Excellent and invaluable content.👌

Looks like you're reading my mind...you answered so many of my questions on a specific topic in astronomy .. astrophotography. Thank you!

Very nice exploration thanks will be interested in seeing the relationship of pixel size and focus length

@SKYST0RY

2 ай бұрын

It is coming. I am sure you know it doesn't relate to focal length but does relate to many other important considerations, such as efficiency catching photons, sampling effects, fine resolution and effectiveness in various seeing conditions.

Cannot wait for the next video about pixel size of the sensor... hope it will help me choose what camera I should get for my 12" LX200 SCT with 3048mm of Focal Length.

@SKYST0RY

2 ай бұрын

The next five weeks videos are already made and uploaded, so I can't post a video on pixel size till after that. But I took the liberty of calculating out your pixel size requirements. You need an exceptional camera for an aperture and FL that large. Minimum 10 µm and preferably 11 - 12 for the most versatility from ok to excellent seeing. Of course, over sampling isn't that big a deal anymore, so you could get away with smaller with good processing. You can run the calculations yourself at astronomy[dot]tools. Just look up the CCD Suitability calculator. It's how I settled on the Ares-M for my C8 SCT.

Nice Video😊 Thinking it further: the image circle produced by the telescope is a very important factor, because focal length is always calculated on fullframe and for that also the f-ratio. Thats why i dont like the 'magic' 8" RASA. It only supports micro4/3 sensors or barely APS-C. So to get the full view of its 400mm focal length, you have to do a 2 by 2 mosaic. Other refractor do the field in a single shot. So a F4 refractor with a much smaller aperture is already gathering more light than the magic RASA 8", that basically becomes F4.5. The crop factor of the camera needs to be applied to both focal length (it doesn't change the focal length in real, but the field of view on your monitor) and f-ratio. That RASA loses 75% of its light capturing capability in a huge uncorrected dark-cut area.

@SKYST0RY

2 ай бұрын

I just went and reread your post, and think I misunderstood you. I agree: I also don't really care for the RASA. I don't like the idea of attaching a camera to the optical glass fixture, or running a cable along the optical glass, and you also bring some other very good reasons not to favor it. As you said: Even if the RASA gives you F2, if its FOV is wasted on a small sensor camera enough that you have to shoot a mosaic, then you are not really saving time as compared to a wide FOV refractor with an F ratio of about 4. That is a really good point.

@ferdigrafie

2 ай бұрын

@@SKYST0RY Yeah you got my point, sorry if my english is bad. Bringing anything in front of the glass seems also very weird for me. Especially a shiny red camera. I calculated the obstruction (93mm diameter), the 20cm aperture is for real more something like 18cm, so the F2 in the specs given is false, it´s a F2.2 (not counting the mosaic thingy). I was very close to order a RASA8, luckily I changed my mind in time. I would get a RASA11, which is full frame compatible, but it is too expensive and requires a very heavy duty mount (minimum EQ8). It´s insane 20kg without accessories. I just pulled the trigger on a 400mm F2.8 camera lens, that i got for 500€ less than a RASA8. Fullframe of course. I cant wait for first light :) Clear Skies

@SKYST0RY

2 ай бұрын

@@ferdigrafie Your English is fine. I've just been editing all day, so I am kind of mentally worn out at the moment. I really like my Williams Optics 81 mm APO refractor. With the reducer, it's about a F5 and 447 mm FL, but I do plan to get a 203 mm Newton this summer. Probably the Quattro. It's plenty fast and the wide aperture will resolve more fine detail than the 81 mm can. I think the real benefit of the aperture is the resolution. You can really see the resolution when you image a star cluster with a refractor and compare against a reflector.

Great video again, ty

Fantastic! Thx for this video😊could you do one about seeing and how to measure it?Also are megapixels that important?

@SKYST0RY

2 ай бұрын

These are two great topics that I will definitely cover.

@davidemancini7853

2 ай бұрын

@@SKYST0RY Great! Keep up the good work😊👍🔭

This is very useful information to me! Let's say, you use a lower megapixal sensor, cut from the same die as a higher MP sensor. Then cropping the higher MP image on the PC. Is there a difference? Hope this makes sense.

@SKYST0RY

2 ай бұрын

Calculate your MP/area. That tells you density of pixels. If the smaller sensor has the same density of pixels and should portray the same quality of image but less of the area at the focal plane (the field of view). Let me know if that helps.

Yep, all make perfect sense. My plan is to have a rig as light and portable as possible yet still have some reach. I'm using the Star Adventurer 2i which has a weight limit of 11 pounds. In keeping well within that limit, I plan to get a 400 mm scope and pair it to a small sensor planetary camera. Yes the optical train will remain at 400 mm, but the resultant reach due to the crop factor of the camera will be quite significant. Question is, will my little star tracker be up to the task??? Thanks for the great videos, love them!!!

@SKYST0RY

2 ай бұрын

You should be able to keep your weight to maybe 6 pounds with a 60 or 70 mm scope with a filter drawer, EAF and OSC, especially if you go with an uncooled camera like the Uranus-C. It's very light.

@barnaclewatcher4060

2 ай бұрын

@@SKYST0RY That's right and thanks for the reply. The scope / camera combo I'm looking at is the Askar FRA400 (no flattener required) with the ZWO ASI585MC (uncooled). Scope (rings and dovetail), camera, guide scope, guide camera and ASIAIR mini , all come in at 8.7 pounds.

@SKYST0RY

2 ай бұрын

@@barnaclewatcher4060 Might be pushing it a little but I think, given the low FL, you'll be okay. I have no experience at all with the Star Adventurer, though.

@mikehardy8247

2 ай бұрын

I'm using a SW SA GTI. Same payload limit. 360mm Doublet. Asi 533mc pro. Asiair, 120mm GS etc. Works great.

Im thinking of sticking an imx 185 osc on my 420mm fl refractor. Hope i still am after watching your video:(

@SKYST0RY

2 ай бұрын

You can check the specs using the CCD Suitability calculator at astronomy[dot]tools. When I purchase a camera, I tend to select a camera that will over sample a bit since modern tech has made that advantageous.

@jesuschrist2284

2 ай бұрын

@@SKYST0RY yeah thats such a good website. Think i can use it to calculate what my dithering setting should be, too :) i need to look into under/oversampling a lot more before i replace my dslr though. Not sure it will matter too much with my budget gear, but then, im not sure :)

Btw its your fault i want to replace my dslr with an uncooled imx585 based camera

@SKYST0RY

2 ай бұрын

LOL It's a very nice camera. Extraordinary what it can do for the price.