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Camera Recommendations for new Scope?

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#1 SeattleStarGazer

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Posted 09 February 2018 - 07:13 PM

Hi all, I’m now the proud owner of a CFF 250 Classical Cassegrain. This is 25cm f/15 3750 fl that I’d plan to use primarily for planets, and just in time for Mars. I’m looking for camera recommendations, also recommendations for extenders.

 

thanks

 

Seattle StarGazer



#2 Tom Glenn

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Posted 09 February 2018 - 07:30 PM

Typical recommendations from ZWO (which many folks use) will be ASI224mc if you want color, or ASI290mm if you want mono.  I've been using ASI224mc on a C9.25 Edge HD and have liked it a lot.  Very fast, low read noise.  Overall a very excellent camera, but the field of view is small.  Not a problem for planets, can be a problem for the moon if you get interested in that. ASI 290 has similar field of view but smaller pixels.  Seems to be an excellent camera from the results you'll find around these forums. 

 

Your scope has an interesting focal ratio, being native at F/15.  For planets, if seeing is good, you will want to be sampling at approximately 5x the pixel size for your focal ratio.  So this would be F/19 for the ASI224 and F/15 for the ASI290.  It's not important that these numbers be exact, but if you are close, you will be getting maximum information available.  It just so happens that you'd have perfect sampling for the ASI290 with your scope.  You wouldn't need to use any barlow lens at all.  With the ASI224, you'd be under sampling slightly on nights of good seeing, and theoretically would want a 1.3x barlow, which because it's not a standard size is not as easy to come by.  1.5x Barlow would be fine.  A 2x could work if seeing is excellent but you would be oversampled beyond what is usually recommended, which won't really hurt the image by itself but what will happen is that the image will become needlessly dimmer and you will have to adjust exposure and this could negatively affect your frame rate. 



#3 Sunspot

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Posted 09 February 2018 - 08:06 PM

I am anxious how you like the CFF. I have a Mewlon (Takahashi) 250 which is F/12. Similar scopes.



#4 SeattleStarGazer

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Posted 09 February 2018 - 08:16 PM

So far here in Seattle’s perpetual gray I’ve had 1 night with it mostly spent collimating. I did easily find a small planetary that I couldn’t see in a 5" APO!

 

I am anxious how you like the CFF. I have a Mewlon (Takahashi) 250 which is F/12. Similar scopes.



#5 RedLionNJ

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Posted 10 February 2018 - 11:34 AM

At f/15, either of the two 290-based sensors should be close to ideal:

 

If you want OSC, I'd go with the ZWO ASI290MC - with an IR-cut filter should suffice.

 

If you're ok with a motorized filter wheel (and filters), then the ZWO ASI290MM ought to do the trick.

 

I'm not familiar with the focusing mechanism on the CFF - if the default focusing mechanism involves moving any of the mirrors, then I'd also want a motorized Crayford-style focuser. You just don't appreciate how fine a focus control you need until you're trying to achieve fine focus at planetary imaging scales. All the more so if you go the MM route and need to switch filters which may not be perfectly parfocal.

 

And if you are indeed at a latitude comparable to Seattle, an ADC is another almost-mandatory accessory for good performance on Mars this summer.

 

Good luck and welcome to the obsession called planetary imaging.


Edited by RedLionNJ, 10 February 2018 - 11:35 AM.

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#6 SeattleStarGazer

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Posted 10 February 2018 - 01:35 PM

Thanks RedLion. I do have a ZWO filter wheel I use with my ASI 1600 with a set of Astrodon filters that should work with the ASI290MM. I have never done RGB planetary, primarily because of the Jupiter rotation issues and Jupiter makes up 95% of planetary images I  have done. But I would be willing to give it a try.

 

No, the CFF250 has fixed mirrors, one of the benefits I liked. It comes with a Starlight Instruments focuser. I just need to get the HSM motor for it, I already have the FocusBoss controller. I will look into the ADC, the furthest south I normally get is Central Oregon.

 

Thanks again

 

Wayne

 

At f/15, either of the two 290-based sensors should be close to ideal:

 

If you want OSC, I'd go with the ZWO ASI290MC - with an IR-cut filter should suffice.

 

If you're ok with a motorized filter wheel (and filters), then the ZWO ASI290MM ought to do the trick.

 

I'm not familiar with the focusing mechanism on the CFF - if the default focusing mechanism involves moving any of the mirrors, then I'd also want a motorized Crayford-style focuser. You just don't appreciate how fine a focus control you need until you're trying to achieve fine focus at planetary imaging scales. All the more so if you go the MM route and need to switch filters which may not be perfectly parfocal.

 

And if you are indeed at a latitude comparable to Seattle, an ADC is another almost-mandatory accessory for good performance on Mars this summer.

 

Good luck and welcome to the obsession called planetary imagin



#7 troyt

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Posted 11 February 2018 - 12:23 AM

Congratulations on the new scope and looking forward to your images  waytogo.gif



#8 djhanson

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Posted 14 February 2018 - 09:07 AM

Hi SSG, congrats on the purchase!  I have a CFF350 f/17 cass myself.  I use a ZWO ASI290MM and ASI224MC with it and they work great.  I use a Pierro Astro ADC nearly most of the time as well.

 

Although you may wish to barlow for planetary imaging, one of the benefits of the CFF's are the long f/15 to f/20 FL's, which put you past the minimum FL for most ADC's (~f/15) and also more near the correct FL for optimal sampling. (~5x of camera pixel size)  cheers, DJ




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