Starting with auto guiding resulted in 100% sub utilization. I could go more than 3 x longer exposure time like before without guiding. So, more focal lenght would be cool 🙂 In other words, I want go to the limit of the Star Adventurer…
Here it is. (Most probably) my last lense 😉 The Canon EF 400mm f/5.6L USM
The 70D and the MGEN Autoguider together have a weight around about 2 kg.
So the absolute maximum for my new telescope or lens would be 3kg. Unfortunately 3kg + 2kg would reach exactly the payload capacity of the SA (5kg).
So I decided that I want stay below 4kg total weight…
It was a hard decision and many hours of comparison.
Here are some thoughts I did:
TS ED 70mm 420mm f/6, 1.7kg
Pro: 420mm f/6, weight ok, cheap
Contra: no flattener… so it’s no longer “cheap”…
TS Imaging Star 70mm 474mm f/6, 2.5kg
Pro: 474mm f/6, cheap, flattener included
I would be almost at the payload limit of the Star Adventurer with the DSLR and Guider…
TS Imaging Star 65mm 420mm f/6.5, 2.8kg
Pro: 420mm f/6.5, very good reviews on the net and very good samples on Astrobin
With it I would definitely reach the payload capacity of the SA…
Takahashi 65mm 355mm f/5.9, 1,3kg
Pro: weight, f/5.9
I currently have a good solution for 280mm with the EF 200mm f/2.8L and the Kenko 1.4x Converter… so 355mm would not be a real benefit…
Canon EF 400mm f/5.6, 1,25kg
Pro: 400mm f/5.6 (!), weight
The Canon 400mm should be usable wide open at f/5.6. This is the best f-value of all scopes I compared 🙂 I think the EF 400mm is a good decision. But this is my last lens…
Lenses with more focal lenght are to expensive for me and the weight would be higher than 2kg.
And anyway, finding objects without a GoTo controller would be very difficult with > 400mm.
In my opinion I’m at the limit of the SA now. But with a wide range of focal lenghts from 24mm to 400mm 🙂
The EF400mm has the perfect weight (total payload for my Star Adventurer now: 3,2kg), the optical quality is very good in various reviews on the net and sample images on Astrobin were fantastic.
Here are 2 shots of M31. 280mm compared to 400mm. Both pics have almost the same resolution. The pictures were taken at my home in Derendingen.
30. Jul. 2016: 280mm f/5.6 ISO1600, 10 x 180″: 30 minutes, 4 darks, 15 bias, 4833 x 3238
6. Aug. 2016: 400mm f/5.6 ISO1600, 14 x 90″: 21 minutes, 4 darks, 15 bias, 4832 x 3235
10. August 2016: Two shootings are over and I’m very satisfied with the 400mm f/5.6L! The image quality is great. Less CA’s than the 200mm f/2.8L 🙂
See all my 400mm images on Astrobin.