sgazer

I completely disagree.   It's not specialist at all.  Long exposure bulb mode has existed since the very earliest days of photography.  It's always been one of the most fundamental things a camera does.  It is not unreasonable to expect it to work in the same simple straightforward way that Bulb mode has done for over a century.

Mark

Bulb mode does work

It's a very alarmist title for what is basically an inconvenience!

It can actually be deactivated by setting the camera to shoot 3 or 5 images in succession, then it doesn't do the darks.

Yes, it would be nice to be able to turn it off in the menus, especially as the a6000 is able to. But at least if you do use it, it means the darks are taken at the same temp as the lights, although it does double the imaging period.

No its not how they produce such low noise images, the sensor is the same as the a6000 and nikon d3300 and is rated by DxOMark as the lowest noise APS-C sensor available.

The camera is simply superb for daytime photography and the image quality far surpasses my canon 1000d despite a 23mp sensor. In fact the high resolution sensor makes it perfect for use with shorter focal length lenses (as opposed to a scope) because the image can be cropped more readily. The low noise, even at iso1600 and 3200, is amazing.

Add to that it's about the size of a compact camera, makes it an awesome bit of kit.

if they were trying to match a batch of correctors to a batch of mirrors and try to set the best orientation of the correctors, how many combinations would that need for each scope, could be thousands (if they had a batch of 1000 correctors and tried rotating each by 10 degrees, it could be 36000 attempts to find the best match for a scope). If they did do that, it would have to be automated. If they figure the mirror to match the corrector, presumably, they have some measuring system to check the inaccuracies of the corrector, then a mirror blank is automatically ground down to match it, prior to silvering.

Personally, I'm dubious about whether they are matched, because the time and costs involved could be immense. How much variability do they get with the correctors and how much do corrector errors contribute to a poor image compared with mirror errors?

wow, I've never seen anything like it. You must have gone to immense effort to create that. Are you a machinist, did you make all the parts yourself? I'm amazed!

thank you Bob and Ralph.

thank you blueastra, another twist in the serial numbers there.

It has 'Celestron C8' written on the secondary holder, near the adjustment screws, I think that's what you mean.

The main corrector corrector lens cover has the knob in the middle with the plastic bit that unclips, but no writing on it.

Mine's a white one! Well it's been repainted, I believe it was orange before, hence it's either pre-1980 or post 2006 according to this link, if it's accurate.

Celestron - Wikipedia, the free encyclopedia

it has a smooth back, not the ribbed one show in the pic in the link.

It has the knob on the dust cover, with the detachable plastic centre bit (I have no idea why it detaches).

Following the serial numbers, it would appear to be more likely post 2006, but then it would seem strange to have repainted if it was less than 3-4 years old. Also, the corrector seems completely clear ie. no visible coatings. I think the info in the Wiki link may not be accurate regarding the post 2006 orange colour.

I'm attempting to date my Celestron C8 and have been drawing up a list of serial numbers and manufacturing years off the internet. I've read that Celestron can't help and the serial numbers themselves don't translate to much, but I was hoping that if I can collect enough serial numbers, I can find the one closest to mine to get a rough year of manufacture. Currently, I have the numbers below.

I would greatly appreciate it if you could spend a minute adding your serial number and year of manufacture to this thread, particularly if it's close to mine, then I will collate them all into a table. The serial number typically appears to be on the front of the secondary, perhaps under the removable cap if it has one. Many thanks in advance.

Serial year

4936 1973

176337 1977

219214 1975

339705 1975

804081 1977

808735 1979

811938 1981

815888 1982

928774 ? - mine