Low power ep for 180pro mak?

[nightfisher]

Im thinking of getting a low power wide field ep for my 180 pro, budget of around £50-70, any suggestions, i have a 32mm gso plossl with a slight optical defect, also im sticking with 1.25 fit

[Mark at Beaufort]

Jules I don't think you are going to get much choice if you keep to the 1.25" format. I would guess that your 32mm plossl has a 50 degree FOV going to a 40mm plossl will reduce this to 40 degrees. EPs like the Hyperions have 68 degree and the Celestron X-Cel is 60 degrees but the max size is going to be a 24/25mm EP.

It might be nice to try a 2" EP before you commit yourself although I think you might need an adapter plus a SCT diagonal. Starting to get expensive!!

Mark

[nightfisher]

With the 180 pro i dont see the point in using 2" diagonal (i have one) as the stub on the rear of the ota only has a hole of around 28mm ish

[John]

Can a focal reducer be used with the 180 Mak ?.

That might be the only way to get a larger field of view and lower power than a 32mm plossl will show, if you stick with the 1.25" format.

[Naemeth]

Very over budget, but how about:

http://www.firstlightoptics.com/baader-planetarium/baader-hyperion-aspheric.html

[nightfisher]

Can a focal reducer be used with the 180 Mak ?.

That might be the only way to get a larger field of view and lower power than a 32mm plossl will show, if you stick with the 1.25" format.

It might be the answer, i have one so might try it next time i have big mak out, even with a 32mm plossl i get x84.375 mag i guess for when i want lower power, wider field i can use the tal with 2" diagonal and my 32mm 2" plossl

[Naemeth]

It might be the answer, i have one so might try it next time i have big mak out, even with a 32mm plossl i get x84.375 mag i guess for when i want lower power, wider field i can use the tal with 2" diagonal and my 32mm 2" plossl

Am I getting it right that the 180 Mak is the F/15 Mak-Cas with 2700mm focal length?

If so, you would probably be better getting the longest focal length of an EP you could have, I've not read anything about these but:

http://www.telescope...epiece_2__.html

There is also a Meade 50mm 2" EP, but at £39, it may exhibit quite a lot of errors... who knows at f/15 though...

http://www.telescopehouse.com/acatalog/Revelation_50mm_Eyepiece_2__.html

[LukeSkywatcher]

Jules I don't think you are going to get much choice if you keep to the 1.25" format. I would guess that your 32mm plossl has a 50 degree FOV going to a 40mm plossl will reduce this to 40 degrees. EPs like the Hyperions have 68 degree and the Celestron X-Cel is 60 degrees but the max size is going to be a 24/25mm EP.

It might be nice to try a 2" EP before you commit yourself although I think you might need an adapter plus a SCT diagonal. Starting to get expensive!!

Mark

I tend to agree. I only use 1.25" and my favourite EP ever was the 32mm GSO. I'm certainly willing to try a 2" EP with my 8"SCT.

Anything above 32mm in a 1.25" format is going to have a very narrow FOV which will make observing feel like you are looking down a narrow cardboard tube (been there done that).

If you insist on sticking with the 1.25" format, then i would say buy a replacement 32mm GSO for the defective one you have. It really is a great EP.

OR

A 30mm Vixen NPL. Its slightly smaller in magnification but its much better in shaprness and contrast then the 32mm GSO.

A lot of people say they dont like the eye relief of the NPL's, but to be honest i dont find it a problem.

[andrew63]

Im thinking of getting a low power wide field ep for my 180 pro, budget of around £50-70, any suggestions, i have a 32mm gso plossl with a slight optical defect, also im sticking with 1.25 fit

I don't think i've ever heard the term low power wide field and mak applied in the same sentence before !

But of course you have that lovely WO 70 to give all the vista you need

andrew

[nightfisher]

I don't think i've ever heard the term low power wide field and mak applied in the same sentence before !

But of course you have that lovely WO 70 to give all the vista you need

andrew

very true on both counts

[Adrian]

If you want more FOV then you need to go 2". I have a 2" back on my gold tube 150 Mak - I used a 38mm panaview straight in the VB for the transit and I didn't notice any narrowing of the FOV. There may be some light loss around the periphery of the FOV, but you still get the full view (as far as I am aware). As a finder, or for framing the view, a little light loss at the edge has no impact (to me).

Also, if the light cone crosses through a focal point and spreads out again, then the illuminated focal plane could be wider than the 28mm rear aperture, if you can position it right... although the baffle tube is pretty narrow, isn't it

Much as I like thinking aloud, I may set up later and try out the Ax 31mm in it

[John]

... I used a 38mm panaview straight in the VB for the transit and I didn't notice any narrowing of the FOV. There may be some light loss around the periphery of the FOV, but you still get the full view (as far as I am aware). As a finder, or for framing the view, a little light loss at the edge has no impact (to me).

Also, if the light cone crosses through a focal point and spreads out again, then the illuminated focal plane could be wider than the 28mm rear aperture, if you can position it right... although the baffle tube is pretty narrow, isn't it

Much as I like thinking aloud, I may set up later and try out the Ax 31mm in it

I think the way vignetting / light cut off works is that the view is dimmed evenly across the field. So you might find the view of a certain faint object brighter through a scope of the same aperture with the same eyepiece, where no vignetting is happening. You would probably need to compare the views side by side to notice this though.

[Stu]

Hi Jules

I am sure there are lots of logical reasons not to use 2" ep's with your scope, same as mine, BUT......all I can say is that I do with my mak, and find they work very well. I often use a 28 mm UWAN, and occasionally the 31t5 and they give good views, with as wide a field of view as you could expect from a scope with such a long f/l. I certainly didn't buy the 31t5 to use in the mak, but I did get the UWAN for it and often use it, if I remember correctly it gives around x150 or so and is very comfortable to use. I don't notice any vignetting, it is probably there but not enough to affect my viewing.

I do have a 41mm panoptic but to be honest, I rarely if ever use that in the mak, just doesn't seem any point.

If it helps, I'll have most of them at PSP if you want to try some.

Stu

[Adrian]

OK.

Using a Skymax 150 with Mak to SCT adaptor and then 2" push fit visual back; Target was the Pleiades; eyepiece was 31mm Celestron Axiom:

Eyepiece straight in the VB: Serious vignetting - AFOV around 50 degrees.

With a 2" diagonal: AFOV appears to be as normal (~80 degrees) however when defocussed the star 'rings' appear clipped on the side nearest the centre of the FOV. This effect starts from around half way out and at the edge of the FOV they are half rings. So there is not full illumination, but there is the wide FOV (not enough to fit the Pleiades in, though).

So, as ever, it depends on what you want. If you want a wider FOV from your skymax then you have to go full 2" fitting and diagonal, but you also have to accept a less than fully illuminated outer field. Or you get a different scope for widefield and forget about going wide with the mak.....

[nightfisher]

OK.

Using a Skymax 150 with Mak to SCT adaptor and then 2" push fit visual back; Target was the Pleiades; eyepiece was 31mm Celestron Axiom:

Eyepiece straight in the VB: Serious vignetting - AFOV around 50 degrees.

With a 2" diagonal: AFOV appears to be as normal (~80 degrees) however when defocussed the star 'rings' appear clipped on the side nearest the centre of the FOV. This effect starts from around half way out and at the edge of the FOV they are half rings. So there is not full illumination, but there is the wide FOV (not enough to fit the Pleiades in, though).

So, as ever, it depends on what you want. If you want a wider FOV from your skymax then you have to go full 2" fitting and diagonal, but you also have to accept a less than fully illuminated outer field. Or you get a different scope for widefield and forget about going wide with the mak.....

Thanks for trying that Adrian, and taking the time to post your findings, maybe i will forget about trying to get wide field with this scope and just stick with the high power planetary work its so good at