badhex Posted September 27, 2022 Share Posted September 27, 2022 (edited) Hello all, As mentioned in the postie thread, I seem to have developed reverse aperture fever. I was lucky enough to be on holiday for around three weeks recently, which was not specifically astro focused but included some darker skies. I took my ZS73 travel kit which is a lovely compact setup and weighs about 12 kg total, and fits in one cabin friendly backpack, however I only really had the opportunity for about four sessions. Although it's certainly very manageable, it's still quite a lot of stuff to take just for a few nights, especially when it's more of a holiday that happens to have darker skies, vs going somewhere with dark skies for astronomy purposes. With this in mind, I spent some time thinking about how one might put together and even smaller, lighter setup for these situations. Something small enough not to take up my whole hand luggage allowance, or even better, can be safely put into hold luggage without concern. So, onto the specific criteria: Scope size, performance, and cost 50mm is probably the smallest you'd want to go. 60mm would be ideal, but as the existing travel kit already contains a 73mm I don't think I'd save much space/weight by going with a 60mm, so 50mm seems like the next step down. With such a small objective, obviously high quality optics are needed to squeeze as much performance as possible out of every mm. Borg's fluorite options and modular nature would work well here, but is too costly for such a small and specific use scope, and would rule out putting it into hold luggage for me. I already own a TS 50mm RACI with 1.25“ fitting, which is okay at being a finder but suffers badly from both field curvature and at higher powers, CA. This brought me to the EvoGuide 50ED with its FPL53 doublet objective, (reasonably) low cost and decent performance - a small scope which I've always admired but not had a good reason to purchase. As this scope was not designed to use a diagonal, some trickery would be necessary to deal with short in-focus. It's pretty fast at F4.8 (242mm FL), so perhaps not all EPs would be compatible, and let's face it this scope will never be a planet killer, but after reading a large number of threads and reviews and specifications here and elsewhere, I realised I could probably make it work. So, I bought the EvoGuide, along with a Baader T2 prism diagonal (miniscule 33mm light path), and will combine it with a Baader ultra-low profile EP holder that I already own (10mm light path). This will screw directly onto the back of the scope, and takes up a total of 43mm which is 6mm less than the supplied extension plus the Baader low profile EP holder (49mm) in straight through mode. Eyepieces As this is meant to be a lightweight kit, I will perhaps need to resist the urge to take my premium EPs which all weigh 350-450g each, so I'm hoping to use some of my existing B-team EPs which are significantly lighter. I do have the APM Superzoom 7.7-15.4mm but it needs a lot of in-focus in 1.25“ mode so I suspect it will not come to focus. I really like the BST 5mm (48x), and my old, but well loved, Meade HD60 9mm (27x) also fits the use case quite well. At lower powers, it will be very hard not to take my Morpheus 17.5mm (14x) because I absolutely love the views through it in every scope I've used it with, but again to save weight I think I will need to stick with an 18mm BST (13x). I may not even need this focal length, as there is not a huge difference between this and the lowest power/max field) The one area where I probably have to take an A-team EP is the APM 24mm UFF (10x) because I don't have anything else as light at that focal length. I do own a MaxVision 24mm SWA which could be decloaked, but I probably won't save that much weight and the APM is just a better EP, so I feel that this is a good compromise for max field of view (6.5°!). I'm also hoping that the UFF will cope better with the field curvature inherent to such a fast scope. I will need to do some testing to determine how well these selections work, and whether I might be able to employ a Powermate for higher powers. I have BST 3.2mm, but I've never found the views to be good through it in multiple scopes, so will try it but probably give it a miss. Mount and tripod I already own a Gitzo Traveller Series 2 which is great, and the logic choice for weight saving/simplicity is probably the AZT6 which again I already own. The problem is that I've never really got on with that mount. It's either too loose, or too sticky, but I will definitely do some more testing once I have everything in hand. Another choice would be the Borg single-arm fork mount, however these are not so cheap. More to come on this. Storage I have found a camera case which look like it will be plenty big enough for everything except the tripod, so that's also on its way. Progress Whilst I'm waiting for the diagonal I have tested a few EPs on Jupiter last night in straight through mode, and they all come to focus with a bit to spare, so I should not have any issues there. I'm happy to say that despite the neckache I was really surprised at how sharp the views were. Banding on Jupiter was clearly visible using the Morpheus 4.5mm and BST 5mm and I'm pretty sure I'd have been able to pick out the GRS had it been visible at that time. The skies were very hazy with intermittent clouds, so I had no opportunity to observe anything at lower powers, but the higher power views really surpassed my expectations! If you've made it this far, thanks for reading! I will update this thread (with pictures) as and when there are more developments. Edited September 28, 2022 by badhex 6 Link to comment Share on other sites More sharing options...
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