet, is that maybe my optical axis doesn't seem to be lining up. I.e. the sun is in focus except for one side - see here in the photo, during the Venus transit - Venus seems out of focus on the outer edge. Alternatively it could be that everything is not in focus, which is also likely. Since then I haven't done very much with these eyepieces.
[Edit] Sorry that was the wrong photo, and different eyepiece. Here is the one I meant, of the sun a couple of days later. See how sharp one side of the sun is?
-John
Last edited by John0z; 20-02-2013 at 02:52 PM.
Reason: Wrong photo
I was using the CPL with a Maksutov - I wasn't sure if this was an issue, but the other photo was using a WO DCL-28 eyepiece and a different camera, so most likely the Maksutov is not the problem - but it could have been dust on the optical train somewhere.
The other thing is that some diagonals - the eyepiece holder is a little larger than the eyepiece, so tightening the lock screw pushes the eyepiece to one side or the other - this may be part of my problem. I might have another look at it - now that you have reminded me.
-John
P.S. I also have a WO 2" 52mm FL projection eyepiece - this one is huge and has a very long eye relief - so much that I need to be about an inch above it to view comfortably - but no problem for a DSLR camera.
Sorry to jump in here guys but this has grabbed my attention. As far as connecting a camera to this eyepiece, how is it different to using a Barlow? At the moment I'm just connecting my camera straight to the scope but want to get higher magnification. Would this be the way to go?
Location: '34 South' Young Hilltops LGA, Australia
Posts: 1,446
Projection eyepiece issues
I can make a few suggestions to some of the issues raised here. I don't own one and have nothing to do with Andrews other than being a past satisfied customer.
John Oz,
Your one side out of focus issue could simply be due to camera sag because the focuser isn't strong enough to hold the eyepiece straight with the weight of the camera. The the focal plane isn't orthogonal to the optical axis - nothing to do with the eyepiece itself or the Mak optics.
Jason,
Quote:
This sounds like an ad.......
I've owned the 2" 42mm and found it to be so visually poor that it's not worth using on anything at f/6 or faster.
They may be ok on slower ratio scopes of course.
Cheers,
Jason.
I agree it sounded like an ad. i don't understand why would you want to use a camera projection eyepiece for visual obs? Wide field eyepieces for faster newts are generally expensive. This is probably a simple Plossl design or similar.
Chif wrote
Quote:
Sorry to jump in here guys but this has grabbed my attention. As far as connecting a camera to this eyepiece, how is it different to using a Barlow? At the moment I'm just connecting my camera straight to the scope but want to get higher magnification. Would this be the way to go?
A projection eyepiece allows afocal projection or eyepiece projection. Afocal projection is where a camera like a compact camera with lens attached is put up to the eyepiece.
A projection eyepiece allows afocal projection or eyepiece projection. Afocal projection is where a camera like a compact camera with lens attached is put up to the eyepiece.
Joe Cali
Thanks Joe. So are there devices that hold the camera in front of the eyepiece or do people just make their own/ hold it by hand? Why did astro guy mention a t-ring?
Location: '34 South' Young Hilltops LGA, Australia
Posts: 1,446
Quote:
Originally Posted by Chif
Thanks Joe. So are there devices that hold the camera in front of the eyepiece or do people just make their own/ hold it by hand? Why did astro guy mention a t-ring?
Before DSLR prices dropped about 8 years ago, amateur astronomers were using compact digital cameras with fixed lenses like this. I never did any myself but I think they used to (maybe still do) sell T thread to filter thread adapters. You can also use these eyepieces for regular eyepiece projection. The eyepiece projection method can make it possible to project an image from an instrument with insufficient back focus for prime focus or use with a barlow or teleconverter.
For pictures of the Moon, it is possible to do afocal hand held. I recall taking some images of Venus this way a long time ago. Anything fainter would be difficult.
I have one of the 32mm one but have never got it working. The last post suggests I might have it wrong, I have been using it with a T-mount to DSLR without the camera lens. Is this wrong? I have never seen a T-thread to filter thread adapter.
Location: '34 South' Young Hilltops LGA, Australia
Posts: 1,446
Quote:
Originally Posted by rogerco
I have one of the 32mm one but have never got it working. The last post suggests I might have it wrong, I have been using it with a T-mount to DSLR without the camera lens. Is this wrong? I have never seen a T-thread to filter thread adapter.
Roger
I don't think you have the optical arrangement wrong. Eyepiece projection however requires the eyepiece to be much closer to the objective than afocal.
For afocal projection you just infinity focus the eyepiece for your eye then infinity focus the camera lens and the focus will be pretty close.
But the eyepiece need to be further in for eyepiece projection so you probably don't have sufficient back focus or maybe need a longer projection distance (a macro type extension tube between the T mount and the camera or a bit of both. The longer the projection distance, the less the distance inside the focus. The shorter the projection distance the further inside the focus. With a T-ring and DLSR camera, your projection distance isn't very big so you need greater backfocus. If the scope is a newt and doesn't have more back focus, all you can do is increase the projection distance - see if you can borrow a set of macro extension tubes.
Yes, I thought it might be either camera sag is causing my eyepiece to move out of optical alignment, or perhaps the lock screw is pushing the eyepiece to one side.
I am going to make a T thread to filter adapter so that I can put it on my Sony Nex5 lens, or even another adapter to use a lighter camera.
