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It’s not the scope it’s…….


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….my eyes! Or should I say my eye.

Let me explain. I’ve been using my 16” dob for the first few times this week, and whilst I never expected it to be top optical quality, I’ve been disappointed by the star shapes and edge performance.

It’s an f4.2 scope, and I have a Paracorr Type 2 fitted, correctly adjusted for the 31mm Nagler I’ve been using, but still things were nowhere near as sharp as I expected them to be. In addition, the scope was showing signs of astigmatism.

I had wondered about how the mirror was secured. Rather than clips it has pads which press against the edges of the mirror, so I wondered if these were causing problems. I have relaxed them now so that the sling is taking the weight, hopefully that removes a potential problem but I’m sure further investigation will be needed.

I’m left eye dominant and always observe with that eye. I prefer the views through my fracs with that eye, but definitely not with the dob. So, eventually, and I’m not sure why, I tried my right eye. What a difference. The stars are pin point out to the edge and the astigmatism is gone!

I’ve had some wonderful views this evening and am really looking forward to getting much more use out of the scope.

Having had Mrs Stu then myself sit on my glasses (🤪) I need a new pair so will specifically ask them to check for this, and may get some contacts to observe with.

Above all I’m just glad that the scope is not a duffer! I’m guessing the larger exit pupils of the 16” aperture are showing up the problem much more than in my fracs?

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