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Ags

Heritage 100p

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I am currently using an ASI178MM together with an ST80 for EEA, and it works quite well but I am bothered by the need to filter out light (blue, UV, IR) to get a decent image quality on my mono chip. So it is making me think about a small all-mirror system.

I am happy with the 400mm focal length of the ST80, so the F4 Heritage 100p has caught my eye. The only issue is - will I be able to get it to focus as the sensor must be about 3cm further out than the focal plane of an eyepiece?

I also wonder if it is collimateable?

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If the sensor needs to be further out then it shouldn't be a huge problem - it's when it needs to go further in than the focusser allows that the problems start. If it won't reach focus a T2 extension tube should get you the extra distance you need.

How big is the chip on that camera? Coma will be pretty significant at f4, but won't affect objects in the centre.

Billy.

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No, I am saying the sensor is further out than the field stop of an eyepiece, so the focusser would sadly need to be further in.

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Oh, that's not so good. Not having one of these scopes I don't know if it would reach focus, but it does sound like quite a bit of extra travel. I suppose the other option might be to move the mirror up the tube a little.

Billy.

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A lower profile focusser would also do the trick I think...

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I think there is a long thread on here on using the 100p for EAA

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Looks like it would work! Definitely something to think about...

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Posted (edited)
On 11/07/2019 at 11:33, Ags said:

I am currently using an ASI178MM together with an ST80 for EEA, and it works quite well but I am bothered by the need to filter out light (blue, UV, IR) to get a decent image quality on my mono chip. So it is making me think about a small all-mirror system.

I am happy with the 400mm focal length of the ST80, so the F4 Heritage 100p has caught my eye. The only issue is - will I be able to get it to focus as the sensor must be about 3cm further out than the focal plane of an eyepiece?

I also wonder if it is collimateable?

Hi Ags, these CMOS type cameras work well with the 100p, check out my Tak60 vs 100P comparison using a ASI120mc :) 

 

 

Edited by Lockie
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Well, I feel a balanced scope collection should include one Newt, one Cat and one Frac...

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@Lockie Had a look at the photos of your ASI-100p combination and it looks very classy! It makes me really want one too.

In terms of light gathering, I am not too sure that it would be a big win over the ST80. Assuming 91% reflectivity on the two mirror surfaces, that loses 9mm of aperture, and probably another 5mm is lost via the central obstruction, leading to light gathering of around 86mm aperture for the Newt. But it would focus all light at the same plane, and would have far less field curvature.

I actually get diffraction spikes with the ST80 (from the lens spacers?), of course they would be somewhat stronger with the Newt.

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31 minutes ago, Ags said:

@Lockie Had a look at the photos of your ASI-100p combination and it looks very classy! It makes me really want one too.

In terms of light gathering, I am not too sure that it would be a big win over the ST80. Assuming 91% reflectivity on the two mirror surfaces, that loses 9mm of aperture, and probably another 5mm is lost via the central obstruction, leading to light gathering of around 86mm aperture for the Newt. But it would focus all light at the same plane, and would have far less field curvature.

I actually get diffraction spikes with the ST80 (from the lens spacers?), of course they would be somewhat stronger with the Newt.

Hi Ags, I think the lack of CA alone makes it a better choice than the ST80. Not that I have the image any more but I took some shots of M42 with the 100p and there was zero star bloat. 

I nickname the 100p f/4 the mini Skywatcher Quattro :) 

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Posted (edited)

@Lockie If you have a spare moment, can you pop it on a scale to see how much the OTA weighs?

Edited by Ags

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