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My current astrophotography rig consists of a Canon EOS 600D (Astromodified) and a Tamron 18-400mm F3.5 -6.3 zoom lens mounted directly onto a Celestron AVX mount. It has produced some good results but is limited to relatively shorter exposures due to the lack of guiding and generally makes it difficult to combine images from multiple nights due to the adjustable focal length. I am therefore looking at upgrading or modifying my setup and would be grateful for some advice.  (47x60" exposures ISO1600 with DSLR clip-in Optolong L-eNhance filter - https://www.astrobin.com/574wgj/) My main questions are: 1) Would it be possible at all to attach a guidescope to my current lens? - as far as I can tell the adjustable focal length makes this difficult and I am struggling to find many easy methods of doing this. 2) If I was to look at changing the lens, should I go for fixed zoom lens like a Samyang 135mm F2 or would a small refractor at a similar price point be a better option? Is there anything in particular I should look at? I have been looking at various options for a while and would be interested to hear your thoughts on this! |
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In the past, I have added guide scope to my DSLR&Lens assembly by way of a small aluminum plate placed across the dovetail and put the shoe for the guide scope onto that plate. |
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1) Would it be possible at all to attach a guidescope to my current lens? - as far as I can tell the adjustable focal length makes this difficult and I am struggling to find many easy methods of doing this. 1) Not directly on the lens but dual bar systems are marketed and employed, by myself included. 2) No zoom can beat a properly made prime lens at the same focal length and focal ratio. I doubt you can find a fast refractor at the same price point of that Samyang. Obviously you could sacrifice speed and aperture and get a ~50mm near-apochromat with close the selling price of that lens. But not a lot of them and I wouldn't even think about it but people here like them. |
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| Thank you very much for your advice. I'll look into a dual bar system - are there any in particular that you would recommend? I have an Altair 60mm guidescope that I use with my Celestron C6 SCT - would it work or would it just cause issues with balancing the setup? |
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Thank you very much for your advice. I'll look into a dual bar system - are there any in particular that you would recommend? I have an Altair 60mm guidescope that I use with my Celestron C6 SCT - would it work or would it just cause issues with balancing the setup? What I have and use aren't made anymore but this one should be just right: https://www.geoptik.com/en/prodotto/double-vixeneq-saddle-plate/ The Altair is plenty. I use the same. And the weight shouldn't be an issue. |
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A lot of people use the samyang 135mm. From my own experience, I upgraded to the William Optics zenithstar 61 pretty early on. I also photographed with the 600D a lot and it worked really well. I'm happy that I went for the refractor because it gives you more astrospecific capapbilities. The feather touch focus is awesome, I also have two mounting points on the scope for a guidecope and my Asi air. I mostly keep my Kit assembled, once I've focused it doesn't really change much when I take the kit out the next night. It also matters what you want to photograph. if you want to stay with widefield the samyang might be plenty but if you want to go closer in like my zenithstar with 360mm instead of the 135mm. In my opinion, If you choose to spend money to upgrade your astrophotography kit, I'd go for the refractor and go proper, which is also future proof if you want to upgrade your camera in the future as example. But if your budget isn't there then go for the samyang  |
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| redcat is better than the samyang |
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redcat is better than the samyang Define "better". |
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@andrea tasselli There you go. |
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| Nice. |
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Just kidding. I think a Redcat is higher quality in both optics and construction, it is Petzvel, it looks cooler, is sharper than a lens (even my astronomical guidebook said so), has integrated dew shield and bahtinov mask, has more reach than the lens, and also the first version of the Redcat can be used visually. |
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| Optically, the Samyang is by far superior and is probably the ONLY lens (or refractor) that can be used at f/2 yielding a basically flat field across an APS-C sized field. The Redcat ( I assume you're talking of the 51 here) is just a posh finder. If you want reach slap a 2x extender and you get all the reach you may want from a 67.5mm aperture. |
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andrea tasselli: For someone who's looking to upgrade their kit, either of these options are totally fine. It doesn't help to pixelpeep at such an early stage. You'll be happy with the quality of either of them. As summary, Telescopes just have more Astrophotography features that will help you down the line and make life easy for you, the samyang lens is very widefield but also sharp for what it is. The future proof choice is definitely a refractor telescope with the focal length that suits you (telescopius is a great tool for visualising framing of different focallenths) The budget friendly one is the samyang. |
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This shows a simple way to attach a guide scope to a DSLR. https://youtu.be/ZcxtdD5rQeQ?si=AAQp9P1Z68v5R2yI You would find it difficult to get a ood refractor in the same price range as the Samyang. I have the samyang 135 mm and a sharpstar 61 EDPHII which is 275mm fl.. both are excellent but the sharpstar was a good bit more expensive. |
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I think if you invest the time in ensuring the Samyang is set up well with particular attention to back-focus and alignment of the optical train (i.e. absolutely no tilt, no EoS adapters, etc., just well made 42mm extension pieces and high quality shims) it can work exceptionally well. I use mine at f3.0 with a step-down-ring coupled to an ASI1600MM via 3nm Antlia filters and it produces exceptional quality images. This mosaic image https://www.astrobin.com/y8zs1i/ combines RedCat 51 and Samyang 135 nebula data with stars taken purely with the Samyang and at 1:1 I think the stars are very acceptable. I also use the RedCat 51 with my ASI1600MM and cannot fault it. Being a Petzval backspacing is not an issue. For me the Samyang and the RedCat are "keepers". As an aside I tried two Askar 180 V2 (both bench tested) and both were sent back due to poor star quality; that said there are many excellent Askar 180 images on this forum. I was unlucky - as you can be with any telescope system. You pay your money and you chance your luck! Good luck! |
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Thank you very much for the advice. Seems that a small refractor is probably the best way to go. I'm probably looking for something in the 300ish mm focal length range, I think (I would like to be able to photograph M31, NGC7000, etc without needing to worry about mosaics if I can). I have a C6 SCT which is good for galaxies but struggles a bit with nebulae (and significant vignetting - not sure there's a huge amount I can do about this beyond a camera with a smaller sensor). William Optics ZS61 and the Redcat 51 are both solid contenders, are there any others that I should be considering? |
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My current astrophotography rig consists of a Canon EOS 600D (Astromodified) and a Tamron 18-400mm F3.5 -6.3 zoom lens mounted directly onto a Celestron AVX mount. It has produced some good results but is limited to relatively shorter exposures due to the lack of guiding and generally makes it difficult to combine images from multiple nights due to the adjustable focal length. I am therefore looking at upgrading or modifying my setup and would be grateful for some advice. Hi, 1) You can try attaching a finder holder to the hot shoe of your dslr so you can mount guide scopes: Teleskop-Express: TS-Optics Finder Holder for the hot shoe of DSLR and system cameras This would be a cheap upgrade, because then you could aim for longer exposures, which make your images a lot cleaner(less noise and more signal). Keep in mind that total imaging time always wins, so try to get as many subs as possible. Not 1 or 2 hours, but several. Wonky stars at edges can be dealt with via processing. Your gear has the potential, you have to utilise it 2) A refractor at similar FOV would be always a better and more expensive solution. But you lose the flexibility of the zoom. And your main problem will still persist: to bury the noise of your pictures with sub length and total imaging time. Hope this helps! Regards |
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I'll have a look at the hot shoe attachment. I've seen some comments suggesting that it may not be as sturdy and could cause damage to the camera. Has this been an issue for you? The other options I've seen is either to use an L-bracket and attach the guidescope to the side of it or use a dual-bar system (I'm struggling to work out how I can effectively do this without making my own or spending a lot on a purpose built one). |
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I'll have a look at the hot shoe attachment. I've seen some comments suggesting that it may not be as sturdy and could cause damage to the camera. Has this been an issue for you? I do not have personal experience with this hot shoe adapter unfortunately. But I think it should be possible to mount a mini guidescope safe and secure. In daylight photography much bigger accessories are used in the hot shoe sometimes(led lights, smartphone holders, even external monitors). For me I would simply try it before I jerryrig a L bracket or something similiar. If it does not suite the purpose you can always resell it at 60-70% of the initial value :-) This would feel like the path of least resistance for me, but on the other hand I have two left hands and cannot build things like custom L brackets and such. Regards |
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I found this solution to take deep sky photos with my reflex and AVX mount .. I find it very practical and light. |
