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Hi, It's all in the title. I'm thinking of treating myself with a Redcat 51 for christmas this year. I can't find any comparison between the new "-u" model and the previous one. I see some stores have the new model, others the old one but all at the same price. Do I need to be careful with this and make sure I get one over the other ? |
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According to the picture on WO website. A small change in appearance, hidden tilt adapter, everything is same. The fourth to last picture. https://williamoptics.com/redcat-51-ii-u |
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| Also, the new version does not support visual viewing. The D-EP90-125-RC51-SL diagonal will not fit on this new version of the scope. |
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| The picture also states, "Please note that, unlike previous versions of the Redcat telescope, this latest II-U version CANNOT be used visually." |
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Hi, This image from the WO website summarizes it all: https://williamoptics.com/media/catalog/product/cache/bdf99b9adad5f42fb7e1393f4e9a2baa/1/_/1_2.jpg It's a bit unfortunate that the product website of the "new" model includes the instructions of the "old" model with external tilt adapter. That completes the confusion. Maybe you should also double-check with the vendor what they are actually going to send to you if you buy. I had the same question when I ordered my model version 2.5 (!!). My recommendation: get the previous version. You're not missing new features or better optics but still have the option (not matter if ever needed) to attach a visual back. Björn |
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Quinn Groessl: Wow, I don't know how I missed that. |
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Eric, I have used the RedCat 51 years ago and found it to be an excellent telescope, but there new RedCat 71 is a good upgrade. I purchased the 71 months ago and it is quite a better telescope. Much like the 51 in features, just better optics and able to get ore detail on deep sky objects. Of course it's more expensive, so that most like would be something to consider. before you make a purchase. i would recommend that you contact High Point Scientific, they are a good vendors that offer excellent customer service and willing to help you make the correct decision on your purchase. I included a like to there web site with the RedCat scopes for your information. Best of luck in your purchase. Gerry D. https://www.highpointscientific.com/shop?q=cat+red |
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| I have the original RedCat 51 and since the new version has a tilt adaptor, this must be an issue with many users. I wonder then how you would correct tilt (if you had an issue) while on the original model? Any ideas? |
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Wayne Arnold: either through a tilt adapter or some cameras have a tilt mechanism included in the camera flange. |
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Gerry: Unfortunately here in Canada it's more than just more expensive, it's twice the price. If I go with the 71 I will have to stick to my modified 600d which I was going to change for a zwo ASI<some model>MC Pro to go with the 51. |
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Why should the RedCat71 be the "better" telescope? They are two different telescopes, following the very same design principle. They have different aperture and focal length and so the choice should be made on the desired framing and possible image scale. From a design perspective, both should deliver excellent image quality (check the diagrams WO provide). Another question of course is manufacturing quality. If there's a lot of variance in the quality, one might get an excellent 71 over a decent 51. Nevertheless, the opposite may hold as well. However, based on my experience with WO all of their scopes delivered excellent quality. Björn |
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Eric Gagne: I gave a look at your current setup (from your posts) and if you are not planning on changing mount (Star Adventurer GTI), I would not consider the 71 if I was in your shoes. You would be pushing it to the very limit, especially if you decide to add a Guidescope + Camera. The RedCat 51 v2 (or 2.5 if you only care about astrophotography) is a perfectly fine telescope, that pairs very well with the IMX533 (e.g. ASI533) or IMX571 (e.g. ASI 2600) sensors, and is a good match for you mount. I have a very similar setup and even though I only posted one picture here on AstroBin, I have plenty more shots that turned out pretty good. Some may say "wait, you are way undersampled!". To whom I answer: "dither+drizzle". |
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Claudio Parisi:Eric Gagne: Yes I know the gti weight limit is quite low, no more than a 2i and not much more than my SAM but I wanted an affordable goto mount until I have the money for an AM5. For the moment I want 2 things. First, more focal length than the Samyang 135, it is a great length but I want a little more. I know the R51 is still wide field but some targets won't be so small anymore. The 2nd thing is a cooled camera. I really like the dslr but a cooled camera will allow me to take darks at anytime leaving me more time for taking lights when I get a clear sky. |
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Eric Gagne:Claudio Parisi:Eric Gagne: It feels like reading myself a few years ago  The GTI is enough for the RedCat51 (I have it on a 2i with it's superflimsy tripod). It becomes a bit challenging on a windy day but using some weights at the base of the tripod helps quite a bit. The cooled camera is gonna be a game changer, for the reason you mention and many, many others. Don't forget to dither and drizzle x2, and you'll end up with a lot of detail, even at the 250mm focal length of the RedCat. IMHO, you're on a good path! |
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I added autofocus and guiding to my setup recently. I want to try very long exposures, 10 to 15 minutes but with a dslr my total exposition time is cut a lot because I need at least 2 hours just for the darks. Those 10-15 minutes exposures are also why I don't want more than the 51 in terms of length. I don't think more than 250 would work even with guiding and near perfect PA. |
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On a GTI definitely nothing more than 2Kg of OTA. Under what sky are you imaging? Bortle? I don't think you'll need 10-15min of exposure to overcome the read noise of a cooled chip. Probably not even of a 600D if it's cold enough outside. I used a 600D as well for a while and if I'm not mistaken I never needed more than 5min under dark sky. |
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I'm under bortle 6 according to lightpollution.org but I think it's closer to 7. OTA ? |
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Eric Gagne: Optical Tube Assembly... basically it means "telescope only", without brackets, filters, etc. So 2Kg of telescope + whatever else you attach to it, and you get to the weight limit of the GTI. the RedCat51 by itself is 1.8Kg, so you are good to go. In a roughly Bortle 6.8 you are getting ~7 e/px/s (electron per pixel per second) from the sky background, without any filter. I don't recall the read noise of the 600D (it also varies with ISO) but, in general, there are diminishing returns after Read Noise < 10% of Sky Background. At a given point is better to shorten the exposures to avoid satellites, wind vibrations, guiding errors, etc. Losing a 10 or 15 minutes sub is way worse than losing a 2 or 3 minutes one for the reasons above. |
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The 10-15 minutes subs is more of a challenge and an experiment than anything else. I think it's also a great way to develop good habits in setting up. I hope one day I will produce great images but for now my priority is learning and I like taking the time to discover. It's not about the image, it's about the journey. |
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Wayne Arnold: My cat didn't come with a tilt adapter (I think it's a v1.5 or something), but never really needed it. Or rather I never had the courage to measure and adjust tilt  If you want to adjust tilt, you can purchase an adapter separately, to "upgrade" your scope: Image Plane Tilt Adjuster - William Optics This adapter simply replaces the rear part of the early RedCats |
