Quote:
Originally Posted by RobF
Would be interested to hear a bit more on your thoughts for this versus high quality lens for widefields Greg. Believe you had fair bit of experience with Pentax medium/large format lenses, which presumably take a bit of work to mount, attach cameras, sort out adaptors, focus.
Even though the Redcat is about $1000 aud, cost of sorting the issues above is probably significant too. Must be advantages in convenience, use of standard astro threads/mountings for dovetails and cameras etc?
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The Redcat is very well made and beautiful to look at. The focuser on mine is slightly stiff but this a good thing as I did read an early model had some shift at different angles and the solution was to tighten the focus lock ring.
I think it will loosen over time and I can still focus it precisely manually.
Stars are quite good to the corners with some images showing some weaker stars in the corners. I am also currently using it at home mounted on a FLI Microline 16 and I had to pack out one corner to get all 4 corners with round stars which I am getting.
I also got a Teleskop Services tilt/tip adapter M48 size that should simply screw onto the end of the Redcat and I can adjust it one night for my full frame cameras to get them as perfect as I can. Probably take me an hour. This adapter I think cost around AUD$80 perhaps less.
The cameras are mounted on T rings and the Sony adapter is a larger one and also very well made. William Optics are now offering a copper T ring adapter for Canon and I'll probably get that to see if that corrects the tilt or not. T rings were about $15 each but the Sony one was more like $40.
I have been using a Pentax 300mm 645 F4 EDIF at about F5.2 with a step down ring. It gives good results, also had to be packed out to get round stars to the corners. Almost the same as the Redcat.
The Redcat though is noticeably sharper and stars are tighter. The Pentax is no slouch though and cost me around AUD$650 or less.
The Redcat also offers a custom diagonal for visual. I would think 51mm is a tad small for visual but maybe its not.
Overall I prefer the Redcat's 250mm focal length as its long enough for many wide objects on a full frame camera but shorter than 300mm. Not a big deal though.
I really did like some downloads I got on Vela using the Redcat. I'll have to process that little mosaic.
The cost of the Redcat is more like $1200 and with the exchange rate falling more like $1300 so you'd have to want to do widefield for that.
Keep in mind its much the same optical design as a Tak FSQ - Petsval.
Not a lot of those around besides the FSQ and the TV NP scopes.
Greg.