Using the zwo 224mc with the 4x powermate

[JokubasJar]

So basically after doing some calculations I found that the 4x powermate is perfecf for my needs. It is a 2” powermate but it comes with an adaptor in the front for 1,25” eyepieces and such. The zwo 224mc comes with a detachable 1,25” nosepiece. But I could also buy a t ring adaptor that would allow me to attach the camera directly. My question is would there be a difference between attaching the camera with the nose piece and 1,25” adaptor, or attaching the camera without a nose piece and a 2” t ring adaptor?

[barbulo]

I don’t think there will be any difference with such a small sensor in terms of vignetting. 
I’ve used it without the 1,25” adapter and directly to the 2” eyepiece holder. Never used a T-ring adaptor. 

[vlaiv]

5 hours ago, JokubasJar said:

So basically after doing some calculations I found that the 4x powermate is perfecf for my needs. It is a 2” powermate but it comes with an adaptor in the front for 1,25” eyepieces and such. The zwo 224mc comes with a detachable 1,25” nosepiece. But I could also buy a t ring adaptor that would allow me to attach the camera directly. My question is would there be a difference between attaching the camera with the nose piece and 1,25” adaptor, or attaching the camera without a nose piece and a 2” t ring adaptor?

I must express my doubt in your need for x4 powermate for ASI224. If you need x4 powermate then it appears that your scope is F/3.75 or faster?

In any case, with barlow lens amplifiers, amplification factor depends on distance of sensor to lens and removing 1.25" nosepiece and going for T2 will vary that distance and change magnification.

Powermates and other telecentric amplifiers should be immune to this - and should offer same amplification regardless of the distance, but that is not always the case. Luckily I think that Televue publishes data on their powermates and amplification factor depending on distance.

Let me see if I can find that for you. See this page:

https://www.televue.com/engine/TV3b_page.asp?id=53&Tab=_app

and in particular this graph:

It looks like x4 powermate is quite uniform as far as amplification goes (unlike their x5 model), but it does increase with distance, and in fact with 0mm distance and below around 20mm it is less than x4.

Interestingly enough x2.5 powermate has negative slope and decreases magnification with distance - not something I would expect, but telecentrics are "special" in this regard as you can see.