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Good scope for photos in Galaxy Season...?

PhotoGav

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PhotoGav

PhotoGav

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So, as the season of galaxies turns towards us, what would people recommend as a good scope to use on an HEQ5 mount to get in close to photograph them? I currently use an 80ed with guide camera through the 9x50 finder. I would ideally carry on with that guiding system to keep weight down. My camera is a DSLR. Budget wise, I don't have a specific limit in mind, but as a relative newbie, I don't want to go top of the range, however, I would rather spend a bit more than entry level and get something that will give really decent results.

So far I have looked at the Skywatcher Reflectors, but ideally would go for something that wouldn't give diffraction spikes and have since looked at the Skywatcher Explorer 190 MN DS-Pro. Looks great, but is it right focal length wise and it is beginning to get costly...?

Any thoughts and advice greatly received.

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GuillermoBarrancos

GuillermoBarrancos

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As you already have the 80ED Pro. You can continue to use it for the larger galaxies.

For the small fainter galaxies, People tend to use RC or SCT Scopes due to their longer focal length.

RC Scopes create diffraction spikes, so then the other option is an SCT. As you got a HEQ5 Pro, you can opt to go for a 8inch SCT XLT from Celestron with a 0,63 focal reducer.

But either way, it ain't going to be cheaper if you think the 190 MN is already expensive to you. As an 8inch SCT + focal reducer will end up the same in costs.

PS. The 190 MN is too heavy for the HEQ5 Pro to use for imaging. The recommended use for this scope is on a NEQ6 Pro or similar Mount.

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PhotoGav

PhotoGav

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Interesting reply, thank you. Good info re. The 190MN, I have crossed it off the list. The Celestron looks a good option, especially having seen Sara's latest work with the 9.25... I will investigate further. As for cost - if that's what it takes, then I will just not feed the family for a while longer!!!!!

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swag72

swag72

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I think that the MN190 is a little inbetwix and between for galaxies really with regards it's focal length - I remember a few good galaxy imagers saying that 1.5m is probably the minimum focal length for the smaller galaxies out there.

When I was looking at a scope for galaxy work I asked three people for their opinions on which scope to go for and ................ I got three different answers!! I suppose you need to narrow it down to budget, what your current mount will hold, and any specific things that you either like or dislike about certain scopes. (Eg: diffraction spikes, open design etc)

Good luck - It's a difficult choice to make and one that I agonised over for ages!!

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ollypenrice

ollypenrice

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I'm glad yoyu're not going to try an MN190 on an HEQ5!!

As Sara says, a metre is not really a galaxy FL. You have small pixels though, so that will give good resolution with shorter than ideal FL.

I'd be looking at John's images from his 6 inch RC and wondering how much better you could get from a comparable class of scope! I'll be trying the 8 inch version at some point, in all probability, but haven't done so yet. You need to budget for good collimation tools if you don't have them, I'd say.

I don't like diff spikes either but at long FLs on galaxies you don't fill the chip with spikey stars so I could live with them myself. At short FLs, no.

I'd also look at an 8 inch Edge. If your targets are small galaxies nearly all of them will fit on the chip without the (expensive) reducer. If this is the case there is absolutely no point in using the reducer because it will not speed up the aquisition of galaxy data. You can't increase the number of object photons by reducing the focal length. This is the dreaded F ratio myth. In a nutshell you are limited by the mount to a physically small, light scope and you need focal length so, ipso facto, you'll need to settle down to collecting a lot of data. 

So for me, 8 inch RC or 8 inch Edge, I reckon.

Olly

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PhotoGav

PhotoGav

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Good stuff Olly, thank you. SGL wins again, no 190MN/HEQ5 disasters will be happening in Wiltshire! Celestron is definitely looking the favourite at the moment. Would I be able to guide successfully through a finder? Could I attach the skywatcher 9x50 finder scope to the Celestron? Could I attach a QHY5-II to the Celestron finder scope? So many questions...... So little knowledge on my part at the moment!

Ah... Collimation.... A whole new thread right there!?! Life would be dull if it were all easy though.

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ollypenrice

ollypenrice

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Someone on here does guide an SCT with a finder guider but I wouldn't, myself. I would always use an OAG. (This is how we guide Yves' 14 inch ODK.) You have a bit of a shock when you see the Himalayan guide trace for the first time but you're guiding at the imaging FL.

You need to be aware of how difficult it is to guide at long FLs without a super mount. The fact that you can guide at around 600mm doesn't mean you'll be fine at two metres, alas. It can be done, though, because people do it. The thing is that the long FL brings you fine details but not if guiding error blurs them out again. We see plenty of that, too.

As you say, we don't do it because it's easy!!

Olly

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swag72

swag72

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I didn't even bother trying to guide with my finder guider with the C9.25. I use an OAG with it and keep the finder guider perfectly aligned on the Tak. This way I have worked out that there is minimal changeover requirements when I swap the scopes on and off (The Lodestar guide camera being the only thing that needs swapping between the two - Imaging cam obviously) - I don't know what guide camera you are using, but you do need a sensitive one - To this end I bought a Lodestar.

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GuillermoBarrancos

GuillermoBarrancos

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The OP is delighted with all your input - thank you. This certainly doesn't seem to be an easy one to solve cheaply. I will continue to look and listen.

Just go for this: https://www.teleskop-express.de/shop/product_info.php/info/p3257_OFFER--Celestron-Edge-HD-800---203-2000mm-Flatfield-Cassegrain-OTA.html

You know you want to. :p

PS. Quartermass. He already has the 80 ED Scope. The just 400mm increase in focal length is neglible on the small galaxies like for example M82.

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PhotoGav

PhotoGav

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Quatermass - great reply, thank you. I was almost at the point of putting in my last post that perhaps a Skywatcher Explorer 200 or 250 PDS would be a good first move into the art of galaxy photography and just not worry about spikes. Your post confirms that this really is a viable route. Cheers.

What would be recommended in the way of coma corrector / flattener for those scopes?

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GuillermoBarrancos

GuillermoBarrancos

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If you're considering a 200PDS then why not consider a SW Quattro :

http://www.firstlightoptics.com/reflectors/skywatcher-quattro-f4-imaging-newtonian.html

Again. Pointless. These are fantastic astrographs. But they are widefield Scopes With only 800mm focal length.

He already has an 80ED refractor.

So why add another widefield scope to the setup?

An 8inch SCT would be a better addition. He could even manage a 9.25 SCT (if he uses OAG) on the HEQ5, but it will be pushing it.

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ollypenrice

ollypenrice

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This was such an intractable problem for me that I never did buy a long FL scope, but then Yves appeared with the 14 inch and the Mesu for me to play with. I really don't know what I would buy for myself for long FL stuff. Probably an Edge for the easy collimation and closed tube. I'm not a fan of open tubes from the maintenance point of view but if you enjoy tinkering then great. (I have so much of it to do at the best of times that I'm not looking for more!)

Olly

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PhotoGav

PhotoGav

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If only the sky had more nice widefield cloudy stuff to photograph through Feb / March / April then I wouldn't even be looking I don't think! Go on, give me a long long list of all the objects I've not realised are available...!

Things certainly seem to really be pointing at the 8" EdgeHD - looks very tasty.

Back to guiding - if using an OAG, would the QHY5-II be sensitive enough?

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