Canon 400d compatibility

[oaguatao]

Hi, I'm back with another newbie question

I've done a bit of research in terms of getting a digital SLR for other half. Leaning towards the Canon 400D at the moment. I also bought him SkyWatcher SW680 (200mm) Dobsonian for Christmas a year ago.

How does one take a photo via a telescope? Not a technical question really. We have a manual SLR and would like to upgrade to a digital SLR for everyday photography, travel etc ... but since we have the Dob, is there anything I need to take into consideration if he ever wanted to use a camera with the telescope? I'm really clueless about this so please be gentle.

Also, I have a Tamron 28-200 lens, would that "fit" the Canon 400D?

[Dennis]

Hello,

Gee, the “other half” must be one very happy person to have such gifts lavished upon them!

In terms of the Tamron lens, I understand that in the 35mm film days of old, Tamron used to make generic lenses and then one purchased a specific “Adaptall Mount” that mated the generic Tamron lens with the specific brand of your camera, be it Pentax, Canon, Nikon, Olympus, Minolta, etc.

However, that was in the days when there was relatively little electrical communication between camera and lens, so these “Adaptall Mounts” had mainly mechanical interfaces.

With the new breed of DSLR’s, I think compatibility is more of an issue as they are fully electrical and so if the Tamron lens does physically fit, it may not actually work as the camera may not recognise it.

In my case, I had a swag of lenses from Pentax 35mm film days and they were all compatible with my Pentax *ist DS DSLR although I had to manually set the exposure settings (aperture and shutter speed) as well as manually focus.

I would also be careful, because on the older lenses, a lug or tab was usually mounted on the lens so that the camera body could engage it. A modern DSLR may not take kindly to having this tab or lug poking into its body, especially when the mirror flips up.

Cheers

Dennis

[madwayne (Wayne)]

Hi,

Not sure about an 8" Dob, but I had a 10" Dob and it just did not have enough in foucs for a 400D (even with a low profile focusser), or any DSLR from what I have since read. The only option is to move the mirror up the tube and I am sure one of the more experienced members will give you some details on this.

As far as the 400D goes, excellent camera in my opinion. I have since moved on to a modded 20D (and kept the 400D for terrestrial work) and it also an excellent camera. It might be worth considering waiting for the 450D to be released as it has live view which is extremely handy for focussing the wonders of the night sky.

Good luck with your choices and above all clear skies.

Regards

[kljucd1 (Daniel)]

Hi,

I have the same telescope and I have found the following options are/may be available.

1. Get yourself a T Ring Adapter for a Canon (or whatever brand of camera you end up getting) and use a 2x Barlow. This method will not allow you to see the whole Moon in the field of view, for example, but it is a pretty cheap way to start. Note that if you still have the telescope on a Dobsonian mount then you will only be able to image really bright objects that require exposure times well under 1 second.

2. You will still need the T Ring Adapter, but as I have said, I have the same telescope, and the low profile focuser did work for me. I am not sure if this means it will work on your telescope though. With this option you will be able to see more in the field of view because you will not need the Barlow to bring it to focus. You only really need to go down this path if you want to image less bright objects, such as nebulae, and therefore your telescope will need to be on an EQ mount with tracking.

3. Ditch both of these and use your camera with a tripod, and whatever lens you have that fits the camera but preferably a wider field lens; I have found that the 55mm is pretty good. This allows for large sections of the sky to be imaged at one time and the exposure times vary but 15-20 seconds is what I can manage. If I use a lens at 18mm then I can get 45-60 seconds without star trails!! Keep in mind that if you have/will get an EQ mount with tracking then you can use this method by "piggybacking" on the back of the telescope. You can then use longer focal length lenses that will allow you to get in a bit closer to something specific, such as M42 in Orion.

There is obviously more to the story than this, but you can see that there are different options. From these and other suggestions that will be made you only need to consider what sounds like something you/your partner would like to do and then ask more questions to get the specifics of each option.

Regards

Daniel...