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If I buy an alt az?

sirmetin

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sirmetin

sirmetin

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I am looking at the CPC925 and C9.25 GT (CG5 stand), I do want to do imaging at some point and if I get the CPC I would not be able to move the tube. However, I want to do DSOs and I will probably buy a good 4 or 5" APO and a HEQ5 or EQ6. I believe I would be able to do planets on the CPC stand and for the DSOs the APO will be better. So does it matter that I cannot move the tube as the alt az will give my wife faster and more comfortable viewing?

NB at the moment the CPC is just short of £300 more expensive

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nightfisher

nightfisher

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one piece of advice i will give you, as i cant comment on the scopes of your choice, dont have a scope that is under mounted, its far better to have smaller aperture and steady than big scope struggling on a mount that is at its limits, i know this from very recent experience! i recently bought my dream scope and its far to heavy for my mount

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jamespels

jamespels

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nightfisher - if it's the 100rs that's too big, you're right - you don't need a bigger mount. You just need to find somebody who can give it a good home. Funnily enough, I may be able to help you there... :)

sirmetin - I agree with the above comments (the ones that are on topic, anyway!). If you are thinking of imaging, spend the pennies on a good mount and accept a smaller aperture for now. Alternatively, but a dob (very easy alt az meaning you can get a decent scope for not too many pennies); this will keep your wife happy until you decide to invest in a decent equatorial mount (think HEQ5 or equivalent minimum, most people consider an EQ6 about right for most setups) when you can take the OTA off the dob mount and put in on the new one. In the meantime, you can still use the dob for planetary, lunar and even solar imaging with the right filters.

Hope this helps,

J.

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ollypenrice

ollypenrice

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Wedges will convert your fork to equatorial but they don't sing for everybody. I never got on with them (to put it mildly!) but some make them work.

A computer driven fork alt-az is, however, the nicest visual mount of all. It will also do webcam solar system imaging happily enough.

Olly

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nightfisher

nightfisher

Posted
Posted
nightfisher - if it's the 100rs that's too big, you're right - you don't need a bigger mount. You just need to find somebody who can give it a good home. Funnily enough, I may be able to help you there... :)

sirmetin - I agree with the above comments (the ones that are on topic, anyway!). If you are thinking of imaging, spend the pennies on a good mount and accept a smaller aperture for now. Alternatively, but a dob (very easy alt az meaning you can get a decent scope for not too many pennies); this will keep your wife happy until you decide to invest in a decent equatorial mount (think HEQ5 or equivalent minimum, most people consider an EQ6 about right for most setups) when you can take the OTA off the dob mount and put in on the new one. In the meantime, you can still use the dob for planetary, lunar and even solar imaging with the right filters.

Hope this helps,

J.

sorry james, no one is getting my 100rs, its the 200k thats to much for my mount, wish i had seen one before rushing into buying one, they are HUGE and HEAVY

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jamespels

jamespels

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worth a shot!

Yeah, I saw a piccie of the 200 next to a 2M - it is massive! Bring it along to PSP2011, somebody must have something it will sit on properly - you could even try putting it up for sale in the astroboot if it's really too much.

J.

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jamespels

jamespels

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Heading out of my experience now, I'm afraid. The other thread you have running has Brantuk and a few others - they will be able to answer this much better than I can.

That said, a good 5" APO will give excellent results of whatever you point it at... At 5" for the APO it's questionable which will be most manageable though - the frac will be a very long and heavy scope unless you get a short focal ratio (and the shorter the focal ratio, the harder it is to get decent APO performance), the SC will be a lot shorter but much bulkier.

If you are considering an apo, try to get a good look at the TAL 125 R - you simply don't get TAL owners who don't love their scopes and FLO have them on an NEQ6 pro for under a grand at the moment. Celestron are all very well but wait until you see how well TALs are made...

Take a look on the TAL owners' group on here and ask for advice.

J.

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jamespels

jamespels

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If you are considering an apo, try to get a good look at the TAL 125 R - FLO have them on an NEQ6 pro for under a grand at the moment.

Sorry, just realised - the £900 odd is just for the NEQ6 pro -I didn't read the ad properly.

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ollypenrice

ollypenrice

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I can help with some comments on deep sky imaging, perhaps.

Firstly, be sure to get your head around the fact that the longer the focal length used, the better the autoguiding has to be and the better the seeing on the night. Also wind will dash all hope of long FL imaging.

With a focal reducer the 9.25 has quite a long FL and, even with 0.63 reducer flattener, will not give a flat field right across an APS chip. The Edge version will do so. In amateur terms a focally reduced 9.25 has a 'fairly long' FL and will need more attention to guiding than you'd need at a metre or 500mm. You are not in the realms of 'very difficult' autoguiding but you are certainly in the 'be careful' zone (as my colleague used to say!)

If you keep the 9.25 with a focal length of around a metre and a half I'd have thought you'd want an apo of significantly shorter FL to cover different targets. Focal length determines what fits on your chip, as in zoom or wide angle in terrestrial terms. I have a 140mm with FL of 980 and an 85 of FL450 or 328 with reducer.

I may be wrong but I get the feeling that you suspect that you need a large-ish aperture for DS imaging. My own experience is that the smallest of our scopes is the most productive. Here are a couple from the 85mm apo.

http://ollypenrice.smugmug.com/Other/Nebulae-and-clusters/M42CCBOV2010/1100345185_HHd4m-X3.jpg

http://ollypenrice.smugmug.com/Other/Galaxies/M31best-v1/1056334673_daDu7-X3.jpg

Note that, even at FL328mm, M31 only fits on the chip when canted corner to corner. To shoot this in the 140 I'd need to do a 4 panel mosaic and each panel, because of the slower F ratio, would take four times as long. Since the image linked above has 11 hours exposure that would mean a cool 176 hours. Hmmm... hand me the 85mm please!!! What you often see on forums are images taken in big, long FL scopes. Because the imager does not have enough data to beat the noise the image is presented at a reduced size. What's the point in that, though? Why not use a smaller, faster apo and get quality that stands up to full sized presentation. (It is an unalterable law that apos get slower as they get bigger, all things being equal.)

Olly

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ollypenrice

ollypenrice

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Beautiful pics Olly.

As an interested thread reader, with no knowledge of the subject whatsoever, I'd like to vote for the 85 Apo as it gives results like those :)

Ah, but the 140 ain't too bad either...

http://ollypenrice.smugmug.com/Other/Nebulae-and-clusters/trifid-finished/928841121_dugLY-X3.jpg

However, the 9.25 ought to make a cracking job of this target.

Olly

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sirmetin

sirmetin

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Thanks Olly that is really useful information, I went back to the shop today to have a listen to some of the mounts when slewing. For some reason they have the C11 on a CG5 for only £80 more than the C9.25 on a CG5 at £1529 it looks like a bargain but everyone says the mount is at its limit and even for visual may not be great.

So I am back to the 9.25 and it looks like I will use the CPC - it will take a guide scope and apparently on the wedge with PEC it holds tracks as well as the CGEM (in the shop was a customer who does a lot of imaging - forgot to get name ). If I had to put the 9.25 on a stand with guide scope etc would need an EQ yet for the APOs I am looking at the HEQ5 should be fine - can use the difference to get wedge so CPC would be for higher mag DSOs and APO would be wide field with a tracking scope on an HEQ5. I am figuring I will probably do lunar/planets on the CPC as is - get wedge do some DSO all using DSLR on 925, then next year get two scopes a HEQ5 and two cameras and set up a tracked assembly. I am thinking I will buy the CPC before the star party but we will see, cannot run to a CPC 1100 I don't think - was gonna buy wife a 6SE two weeks ago!!

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