GalileoCanon

I have a 6mm and 20mm eyepiece and a basic telescope that we found at a yard sale for super cheap, with no extra tracking mounts, etc. I was able to get a great view of the moon, Jupiter, etc... I also bought a Canon T-Mount for $30 for my DSLR and was able to get some great shots of the moon recently. My total investment was under $50 probably.

Thanks again for everything guys. I really appreciate the calculations, links, etc.. I now have an idea how magnified the image will be (about ~ 29X roughly) and how large it will appear in my camera sensor. (1/4 to 1/2 the screen) An update: I got my t-mount and t-ring adapter from B&H a couple days ago. I had to wait until 2:30am for the moon to rise so I could try it out. I first got the moon into focus without the camera attached with no Barlow lens and with my basic 6mm telescope eyepiece. I then connected the camera. (I was happy to see that my t-ring adapter DOES accept a 1.25" eyepiece if needed by the way.) From the start I could see a blurred bright blob of a moon on my camera's screen. When I dialed the focuser closer down, it got a bit more in focus. Then I hit the stop on the focuser and couldn't dial in any closer. SO, as anticipated I will need to buy a Barlow lens so that I can bring the focal plane out to where my camera's sensor can reach it. Will a 2X power Barlow be enough to reach the focal plane with my DSLR sensor or will I need a 3X? I'd like to keep the power as low as possible, so that I don't lose any more brightness than necessary. I want my camera to be able to reach it obviously though. I know they make 1.5x, 2x, 3x etc... Will 1.5x be enough? Is 2X enough?? I will state in advance that I am well aware of the limitations of this power telescope and this setup without an equatorial tracking tripod/mount, etc... My expectations are properly set, so no need to reiterate the limitations of this setup. What power Barlow lens would you guys recommend? Also, now that I know that the t-ring adapter WILL accept a 1.25" eyepiece if needed, can you recommend an eyepiece size that is best for viewing the moon (and maybe the Andromeda Galaxy)? If I use an eyepiece lens will I still need the Barlow lens to reach the focal plane if I don't use the prime viewing setup? Thanks guys!

vlaiv, I also used your calculator site. I used my Canon 1000D camera with the measurements you provided. I did it both with a Barlow lens added to the configuration and without a Barlow lens in the image below. Thanks!!

Cornelius Varley. If that's the case, with my sensor the moon would roughly fill 1/3 horizontally and 1/2 vertically. (7/22 and 7/15) Thanks! Ouroboros, I used your lunar picture from above, made the moon 117% larger to accommodate for my 700mm telescope instead of your 600mm. I saved it in grey scale to show the moon as it will look normally. Then I resized it to the 3888 pixel width of my sensor. The image I attached below should be as near as possible to what I will see I guess. Nice!! Thanks again guys!

Cool! Thanks vlaiv and ouroboros! That really helps! So vlaiv, at 1070 pixels, the moon will fill 41% of my image vertically and 28% of my image horizontally. That really clears things up in extreme detail. Thanks a lot!! Thanks for providing your picture of the moon ouroboros. That also really clears it up. I appreciate the info guys! Thanks!

Good point Stu! Thanks guys! I REALLY appreciate the assistance. I guess this is a new language to me at this point. It's a bit overwhelming at this point. The good news is that I'm a quick learner. When I got a DSLR, all the language was new and overly complicated compared to point and shoots I'd used previously (aperture, ISO, shutter priority, lens zoom measured in millimeters, f-stops, f3.5 vs f22, field of view, EF-S vs EF lens mounts, crop sensors vs full frame, STM, white balance, exposure, polarizers, etc...) That stuff all makes sense to me now. Ouroboros, I have a Canon EOS Rebel XS DSLR. (or 1000D) I checked and it has a 22.2mm X 14.8mm image sensor. It is 3888 X 2592 pixels. My telescope is a Galileo brand 700x76mm reflector. Thanks also for that astronomy too link Stu. That really helped. Also seeing the image you posted of the moon in the camera sensor in my scope really helped clarify things. Thanks!

Thanks Luna-Tic! That helps a lot!! I guess the "proper" semantics for what I was trying to ask in the first place is, how large will the image of the moon look in my pictures compared to how large it looks at 18mm and at 55mm with my camera's kit lens. OR How large will the image look compared to how it looks on my 50mm lens. My camera has a crop sensor. If I'm not mistaken isn't a 50mm lens pretty close to what the naked eye sees? If I hold my camera to my right eye with a 50mm lens isn't that pretty close to what I'd see in size if I looked at the image directly with my left eye? So to filter past all the semantics couldn't we just say that the image that my DSLR sensor will view through the telescope will be magnified about 14x using the prime setup?? (700mm / 50mm = 14x magnification with the telescope in prime setup)

eye roll..... OK, thanks for the "CLARIFICATION"!! LOL!! Clear as mud now! ha-ha! The telescope without an eyepiece lens surely will make the image look larger than if I was standing next to the telescope with my naked eye. YES??? And it will surely make the image on my camera's sensor look larger than if I just took a picture with my camera and a basic 35mm lens for example. YES??? I am just trying to figure out (roughly) how much magnification hooking a DSLR up to a telescope in prime mode will get me, compared to say, using a 35mm lens or a 50mm lens or an 18mm lens for example. Do I simply look at the focal length of the telescope and compare that to any normal DSLR lens' length? So 700mm will be 20x more zoomed in than a 35mm DSLR lens?! (for example)

Hi everyone! I am new to astrophotography so please pardon me if my inquiry is a novice question. I have a Canon EOS DSLR camera. I also have a Galileo brand 700x76mm reflector telescope with 1.25" eyepiece. I just ordered a T-mount for Canon DSLRs and a t-ring 1.25" adapter to slide into my telescope. (from B&H) Those adapter parts will arrive later this week. I will be viewing it in the prime configuration where I will use no eyepiece lens. I may or may not need a Barlow lens in this configuration. (I have been told it depends upon the telescope, whether or not you need a Barlow, so I will buy that later if I end up needing it to reach the telescope's focal plane). My question is: How much magnification will I see from the telescope's mirrors alone with no eyepiece glass and no Barlow lens in between the telescope's focuser and my camera's sensor? What is the magnification that the telescope's mirrors alone create with no eyepiece in the focuser? I know that if I have to drop in a Barlow lens, that will change the magnification depending on the Barlow's power. I was just wondering how large the moon will look compared to what I see with the naked eye. I know that if I was using an eyepiece, I would simply divide the 700mm focal length by the eyepiece size (700mm/20mm= 35x magnification or 700mm /6mm = 117x magnification) etc... Thanks!